START-INFO-DIR-ENTRY
* As: (as).                     The GNU assembler.
END-INFO-DIR-ENTRY

This file documents the GNU Assembler "as".

Copyright (C) 1991, 1992, 1993, 1994 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions.


Using as
Node: Top, Next: Overview, Prev: , Up: (dir)

Using as

This file is a user guide to the GNU assembler as.

* Menu:

Overview	Overview

Invoking	Command-Line Options

Syntax	Syntax

Sections	Sections and Relocation

Symbols	Symbols

Expressions	Expressions

Pseudo Ops	Assembler Directives

Machine Dependencies	Machine Dependent Features

Acknowledgements	Who Did What

Index	Index


Overview
Node: Overview, Next: Invoking, Prev: Top, Up: Top

Overview

Here is a brief summary of how to invoke as.  For details, see Comand-Line Options.

{No Value For "\keep\f1{}AS"} [ -a[dhlns] ] [ -D ] [ -f ] [ --help ]
 [ -I dir ] [ -J ] [ -K ] [ -L ] [ -o objfile ]
 [ -R ] [ --statistics ] [ -v ] [ -version ] [ --version ]
 [ -W ] [ -w ] [ -x ] [ -Z ]
 [ -Av6 | -Av7 | -Av8 | -Asparclite | -bump ]
 [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ]
 [ -b ] [ -no-relax ]
 [ -l ] [ -m68000 | -m68010 | -m68020 | ... ]
 [ -nocpp ] [ -EL ] [ -EB ] [ -G num ]
 [ -mips1 ] [ -mips2 ] [ -mips3 ]
 [ --trap ] [ --break ]
 [ -- | files ... ]

-a[dhlns]

Turn on listings, in any of a variety of ways:

-ad

omit debugging directives

-ah

include high-level source

-al

include assembly

-an

omit forms processing

-as

include symbols

You may combine these options; for example, use '-aln' for assembly listing without forms processing.  By itself, '-a' defaults to '-ahls'--that is, all listings turned on.

-D

Ignored.  This option is accepted for script compatibility with calls to other assemblers.

-f

"fast"--skip whitespace and comment preprocessing (assume source is compiler output).

--help

Print a summary of the command line options and exit.

-I dir

Add directory dir to the search list for .include directives.

-J

Don't warn about signed overflow.

-K

Issue warnings when difference tables altered for long displacements.

-L

Keep (in the symbol table) local symbols, starting with 'L'.

-o objfile

Name the object-file output from as objfile.

-R

Fold the data section into the text section.

--statistics

Print the maximum space (in bytes) and total time (in seconds) used by assembly.

-v

-version

Print the as version.

--version

Print the as version and exit.

-W

Suppress warning messages.

-w

Ignored.

-x

Ignored.

-Z

Generate an object file even after errors.

-- | files ...

Standard input, or source files to assemble.

The following options are available when as is configured for the Intel 80960 processor.

-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC

Specify which variant of the 960 architecture is the target.

-b

Add code to collect statistics about branches taken.

-no-relax

Do not alter compare-and-branch instructions for long displacements; error if necessary.

The following options are available when as is configured for the Motorola 68000 series.

-l

Shorten references to undefined symbols, to one word instead of two.

-m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040

| -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32

Specify what processor in the 68000 family is the target.  The default is normally the 68020, but this can be changed at configuration time.

-m68881 | -m68882 | -mno-68881 | -mno-68882

The target machine does (or does not) have a floating-point coprocessor.  The default is to assume a coprocessor for 68020, 68030, and cpu32.  Although the basic 68000 is not compatible with the 68881, a combination of the two can be specified, since it's possible to do emulation of the coprocessor instructions with the main processor.

-m68851 | -mno-68851

The target machine does (or does not) have a memory-management unit coprocessor.  The default is to assume an MMU for 68020 and up.

The following options are available when as is configured for the SPARC architecture:

-Av6 | -Av7 | -Av8 | -Asparclite

Explicitly select a variant of the SPARC architecture.

-bump

Warn when the assembler switches to another architecture.

The following options are available when as is configured for a MIPS processor.

-G num

This option sets the largest size of an object that can be referenced implicitly with the gp register.  It is only accepted for targets that use ECOFF format, such as a DECstation running Ultrix.  The default value is 8.

-EB

Generate "big endian" format output.

-EL

Generate "little endian" format output.

-mips1

-mips2

-mips3

Generate code for a particular MIPS Instruction Set Architecture level.  '-mips1' corresponds to the R2000 and R3000 processors, '-mips2' to the R6000 processor, and '-mips3' to the R4000 processor.

-nocpp

{No Value For "\li720{}AS"} ignores this option.  It is accepted for compatibility with the native tools.

--trap

--no-trap

--break

--no-break

Control how to deal with multiplication overflow and division by zero.  '--trap' or '--no-break' (which are synonyms) take a trap exception (and only work for Instruction Set Architecture level 2 and higher); '--break' or '--no-trap' (also synonyms, and the default) take a break exception.

* Menu:

Manual	Structure of this Manual

GNU Assembler	as, the GNU Assembler

Object Formats	Object File Formats

Command Line	Command Line

Input Files	Input Files

Object	Output (Object) File

Errors	Error and Warning Messages


Structure of this Manual
Node: Manual, Next: GNU Assembler, Prev: , Up: Overview

Structure of this Manual

This manual is intended to describe what you need to know to use GNU as.  We cover the syntax expected in source files, including notation for symbols, constants, and expressions; the directives that as understands; and of course how to invoke as.

This manual also describes some of the machine-dependent features of various flavors of the assembler.

On the other hand, this manual is not intended as an introduction to programming in assembly language--let alone programming in general!  In a similar vein, we make no attempt to introduce the machine architecture; we do not describe the instruction set, standard mnemonics, registers or addressing modes that are standard to a particular architecture.  You may want to consult the manufacturer's machine architecture manual for this information.


{No Value For "rd{}AS"}, the GNU Assembler
Node: GNU Assembler, Next: Object Formats, Prev: Manual, Up: Overview

as, the GNU Assembler

GNU as is really a family of assemblers.  If you use (or have used) the GNU assembler on one architecture, you should find a fairly similar environment when you use it on another architecture.  Each version has much in common with the others, including object file formats, most assembler directives (often called "pseudo-ops") and assembler syntax.

as is primarily intended to assemble the output of the GNU C compiler gcc for use by the linker ld.  Nevertheless, we've tried to make as assemble correctly everything that other assemblers for the same machine would assemble.  Any exceptions are documented explicitly (see Machine Dependencies).  This doesn't mean as always uses the same syntax as another assembler for the same architecture; for example, we know of several incompatible versions of 680x0 assembly language syntax.

Unlike older assemblers, as is designed to assemble a source program in one pass of the source file.  This has a subtle impact on the ^.org directive (see .org).


Object File Formats
Node: Object Formats, Next: Command Line, Prev: GNU Assembler, Up: Overview

Object File Formats

The GNU assembler can be configured to produce several alternative object file formats.  For the most part, this does not affect how you write assembly language programs; but directives for debugging symbols are typically different in different file formats.  See Symbol Attributes.


Command Line
Node: Command Line, Next: Input Files, Prev: Object Formats, Up: Overview

Command Line

After the program name as, the command line may contain options and file names.  Options may appear in any order, and may be before, after, or between file names.  The order of file names is significant.

'--' (two hyphens) by itself names the standard input file explicitly, as one of the files for as to assemble.

Except for '--' any command line argument that begins with a hyphen ('-') is an option.  Each option changes the behavior of as.  No option changes the way another option works.  An option is a '-' followed by one or more letters; the case of the letter is important.   All options are optional.

Some options expect exactly one file name to follow them.  The file name may either immediately follow the option's letter (compatible with older assemblers) or it may be the next command argument (GNU standard).  These two command lines are equivalent:

{No Value For "\keep\f1{}AS"} -o my-object-file.o mumble.s
as -omy-object-file.o mumble.s


Input Files
Node: Input Files, Next: Object, Prev: Command Line, Up: Overview

Input Files

We use the phrase "source program", abbreviated "source", to describe the program input to one run of as.  The program may be in one or more files; how the source is partitioned into files doesn't change the meaning of the source.

The source program is a concatenation of the text in all the files, in the order specified.

Each time you run as it assembles exactly one source program.  The source program is made up of one or more files.  (The standard input is also a file.)

You give as a command line that has zero or more input file names.  The input files are read (from left file name to right).  A command line argument (in any position) that has no special meaning is taken to be an input file name.

If you give as no file names it attempts to read one input file from the as standard input, which is normally your terminal.  You may have to type ctl-D to tell as there is no more program to assemble.

Use '--' if you need to explicitly name the standard input file in your command line.

If the source is empty, as produces a small, empty object file.

Filenames and Line-numbers

There are two ways of locating a line in the input file (or files) and either may be used in reporting error messages.  One way refers to a line number in a physical file; the other refers to a line number in a "logical" file.  See Error and Warning Messages.

"Physical files" are those files named in the command line given to as.

"Logical files" are simply names declared explicitly by assembler directives; they bear no relation to physical files.  Logical file names help error messages reflect the original source file, when as source is itself synthesized from other files.  See .app-file.


Output (Object) File
Node: Object, Next: Errors, Prev: Input Files, Up: Overview

Output (Object) File

Every time you run as it produces an output file, which is your assembly language program translated into numbers.  This file is the object file.  Its default name is a.out, or b.out when as is configured for the Intel 80960.  You can give it another name by using the -o option.  Conventionally, object file names end with '.o'.  The default name is used for historical reasons: older assemblers were capable of assembling self-contained programs directly into a runnable program.  (For some formats, this isn't currently possible, but it can be done for the a.out format.)

The object file is meant for input to the linker ld.  It contains assembled program code, information to help ld integrate the assembled program into a runnable file, and (optionally) symbolic information for the debugger.


Error and Warning Messages
Node: Errors, Next: , Prev: Object, Up: Overview

Error and Warning Messages

as may write warnings and error messages to the standard error file (usually your terminal).  This should not happen when  a compiler runs as automatically.  Warnings report an assumption made so that as could keep assembling a flawed program; errors report a grave problem that stops the assembly.

Warning messages have the format

file_name:NNN:Warning Message Text

(where NNN is a line number).  If a logical file name has been given (see .app-file) it is used for the filename, otherwise the name of the current input file is used.  If a logical line number was given (see .line) then it is used to calculate the number printed, otherwise the actual line in the current source file is printed.  The message text is intended to be self explanatory (in the grand Unix tradition).

Error messages have the format

file_name:NNN:FATAL:Error Message Text

The file name and line number are derived as for warning messages.  The actual message text may be rather less explanatory because many of them aren't supposed to happen.


Command-Line Options
Node: Invoking, Next: Syntax, Prev: Overview, Up: Top

Command-Line Options

This chapter describes command-line options available in all versions of the GNU assembler; see Machine Dependencies, for options specific to particular machine architectures.

If you are invoking as via the GNU C compiler (version 2), you can use the '-Wa' option to pass arguments through to the assembler.  The assembler arguments must be separated from each other (and the '-Wa') by commas.  For example:

gcc -c -g -O -Wa,-alh,-L file.c

emits a listing to standard output with high-level and assembly source.

Usually you do not need to use this '-Wa' mechanism, since many compiler command-line options are automatically passed to the assembler by the compiler.  (You can call the GNU compiler driver with the '-v' option to see precisely what options it passes to each compilation pass, including the assembler.)

* Menu:

a	-a[dhlns] enable listings

D	-D for compatibility

f	-f to work faster

I	-I for .include search path

K	-K for difference tables

L	-L to retain local labels

o	-o to name the object file

R	-R to join data and text sections

statistics	-statistics to see statistics about assembly

v	-v to announce version

W	-W to suppress warnings

Z	-Z to make object file even after errors


Enable Listings: -a[dhlns]
Node: a, Next: D, Prev: , Up: Invoking

Enable Listings: -a[dhlns]

These options enable listing output from the assembler.  By itself, '-a' requests high-level, assembly, and symbols listing.  You can use other letters to select specific options for the list: '-ah' requests a high-level language listing, '-al' requests an output-program assembly listing, and '-as' requests a symbol table listing.  High-level listings require that a compiler debugging option like '-g' be used, and that assembly listings ('-al') be requested also.

Use the '-ad' option to omit debugging directives from the listing.

Once you have specified one of these options, you can further control listing output and its appearance using the directives .list, .nolist, .psize, .eject, .title, and .sbttl.  The '-an' option turns off all forms processing.  If you do not request listing output with one of the '-a' options, the listing-control directives have no effect.

The letters after '-a' may be combined into one option, e.g., '-aln'.


-D
Node: D, Next: f, Prev: a, Up: Invoking

-D

This option has no effect whatsoever, but it is accepted to make it more likely that scripts written for other assemblers also work with as.


Work Faster: -f
Node: f, Next: I, Prev: D, Up: Invoking

Work Faster: -f

'-f' should only be used when assembling programs written by a (trusted) compiler.  '-f' stops the assembler from doing whitespace and comment preprocessing on the input file(s) before assembling them.  See Preprocessing.

Warning: if you use '-f' when the files actually need to be preprocessed (if they contain comments, for example), as does not work correctly.


.include search path: -I path
Node: I, Next: K, Prev: f, Up: Invoking

.include search path: -I path

Use this option to add a path to the list of directories as searches for files specified in .include directives (see .include).  You may use -I as many times as necessary to include a variety of paths.  The current working directory is always searched first; after that, as searches any '-I' directories in the same order as they were specified (left to right) on the command line.


Difference Tables: -K
Node: K, Next: L, Prev: I, Up: Invoking

Difference Tables: -K

as sometimes alters the code emitted for directives of the form '.word sym1-sym2'; see .word.  You can use the '-K' option if you want a warning issued when this is done.


Include Local Labels: -L
Node: L, Next: o, Prev: K, Up: Invoking

Include Local Labels: -L

Labels beginning with 'L' (upper case only) are called "local labels". See Symbol Names.  Normally you do not see such labels when debugging, because they are intended for the use of programs (like compilers) that compose assembler programs, not for your notice.  Normally both as and ld discard such labels, so you do not normally debug with them.

This option tells as to retain those 'L...' symbols in the object file.  Usually if you do this you also tell the linker ld to preserve symbols whose names begin with 'L'.

By default, a local label is any label beginning with 'L', but each target is allowed to redefine the local label prefix.  On the HPPA local labels begin with 'L$'.


Name the Object File: -o
Node: o, Next: R, Prev: L, Up: Invoking

Name the Object File: -o

There is always one object file output when you run as.  By default it has the name 'a.out' (or 'b.out', for Intel 960 targets only).  You use this option (which takes exactly one filename) to give the object file a different name.

Whatever the object file is called, as overwrites any existing file of the same name.


Join Data and Text Sections: -R
Node: R, Next: statistics, Prev: o, Up: Invoking

Join Data and Text Sections: -R

-R tells as to write the object file as if all data-section data lives in the text section.  This is only done at the very last moment:  your binary data are the same, but data section parts are relocated differently.  The data section part of your object file is zero bytes long because all its bytes are appended to the text section.  (See Sections and Relocation.)

When you specify -R it would be possible to generate shorter address displacements (because we do not have to cross between text and data section).  We refrain from doing this simply for compatibility with older versions of as.  In future, -R may work this way.

When as is configured for COFF output, this option is only useful if you use sections named '.text' and '.data'.

-R is not supported for any of the HPPA targets.  Using -R generates a warning from as.


Display Assembly Statistics: --statistics
Node: statistics, Next: v, Prev: R, Up: Invoking

Display Assembly Statistics: --statistics

Use '--statistics' to display two statistics about the resources used by as: the maximum amount of space allocated during the assembly (in bytes), and the total execution time taken for the assembly (in CPU seconds).


Announce Version: -v
Node: v, Next: W, Prev: statistics, Up: Invoking

Announce Version: -v

You can find out what version of as is running by including the option '-v' (which you can also spell as '-version') on the command line.


Suppress Warnings: -W
Node: W, Next: Z, Prev: v, Up: Invoking

Suppress Warnings: -W

as should never give a warning or error message when assembling compiler output.  But programs written by people often cause as to give a warning that a particular assumption was made.  All such warnings are directed to the standard error file.  If you use this option, no warnings are issued.  This option only affects the warning messages: it does not change any particular of how as assembles your file.  Errors, which stop the assembly, are still reported.


Generate Object File in Spite of Errors: -Z
Node: Z, Next: , Prev: W, Up: Invoking

Generate Object File in Spite of Errors: -Z

After an error message, as normally produces no output.  If for some reason you are interested in object file output even after as gives an error message on your program, use the '-Z' option.  If there are any errors, as continues anyways, and writes an object file after a final warning message of the form 'n errors, m warnings, generating bad object file.'


Syntax
Node: Syntax, Next: Sections, Prev: Invoking, Up: Top

Syntax

This chapter describes the machine-independent syntax allowed in a source file.  as syntax is similar to what many other assemblers use; it is inspired by the BSD 4.2 assembler, except that as does not assemble Vax bit-fields.

* Menu:

Preprocessing	Preprocessing

Whitespace	Whitespace

Comments	Comments

Symbol Intro	Symbols

Statements	Statements

Constants	Constants


Preprocessing
Node: Preprocessing, Next: Whitespace, Prev: , Up: Syntax

Preprocessing

The as internal preprocessor:

•	adjusts and removes extra whitespace.  It leaves one space or tab before the keywords on a line, and turns any other whitespace on the line into a single space.

•	removes all comments, replacing them with a single space, or an appropriate number of newlines.

•	converts character constants into the appropriate numeric values.

It does not do macro processing, include file handling, or anything else you may get from your C compiler's preprocessor.  You can do include file processing with the .include directive (see .include).  You can use the GNU C compiler driver to get other "CPP" style preprocessing, by giving the input file a '.S' suffix.  See Options Controlling the Kind of Output.

Excess whitespace, comments, and character constants cannot be used in the portions of the input text that are not preprocessed.

If the first line of an input file is #NO_APP or if you use the '-f' option, whitespace and comments are not removed from the input file.  Within an input file, you can ask for whitespace and comment removal in specific portions of the by putting a line that says #APP before the text that may contain whitespace or comments, and putting a line that says #NO_APP after this text.  This feature is mainly intend to support asm statements in compilers whose output is otherwise free of comments and whitespace.


Whitespace
Node: Whitespace, Next: Comments, Prev: Preprocessing, Up: Syntax

Whitespace

"Whitespace" is one or more blanks or tabs, in any order.  Whitespace is used to separate symbols, and to make programs neater for people to read.  Unless within character constants (see Character Constants), any whitespace means the same as exactly one space.


Comments
Node: Comments, Next: Symbol Intro, Prev: Whitespace, Up: Syntax

Comments

There are two ways of rendering comments to as.  In both cases the comment is equivalent to one space.

Anything from '/*' through the next '*/' is a comment.  This means you may not nest these comments.

/*
  The only way to include a newline ('\n') in a comment
  is to use this sort of comment.
*/

/* This sort of comment does not nest. */

Anything from the "line comment" character to the next newline is considered a comment and is ignored.  The line comment character is '#' on the Vax; '#' on the i960; '!' on the SPARC; '|' on the 680x0; ';' for the AMD 29K family; ';' for the H8/300 family; '!' for the H8/500 family; ';' for the HPPA; '!' for the Hitachi SH; '!' for the Z8000; see See Machine Dependencies.

On some machines there are two different line comment characters.  One character only begins a comment if it is the first non-whitespace character on a line, while the other always begins a comment.

To be compatible with past assemblers, lines that begin with '#' have a special interpretation.  Following the '#' should be an absolute expression (see Expressions): the logical line number of the next line.  Then a string (see Strings) is allowed: if present it is a new logical file name.  The rest of the line, if any, should be whitespace.

If the first non-whitespace characters on the line are not numeric, the line is ignored.  (Just like a comment.)

                          # This is an ordinary comment.
# 42-6 "new_file_name"    # New logical file name
                          # This is logical line # 36.

This feature is deprecated, and may disappear from future versions of as.


Symbols
Node: Symbol Intro, Next: Statements, Prev: Comments, Up: Syntax

Symbols

A "symbol" is one or more characters chosen from the set of all letters (both upper and lower case), digits and the three characters '_.$'.  On most machines, you can also use $ in symbol names; exceptions are noted in See Machine Dependencies.  No symbol may begin with a digit.  Case is significant.  There is no length limit: all characters are significant.  Symbols are delimited by characters not in that set, or by the beginning of a file (since the source program must end with a newline, the end of a file is not a possible symbol delimiter).  See Symbols.  K


Statements
Node: Statements, Next: Constants, Prev: Symbol Intro, Up: Syntax

Statements

A "statement" ends at a newline character ('\n') or line separator character.  (The line separator is usually ';', unless this conflicts with the comment character; see Machine Dependencies.)  The newline or separator character is considered part of the preceding statement.  Newlines and separators within character constants are an exception: they do not end statements.

It is an error to end any statement with end-of-file:  the last character of any input file should be a newline.

You may write a statement on more than one line if you put a backslash (^\) immediately in front of any newlines within the statement.  When as reads a backslashed newline both characters are ignored.  You can even put backslashed newlines in the middle of symbol names without changing the meaning of your source program.

An empty statement is allowed, and may include whitespace.  It is ignored.

A statement begins with zero or more labels, optionally followed by a key symbol which determines what kind of statement it is.  The key symbol determines the syntax of the rest of the statement.  If the symbol begins with a dot '.' then the statement is an assembler directive: typically valid for any computer.  If the symbol begins with a letter the statement is an assembly language "instruction": it assembles into a machine language instruction.  Different versions of as for different computers recognize different instructions.  In fact, the same symbol may represent a different instruction in a different computer's assembly language.

A label is a symbol immediately followed by a colon (:).  Whitespace before a label or after a colon is permitted, but you may not have whitespace between a label's symbol and its colon. See Labels.

For HPPA targets, labels need not be immediately followed by a colon, but the definition of a label must begin in column zero.  This also implies that only one label may be defined on each line.

label:     .directive    followed by something
another_label:           # This is an empty statement.
           instruction   operand_1, operand_2, ...


Constants
Node: Constants, Next: , Prev: Statements, Up: Syntax

Constants

A constant is a number, written so that its value is known by inspection, without knowing any context.  Like this:

.byte  74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
.ascii "Ring the bell\7"                  # A string constant.
.octa  0x123456789abcdef0123456789ABCDEF0 # A bignum.
.float 0f-314159265358979323846264338327\
95028841971.693993751E-40                 # - pi, a flonum.

* Menu:

Characters	Character Constants

Numbers	Number Constants


Character Constants
Node: Characters, Next: Numbers, Prev: , Up: Constants

Character Constants

There are two kinds of character constants.  A "character" stands for one character in one byte and its value may be used in numeric expressions.  String constants (properly called string literals) are potentially many bytes and their values may not be used in arithmetic expressions.

* Menu:

Strings	Strings

Chars	Characters


Strings
Node: Strings, Next: Chars, Prev: , Up: Characters

Strings

A "string" is written between double-quotes.  It may contain double-quotes or null characters.  The way to get special characters into a string is to "escape" these characters: precede them with a backslash '\' character.  For example '\\' represents one backslash:  the first \ is an escape which tells as to interpret the second character literally as a backslash (which prevents as from recognizing the second \ as an escape character).  The complete list of escapes follows.

^\b

Mnemonic for backspace; for ASCII this is octal code 010.

^\f

Mnemonic for FormFeed; for ASCII this is octal code 014.

^\n

Mnemonic for newline; for ASCII this is octal code 012.

^\r

Mnemonic for carriage-Return; for ASCII this is octal code 015.

^\t

Mnemonic for horizontal Tab; for ASCII this is octal code 011.

^\ digit digit digit

An octal character code.  The numeric code is 3 octal digits.  For compatibility with other Unix systems, 8 and 9 are accepted as digits: for example, \008 has the value 010, and \009 the value 011.

^\x hex-digit hex-digit

A hex character code.  The numeric code is 2 hexadecimal digits.  Either upper or lower case x works.

^\\

Represents one '\' character.

^\"

Represents one '"' character.  Needed in strings to represent this character, because an unescaped '"' would end the string.

^\ anything-else

Any other character when escaped by ^\ gives a warning, but assembles as if the '\' was not present.  The idea is that if you used an escape sequence you clearly didn't want the literal interpretation of the following character.  However as has no other interpretation, so as knows it is giving you the wrong code and warns you of the fact.

Which characters are escapable, and what those escapes represent, varies widely among assemblers.  The current set is what we think the BSD 4.2 assembler recognizes, and is a subset of what most C compilers recognize.  If you are in doubt, do not use an escape sequence.


Characters
Node: Chars, Next: , Prev: Strings, Up: Characters

Characters

A single character may be written as a single quote immediately followed by that character.  The same escapes apply to characters as to strings.  So if you want to write the character backslash, you must write ^'\\ where the first \ escapes the second \.  As you can see, the quote is an acute accent, not a grave accent.  A newline immediately following an acute accent is taken as a literal character and does not count as the end of a statement.  The value of a character constant in a numeric expression is the machine's byte-wide code for that character.  as assumes your character code is ASCII: ^'A means 65, ^'B means 66, and so on.


Number Constants
Node: Numbers, Next: , Prev: Characters, Up: Constants

Number Constants

as distinguishes three kinds of numbers according to how they are stored in the target machine.  Integers are numbers that would fit into an int in the C language.  Bignums are integers, but they are stored in more than 32 bits.  Flonums are floating point numbers, described below.

* Menu:

Integers	Integers

Bignums	Bignums

Flonums	Flonums


Integers
Node: Integers, Next: Bignums, Prev: , Up: Numbers

Integers

A binary integer is '0b' or '0B' followed by zero or more of the binary digits '01'.

An octal integer is '0' followed by zero or more of the octal digits ('01234567').

A decimal integer starts with a non-zero digit followed by zero or more digits ('0123456789').

A hexadecimal integer is '0x' or '0X' followed by one or more hexadecimal digits chosen from '0123456789abcdefABCDEF'.

Integers have the usual values.  To denote a negative integer, use the prefix operator '-' discussed under expressions (see Prefix Operators).


Bignums
Node: Bignums, Next: Flonums, Prev: Integers, Up: Numbers

Bignums

A "bignum" has the same syntax and semantics as an integer except that the number (or its negative) takes more than 32 bits to represent in binary.  The distinction is made because in some places integers are permitted while bignums are not.


Flonums
Node: Flonums, Next: , Prev: Bignums, Up: Numbers

Flonums

A "flonum" represents a floating point number.  The translation is indirect: a decimal floating point number from the text is converted by as to a generic binary floating point number of more than sufficient precision.  This generic floating point number is converted to a particular computer's floating point format (or formats) by a portion of as specialized to that computer.

A flonum is written by writing (in order)

•	The digit '0'.  ('0' is optional on the HPPA.)

•	A letter, to tell as the rest of the number is a flonum.  ^e is recommended.  Case is not important.

On the H8/300, H8/500, Hitachi SH, and AMD 29K architectures, the letter must be one of the letters 'DFPRSX' (in upper or lower case).

On the Intel 960 architecture, the letter must be one of the letters 'DFT' (in upper or lower case).

On the HPPA architecture, the letter must be 'E' (upper case only).

•	An optional sign: either '+' or '-'.

•	An optional "integer part": zero or more decimal digits.

•	An optional "fractional part": '.' followed by zero or more decimal digits.

•	An optional exponent, consisting of:

•	An 'E' or 'e'.

•	Optional sign: either '+' or '-'.

•	One or more decimal digits.

At least one of the integer part or the fractional part must be present.  The floating point number has the usual base-10 value.

{No Value For "rd{}AS"} does all processing using integers.  Flonums are computed independently of any floating point hardware in the computer running as.


Sections and Relocation
Node: Sections, Next: Symbols, Prev: Syntax, Up: Top

Sections and Relocation

* Menu:

Secs Background	Background

Ld Sections	ld Sections

As Sections	as Internal Sections

Sub-Sections	Sub-Sections

bss	bss Section


Background
Node: Secs Background, Next: Ld Sections, Prev: , Up: Sections

Background

Roughly, a section is a range of addresses, with no gaps; all data "in" those addresses is treated the same for some particular purpose.  For example there may be a "read only" section.

The linker ld reads many object files (partial programs) and combines their contents to form a runnable program.  When as emits an object file, the partial program is assumed to start at address 0.  ld assigns the final addresses for the partial program, so that different partial programs do not overlap.  This is actually an oversimplification, but it suffices to explain how as uses sections.

{No Value For "rd{}LD"} moves blocks of bytes of your program to their run-time addresses.  These blocks slide to their run-time addresses as rigid units; their length does not change and neither does the order of bytes within them.  Such a rigid unit is called a section.  Assigning run-time addresses to sections is called "relocation".  It includes the task of adjusting mentions of object-file addresses so they refer to the proper run-time addresses.  For the H8/300 and H8/500, and for the Hitachi SH, as pads sections if needed to ensure they end on a word (sixteen bit) boundary.

An object file written by as has at least three sections, any of which may be empty.  These are named "text", "data" and "bss" sections.

When it generates COFF output, as can also generate whatever other named sections you specify using the '.section' directive (see .section).  If you do not use any directives that place output in the '.text' or '.data' sections, these sections still exist, but are empty.

When as generates SOM or ELF output for the HPPA, as can also generate whatever other named sections you specify using the '.space' and '.subspace' directives.  See `HP9000 Series 800 Assembly Language Reference Manual' (HP 92432-90001) for details on the '.space' and '.subspace' assembler directives.

Additionally, as uses different names for the standard text, data, and bss sections when generating SOM output.  Program text is placed into the '$CODE$' section, data into '$DATA$', and BSS into '$BSS$'.

Within the object file, the text section starts at address 0, the data section follows, and the bss section follows the data section.

When generating either SOM or ELF output files on the HPPA, the text section starts at address 0, the data section at address 0x4000000, and the bss section follows the data section.

To let ld know which data changes when the sections are relocated, and how to change that data, as also writes to the object file details of the relocation needed.  To perform relocation ld must know, each time an address in the object file is mentioned:

•	Where in the object file is the beginning of this reference to an address?

•	How long (in bytes) is this reference?

•	Which section does the address refer to?  What is the numeric value of

(address) - (start-address of section)?

•	Is the reference to an address "Program-Counter relative"?

In fact, every address as ever uses is expressed as

(section) + (offset into section)

Further, most expressions as computes have this section-relative nature.  (For some object formats, such as SOM for the HPPA, some expressions are symbol-relative instead.)

In this manual we use the notation {secname N} to mean "offset N into section secname."

Apart from text, data and bss sections you need to know about the "absolute" section.  When ld mixes partial programs, addresses in the absolute section remain unchanged.  For example, address {absolute 0} is "relocated" to run-time address 0 by ld.  Although the linker never arranges two partial programs' data sections with overlapping addresses after linking, by definition their absolute sections must overlap.  Address {absolute 239} in one part of a program is always the same address when the program is running as address {absolute 239} in any other part of the program.

The idea of sections is extended to the "undefined" section.  Any address whose section is unknown at assembly time is by definition rendered {undefined U}--where U is filled in later.  Since numbers are always defined, the only way to generate an undefined address is to mention an undefined symbol.  A reference to a named common block would be such a symbol: its value is unknown at assembly time so it has section undefined.

By analogy the word section is used to describe groups of sections in the linked program.  ld puts all partial programs' text sections in contiguous addresses in the linked program.  It is customary to refer to the text section of a program, meaning all the addresses of all partial programs' text sections.  Likewise for data and bss sections.

Some sections are manipulated by ld; others are invented for use of as and have no meaning except during assembly.


{No Value For "rd{}LD"} Sections
Node: Ld Sections, Next: As Sections, Prev: Secs Background, Up: Sections

ld Sections

{No Value For "rd{}LD"} deals with just four kinds of sections, summarized below.

named sections

text section

data section

These sections hold your program.  as and ld treat them as separate but equal sections.  Anything you can say of one section is true another.  When the program is running, however, it is customary for the text section to be unalterable.  The text section is often shared among processes: it contains instructions, constants and the like.  The data section of a running program is usually alterable: for example, C variables would be stored in the data section.

bss section

This section contains zeroed bytes when your program begins running.  It is used to hold unitialized variables or common storage.  The length of each partial program's bss section is important, but because it starts out containing zeroed bytes there is no need to store explicit zero bytes in the object file.  The bss section was invented to eliminate those explicit zeros from object files.

absolute section

Address 0 of this section is always "relocated" to runtime address 0.  This is useful if you want to refer to an address that ld must not change when relocating.  In this sense we speak of absolute addresses being "unrelocatable": they do not change during relocation.

undefined section

This "section" is a catch-all for address references to objects not in the preceding sections.

An idealized example of three relocatable sections follows.  The example uses the traditional section names '.text' and '.data'.  Memory addresses are on the horizontal axis.

                      +-----+----+--+
partial program # 1:  |ttttt|dddd|00|
                      +-----+----+--+

                      text   data bss
                      seg.   seg. seg.

                      +---+---+---+
partial program # 2:  |TTT|DDD|000|
                      +---+---+---+

                      +--+---+-----+--+----+---+-----+~~
linked program:       |  |TTT|ttttt|  |dddd|DDD|00000|
                      +--+---+-----+--+----+---+-----+~~

    addresses:        0 ...


{No Value For "rd{}AS"} Internal Sections
Node: As Sections, Next: Sub-Sections, Prev: Ld Sections, Up: Sections

as Internal Sections

These sections are meant only for the internal use of as.  They have no meaning at run-time.  You do not really need to know about these sections for most purposes; but they can be mentioned in as warning messages, so it might be helpful to have an idea of their meanings to as.  These sections are used to permit the value of every expression in your assembly language program to be a section-relative address.

ASSEMBLER-INTERNAL-LOGIC-ERROR!

An internal assembler logic error has been found.  This means there is a bug in the assembler.

expr section

The assembler stores complex expression internally as combinations of symbols.  When it needs to represent an expression as a symbol, it puts it in the expr section.


Sub-Sections
Node: Sub-Sections, Next: bss, Prev: As Sections, Up: Sections

Sub-Sections

Assembled bytes conventionally fall into two sections: text and data.  You may have separate groups of data in named sections that you want to end up near to each other in the object file, even though they are not contiguous in the assembler source.  as allows you to use "subsections" for this purpose.  Within each section, there can be numbered subsections with values from 0 to 8192.  Objects assembled into the same subsection go into the object file together with other objects in the same subsection.  For example, a compiler might want to store constants in the text section, but might not want to have them interspersed with the program being assembled.  In this case, the compiler could issue a '.text 0' before each section of code being output, and a '.text 1' before each group of constants being output.

Subsections are optional.  If you do not use subsections, everything goes in subsection number zero.

Each subsection is zero-padded up to a multiple of four bytes.  (Subsections may be padded a different amount on different flavors of as.)

Subsections appear in your object file in numeric order, lowest numbered to highest.  (All this to be compatible with other people's assemblers.) The object file contains no representation of subsections; ld and other programs that manipulate object files see no trace of them.  They just see all your text subsections as a text section, and all your data subsections as a data section.

To specify which subsection you want subsequent statements assembled into, use a numeric argument to specify it, in a '.text expression' or a '.data expression' statement.  When generating COFF output, you can also use an extra subsection argument with arbitrary named sections: '.section name, expression'.  Expression should be an absolute expression.  (See Expressions.)  If you just say '.text' then '.text 0' is assumed.  Likewise '.data' means '.data 0'.  Assembly begins in text 0.  For instance:

.text 0     # The default subsection is text 0 anyway.
.ascii "This lives in the first text subsection. *"
.text 1
.ascii "But this lives in the second text subsection."
.data 0
.ascii "This lives in the data section,"
.ascii "in the first data subsection."
.text 0
.ascii "This lives in the first text section,"
.ascii "immediately following the asterisk (*)."

Each section has a "location counter" incremented by one for every byte assembled into that section.  Because subsections are merely a convenience restricted to as there is no concept of a subsection location counter.  There is no way to directly manipulate a location counter--but the .align directive changes it, and any label definition captures its current value.  The location counter of the section where statements are being assembled is said to be the "active" location counter.


bss Section
Node: bss, Next: , Prev: Sub-Sections, Up: Sections

bss Section

The bss section is used for local common variable storage.  You may allocate address space in the bss section, but you may not dictate data to load into it before your program executes.  When your program starts running, all the contents of the bss section are zeroed bytes.

Addresses in the bss section are allocated with special directives; you may not assemble anything directly into the bss section.  Hence there are no bss subsections. See .comm, see .lcomm.


Symbols
Node: Symbols, Next: Expressions, Prev: Sections, Up: Top

Symbols

Symbols are a central concept: the programmer uses symbols to name things, the linker uses symbols to link, and the debugger uses symbols to debug.

Warning: as does not place symbols in the object file in the same order they were declared.  This may break some debuggers.

* Menu:

Labels	Labels

Setting Symbols	Giving Symbols Other Values

Symbol Names	Symbol Names

Dot	The Special Dot Symbol

Symbol Attributes	Symbol Attributes


Labels
Node: Labels, Next: Setting Symbols, Prev: , Up: Symbols

Labels

A "label" is written as a symbol immediately followed by a colon ':'.  The symbol then represents the current value of the active location counter, and is, for example, a suitable instruction operand.  You are warned if you use the same symbol to represent two different locations: the first definition overrides any other definitions.

On the HPPA, the usual form for a label need not be immediately followed by a colon, but instead must start in column zero.  Only one label may be defined on a single line.  To work around this, the HPPA version of as also provides a special directive .label for defining labels more flexibly.


Giving Symbols Other Values
Node: Setting Symbols, Next: Symbol Names, Prev: Labels, Up: Symbols

Giving Symbols Other Values

A symbol can be given an arbitrary value by writing a symbol, followed by an equals sign '=', followed by an expression (see Expressions).  This is equivalent to using the .set directive.  See .set.


Symbol Names
Node: Symbol Names, Next: Dot, Prev: Setting Symbols, Up: Symbols

Symbol Names

Symbol names begin with a letter or with one of '._'.  On most machines, you can also use $ in symbol names; exceptions are noted in See Machine Dependencies.  That character may be followed by any string of digits, letters, dollar signs (unless otherwise noted in See Machine Dependencies), and underscores.  For the AMD 29K family, '?' is also allowed in the body of a symbol name, though not at its beginning.

Case of letters is significant: foo is a different symbol name than Foo.

Each symbol has exactly one name.  Each name in an assembly language program refers to exactly one symbol.  You may use that symbol name any number of times in a program.

Local Symbol Names

Local symbols help compilers and programmers use names temporarily.  There are ten local symbol names, which are re-used throughout the program.  You may refer to them using the names '0' '1' ... '9'.  To define a local symbol, write a label of the form 'N:' (where N represents any digit).  To refer to the most recent previous definition of that symbol write 'Nb', using the same digit as when you defined the label.  To refer to the next definition of a local label, write 'Nf'--where N gives you a choice of 10 forward references.  The 'b' stands for "backwards" and the 'f' stands for "forwards".

Local symbols are not emitted by the current GNU C compiler.

There is no restriction on how you can use these labels, but remember that at any point in the assembly you can refer to at most 10 prior local labels and to at most 10 forward local labels.

Local symbol names are only a notation device.  They are immediately transformed into more conventional symbol names before the assembler uses them.  The symbol names stored in the symbol table, appearing in error messages and optionally emitted to the object file have these parts:

L

All local labels begin with 'L'. Normally both as and ld forget symbols that start with 'L'. These labels are used for symbols you are never intended to see.  If you use the '-L' option then as retains these symbols in the object file. If you also instruct ld to retain these symbols, you may use them in debugging.

digit

If the label is written '0:' then the digit is '0'.  If the label is written '1:' then the digit is '1'.  And so on up through '9:'.

^A

This unusual character is included so you do not accidentally invent a symbol of the same name.  The character has ASCII value '\001'.

ordinal number

This is a serial number to keep the labels distinct.  The first '0:' gets the number '1'; The 15th '0:' gets the number '15'; etc..  Likewise for the other labels '1:' through '9:'.

For instance, the first 1: is named L1^A1, the 44th 3: is named L3^A44.


The Special Dot Symbol
Node: Dot, Next: Symbol Attributes, Prev: Symbol Names, Up: Symbols

The Special Dot Symbol

The special symbol '.' refers to the current address that as is assembling into.  Thus, the expression 'melvin: .long .' defines melvin to contain its own address.  Assigning a value to . is treated the same as a .org directive.  Thus, the expression '.=.+4' is the same as saying '.space 4'.


Symbol Attributes
Node: Symbol Attributes, Next: , Prev: Dot, Up: Symbols

Symbol Attributes

Every symbol has, as well as its name, the attributes "Value" and "Type".  Depending on output format, symbols can also have auxiliary attributes.

If you use a symbol without defining it, as assumes zero for all these attributes, and probably won't warn you.  This makes the symbol an externally defined symbol, which is generally what you would want.

* Menu:

Symbol Value	Value

Symbol Type	Type

a.out Symbols	Symbol Attributes: a.out

COFF Symbols	Symbol Attributes for COFF

SOM Symbols	Symbol Attributes for SOM


Value
Node: Symbol Value, Next: Symbol Type, Prev: , Up: Symbol Attributes

Value

The value of a symbol is (usually) 32 bits.  For a symbol which labels a location in the text, data, bss or absolute sections the value is the number of addresses from the start of that section to the label.  Naturally for text, data and bss sections the value of a symbol changes as ld changes section base addresses during linking.  Absolute symbols' values do not change during linking: that is why they are called absolute.

The value of an undefined symbol is treated in a special way.  If it is 0 then the symbol is not defined in this assembler source file, and ld tries to determine its value from other files linked into the same program.  You make this kind of symbol simply by mentioning a symbol name without defining it.  A non-zero value represents a .comm common declaration.  The value is how much common storage to reserve, in bytes (addresses).  The symbol refers to the first address of the allocated storage.


Type
Node: Symbol Type, Next: a.out Symbols, Prev: Symbol Value, Up: Symbol Attributes

Type

The type attribute of a symbol contains relocation (section) information, any flag settings indicating that a symbol is external, and (optionally), other information for linkers and debuggers.  The exact format depends on the object-code output format in use.


Symbol Attributes: a.out
Node: a.out Symbols, Next: COFF Symbols, Prev: Symbol Type, Up: Symbol Attributes

Symbol Attributes: a.out

* Menu:

Symbol Desc	Descriptor

Symbol Other	Other


Descriptor
Node: Symbol Desc, Next: Symbol Other, Prev: , Up: a.out Symbols

Descriptor

This is an arbitrary 16-bit value.  You may establish a symbol's descriptor value by using a .desc statement (see .desc).  A descriptor value means nothing to as.


Other
Node: Symbol Other, Next: , Prev: Symbol Desc, Up: a.out Symbols

Other

This is an arbitrary 8-bit value.  It means nothing to as.


Symbol Attributes for COFF
Node: COFF Symbols, Next: SOM Symbols, Prev: a.out Symbols, Up: Symbol Attributes

Symbol Attributes for COFF

The COFF format supports a multitude of auxiliary symbol attributes; like the primary symbol attributes, they are set between .def and .endef directives.

Primary Attributes

The symbol name is set with .def; the value and type, respectively, with .val and .type.

Auxiliary Attributes

The as directives .dim, .line, .scl, .size, and .tag can generate auxiliary symbol table information for COFF.


Symbol Attributes for SOM
Node: SOM Symbols, Next: , Prev: COFF Symbols, Up: Symbol Attributes

Symbol Attributes for SOM

The SOM format for the HPPA supports a multitude of symbol attributes set with the .EXPORT and .IMPORT directives.

The attributes are described in `HP9000 Series 800 Assembly Language Reference Manual' (HP 92432-90001) under the IMPORT and EXPORT assembler directive documentation.


Expressions
Node: Expressions, Next: Pseudo Ops, Prev: Symbols, Up: Top

Expressions

An "expression" specifies an address or numeric value.  Whitespace may precede and/or follow an expression.

The result of an expression must be an absolute number, or else an offset into a particular section.  If an expression is not absolute, and there is not enough information when as sees the expression to know its section, a second pass over the source program might be necessary to interpret the expression--but the second pass is currently not implemented.  as aborts with an error message in this situation.

* Menu:

Empty Exprs	Empty Expressions

Integer Exprs	Integer Expressions


Empty Expressions
Node: Empty Exprs, Next: Integer Exprs, Prev: , Up: Expressions

Empty Expressions

An empty expression has no value: it is just whitespace or null.  Wherever an absolute expression is required, you may omit the expression, and as assumes a value of (absolute) 0.  This is compatible with other assemblers.


Integer Expressions
Node: Integer Exprs, Next: , Prev: Empty Exprs, Up: Expressions

Integer Expressions

An "integer expression" is one or more arguments delimited by operators.

* Menu:

Arguments	Arguments

Operators	Operators

Prefix Ops	Prefix Operators

Infix Ops	Infix Operators


Arguments
Node: Arguments, Next: Operators, Prev: , Up: Integer Exprs

Arguments

"Arguments" are symbols, numbers or subexpressions.  In other contexts arguments are sometimes called "arithmetic operands".  In this manual, to avoid confusing them with the "instruction operands" of the machine language, we use the term "argument" to refer to parts of expressions only, reserving the word "operand" to refer only to machine instruction operands.

Symbols are evaluated to yield {section NNN} where section is one of text, data, bss, absolute, or undefined.  NNN is a signed, 2's complement 32 bit integer.

Numbers are usually integers.

A number can be a flonum or bignum.  In this case, you are warned that only the low order 32 bits are used, and as pretends these 32 bits are an integer.  You may write integer-manipulating instructions that act on exotic constants, compatible with other assemblers.

Subexpressions are a left parenthesis '(' followed by an integer expression, followed by a right parenthesis ')'; or a prefix operator followed by an argument.


Operators
Node: Operators, Next: Prefix Ops, Prev: Arguments, Up: Integer Exprs

Operators

"Operators" are arithmetic functions, like + or %.  Prefix operators are followed by an argument.  Infix operators appear between their arguments.  Operators may be preceded and/or followed by whitespace.


Prefix Operator
Node: Prefix Ops, Next: Infix Ops, Prev: Operators, Up: Integer Exprs

Prefix Operator

as has the following "prefix operators".  They each take one argument, which must be absolute.

-

"Negation".  Two's complement negation.

~

"Complementation".  Bitwise not.


Infix Operators
Node: Infix Ops, Next: , Prev: Prefix Ops, Up: Integer Exprs

Infix Operators

"Infix operators" take two arguments, one on either side.  Operators have precedence, but operations with equal precedence are performed left to right.  Apart from + or -, both arguments must be absolute, and the result is absolute.

1. 	Highest Precedence

*

"Multiplication".

/

"Division".  Truncation is the same as the C operator '/'

%

"Remainder".

<

<<

"Shift Left".  Same as the C operator '<<'.

>

>>

"Shift Right".  Same as the C operator '>>'.

2. 	Intermediate precedence

|

"Bitwise Inclusive Or".

&

"Bitwise And".

^

"Bitwise Exclusive Or".

!

"Bitwise Or Not".

3. 	Lowest Precedence

+

"Addition".  If either argument is absolute, the result has the section of the other argument.  You may not add together arguments from different sections.

-

"Subtraction".  If the right argument is absolute, the result has the section of the left argument.  If both arguments are in the same section, the result is absolute.  You may not subtract arguments from different sections.

In short, it's only meaningful to add or subtract the offsets in an address; you can only have a defined section in one of the two arguments.


Assembler Directives
Node: Pseudo Ops, Next: Machine Dependencies, Prev: Expressions, Up: Top

Assembler Directives

All assembler directives have names that begin with a period ('.').  The rest of the name is letters, usually in lower case.

This chapter discusses directives that are available regardless of the target machine configuration for the GNU assembler.  Some machine configurations provide additional directives.  See Machine Dependencies.

* Menu:

Abort	.abort

ABORT	.ABORT

Align	.align abs-expr , abs-expr

App-File	.app-file string

Ascii	.ascii "string"...

Asciz	.asciz "string"...

Byte	.byte expressions

Comm	.comm symbol , length

Data	.data subsection

Def	.def name

Desc	.desc symbol, abs-expression

Dim	.dim

Double	.double flonums

Eject	.eject

Else	.else

Endef	.endef

Endif	.endif

Equ	.equ symbol, expression

Extern	.extern

File	.file string

Fill	.fill repeat , size , value

Float	.float flonums

Global	.global symbol, .globl symbol

hword	.hword expressions

Ident	.ident

If	.if absolute expression

Include	.include "file"

Int	.int expressions

Lcomm	.lcomm symbol , length

Lflags	.lflags

Line	.line line-number

Ln	.ln line-number

List	.list

Long	.long expressions

Nolist	.nolist

Octa	.octa bignums

Org	.org new-lc , fill

Psize	.psize lines, columns

Quad	.quad bignums

Sbttl	.sbttl "subheading"

Scl	.scl class

Section	.section name, subsection

Set	.set symbol, expression

Short	.short expressions

Single	.single flonums

Size	.size

Space	.space size , fill

Stab	.stabd, .stabn, .stabs

String	.string "str"

Tag	.tag structname

Text	.text subsection

Title	.title "heading"

Type	.type int

Val	.val addr

Word	.word expressions

Deprecated	Deprecated Directives


.abort
Node: Abort, Next: ABORT, Prev: , Up: Pseudo Ops

.abort

This directive stops the assembly immediately.  It is for compatibility with other assemblers.  The original idea was that the assembly language source would be piped into the assembler.  If the sender of the source quit, it could use this directive tells as to quit also.  One day .abort will not be supported.


.ABORT
Node: ABORT, Next: Align, Prev: Abort, Up: Pseudo Ops

.ABORT

When producing COFF output, as accepts this directive as a synonym for '.abort'.

When producing b.out output, as accepts this directive, but ignores it.


.align abs-expr , abs-expr
Node: Align, Next: App-File, Prev: ABORT, Up: Pseudo Ops

.align abs-expr , abs-expr

Pad the location counter (in the current subsection) to a particular storage boundary.  The first expression (which must be absolute) is the number of low-order zero bits the location counter must have after advancement.  For example '.align 3' advances the location counter until it a multiple of 8.  If the location counter is already a multiple of 8, no change is needed.

For the HPPA, the first expression (which must be absolute) is the alignment request in bytes.  For example '.align 8' advances the location counter until it is a multiple of 8.  If the location counter is already a multiple of 8, no change is needed.

The second expression (also absolute) gives the value to be stored in the padding bytes.  It (and the comma) may be omitted.  If it is omitted, the padding bytes are zero.


.app-file string
Node: App-File, Next: Ascii, Prev: Align, Up: Pseudo Ops

.app-file string

.app-file (which may also be spelled '.file') tells as that we are about to start a new logical file.  string is the new file name.  In general, the filename is recognized whether or not it is surrounded by quotes '"'; but if you wish to specify an empty file name is permitted, you must give the quotes-"".  This statement may go away in future: it is only recognized to be compatible with old as programs.


.ascii "string"...
Node: Ascii, Next: Asciz, Prev: App-File, Up: Pseudo Ops

.ascii "string"...

.ascii expects zero or more string literals (see Strings) separated by commas.  It assembles each string (with no automatic trailing zero byte) into consecutive addresses.


.asciz "string"...
Node: Asciz, Next: Byte, Prev: Ascii, Up: Pseudo Ops

.asciz "string"...

.asciz is just like .ascii, but each string is followed by a zero byte.  The "z" in '.asciz' stands for "zero".


.byte expressions
Node: Byte, Next: Comm, Prev: Asciz, Up: Pseudo Ops

.byte expressions

.byte expects zero or more expressions, separated by commas.  Each expression is assembled into the next byte.


.comm symbol , length
Node: Comm, Next: Data, Prev: Byte, Up: Pseudo Ops

.comm symbol , length

.comm declares a named common area in the bss section.  Normally ld reserves memory addresses for it during linking, so no partial program defines the location of the symbol.  Use .comm to tell ld that it must be at least length bytes long.  ld allocates space for each .comm symbol that is at least as long as the longest .comm request in any of the partial programs linked.  length is an absolute expression.

The syntax for .comm differs slightly on the HPPA.  The syntax is 'symbol .comm, length'; symbol is optional.


.data subsection
Node: Data, Next: Def, Prev: Comm, Up: Pseudo Ops

.data subsection

.data tells as to assemble the following statements onto the end of the data subsection numbered subsection (which is an absolute expression).  If subsection is omitted, it defaults to zero.


.def name
Node: Def, Next: Desc, Prev: Data, Up: Pseudo Ops

.def name

Begin defining debugging information for a symbol name; the definition extends until the .endef directive is encountered.

This directive is only observed when as is configured for COFF format output; when producing b.out, '.def' is recognized, but ignored.


.desc symbol, abs-expression
Node: Desc, Next: Dim, Prev: Def, Up: Pseudo Ops

.desc symbol, abs-expression

This directive sets the descriptor of the symbol (see Symbol Attributes) to the low 16 bits of an absolute expression.

The '.desc' directive is not available when as is configured for COFF output; it is only for a.out or b.out object format.  For the sake of compatibility, as accepts it, but produces no output, when configured for COFF.


.dim
Node: Dim, Next: Double, Prev: Desc, Up: Pseudo Ops

.dim

This directive is generated by compilers to include auxiliary debugging information in the symbol table.  It is only permitted inside .def/.endef pairs.

'.dim' is only meaningful when generating COFF format output; when as is generating b.out, it accepts this directive but ignores it.


.double flonums
Node: Double, Next: Eject, Prev: Dim, Up: Pseudo Ops

.double flonums

.double expects zero or more flonums, separated by commas.  It assembles floating point numbers.  The exact kind of floating point numbers emitted depends on how as is configured.  See Machine Dependencies.


.eject
Node: Eject, Next: Else, Prev: Double, Up: Pseudo Ops

.eject

Force a page break at this point, when generating assembly listings.


.else
Node: Else, Next: Endef, Prev: Eject, Up: Pseudo Ops

.else

.else is part of the as support for conditional assembly; see .if.  It marks the beginning of a section of code to be assembled if the condition for the preceding .if was false.


.endef
Node: Endef, Next: Endif, Prev: Else, Up: Pseudo Ops

.endef

This directive flags the end of a symbol definition begun with .def.

'.endef' is only meaningful when generating COFF format output; if as is configured to generate b.out, it accepts this directive but ignores it.


.endif
Node: Endif, Next: Equ, Prev: Endef, Up: Pseudo Ops

.endif

.endif is part of the as support for conditional assembly; it marks the end of a block of code that is only assembled conditionally.  See .if.


.equ symbol, expression
Node: Equ, Next: Extern, Prev: Endif, Up: Pseudo Ops

.equ symbol, expression

This directive sets the value of symbol to expression.  It is synonymous with '.set'; see .set.

The syntax for equ on the HPPA is 'symbol .equ expression'.


.extern
Node: Extern, Next: File, Prev: Equ, Up: Pseudo Ops

.extern

.extern is accepted in the source program--for compatibility with other assemblers--but it is ignored.  as treats all undefined symbols as external.


.file string
Node: File, Next: Fill, Prev: Extern, Up: Pseudo Ops

.file string

.file (which may also be spelled '.app-file') tells as that we are about to start a new logical file.  string is the new file name.  In general, the filename is recognized whether or not it is surrounded by quotes '"'; but if you wish to specify an empty file name, you must give the quotes-"".  This statement may go away in future: it is only recognized to be compatible with old as programs.  In some configurations of as, .file has already been removed to avoid conflicts with other assemblers.  See Machine Dependencies.


.fill repeat , size , value
Node: Fill, Next: Float, Prev: File, Up: Pseudo Ops

.fill repeat , size , value

result, size and value are absolute expressions.  This emits repeat copies of size bytes.  Repeat may be zero or more.  Size may be zero or more, but if it is more than 8, then it is deemed to have the value 8, compatible with other people's assemblers.  The contents of each repeat bytes is taken from an 8-byte number.  The highest order 4 bytes are zero.  The lowest order 4 bytes are value rendered in the byte-order of an integer on the computer as is assembling for.  Each size bytes in a repetition is taken from the lowest order size bytes of this number.  Again, this bizarre behavior is compatible with other people's assemblers.

size and value are optional.  If the second comma and value are absent, value is assumed zero.  If the first comma and following tokens are absent, size is assumed to be 1.


.float flonums
Node: Float, Next: Global, Prev: Fill, Up: Pseudo Ops

.float flonums

This directive assembles zero or more flonums, separated by commas.  It has the same effect as .single.  The exact kind of floating point numbers emitted depends on how as is configured.  See Machine Dependencies.


.global symbol, .globl symbol
Node: Global, Next: hword, Prev: Float, Up: Pseudo Ops

.global symbol, .globl symbol

.global makes the symbol visible to ld.  If you define symbol in your partial program, its value is made available to other partial programs that are linked with it.  Otherwise, symbol takes its attributes from a symbol of the same name from another file linked into the same program.

Both spellings ('.globl' and '.global') are accepted, for compatibility with other assemblers.

On the HPPA, .global is not always enough to make it accessible to other partial programs.  You may need the HPPA-only .EXPORT directive as well.  See HPPA Assembler Directives.


.hword expressions
Node: hword, Next: Ident, Prev: Global, Up: Pseudo Ops

.hword expressions

This expects zero or more expressions, and emits a 16 bit number for each.

This directive is a synonym for '.short'; depending on the target architecture, it may also be a synonym for '.word'.


.ident
Node: Ident, Next: If, Prev: hword, Up: Pseudo Ops

.ident

This directive is used by some assemblers to place tags in object files.  as simply accepts the directive for source-file compatibility with such assemblers, but does not actually emit anything for it.


.if absolute expression
Node: If, Next: Include, Prev: Ident, Up: Pseudo Ops

.if absolute expression

.if marks the beginning of a section of code which is only considered part of the source program being assembled if the argument (which must be an absolute expression) is non-zero.  The end of the conditional section of code must be marked by .endif (see .endif); optionally, you may include code for the alternative condition, flagged by .else (see .else.

The following variants of .if are also supported:

.ifdef symbol

Assembles the following section of code if the specified symbol has been defined.

.ifndef symbol

ifnotdef symbol

Assembles the following section of code if the specified symbol has not been defined.  Both spelling variants are equivalent.


.include "file"
Node: Include, Next: Int, Prev: If, Up: Pseudo Ops

.include "file"

This directive provides a way to include supporting files at specified points in your source program.  The code from file is assembled as if it followed the point of the .include; when the end of the included file is reached, assembly of the original file continues.  You can control the search paths used with the '-I' command-line option (see Command-Line Options).  Quotation marks are required around file.


.int expressions
Node: Int, Next: Lcomm, Prev: Include, Up: Pseudo Ops

.int expressions

Expect zero or more expressions, of any section, separated by commas.  For each expression, emit a number that, at run time, is the value of that expression.  The byte order and bit size of the number depends on what kind of target the assembly is for.


.lcomm symbol , length
Node: Lcomm, Next: Lflags, Prev: Int, Up: Pseudo Ops

.lcomm symbol , length

Reserve length (an absolute expression) bytes for a local common denoted by symbol.  The section and value of symbol are those of the new local common.  The addresses are allocated in the bss section, so that at run-time the bytes start off zeroed.  Symbol is not declared global (see .global), so is normally not visible to ld.

The syntax for .lcomm differs slightly on the HPPA.  The syntax is 'symbol .lcomm, length'; symbol is optional.


.lflags
Node: Lflags, Next: Line, Prev: Lcomm, Up: Pseudo Ops

.lflags

as accepts this directive, for compatibility with other assemblers, but ignores it.


.line line-number
Node: Line, Next: Ln, Prev: Lflags, Up: Pseudo Ops

.line line-number

Change the logical line number.  line-number must be an absolute expression.  The next line has that logical line number.  Therefore any other statements on the current line (after a statement separator character) are reported as on logical line number line-number - 1.  One day as will no longer support this directive: it is recognized only for compatibility with existing assembler programs.

Warning: In the AMD29K configuration of as, this command is not available; use the synonym .ln in that context.

Even though this is a directive associated with the a.out or b.out object-code formats, as still recognizes it when producing COFF output, and treats '.line' as though it were the COFF '.ln' if it is found outside a .def/.endef pair.

Inside a .def, '.line' is, instead, one of the directives used by compilers to generate auxiliary symbol information for debugging.


.ln line-number
Node: Ln, Next: List, Prev: Line, Up: Pseudo Ops

.ln line-number

'.ln' is a synonym for '.line'.


.list
Node: List, Next: Long, Prev: Ln, Up: Pseudo Ops

.list

Control (in conjunction with the .nolist directive) whether or not assembly listings are generated.  These two directives maintain an internal counter (which is zero initially).   .list increments the counter, and .nolist decrements it.  Assembly listings are generated whenever the counter is greater than zero.

By default, listings are disabled.  When you enable them (with the '-a' command line option; see Command-Line Options), the initial value of the listing counter is one.


.long expressions
Node: Long, Next: Nolist, Prev: List, Up: Pseudo Ops

.long expressions

.long is the same as '.int', see .int.


.nolist
Node: Nolist, Next: Octa, Prev: Long, Up: Pseudo Ops

.nolist

Control (in conjunction with the .list directive) whether or not assembly listings are generated.  These two directives maintain an internal counter (which is zero initially).   .list increments the counter, and .nolist decrements it.  Assembly listings are generated whenever the counter is greater than zero.


.octa bignums
Node: Octa, Next: Org, Prev: Nolist, Up: Pseudo Ops

.octa bignums

This directive expects zero or more bignums, separated by commas.  For each bignum, it emits a 16-byte integer.

The term "octa" comes from contexts in which a "word" is two bytes; hence octa-word for 16 bytes.


.org new-lc , fill
Node: Org, Next: Psize, Prev: Octa, Up: Pseudo Ops

.org new-lc , fill

Advance the location counter of the current section to new-lc.  new-lc is either an absolute expression or an expression with the same section as the current subsection.  That is, you can't use .org to cross sections: if new-lc has the wrong section, the .org directive is ignored.  To be compatible with former assemblers, if the section of new-lc is absolute, as issues a warning, then pretends the section of new-lc is the same as the current subsection.

.org may only increase the location counter, or leave it unchanged; you cannot use .org to move the location counter backwards.

Because as tries to assemble programs in one pass, new-lc may not be undefined.  If you really detest this restriction we eagerly await a chance to share your improved assembler.

Beware that the origin is relative to the start of the section, not to the start of the subsection.  This is compatible with other people's assemblers.

When the location counter (of the current subsection) is advanced, the intervening bytes are filled with fill which should be an absolute expression.  If the comma and fill are omitted, fill defaults to zero.


.psize lines , columns
Node: Psize, Next: Quad, Prev: Org, Up: Pseudo Ops

.psize lines , columns

Use this directive to declare the number of lines--and, optionally, the number of columns--to use for each page, when generating listings.

If you do not use .psize, listings use a default line-count of 60.  You may omit the comma and columns specification; the default width is 200 columns.

{No Value For "rd{}AS"} generates formfeeds whenever the specified number of lines is exceeded (or whenever you explicitly request one, using .eject).

If you specify lines as 0, no formfeeds are generated save those explicitly specified with .eject.


.quad bignums
Node: Quad, Next: Sbttl, Prev: Psize, Up: Pseudo Ops

.quad bignums

.quad expects zero or more bignums, separated by commas.  For each bignum, it emits an 8-byte integer.  If the bignum won't fit in 8 bytes, it prints a warning message; and just takes the lowest order 8 bytes of the bignum.  KThe term "quad" comes from contexts in which a "word" is two bytes; hence quad-word for 8 bytes.


.sbttl "subheading"
Node: Sbttl, Next: Scl, Prev: Quad, Up: Pseudo Ops

.sbttl "subheading"

Use subheading as the title (third line, immediately after the title line) when generating assembly listings.

This directive affects subsequent pages, as well as the current page if it appears within ten lines of the top of a page.


.scl class
Node: Scl, Next: Section, Prev: Sbttl, Up: Pseudo Ops

.scl class

Set the storage-class value for a symbol.  This directive may only be used inside a .def/.endef pair.  Storage class may flag whether a symbol is static or external, or it may record further symbolic debugging information.

The '.scl' directive is primarily associated with COFF output; when configured to generate b.out output format, as accepts this directive but ignores it.


.section name, subsection
Node: Section, Next: Set, Prev: Scl, Up: Pseudo Ops

.section name, subsection

Assemble the following code into end of subsection numbered subsection in the COFF named section name.  If you omit subsection, as uses subsection number zero.  '.section .text' is equivalent to the .text directive; '.section .data' is equivalent to the .data directive.  This directive is only supported for targets that actually support arbitrarily named sections; on a.out targets, for example, it is not accepted, even with a standard a.out section name as its parameter.


.set symbol, expression
Node: Set, Next: Short, Prev: Section, Up: Pseudo Ops

.set symbol, expression

Set the value of symbol to expression.  This changes symbol's value and type to conform to expression.  If symbol was flagged as external, it remains flagged. (See Symbol Attributes.)

You may .set a symbol many times in the same assembly.

If you .set a global symbol, the value stored in the object file is the last value stored into it.

The syntax for set on the HPPA is 'symbol .set expression'.


.short expressions
Node: Short, Next: Single, Prev: Set, Up: Pseudo Ops

.short expressions

.short is normally the same as '.word'.  See .word.

In some configurations, however, .short and .word generate numbers of different lengths; see Machine Dependencies.


.single flonums
Node: Single, Next: Size, Prev: Short, Up: Pseudo Ops

.single flonums

This directive assembles zero or more flonums, separated by commas.  It has the same effect as .float.  The exact kind of floating point numbers emitted depends on how as is configured.  See Machine Dependencies.


.size
Node: Size, Next: Space, Prev: Single, Up: Pseudo Ops

.size

This directive is generated by compilers to include auxiliary debugging information in the symbol table.  It is only permitted inside .def/.endef pairs.

'.size' is only meaningful when generating COFF format output; when as is generating b.out, it accepts this directive but ignores it.


.space size , fill
Node: Space, Next: Stab, Prev: Size, Up: Pseudo Ops

.space size , fill

This directive emits size bytes, each of value fill.  Both size and fill are absolute expressions.  If the comma and fill are omitted, fill is assumed to be zero.

Warning: .space has a completely different meaning for HPPA targets; use .block as a substitute.  See `HP9000 Series 800 Assembly Language Reference Manual' (HP 92432-90001) for the meaning of the .space directive.  See HPPA Assembler Directives, for a summary.

On the AMD 29K, this directive is ignored; it is accepted for compatibility with other AMD 29K assemblers.

Warning: In most versions of the GNU assembler, the directive .space has the effect of .block  See Machine Dependencies.


.stabd, .stabn, .stabs
Node: Stab, Next: String, Prev: Space, Up: Pseudo Ops

.stabd, .stabn, .stabs

There are three directives that begin '.stab'.  All emit symbols (see Symbols), for use by symbolic debuggers.  The symbols are not entered in the as hash table: they cannot be referenced elsewhere in the source file.  Up to five fields are required:

string

This is the symbol's name.  It may contain any character except '\000', so is more general than ordinary symbol names.  Some debuggers used to code arbitrarily complex structures into symbol names using this field.

type

An absolute expression.  The symbol's type is set to the low 8 bits of this expression.  Any bit pattern is permitted, but ld and debuggers choke on silly bit patterns.

other

An absolute expression.  The symbol's "other" attribute is set to the low 8 bits of this expression.

desc

An absolute expression.  The symbol's descriptor is set to the low 16 bits of this expression.

value

An absolute expression which becomes the symbol's value.

If a warning is detected while reading a .stabd, .stabn, or .stabs statement, the symbol has probably already been created; you get a half-formed symbol in your object file.  This is compatible with earlier assemblers!

.stabd type , other , desc

The "name" of the symbol generated is not even an empty string.  It is a null pointer, for compatibility.  Older assemblers used a null pointer so they didn't waste space in object files with empty strings.

The symbol's value is set to the location counter, relocatably.  When your program is linked, the value of this symbol is the address of the location counter when the .stabd was assembled.

.stabn type , other , desc , value

The name of the symbol is set to the empty string "".

.stabs string ,  type , other , desc , value

All five fields are specified.


.string "str"
Node: String, Next: Tag, Prev: Stab, Up: Pseudo Ops

.string "str"

Copy the characters in str to the object file.  You may specify more than one string to copy, separated by commas.  Unless otherwise specified for a particular machine, the assembler marks the end of each string with a 0 byte.  You can use any of the escape sequences described in See Strings.


.tag structname
Node: Tag, Next: Text, Prev: String, Up: Pseudo Ops

.tag structname

This directive is generated by compilers to include auxiliary debugging information in the symbol table.  It is only permitted inside .def/.endef pairs.  Tags are used to link structure definitions in the symbol table with instances of those structures.

'.tag' is only used when generating COFF format output; when as is generating b.out, it accepts this directive but ignores it.


.text subsection
Node: Text, Next: Title, Prev: Tag, Up: Pseudo Ops

.text subsection

Tells as to assemble the following statements onto the end of the text subsection numbered subsection, which is an absolute expression.  If subsection is omitted, subsection number zero is used.


.title "heading"
Node: Title, Next: Type, Prev: Text, Up: Pseudo Ops

.title "heading"

Use heading as the title (second line, immediately after the source file name and pagenumber) when generating assembly listings.

This directive affects subsequent pages, as well as the current page if it appears within ten lines of the top of a page.


.type int
Node: Type, Next: Val, Prev: Title, Up: Pseudo Ops

.type int

This directive, permitted only within .def/.endef pairs, records the integer int as the type attribute of a symbol table entry.

'.type' is associated only with COFF format output; when as is configured for b.out output, it accepts this directive but ignores it.


.val addr
Node: Val, Next: Word, Prev: Type, Up: Pseudo Ops

.val addr

This directive, permitted only within .def/.endef pairs, records the address addr as the value attribute of a symbol table entry.

'.val' is used only for COFF output; when as is configured for b.out, it accepts this directive but ignores it.


.word expressions
Node: Word, Next: Deprecated, Prev: Val, Up: Pseudo Ops

.word expressions

This directive expects zero or more expressions, of any section, separated by commas.

The size of the number emitted, and its byte order, depend on what target computer the assembly is for.

Warning: Special Treatment to support Compilers

Machines with a 32-bit address space, but that do less than 32-bit addressing, require the following special treatment.  If the machine of interest to you does 32-bit addressing (or doesn't require it; see Machine Dependencies), you can ignore this issue.

In order to assemble compiler output into something that works, as occasionlly does strange things to '.word' directives.  Directives of the form '.word sym1-sym2' are often emitted by compilers as part of jump tables.  Therefore, when as assembles a directive of the form '.word sym1-sym2', and the difference between sym1 and sym2 does not fit in 16 bits, as creates a "secondary jump table", immediately before the next label.  This secondary jump table is preceded by a short-jump to the first byte after the secondary table.  This short-jump prevents the flow of control from accidentally falling into the new table.  Inside the table is a long-jump to sym2.  The original '.word' contains sym1 minus the address of the long-jump to sym2.

If there were several occurrences of '.word sym1-sym2' before the secondary jump table, all of them are adjusted.  If there was a '.word sym3-sym4', that also did not fit in sixteen bits, a long-jump to sym4 is included in the secondary jump table, and the .word directives are adjusted to contain sym3 minus the address of the long-jump to sym4; and so on, for as many entries in the original jump table as necessary.


Deprecated Directives
Node: Deprecated, Next: , Prev: Word, Up: Pseudo Ops

Deprecated Directives

One day these directives won't work.  They are included for compatibility with older assemblers.

.abort

.app-file

.line


Machine Dependent Features
Node: Machine Dependencies, Next: Acknowledgements, Prev: Pseudo Ops, Up: Top

Machine Dependent Features

The machine instruction sets are (almost by definition) different on each machine where as runs.  Floating point representations vary as well, and as often supports a few additional directives or command-line options for compatibility with other assemblers on a particular platform.  Finally, some versions of as support special pseudo-instructions for branch optimization.

This chapter discusses most of these differences, though it does not include details on any machine's instruction set.  For details on that subject, see the hardware manufacturer's manual.

* Menu:

Vax-Dependent	VAX Dependent Features

AMD29K-Dependent	AMD 29K Dependent Features

H8/300-Dependent	Hitachi H8/300 Dependent Features

H8/500-Dependent	Hitachi H8/500 Dependent Features

HPPA-Dependent	HPPA Dependent Features

SH-Dependent	Hitachi SH Dependent Features

i960-Dependent	Intel 80960 Dependent Features

M68K-Dependent	M680x0 Dependent Features

Sparc-Dependent	SPARC Dependent Features

Z8000-Dependent	Z8000 Dependent Features

MIPS-Dependent	MIPS Dependent Features

i386-Dependent	80386 Dependent Features


VAX Dependent Features
Node: Vax-Dependent, Next: AMD29K-Dependent, Prev: , Up: Machine Dependencies

VAX Dependent Features

* Menu:

Vax-Opts	VAX Command-Line Options

VAX-float	VAX Floating Point

VAX-directives	Vax Machine Directives

VAX-opcodes	VAX Opcodes

VAX-branch	VAX Branch Improvement

VAX-operands	VAX Operands

VAX-no	Not Supported on VAX


VAX Command-Line Options
Node: Vax-Opts, Next: VAX-float, Prev: , Up: Vax-Dependent

VAX Command-Line Options

The Vax version of as accepts any of the following options, gives a warning message that the option was ignored and proceeds.  These options are for compatibility with scripts designed for other people's assemblers.

-D (Debug)

-S (Symbol Table)

-T (Token Trace)

These are obsolete options used to debug old assemblers.

-d (Displacement size for JUMPs)

This option expects a number following the '-d'.  Like options that expect filenames, the number may immediately follow the '-d' (old standard) or constitute the whole of the command line argument that follows '-d' (GNU standard).

-V (Virtualize Interpass Temporary File)

Some other assemblers use a temporary file.  This option commanded them to keep the information in active memory rather than in a disk file.  as always does this, so this option is redundant.

-J (JUMPify Longer Branches)

Many 32-bit computers permit a variety of branch instructions to do the same job.  Some of these instructions are short (and fast) but have a limited range; others are long (and slow) but can branch anywhere in virtual memory.  Often there are 3 flavors of branch: short, medium and long.  Some other assemblers would emit short and medium branches, unless told by this option to emit short and long branches.

-t (Temporary File Directory)

Some other assemblers may use a temporary file, and this option takes a filename being the directory to site the temporary file.  Since as does not use a temporary disk file, this option makes no difference.  '-t' needs exactly one filename.

The Vax version of the assembler accepts two options when compiled for VMS.  They are '-h', and '-+'.  The '-h' option prevents as from modifying the symbol-table entries for symbols that contain lowercase characters (I think).  The '-+' option causes as to print warning messages if the FILENAME part of the object file, or any symbol name is larger than 31 characters.  The '-+' option also inserts some code following the '_main' symbol so that the object file is compatible with Vax-11 "C".


VAX Floating Point
Node: VAX-float, Next: VAX-directives, Prev: Vax-Opts, Up: Vax-Dependent

VAX Floating Point

Conversion of flonums to floating point is correct, and compatible with previous assemblers.  Rounding is towards zero if the remainder is exactly half the least significant bit.

D, F, G and H floating point formats are understood.

Immediate floating literals (e.g. 'S`$6.9') are rendered correctly.  Again, rounding is towards zero in the boundary case.

The .float directive produces f format numbers.  The .double directive produces d format numbers.


Vax Machine Directives
Node: VAX-directives, Next: VAX-opcodes, Prev: VAX-float, Up: Vax-Dependent

Vax Machine Directives

The Vax version of the assembler supports four directives for generating Vax floating point constants.  They are described in the table below.

.dfloat

This expects zero or more flonums, separated by commas, and assembles Vax d format 64-bit floating point constants.

.ffloat

This expects zero or more flonums, separated by commas, and assembles Vax f format 32-bit floating point constants.

.gfloat

This expects zero or more flonums, separated by commas, and assembles Vax g format 64-bit floating point constants.

.hfloat

This expects zero or more flonums, separated by commas, and assembles Vax h format 128-bit floating point constants.


VAX Opcodes
Node: VAX-opcodes, Next: VAX-branch, Prev: VAX-directives, Up: Vax-Dependent

VAX Opcodes

All DEC mnemonics are supported.  Beware that case...  instructions have exactly 3 operands.  The dispatch table that follows the case... instruction should be made with .word statements.  This is compatible with all unix assemblers we know of.


VAX Branch Improvement
Node: VAX-branch, Next: VAX-operands, Prev: VAX-opcodes, Up: Vax-Dependent

VAX Branch Improvement

Certain pseudo opcodes are permitted.  They are for branch instructions.  They expand to the shortest branch instruction that reaches the target.  Generally these mnemonics are made by substituting 'j' for 'b' at the start of a DEC mnemonic.  This feature is included both for compatibility and to help compilers.  If you do not need this feature, avoid these opcodes.  Here are the mnemonics, and the code they can expand into.

jbsb

'Jsb' is already an instruction mnemonic, so we chose 'jbsb'.

(byte displacement)

^bsbb ...

(word displacement)

^bsbw ...

(long displacement)

^jsb ...

jbr

jr

Unconditional branch.

(byte displacement)

^brb ...

(word displacement)

^brw ...

(long displacement)

^jmp ...

jCOND

COND may be any one of the conditional branches neq, nequ, eql, eqlu, gtr, geq, lss, gtru, lequ, vc, vs, gequ, cc, lssu, cs.  COND may also be one of the bit tests bs, bc, bss, bcs, bsc, bcc, bssi, bcci, lbs, lbc.  NOTCOND is the opposite condition to COND.

(byte displacement)

^bCOND ...

(word displacement)

^bNOTCOND foo ; brw ... ; foo:

(long displacement)

^bNOTCOND foo ; jmp ... ; foo:

jacbX

X may be one of b d f g h l w.

(word displacement)

^OPCODE ...

(long displacement)

OPCODE ..., foo ;
brb bar ;
foo: jmp ... ;
bar:

jaobYYY

YYY may be one of lss leq.

jsobZZZ

ZZZ may be one of geq gtr.

(byte displacement)

^OPCODE ...

(word displacement)

OPCODE ..., foo ;
brb bar ;
foo: brw destination ;
bar:

(long displacement)

OPCODE ..., foo ;
brb bar ;
foo: jmp destination ;
bar:

aobleq

aoblss

sobgeq

sobgtr

(byte displacement)

^OPCODE ...

(word displacement)

OPCODE ..., foo ;
brb bar ;
foo: brw destination ;
bar:

(long displacement)

OPCODE ..., foo ;
brb bar ;
foo: jmp destination ;
bar:


VAX Operands
Node: VAX-operands, Next: VAX-no, Prev: VAX-branch, Up: Vax-Dependent

VAX Operands

The immediate character is '$' for Unix compatibility, not '#' as DEC writes it.

The indirect character is '*' for Unix compatibility, not '@' as DEC writes it.

The displacement sizing character is '`' (an accent grave) for Unix compatibility, not '^' as DEC writes it.  The letter preceding '`' may have either case.  'G' is not understood, but all other letters (b i l s w) are understood.

Register names understood are r0 r1 r2 ... r15 ap fp sp pc.  Upper and lower case letters are equivalent.

For instance

tstb *w`$4(r5)

Any expression is permitted in an operand.  Operands are comma separated.


Not Supported on VAX
Node: VAX-no, Next: , Prev: VAX-operands, Up: Vax-Dependent

Not Supported on VAX

Vax bit fields can not be assembled with as.  Someone can add the required code if they really need it.


AMD 29K Dependent Features
Node: AMD29K-Dependent, Next: H8/300-Dependent, Prev: Vax-Dependent, Up: Machine Dependencies

AMD 29K Dependent Features

* Menu:

AMD29K Options	Options

AMD29K Syntax	Syntax

AMD29K Floating Point	Floating Point

AMD29K Directives	AMD 29K Machine Directives

AMD29K Opcodes	Opcodes


Options
Node: AMD29K Options, Next: AMD29K Syntax, Prev: , Up: AMD29K-Dependent

Options

as has no additional command-line options for the AMD 29K family.


Syntax
Node: AMD29K Syntax, Next: AMD29K Floating Point, Prev: AMD29K Options, Up: AMD29K-Dependent

Syntax

* Menu:

AMD29K-Chars	Special Characters

AMD29K-Regs	Register Names


Special Characters
Node: AMD29K-Chars, Next: AMD29K-Regs, Prev: , Up: AMD29K Syntax

Special Characters

';' is the line comment character.

'@' can be used instead of a newline to separate statements.

The character '?' is permitted in identifiers (but may not begin an identifier).


Register Names
Node: AMD29K-Regs, Next: , Prev: AMD29K-Chars, Up: AMD29K Syntax

Register Names

General-purpose registers are represented by predefined symbols of the form 'GRnnn' (for global registers) or 'LRnnn' (for local registers), where nnn represents a number between 0 and 127, written with no leading zeros.  The leading letters may be in either upper or lower case; for example, 'gr13' and 'LR7' are both valid register names.

You may also refer to general-purpose registers by specifying the register number as the result of an expression (prefixed with '%%' to flag the expression as a register number):

%%expression

--where expression must be an absolute expression evaluating to a number between 0 and 255.  The range [0, 127] refers to global registers, and the range [128, 255] to local registers.

In addition, as understands the following protected special-purpose register names for the AMD 29K family:

  vab    chd    pc0
  ops    chc    pc1
  cps    rbp    pc2
  cfg    tmc    mmu
  cha    tmr    lru

These unprotected special-purpose register names are also recognized:

  ipc    alu    fpe
  ipa    bp     inte
  ipb    fc     fps
  q      cr     exop


Floating Point
Node: AMD29K Floating Point, Next: AMD29K Directives, Prev: AMD29K Syntax, Up: AMD29K-Dependent

Floating Point

The AMD 29K family uses IEEE floating-point numbers.


AMD 29K Machine Directives
Node: AMD29K Directives, Next: AMD29K Opcodes, Prev: AMD29K Floating Point, Up: AMD29K-Dependent

AMD 29K Machine Directives

.block size , fill

This directive emits size bytes, each of value fill.  Both size and fill are absolute expressions.  If the comma and fill are omitted, fill is assumed to be zero.

In other versions of the GNU assembler, this directive is called '.space'.

.cputype

This directive is ignored; it is accepted for compatibility with other AMD 29K assemblers.

.file

This directive is ignored; it is accepted for compatibility with other AMD 29K assemblers.

Warning: in other versions of the GNU assembler, .file is used for the directive called .app-file in the AMD 29K support.

.line

This directive is ignored; it is accepted for compatibility with other AMD 29K assemblers.

.sect

This directive is ignored; it is accepted for compatibility with other AMD 29K assemblers.

.use section name

Establishes the section and subsection for the following code; section name may be one of .text, .data, .data1, or .lit.  With one of the first three section name options, '.use' is equivalent to the machine directive section name; the remaining case, '.use .lit', is the same as '.data 200'.


Opcodes
Node: AMD29K Opcodes, Next: , Prev: AMD29K Directives, Up: AMD29K-Dependent

Opcodes

as implements all the standard AMD 29K opcodes.  No additional pseudo-instructions are needed on this family.

For information on the 29K machine instruction set, see `Am29000 User's Manual', Advanced Micro Devices, Inc.


H8/300 Dependent Features
Node: H8/300-Dependent, Next: H8/500-Dependent, Prev: AMD29K-Dependent, Up: Machine Dependencies

H8/300 Dependent Features

* Menu:

H8/300 Options	Options

H8/300 Syntax	Syntax

H8/300 Floating Point	Floating Point

H8/300 Directives	H8/300 Machine Directives

H8/300 Opcodes	Opcodes


Options
Node: H8/300 Options, Next: H8/300 Syntax, Prev: , Up: H8/300-Dependent

Options

as has no additional command-line options for the Hitachi H8/300 family.


Syntax
Node: H8/300 Syntax, Next: H8/300 Floating Point, Prev: H8/300 Options, Up: H8/300-Dependent

Syntax

* Menu:

H8/300-Chars	Special Characters

H8/300-Regs	Register Names

H8/300-Addressing	Addressing Modes


Special Characters
Node: H8/300-Chars, Next: H8/300-Regs, Prev: , Up: H8/300 Syntax

Special Characters

';' is the line comment character.

'$' can be used instead of a newline to separate statements.  Therefore you may not use '$' in symbol names on the H8/300.


Register Names
Node: H8/300-Regs, Next: H8/300-Addressing, Prev: H8/300-Chars, Up: H8/300 Syntax

Register Names

You can use predefined symbols of the form 'rnh' and 'rnl' to refer to the H8/300 registers as sixteen 8-bit general-purpose registers.  n is a digit from '0' to '7'); for instance, both 'r0h' and 'r7l' are valid register names.

You can also use the eight predefined symbols 'rn' to refer to the H8/300 registers as 16-bit registers (you must use this form for addressing).

On the H8/300H, you can also use the eight predefined symbols 'ern' ('er0' ... 'er7') to refer to the 32-bit general purpose registers.

The two control registers are called pc (program counter; a 16-bit register, except on the H8/300H where it is 24 bits) and ccr (condition code register; an 8-bit register).  r7 is used as the stack pointer, and can also be called sp.


Addressing Modes
Node: H8/300-Addressing, Next: , Prev: H8/300-Regs, Up: H8/300 Syntax

Addressing Modes

as understands the following addressing modes for the H8/300:

rn

Register direct

@rn

Register indirect

@(d, rn)

@(d:16, rn)

@(d:24, rn)

Register indirect: 16-bit or 24-bit displacement d from register n.  (24-bit displacements are only meaningful on the H8/300H.)

@rn+

Register indirect with post-increment

@-rn

Register indirect with pre-decrement

@aa

@aa:8

@aa:16

@aa:24

Absolute address aa.  (The address size ':24' only makes sense on the H8/300H.)

#xx

#xx:8

#xx:16

#xx:32

Immediate data xx.  You may specify the ':8', ':16', or ':32' for clarity, if you wish; but as neither requires this nor uses it--the data size required is taken from context.

@@aa

@@aa:8

Memory indirect.  You may specify the ':8' for clarity, if you wish; but as neither requires this nor uses it.


Floating Point
Node: H8/300 Floating Point, Next: H8/300 Directives, Prev: H8/300 Syntax, Up: H8/300-Dependent

Floating Point

The H8/300 family has no hardware floating point, but the .float directive generates IEEE floating-point numbers for compatibility with other development tools.


H8/300 Machine Directives
Node: H8/300 Directives, Next: H8/300 Opcodes, Prev: H8/300 Floating Point, Up: H8/300-Dependent

H8/300 Machine Directives

as has only one machine-dependent directive for the H8/300:

.h8300h

Recognize and emit additional instructions for the H8/300H variant, and also make .int emit 32-bit numbers rather than the usual (16-bit) for the H8/300 family.

On the H8/300 family (including the H8/300H) '.word' directives generate 16-bit numbers.


Opcodes
Node: H8/300 Opcodes, Next: , Prev: H8/300 Directives, Up: H8/300-Dependent

Opcodes

For detailed information on the H8/300 machine instruction set, see `H8/300 Series Programming Manual' (Hitachi ADE-602-025).  For information specific to the H8/300H, see `H8/300H Series Programming Manual' (Hitachi).

{No Value For "rd{}AS"} implements all the standard H8/300 opcodes.  No additional pseudo-instructions are needed on this family.

The following table summarizes the H8/300 opcodes, and their arguments.  Entries marked '*' are opcodes used only on the H8/300H.

         Legend:
            Rs   source register
            Rd   destination register
            abs  absolute address
            imm  immediate data
         disp:N  N-bit displacement from a register
        pcrel:N  N-bit displacement relative to program counter

   add.b #imm,rd              *  andc #imm,ccr
   add.b rs,rd                   band #imm,rd
   add.w rs,rd                   band #imm,@rd
*  add.w #imm,rd                 band #imm,@abs:8
*  add.l rs,rd                   bra  pcrel:8
*  add.l #imm,rd              *  bra  pcrel:16
   adds #imm,rd                  bt   pcrel:8
   addx #imm,rd               *  bt   pcrel:16
   addx rs,rd                    brn  pcrel:8
   and.b #imm,rd              *  brn  pcrel:16
   and.b rs,rd                   bf   pcrel:8
*  and.w rs,rd                *  bf   pcrel:16
*  and.w #imm,rd                 bhi  pcrel:8
*  and.l #imm,rd              *  bhi  pcrel:16
*  and.l rs,rd                   bls  pcrel:8

*  bls  pcrel:16                 bld  #imm,rd
   bcc  pcrel:8                  bld  #imm,@rd
*  bcc  pcrel:16                 bld  #imm,@abs:8
   bhs  pcrel:8                  bnot #imm,rd
*  bhs  pcrel:16                 bnot #imm,@rd
   bcs  pcrel:8                  bnot #imm,@abs:8
*  bcs  pcrel:16                 bnot rs,rd
   blo  pcrel:8                  bnot rs,@rd
*  blo  pcrel:16                 bnot rs,@abs:8
   bne  pcrel:8                  bor  #imm,rd
*  bne  pcrel:16                 bor  #imm,@rd
   beq  pcrel:8                  bor  #imm,@abs:8
*  beq  pcrel:16                 bset #imm,rd
   bvc  pcrel:8                  bset #imm,@rd
*  bvc  pcrel:16                 bset #imm,@abs:8
   bvs  pcrel:8                  bset rs,rd
*  bvs  pcrel:16                 bset rs,@rd
   bpl  pcrel:8                  bset rs,@abs:8
*  bpl  pcrel:16                 bsr  pcrel:8
   bmi  pcrel:8                  bsr  pcrel:16
*  bmi  pcrel:16                 bst  #imm,rd
   bge  pcrel:8                  bst  #imm,@rd
*  bge  pcrel:16                 bst  #imm,@abs:8
   blt  pcrel:8                  btst #imm,rd
*  blt  pcrel:16                 btst #imm,@rd
   bgt  pcrel:8                  btst #imm,@abs:8
*  bgt  pcrel:16                 btst rs,rd
   ble  pcrel:8                  btst rs,@rd
*  ble  pcrel:16                 btst rs,@abs:8
   bclr #imm,rd                  bxor #imm,rd
   bclr #imm,@rd                 bxor #imm,@rd
   bclr #imm,@abs:8              bxor #imm,@abs:8
   bclr rs,rd                    cmp.b #imm,rd
   bclr rs,@rd                   cmp.b rs,rd
   bclr rs,@abs:8                cmp.w rs,rd
   biand #imm,rd                 cmp.w rs,rd
   biand #imm,@rd             *  cmp.w #imm,rd
   biand #imm,@abs:8          *  cmp.l #imm,rd
   bild #imm,rd               *  cmp.l rs,rd
   bild #imm,@rd                 daa  rs
   bild #imm,@abs:8              das  rs
   bior #imm,rd                  dec.b rs
   bior #imm,@rd              *  dec.w #imm,rd
   bior #imm,@abs:8           *  dec.l #imm,rd
   bist #imm,rd                  divxu.b rs,rd
   bist #imm,@rd              *  divxu.w rs,rd
   bist #imm,@abs:8           *  divxs.b rs,rd
   bixor #imm,rd              *  divxs.w rs,rd
   bixor #imm,@rd                eepmov
   bixor #imm,@abs:8          *  eepmovw

*  exts.w rd                     mov.w rs,@abs:16
*  exts.l rd                  *  mov.l #imm,rd
*  extu.w rd                  *  mov.l rs,rd
*  extu.l rd                  *  mov.l @rs,rd
   inc  rs                    *  mov.l @(disp:16,rs),rd
*  inc.w #imm,rd              *  mov.l @(disp:24,rs),rd
*  inc.l #imm,rd              *  mov.l @rs+,rd
   jmp  @rs                   *  mov.l @abs:16,rd
   jmp  abs                   *  mov.l @abs:24,rd
   jmp  @@abs:8               *  mov.l rs,@rd
   jsr  @rs                   *  mov.l rs,@(disp:16,rd)
   jsr  abs                   *  mov.l rs,@(disp:24,rd)
   jsr  @@abs:8               *  mov.l rs,@-rd
   ldc  #imm,ccr              *  mov.l rs,@abs:16
   ldc  rs,ccr                *  mov.l rs,@abs:24
*  ldc  @abs:16,ccr              movfpe @abs:16,rd
*  ldc  @abs:24,ccr              movtpe rs,@abs:16
*  ldc  @(disp:16,rs),ccr        mulxu.b rs,rd
*  ldc  @(disp:24,rs),ccr     *  mulxu.w rs,rd
*  ldc  @rs+,ccr              *  mulxs.b rs,rd
*  ldc  @rs,ccr               *  mulxs.w rs,rd
*  mov.b @(disp:24,rs),rd        neg.b rs
*  mov.b rs,@(disp:24,rd)     *  neg.w rs
   mov.b @abs:16,rd           *  neg.l rs
   mov.b rs,rd                   nop
   mov.b @abs:8,rd               not.b rs
   mov.b rs,@abs:8            *  not.w rs
   mov.b rs,rd                *  not.l rs
   mov.b #imm,rd                 or.b #imm,rd
   mov.b @rs,rd                  or.b rs,rd
   mov.b @(disp:16,rs),rd     *  or.w #imm,rd
   mov.b @rs+,rd              *  or.w rs,rd
   mov.b @abs:8,rd            *  or.l #imm,rd
   mov.b rs,@rd               *  or.l rs,rd
   mov.b rs,@(disp:16,rd)        orc  #imm,ccr
   mov.b rs,@-rd                 pop.w rs
   mov.b rs,@abs:8            *  pop.l rs
   mov.w rs,@rd                  push.w rs
*  mov.w @(disp:24,rs),rd     *  push.l rs
*  mov.w rs,@(disp:24,rd)        rotl.b rs
*  mov.w @abs:24,rd           *  rotl.w rs
*  mov.w rs,@abs:24           *  rotl.l rs
   mov.w rs,rd                   rotr.b rs
   mov.w #imm,rd              *  rotr.w rs
   mov.w @rs,rd               *  rotr.l rs
   mov.w @(disp:16,rs),rd        rotxl.b rs
   mov.w @rs+,rd              *  rotxl.w rs
   mov.w @abs:16,rd           *  rotxl.l rs
   mov.w rs,@(disp:16,rd)        rotxr.b rs
   mov.w rs,@-rd              *  rotxr.w rs

*  rotxr.l rs                 *  stc  ccr,@(disp:24,rd)
   bpt                        *  stc  ccr,@-rd
   rte                        *  stc  ccr,@abs:16
   rts                        *  stc  ccr,@abs:24
   shal.b rs                     sub.b rs,rd
*  shal.w rs                     sub.w rs,rd
*  shal.l rs                  *  sub.w #imm,rd
   shar.b rs                  *  sub.l rs,rd
*  shar.w rs                  *  sub.l #imm,rd
*  shar.l rs                     subs #imm,rd
   shll.b rs                     subx #imm,rd
*  shll.w rs                     subx rs,rd
*  shll.l rs                  *  trapa #imm
   shlr.b rs                     xor  #imm,rd
*  shlr.w rs                     xor  rs,rd
*  shlr.l rs                  *  xor.w #imm,rd
   sleep                      *  xor.w rs,rd
   stc  ccr,rd                *  xor.l #imm,rd
*  stc  ccr,@rs               *  xor.l rs,rd
*  stc  ccr,@(disp:16,rd)        xorc #imm,ccr

Four H8/300 instructions (add, cmp, mov, sub) are defined with variants using the suffixes '.b', '.w', and '.l' to specify the size of a memory operand.  as supports these suffixes, but does not require them; since one of the operands is always a register, as can deduce the correct size.

For example, since r0 refers to a 16-bit register,

mov    r0,@foo

is equivalent to

mov.w  r0,@foo

If you use the size suffixes, as issues a warning when the suffix and the register size do not match.


H8/500 Dependent Features
Node: H8/500-Dependent, Next: HPPA-Dependent, Prev: H8/300-Dependent, Up: Machine Dependencies

H8/500 Dependent Features

* Menu:

H8/500 Options	Options

H8/500 Syntax	Syntax

H8/500 Floating Point	Floating Point

H8/500 Directives	H8/500 Machine Directives

H8/500 Opcodes	Opcodes


Options
Node: H8/500 Options, Next: H8/500 Syntax, Prev: , Up: H8/500-Dependent

Options

as has no additional command-line options for the Hitachi H8/500 family.


Syntax
Node: H8/500 Syntax, Next: H8/500 Floating Point, Prev: H8/500 Options, Up: H8/500-Dependent

Syntax

* Menu:

H8/500-Chars	Special Characters

H8/500-Regs	Register Names

H8/500-Addressing	Addressing Modes


Special Characters
Node: H8/500-Chars, Next: H8/500-Regs, Prev: , Up: H8/500 Syntax

Special Characters

'!' is the line comment character.

';' can be used instead of a newline to separate statements.

Since '$' has no special meaning, you may use it in symbol names.


Register Names
Node: H8/500-Regs, Next: H8/500-Addressing, Prev: H8/500-Chars, Up: H8/500 Syntax

Register Names

You can use the predefined symbols 'r0', 'r1', 'r2', 'r3', 'r4', 'r5', 'r6', and 'r7' to refer to the H8/500 registers.

The H8/500 also has these control registers:

cp

code pointer

dp

data pointer

bp

base pointer

tp

stack top pointer

ep

extra pointer

sr

status register

ccr

condition code register

All registers are 16 bits long.  To represent 32 bit numbers, use two adjacent registers; for distant memory addresses, use one of the segment pointers (cp for the program counter; dp for r0-r3; ep for r4 and r5; and tp for r6 and r7.


Addressing Modes
Node: H8/500-Addressing, Next: , Prev: H8/500-Regs, Up: H8/500 Syntax

Addressing Modes

as understands the following addressing modes for the H8/500:

Rn

Register direct

@Rn

Register indirect

@(d:8, Rn)

Register indirect with 8 bit signed displacement

@(d:16, Rn)

Register indirect with 16 bit signed displacement

@-Rn

Register indirect with pre-decrement

@Rn+

Register indirect with post-increment

@aa:8

8 bit absolute address

@aa:16

16 bit absolute address

#xx:8

8 bit immediate

#xx:16

16 bit immediate


Floating Point
Node: H8/500 Floating Point, Next: H8/500 Directives, Prev: H8/500 Syntax, Up: H8/500-Dependent

Floating Point

The H8/500 family uses IEEE floating-point numbers.


H8/500 Machine Directives
Node: H8/500 Directives, Next: H8/500 Opcodes, Prev: H8/500 Floating Point, Up: H8/500-Dependent

H8/500 Machine Directives

as has no machine-dependent directives for the H8/500.  However, on this platform the '.int' and '.word' directives generate 16-bit numbers.


Opcodes
Node: H8/500 Opcodes, Next: , Prev: H8/500 Directives, Up: H8/500-Dependent

Opcodes

For detailed information on the H8/500 machine instruction set, see `H8/500 Series Programming Manual' (Hitachi M21T001).

{No Value For "rd{}AS"} implements all the standard H8/500 opcodes.  No additional pseudo-instructions are needed on this family.

The following table summarizes H8/500 opcodes and their operands:

Legend:
abs8      8-bit absolute address
abs16     16-bit absolute address
abs24     24-bit absolute address
crb       ccr, br, ep, dp, tp, dp
disp8     8-bit displacement
ea        rn, @rn, @(d:8, rn), @(d:16, rn),
          @-rn, @rn+, @aa:8, @aa:16,
          #xx:8, #xx:16
ea_mem    @rn, @(d:8, rn), @(d:16, rn),
          @-rn, @rn+, @aa:8, @aa:16
ea_noimm  rn, @rn, @(d:8, rn), @(d:16, rn),
          @-rn, @rn+, @aa:8, @aa:16
fp        r6
imm4      4-bit immediate data
imm8      8-bit immediate data
imm16     16-bit immediate data
pcrel8    8-bit offset from program counter
pcrel16   16-bit offset from program counter
qim       -2, -1, 1, 2
rd        any register
rs        a register distinct from rd
rlist     comma-separated list of registers in parentheses;
          register ranges rd-rs are allowed
sp        stack pointer (r7)
sr        status register
sz        size; '.b' or '.w'.  If omitted, default '.w'

ldc[.b] ea,crb                 bcc[.w] pcrel16
ldc[.w] ea,sr                  bcc[.b] pcrel8
add[:q] sz qim,ea_noimm        bhs[.w] pcrel16
add[:g] sz ea,rd               bhs[.b] pcrel8
adds sz ea,rd                  bcs[.w] pcrel16
addx sz ea,rd                  bcs[.b] pcrel8
and sz ea,rd                   blo[.w] pcrel16
andc[.b] imm8,crb              blo[.b] pcrel8
andc[.w] imm16,sr              bne[.w] pcrel16
bpt                            bne[.b] pcrel8
bra[.w] pcrel16                beq[.w] pcrel16
bra[.b] pcrel8                 beq[.b] pcrel8
bt[.w] pcrel16                 bvc[.w] pcrel16
bt[.b] pcrel8                  bvc[.b] pcrel8
brn[.w] pcrel16                bvs[.w] pcrel16
brn[.b] pcrel8                 bvs[.b] pcrel8
bf[.w] pcrel16                 bpl[.w] pcrel16
bf[.b] pcrel8                  bpl[.b] pcrel8
bhi[.w] pcrel16                bmi[.w] pcrel16
bhi[.b] pcrel8                 bmi[.b] pcrel8
bls[.w] pcrel16                bge[.w] pcrel16
bls[.b] pcrel8                 bge[.b] pcrel8

blt[.w] pcrel16                mov[:g][.b] imm8,ea_mem
blt[.b] pcrel8                 mov[:g][.w] imm16,ea_mem
bgt[.w] pcrel16                movfpe[.b] ea,rd
bgt[.b] pcrel8                 movtpe[.b] rs,ea_noimm
ble[.w] pcrel16                mulxu sz ea,rd
ble[.b] pcrel8                 neg sz ea
bclr sz imm4,ea_noimm          nop
bclr sz rs,ea_noimm            not sz ea
bnot sz imm4,ea_noimm          or sz ea,rd
bnot sz rs,ea_noimm            orc[.b] imm8,crb
bset sz imm4,ea_noimm          orc[.w] imm16,sr
bset sz rs,ea_noimm            pjmp abs24
bsr[.b] pcrel8                 pjmp @rd
bsr[.w] pcrel16                pjsr abs24
btst sz imm4,ea_noimm          pjsr @rd
btst sz rs,ea_noimm            prtd imm8
clr sz ea                      prtd imm16
cmp[:e][.b] imm8,rd            prts
cmp[:i][.w] imm16,rd           rotl sz ea
cmp[:g].b imm8,ea_noimm        rotr sz ea
cmp[:g][.w] imm16,ea_noimm     rotxl sz ea
Cmp[:g] sz ea,rd               rotxr sz ea
dadd rs,rd                     rtd imm8
divxu sz ea,rd                 rtd imm16
dsub rs,rd                     rts
exts[.b] rd                    scb/f rs,pcrel8
extu[.b] rd                    scb/ne rs,pcrel8
jmp @rd                        scb/eq rs,pcrel8
jmp @(imm8,rd)                 shal sz ea
jmp @(imm16,rd)                shar sz ea
jmp abs16                      shll sz ea
jsr @rd                        shlr sz ea
jsr @(imm8,rd)                 sleep
jsr @(imm16,rd)                stc[.b] crb,ea_noimm
jsr abs16                      stc[.w] sr,ea_noimm
ldm @sp+,(rlist)               stm (rlist),@-sp
link fp,imm8                   sub sz ea,rd
link fp,imm16                  subs sz ea,rd
mov[:e][.b] imm8,rd            subx sz ea,rd
mov[:i][.w] imm16,rd           swap[.b] rd
mov[:l][.w] abs8,rd            tas[.b] ea
mov[:l].b abs8,rd              trapa imm4
mov[:s][.w] rs,abs8            trap/vs
mov[:s].b rs,abs8              tst sz ea
mov[:f][.w] @(disp8,fp),rd     unlk fp
mov[:f][.w] rs,@(disp8,fp)     xch[.w] rs,rd
mov[:f].b @(disp8,fp),rd       xor sz ea,rd
mov[:f].b rs,@(disp8,fp)       xorc.b imm8,crb
mov[:g] sz rs,ea_mem           xorc.w imm16,sr
mov[:g] sz ea,rd


HPPA Dependent Features
Node: HPPA-Dependent, Next: SH-Dependent, Prev: H8/500-Dependent, Up: Machine Dependencies

HPPA Dependent Features

* Menu:

HPPA Notes	Notes

HPPA Options	Options

HPPA Syntax	Syntax

HPPA Floating Point	Floating Point

HPPA Directives	HPPA Machine Directives

HPPA Opcodes	Opcodes


Notes
Node: HPPA Notes, Next: HPPA Options, Prev: , Up: HPPA-Dependent

Notes

As a back end for GNU CC as has been throughly tested and should work extremely well.  We have tested it only minimally on hand written assembly code and no one has tested it much on the assembly output from the HP compilers.

The format of the debugging sections has changed since the original as port (version 1.3X) was released; therefore, you must rebuild all HPPA objects and libraries with the new assembler so that you can debug the final executable.

The HPPA as port generates a small subset of the relocations available in the SOM and ELF object file formats.  Additional relocation support will be added as it becomes necessary.


Options
Node: HPPA Options, Next: HPPA Syntax, Prev: HPPA Notes, Up: HPPA-Dependent

Options

{No Value For "rd{}AS"} has no machine-dependent command-line options for the HPPA.


Syntax
Node: HPPA Syntax, Next: HPPA Floating Point, Prev: HPPA Options, Up: HPPA-Dependent

Syntax

The assembler syntax closely follows the HPPA instruction set reference manual; assembler directives and general syntax closely follow the HPPA assembly language reference manual, with a few noteworthy differences.

First, a colon may immediately follow a label definition.  This is simply for compatibility with how most assembly language programmers write code.

Some obscure expression parsing problems may affect hand written code which uses the spop instructions, or code which makes significant use of the ! line separator.

{No Value For "rd{}AS"} is much less forgiving about missing arguments and other similar oversights than the HP assembler.  as notifies you of missing arguments as syntax errors; this is regarded as a feature, not a bug.

Finally, as allows you to use an external symbol without explicitly importing the symbol.  Warning: in the future this will be an error for HPPA targets.

Special characters for HPPA targets include:

';' is the line comment character.

'!' can be used instead of a newline to separate statements.

Since '$' has no special meaning, you may use it in symbol names.


Floating Point
Node: HPPA Floating Point, Next: HPPA Directives, Prev: HPPA Syntax, Up: HPPA-Dependent

Floating Point

The HPPA family uses IEEE floating-point numbers.


HPPA Assembler Directives
Node: HPPA Directives, Next: HPPA Opcodes, Prev: HPPA Floating Point, Up: HPPA-Dependent

HPPA Assembler Directives

{No Value For "rd{}AS"} for the HPPA supports many additional directives for compatibility with the native assembler.  This section describes them only briefly.  For detailed information on HPPA-specific assembler directives, see `HP9000 Series 800 Assembly Language Reference Manual' (HP 92432-90001).

as does not support the following assembler directives described in the HP manual:

.endm           .liston
.enter          .locct
.leave          .macro
.listoff

Beyond those implemented for compatibility, as supports one additional assembler directive for the HPPA: .param.  It conveys register argument locations for static functions.  Its syntax closely follows the .export directive.

These are the additional directives in as for the HPPA:

.block n

.blockz n

Reserve n bytes of storage, and initialize them to zero.

.call

Mark the beginning of a procedure call.  Only the special case with no arguments is allowed.

.callinfo [ param=value, ... ]  [ flag, ... ]

Specify a number of parameters and flags that define the environment for a procedure.

param may be any of 'frame' (frame size), 'entry_gr' (end of general register range), 'entry_fr' (end of float register range), 'entry_sr' (end of space register range).

The values for flag are 'calls' or 'caller' (proc has subroutines), 'no_calls' (proc does not call subroutines), 'save_rp' (preserve return pointer), 'save_sp' (proc preserves stack pointer), 'no_unwind' (do not unwind this proc), 'hpux_int' (proc is interrupt routine).

.code

Assemble into the standard section called '$TEXT$', subsection '$CODE$'.

.copyright "string"

In the SOM object format, insert string into the object code, marked as a copyright string.

.copyright "string"

In the ELF object format, insert string into the object code, marked as a version string.

.enter

Not yet supported; the assembler rejects programs containing this directive.

.entry

Mark the beginning of a procedure.

.exit

Mark the end of a procedure.

.export name [ ,typ ]  [ ,param=r ]

Make a procedure name available to callers.  typ, if present, must be one of 'absolute', 'code' (ELF only, not SOM), 'data', 'entry', 'data', 'entry', 'millicode', 'plabel', 'pri_prog', or 'sec_prog'.

param, if present, provides either relocation information for the procedure arguments and result, or a privilege level.  param may be 'argwn' (where n ranges from 0 to 3, and indicates one of four one-word arguments); 'rtnval' (the procedure's result); or 'priv_lev' (privilege level).  For arguments or the result, r specifies how to relocate, and must be one of 'no' (not relocatable), 'gr' (argument is in general register), 'fr' (in floating point register), or 'fu' (upper half of float register).  For 'priv_lev', r is an integer.

.half n

Define a two-byte integer constant n; synonym for the portable as directive .short.

.import name [ ,typ ]

Converse of .export; make a procedure available to call.  The arguments use the same conventions as the first two arguments for .export.

.label name

Define name as a label for the current assembly location.

.leave

Not yet supported; the assembler rejects programs containing this directive.

.origin lc

Advance location counter to lc. Synonym for the {No Value For "as"} portable directive .org.

.param name [ ,typ ]  [ ,param=r ]

Similar to .export, but used for static procedures.

.proc

Use preceding the first statement of a procedure.

.procend

Use following the last statement of a procedure.

label .reg expr

Synonym for .equ; define label with the absolute expression expr as its value.

.space secname [ ,params ]

Switch to section secname, creating a new section by that name if necessary.  You may only use params when creating a new section, not when switching to an existing one.  secname may identify a section by number rather than by name.

If specified, the list params declares attributes of the section, identified by keywords.  The keywords recognized are 'spnum=exp' (identify this section by the number exp, an absolute expression), 'sort=exp' (order sections according to this sort key when linking; exp is an absolute expression), 'unloadable' (section contains no loadable data), 'notdefined' (this section defined elsewhere), and 'private' (data in this section not available to other programs).

.spnum secnam

Allocate four bytes of storage, and initialize them with the section number of the section named secnam.  (You can define the section number with the HPPA .space directive.)

.string "str"

Copy the characters in the string str to the object file.  See Strings, for information on escape sequences you can use in as strings.

Warning! The HPPA version of .string differs from the usual as definition: it does not write a zero byte after copying str.

.stringz "str"

Like .string, but appends a zero byte after copying str to object file.

.subspa name [ ,params ]

Similar to .space, but selects a subsection name within the current section.  You may only specify params when you create a subsection (in the first instance of .subspa for this name).

If specified, the list params declares attributes of the subsection, identified by keywords.  The keywords recognized are 'quad=expr' ("quadrant" for this subsection), 'align=expr' (alignment for beginning of this subsection; a power of two), 'access=expr' (value for "access rights" field), 'sort=expr' (sorting order for this subspace in link), 'code_only' (subsection contains only code), 'unloadable' (subsection cannot be loaded into memory), 'common' (subsection is common block), 'dup_comm' (initialized data may have duplicate names), or 'zero' (subsection is all zeros, do not write in object file).

.version "str"

Write str as version identifier in object code.


Opcodes
Node: HPPA Opcodes, Next: , Prev: HPPA Directives, Up: HPPA-Dependent

Opcodes

For detailed information on the HPPA machine instruction set, see `PA-RISC Architecture and Instruction Set Reference Manual' (HP 09740-90039).


Hitachi SH Dependent Features
Node: SH-Dependent, Next: i960-Dependent, Prev: HPPA-Dependent, Up: Machine Dependencies

Hitachi SH Dependent Features

* Menu:

SH Options	Options

SH Syntax	Syntax

SH Floating Point	Floating Point

SH Directives	SH Machine Directives

SH Opcodes	Opcodes


Options
Node: SH Options, Next: SH Syntax, Prev: , Up: SH-Dependent

Options

as has no additional command-line options for the Hitachi SH family.


Syntax
Node: SH Syntax, Next: SH Floating Point, Prev: SH Options, Up: SH-Dependent

Syntax

* Menu:

SH-Chars	Special Characters

SH-Regs	Register Names

SH-Addressing	Addressing Modes


Special Characters
Node: SH-Chars, Next: SH-Regs, Prev: , Up: SH Syntax

Special Characters

'!' is the line comment character.

You can use ';' instead of a newline to separate statements.

Since '$' has no special meaning, you may use it in symbol names.


Register Names
Node: SH-Regs, Next: SH-Addressing, Prev: SH-Chars, Up: SH Syntax

Register Names

You can use the predefined symbols 'r0', 'r1', 'r2', 'r3', 'r4', 'r5', 'r6', 'r7', 'r8', 'r9', 'r10', 'r11', 'r12', 'r13', 'r14', and 'r15' to refer to the SH registers.

The SH also has these control registers:

pr

procedure register (holds return address)

pc

program counter

mach

macl

high and low multiply accumulator registers

sr

status register

gbr

global base register

vbr

vector base register (for interrupt vectors)


Addressing Modes
Node: SH-Addressing, Next: , Prev: SH-Regs, Up: SH Syntax

Addressing Modes

as understands the following addressing modes for the SH.  Rn in the following refers to any of the numbered registers, but not the control registers.

Rn

Register direct

@Rn

Register indirect

@-Rn

Register indirect with pre-decrement

@Rn+

Register indirect with post-increment

@(disp, Rn)

Register indirect with displacement

@(R0, Rn)

Register indexed

@(disp, GBR)

GBR offset

@(R0, GBR)

GBR indexed

addr

@(disp, PC)

PC relative address (for branch or for addressing memory).  The as implementation allows you to use the simpler form addr anywhere a PC relative address is called for; the alternate form is supported for compatibility with other assemblers.

#imm

Immediate data


Floating Point
Node: SH Floating Point, Next: SH Directives, Prev: SH Syntax, Up: SH-Dependent

Floating Point

The SH family uses IEEE floating-point numbers.


SH Machine Directives
Node: SH Directives, Next: SH Opcodes, Prev: SH Floating Point, Up: SH-Dependent

SH Machine Directives

as has no machine-dependent directives for the SH.


Opcodes
Node: SH Opcodes, Next: , Prev: SH Directives, Up: SH-Dependent

Opcodes

For detailed information on the SH machine instruction set, see `SH-Microcomputer User's Manual' (Hitachi Micro Systems, Inc.).

{No Value For "rd{}AS"} implements all the standard SH opcodes.  No additional pseudo-instructions are needed on this family.  Note, however, that because as supports a simpler form of PC-relative addressing, you may simply write (for example)

mov.l  bar,r0

where other assemblers might require an explicit displacement to bar from the program counter:

mov.l  @(disp, PC)

Here is a summary of SH opcodes:

Legend:
Rn        a numbered register
Rm        another numbered register
#imm      immediate data
disp      displacement
disp8     8-bit displacement
disp12    12-bit displacement

add #imm,Rn                    lds.l @Rn+,PR
add Rm,Rn                      mac.w @Rm+,@Rn+
addc Rm,Rn                     mov #imm,Rn
addv Rm,Rn                     mov Rm,Rn
and #imm,R0                    mov.b Rm,@(R0,Rn)
and Rm,Rn                      mov.b Rm,@-Rn
and.b #imm,@(R0,GBR)           mov.b Rm,@Rn
bf disp8                       mov.b @(disp,Rm),R0
bra disp12                     mov.b @(disp,GBR),R0
bsr disp12                     mov.b @(R0,Rm),Rn
bt disp8                       mov.b @Rm+,Rn
clrmac                         mov.b @Rm,Rn
clrt                           mov.b R0,@(disp,Rm)
cmp/eq #imm,R0                 mov.b R0,@(disp,GBR)
cmp/eq Rm,Rn                   mov.l Rm,@(disp,Rn)
cmp/ge Rm,Rn                   mov.l Rm,@(R0,Rn)
cmp/gt Rm,Rn                   mov.l Rm,@-Rn
cmp/hi Rm,Rn                   mov.l Rm,@Rn
cmp/hs Rm,Rn                   mov.l @(disp,Rn),Rm
cmp/pl Rn                      mov.l @(disp,GBR),R0
cmp/pz Rn                      mov.l @(disp,PC),Rn
cmp/str Rm,Rn                  mov.l @(R0,Rm),Rn
div0s Rm,Rn                    mov.l @Rm+,Rn
div0u                          mov.l @Rm,Rn
div1 Rm,Rn                     mov.l R0,@(disp,GBR)
exts.b Rm,Rn                   mov.w Rm,@(R0,Rn)
exts.w Rm,Rn                   mov.w Rm,@-Rn
extu.b Rm,Rn                   mov.w Rm,@Rn
extu.w Rm,Rn                   mov.w @(disp,Rm),R0
jmp @Rn                        mov.w @(disp,GBR),R0
jsr @Rn                        mov.w @(disp,PC),Rn
ldc Rn,GBR                     mov.w @(R0,Rm),Rn
ldc Rn,SR                      mov.w @Rm+,Rn
ldc Rn,VBR                     mov.w @Rm,Rn
ldc.l @Rn+,GBR                 mov.w R0,@(disp,Rm)
ldc.l @Rn+,SR                  mov.w R0,@(disp,GBR)
ldc.l @Rn+,VBR                 mova @(disp,PC),R0
lds Rn,MACH                    movt Rn
lds Rn,MACL                    muls Rm,Rn
lds Rn,PR                      mulu Rm,Rn
lds.l @Rn+,MACH                neg Rm,Rn
lds.l @Rn+,MACL                negc Rm,Rn

nop                            stc VBR,Rn
not Rm,Rn                      stc.l GBR,@-Rn
or #imm,R0                     stc.l SR,@-Rn
or Rm,Rn                       stc.l VBR,@-Rn
or.b #imm,@(R0,GBR)            sts MACH,Rn
rotcl Rn                       sts MACL,Rn
rotcr Rn                       sts PR,Rn
rotl Rn                        sts.l MACH,@-Rn
rotr Rn                        sts.l MACL,@-Rn
rte                            sts.l PR,@-Rn
rts                            sub Rm,Rn
sett                           subc Rm,Rn
shal Rn                        subv Rm,Rn
shar Rn                        swap.b Rm,Rn
shll Rn                        swap.w Rm,Rn
shll16 Rn                      tas.b @Rn
shll2 Rn                       trapa #imm
shll8 Rn                       tst #imm,R0
shlr Rn                        tst Rm,Rn
shlr16 Rn                      tst.b #imm,@(R0,GBR)
shlr2 Rn                       xor #imm,R0
shlr8 Rn                       xor Rm,Rn
sleep                          xor.b #imm,@(R0,GBR)
stc GBR,Rn                     xtrct Rm,Rn
stc SR,Rn


Intel 80960 Dependent Features
Node: i960-Dependent, Next: M68K-Dependent, Prev: SH-Dependent, Up: Machine Dependencies

Intel 80960 Dependent Features

* Menu:

Options-i960	i960 Command-line Options

Floating Point-i960	Floating Point

Directives-i960	i960 Machine Directives

Opcodes for i960	i960 Opcodes


i960 Command-line Options
Node: Options-i960, Next: Floating Point-i960, Prev: , Up: i960-Dependent

i960 Command-line Options

-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC

Select the 80960 architecture.  Instructions or features not supported by the selected architecture cause fatal errors.

'-ACA' is equivalent to '-ACA_A'; '-AKC' is equivalent to '-AMC'.  Synonyms are provided for compatibility with other tools.

If you do not specify any of these options, as generates code for any instruction or feature that is supported by some version of the 960 (even if this means mixing architectures!).  In principle, as attempts to deduce the minimal sufficient processor type if none is specified; depending on the object code format, the processor type may be recorded in the object file.  If it is critical that the as output match a specific architecture, specify that architecture explicitly.

-b

Add code to collect information about conditional branches taken, for later optimization using branch prediction bits.  (The conditional branch instructions have branch prediction bits in the CA, CB, and CC architectures.)  If BR represents a conditional branch instruction, the following represents the code generated by the assembler when '-b' is specified:

        call    increment routine
        .word   0       # pre-counter
Label:  BR
        call    increment routine
        .word   0       # post-counter

The counter following a branch records the number of times that branch was not taken; the differenc between the two counters is the number of times the branch was taken.

A table of every such Label is also generated, so that the external postprocessor gbr960 (supplied by Intel) can locate all the counters.  This table is always labelled '__BRANCH_TABLE__'; this is a local symbol to permit collecting statistics for many separate object files.  The table is word aligned, and begins with a two-word header.  The first word, initialized to 0, is used in maintaining linked lists of branch tables.  The second word is a count of the number of entries in the table, which follow immediately: each is a word, pointing to one of the labels illustrated above.

 +------------+------------+------------+ ... +------------+
 |            |            |            |     |            |
 |  *NEXT     |  COUNT: N  | *BRLAB 1   |     | *BRLAB N   |
 |            |            |            |     |            |
 +------------+------------+------------+ ... +------------+

               __BRANCH_TABLE__ layout

The first word of the header is used to locate multiple branch tables, since each object file may contain one. Normally the links are maintained with a call to an initialization routine, placed at the beginning of each function in the file.  The GNU C compiler generates these calls automatically when you give it a '-b' option.  For further details, see the documentation of 'gbr960'.

-no-relax

Normally, Compare-and-Branch instructions with targets that require displacements greater than 13 bits (or that have external targets) are replaced with the corresponding compare (or 'chkbit') and branch instructions.  You can use the '-no-relax' option to specify that as should generate errors instead, if the target displacement is larger than 13 bits.

This option does not affect the Compare-and-Jump instructions; the code emitted for them is always adjusted when necessary (depending on displacement size), regardless of whether you use '-no-relax'.


Floating Point
Node: Floating Point-i960, Next: Directives-i960, Prev: Options-i960, Up: i960-Dependent

Floating Point

as generates IEEE floating-point numbers for the directives '.float', '.double', '.extended', and '.single'.


i960 Machine Directives
Node: Directives-i960, Next: Opcodes for i960, Prev: Floating Point-i960, Up: i960-Dependent

i960 Machine Directives

.bss symbol, length, align

Reserve length bytes in the bss section for a local symbol, aligned to the power of two specified by align.  length and align must be positive absolute expressions.  This directive differs from '.lcomm' only in that it permits you to specify an alignment.  See .lcomm.

.extended flonums

.extended expects zero or more flonums, separated by commas; for each flonum, '.extended' emits an IEEE extended-format (80-bit) floating-point number.

.leafproc call-lab, bal-lab

You can use the '.leafproc' directive in conjunction with the optimized callj instruction to enable faster calls of leaf procedures.  If a procedure is known to call no other procedures, you may define an entry point that skips procedure prolog code (and that does not depend on system-supplied saved context), and declare it as the bal-lab using '.leafproc'.  If the procedure also has an entry point that goes through the normal prolog, you can specify that entry point as call-lab.

A '.leafproc' declaration is meant for use in conjunction with the optimized call instruction 'callj'; the directive records the data needed later to choose between converting the 'callj' into a bal or a call.

call-lab is optional; if only one argument is present, or if the two arguments are identical, the single argument is assumed to be the bal entry point.

.sysproc name, index

The '.sysproc' directive defines a name for a system procedure.  After you define it using '.sysproc', you can use name to refer to the system procedure identified by index when calling procedures with the optimized call instruction 'callj'.

Both arguments are required; index must be between 0 and 31 (inclusive).


i960 Opcodes
Node: Opcodes for i960, Next: , Prev: Directives-i960, Up: i960-Dependent

i960 Opcodes

All Intel 960 machine instructions are supported; see i960 Command-line Options for a discussion of selecting the instruction subset for a particular 960 architecture.

Some opcodes are processed beyond simply emitting a single corresponding instruction: 'callj', and Compare-and-Branch or Compare-and-Jump instructions with target displacements larger than 13 bits.

* Menu:

callj-i960	callj

Compare-and-branch-i960	Compare-and-Branch


callj
Node: callj-i960, Next: Compare-and-branch-i960, Prev: , Up: Opcodes for i960

callj

You can write callj to have the assembler or the linker determine the most appropriate form of subroutine call: 'call', 'bal', or 'calls'.  If the assembly source contains enough information--a '.leafproc' or '.sysproc' directive defining the operand--then as translates the callj; if not, it simply emits the callj, leaving it for the linker to resolve.


Compare-and-Branch
Node: Compare-and-branch-i960, Next: , Prev: callj-i960, Up: Opcodes for i960

Compare-and-Branch

The 960 architectures provide combined Compare-and-Branch instructions that permit you to store the branch target in the lower 13 bits of the instruction word itself.  However, if you specify a branch target far enough away that its address won't fit in 13 bits, the assembler can either issue an error, or convert your Compare-and-Branch instruction into separate instructions to do the compare and the branch.

Whether as gives an error or expands the instruction depends on two choices you can make: whether you use the '-no-relax' option, and whether you use a "Compare and Branch" instruction or a "Compare and Jump" instruction.  The "Jump" instructions are always expanded if necessary; the "Branch" instructions are expanded when necessary unless you specify -no-relax--in which case as gives an error instead.

These are the Compare-and-Branch instructions, their "Jump" variants, and the instruction pairs they may expand into:

        Compare and
     Branch      Jump       Expanded to
     ------    ------       ------------
        bbc                 chkbit; bno
        bbs                 chkbit; bo
     cmpibe    cmpije       cmpi; be
     cmpibg    cmpijg       cmpi; bg
    cmpibge   cmpijge       cmpi; bge
     cmpibl    cmpijl       cmpi; bl
    cmpible   cmpijle       cmpi; ble
    cmpibno   cmpijno       cmpi; bno
    cmpibne   cmpijne       cmpi; bne
     cmpibo    cmpijo       cmpi; bo
     cmpobe    cmpoje       cmpo; be
     cmpobg    cmpojg       cmpo; bg
    cmpobge   cmpojge       cmpo; bge
     cmpobl    cmpojl       cmpo; bl
    cmpoble   cmpojle       cmpo; ble
    cmpobne   cmpojne       cmpo; bne


M680x0 Dependent Features
Node: M68K-Dependent, Next: Sparc-Dependent, Prev: i960-Dependent, Up: Machine Dependencies

M680x0 Dependent Features

* Menu:

M68K-Opts	M680x0 Options

M68K-Syntax	Syntax

M68K-Moto-Syntax	Motorola Syntax

M68K-Float	Floating Point

M68K-Directives	680x0 Machine Directives

M68K-opcodes	Opcodes


M680x0 Options
Node: M68K-Opts, Next: M68K-Syntax, Prev: , Up: M68K-Dependent

M680x0 Options

The Motorola 680x0 version of as has two machine dependent options.  One shortens undefined references from 32 to 16 bits, while the other is used to tell as what kind of machine it is assembling for.

You can use the '-l' option to shorten the size of references to undefined symbols.  If you do not use the '-l' option, references to undefined symbols are wide enough for a full long (32 bits).  (Since as cannot know where these symbols end up, as can only allocate space for the linker to fill in later.  Since as does not know how far away these symbols are, it allocates as much space as it can.)  If you use this option, the references are only one word wide (16 bits).  This may be useful if you want the object file to be as small as possible, and you know that the relevant symbols are always less than 17 bits away.

The 680x0 version of as is most frequently used to assemble programs for the Motorola MC68020 microprocessor.  Occasionally it is used to assemble programs for the mostly similar, but slightly different MC68000 or MC68010 microprocessors.  You can give as the options '-m68000', '-mc68000', '-m68010', '-mc68010', '-m68020', and '-mc68020' to tell it what processor is the target.


Syntax
Node: M68K-Syntax, Next: M68K-Moto-Syntax, Prev: M68K-Opts, Up: M68K-Dependent

Syntax

This syntax for the Motorola 680x0 was developed at MIT.

The 680x0 version of as uses syntax compatible with the Sun assembler.  Intervening periods are ignored; for example, 'movl' is equivalent to 'move.l'.

In the following table "apc" stands for any of the address registers ('a0' through 'a7'), nothing, (''), the Program Counter ('pc'), or the zero-address relative to the program counter ('zpc').

The following addressing modes are understood:

"Immediate"

'#digits'

"Data Register"

'd0' through 'd7'

"Address Register"

'a0' through 'a7'

'a7' is also known as 'sp', i.e. the Stack Pointer.  a6 is also known as 'fp', the Frame Pointer.

"Address Register Indirect"

'a0@' through 'a7@'

"Address Register Postincrement"

'a0@+' through 'a7@+'

"Address Register Predecrement"

'a0@-' through 'a7@-'

"Indirect Plus Offset"

'apc@(digits)'

"Index"

'apc@(digits,register:size:scale)'

or 'apc@(register:size:scale)'

"Postindex"

'apc@(digits)@(digits,register:size:scale)'

or 'apc@(digits)@(register:size:scale)'

"Preindex"

'apc@(digits,register:size:scale)@(digits)'

or 'apc@(register:size:scale)@(digits)'

"Memory Indirect"

'apc@(digits)@(digits)'

"Absolute"

'symbol', or 'digits'

For some configurations, especially those where the compiler normally does not prepend an underscore to the names of user variables, the assembler requires a '%' before any use of a register name.  This is intended to let the assembler distinguish between user variables and registers named 'a0' through 'a7', and so on.  The '%' is always accepted, but is only required for some configurations, notably 'm68k-coff'.


Motorola Syntax
Node: M68K-Moto-Syntax, Next: M68K-Float, Prev: M68K-Syntax, Up: M68K-Dependent

Motorola Syntax

The standard Motorola syntax for this chip differs from the syntax already discussed (see Syntax).  as can accept both kinds of syntax, even within a single instruction.  The two kinds of syntax are fully compatible.

In particular, you may write or generate M68K assembler with the following conventions:

(In the following table "apc" stands for any of the address registers ('a0' through 'a7'), nothing, (''), the Program Counter ('pc'), or the zero-address relative to the program counter ('zpc').)

The following additional addressing modes are understood:

"Address Register Indirect"

'a0' through 'a7'

'a7' is also known as 'sp', i.e. the Stack Pointer.  a6 is also known as 'fp', the Frame Pointer.

"Address Register Postincrement"

'(a0)+' through '(a7)+'

"Address Register Predecrement"

'-(a0)' through '-(a7)'

"Indirect Plus Offset"

'digits(apc)'

"Index"

'digits(apc,(register.size*scale)'

or '(apc,register.size*scale)'

In either case, size and scale are optional (scale defaults to '1', size defaults to 'l').   scale can be '1', '2', '4', or '8'.   size can be 'w' or 'l'.  scale is only supported on the 68020 and greater.


Floating Point
Node: M68K-Float, Next: M68K-Directives, Prev: M68K-Moto-Syntax, Up: M68K-Dependent

Floating Point

The floating point code is not too well tested, and may have subtle bugs in it.

Packed decimal (P) format floating literals are not supported.  Feel free to add the code!

The floating point formats generated by directives are these.

.float

Single precision floating point constants.

.double

Double precision floating point constants.

There is no directive to produce regions of memory holding extended precision numbers, however they can be used as immediate operands to floating-point instructions.  Adding a directive to create extended precision numbers would not be hard, but it has not yet seemed necessary.


680x0 Machine Directives
Node: M68K-Directives, Next: M68K-opcodes, Prev: M68K-Float, Up: M68K-Dependent

680x0 Machine Directives

In order to be compatible with the Sun assembler the 680x0 assembler understands the following directives.

.data1

This directive is identical to a .data 1 directive.

.data2

This directive is identical to a .data 2 directive.

.even

This directive is identical to a .align 1 directive.

.skip

This directive is identical to a .space directive.


Opcodes
Node: M68K-opcodes, Next: , Prev: M68K-Directives, Up: M68K-Dependent

Opcodes

* Menu:

M68K-Branch	Branch Improvement

M68K-Chars	Special Characters


Branch Improvement
Node: M68K-Branch, Next: M68K-Chars, Prev: , Up: M68K-opcodes

Branch Improvement

Certain pseudo opcodes are permitted for branch instructions.  They expand to the shortest branch instruction that reach the target.  Generally these mnemonics are made by substituting 'j' for 'b' at the start of a Motorola mnemonic.

The following table summarizes the pseudo-operations.  A * flags cases that are more fully described after the table:

          Displacement
          +-------------------------------------------------
          |                68020   68000/10
Pseudo-Op |BYTE    WORD    LONG    LONG      non-PC relative
          +-------------------------------------------------
     jbsr |bsrs    bsr     bsrl    jsr       jsr
      jra |bras    bra     bral    jmp       jmp
*     jXX |bXXs    bXX     bXXl    bNXs;jmpl bNXs;jmp
*    dbXX |dbXX    dbXX        dbXX; bra; jmpl
*    fjXX |fbXXw   fbXXw   fbXXl             fbNXw;jmp

XX: condition
NX: negative of condition XX

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               *--see full description below

jbsr

jra

These are the simplest jump pseudo-operations; they always map to one particular machine instruction, depending on the displacement to the branch target.

jXX

Here, 'jXX' stands for an entire family of pseudo-operations, where XX is a conditional branch or condition-code test.  The full list of pseudo-ops in this family is:

 jhi   jls   jcc   jcs   jne   jeq   jvc
 jvs   jpl   jmi   jge   jlt   jgt   jle

For the cases of non-PC relative displacements and long displacements on the 68000 or 68010, as issues a longer code fragment in terms of NX, the opposite condition to XX.  For example, for the non-PC relative case:

    jXX foo

gives

     bNXs oof
     jmp foo
 oof:

dbXX

The full family of pseudo-operations covered here is

 dbhi   dbls   dbcc   dbcs   dbne   dbeq   dbvc
 dbvs   dbpl   dbmi   dbge   dblt   dbgt   dble
 dbf    dbra   dbt

Other than for word and byte displacements, when the source reads 'dbXX foo', as emits

     dbXX oo1
     bra oo2
 oo1:jmpl foo
 oo2:

fjXX

This family includes

 fjne   fjeq   fjge   fjlt   fjgt   fjle   fjf
 fjt    fjgl   fjgle  fjnge  fjngl  fjngle fjngt
 fjnle  fjnlt  fjoge  fjogl  fjogt  fjole  fjolt
 fjor   fjseq  fjsf   fjsne  fjst   fjueq  fjuge
 fjugt  fjule  fjult  fjun

For branch targets that are not PC relative, as emits

     fbNX oof
     jmp foo
 oof:

when it encounters 'fjXX foo'.


Special Characters
Node: M68K-Chars, Next: , Prev: M68K-Branch, Up: M68K-opcodes

Special Characters

The immediate character is '#' for Sun compatibility.  The line-comment character is '|'.  If a '#' appears at the beginning of a line, it is treated as a comment unless it looks like '# line file', in which case it is treated normally.


SPARC Dependent Features
Node: Sparc-Dependent, Next: Z8000-Dependent, Prev: M68K-Dependent, Up: Machine Dependencies

SPARC Dependent Features

* Menu:

Sparc-Opts	Options

Sparc-Float	Floating Point

Sparc-Directives	Sparc Machine Directives


Options
Node: Sparc-Opts, Next: Sparc-Float, Prev: , Up: Sparc-Dependent

Options

The SPARC chip family includes several successive levels (or other variants) of chip, using the same core instruction set, but including a few additional instructions at each level.

By default, as assumes the core instruction set (SPARC v6), but "bumps" the architecture level as needed: it switches to successively higher architectures as it encounters instructions that only exist in the higher levels.

-Av6 | -Av7 | -Av8 | -Asparclite

Use one of the '-A' options to select one of the SPARC architectures explicitly.  If you select an architecture explicitly, as reports a fatal error if it encounters an instruction or feature requiring a higher level.

-bump

Permit the assembler to "bump" the architecture level as required, but warn whenever it is necessary to switch to another level.


Floating Point
Node: Sparc-Float, Next: Sparc-Directives, Prev: Sparc-Opts, Up: Sparc-Dependent

Floating Point

The Sparc uses IEEE floating-point numbers.


Sparc Machine Directives
Node: Sparc-Directives, Next: , Prev: Sparc-Float, Up: Sparc-Dependent

Sparc Machine Directives

The Sparc version of as supports the following additional machine directives:

.common

This must be followed by a symbol name, a positive number, and "bss".  This behaves somewhat like .comm, but the syntax is different.

.half

This is functionally identical to .short.

.proc

This directive is ignored.  Any text following it on the same line is also ignored.

.reserve

This must be followed by a symbol name, a positive number, and "bss".  This behaves somewhat like .lcomm, but the syntax is different.

.seg

This must be followed by "text", "data", or "data1".  It behaves like .text, .data, or .data 1.

.skip

This is functionally identical to the .space directive.

.word

On the Sparc, the .word directive produces 32 bit values, instead of the 16 bit values it produces on many other machines.


80386 Dependent Features
Node: i386-Dependent, Next: , Prev: MIPS-Dependent, Up: Machine Dependencies

80386 Dependent Features

* Menu:

i386-Options	Options

i386-Syntax	AT&T Syntax versus Intel Syntax

i386-Opcodes	Opcode Naming

i386-Regs	Register Naming

i386-prefixes	Opcode Prefixes

i386-Memory	Memory References

i386-jumps	Handling of Jump Instructions

i386-Float	Floating Point

i386-Notes	Notes


Options
Node: i386-Options, Next: i386-Syntax, Prev: , Up: i386-Dependent

Options

The 80386 has no machine dependent options.


AT&T Syntax versus Intel Syntax
Node: i386-Syntax, Next: i386-Opcodes, Prev: i386-Options, Up: i386-Dependent

AT&T Syntax versus Intel Syntax

In order to maintain compatibility with the output of gcc, as supports AT&T System V/386 assembler syntax.  This is quite different from Intel syntax.  We mention these differences because almost all 80386 documents used only Intel syntax.  Notable differences between the two syntaxes are:

•	AT&T immediate operands are preceded by '$'; Intel immediate operands are undelimited (Intel 'push 4' is AT&T 'pushl $4').  AT&T register operands are preceded by '%'; Intel register operands are undelimited.  AT&T absolute (as opposed to PC relative) jump/call operands are prefixed by '*'; they are undelimited in Intel syntax.

•	AT&T and Intel syntax use the opposite order for source and destination operands.  Intel 'add eax, 4' is 'addl $4, %eax'.  The 'source, dest' convention is maintained for compatibility with previous Unix assemblers.

•	In AT&T syntax the size of memory operands is determined from the last character of the opcode name.  Opcode suffixes of 'b', 'w', and 'l' specify byte (8-bit), word (16-bit), and long (32-bit) memory references.  Intel syntax accomplishes this by prefixes memory operands (not the opcodes themselves) with 'byte ptr', 'word ptr', and 'dword ptr'.  Thus, Intel 'mov al, byte ptr foo' is 'movb foo, %al' in AT&T syntax.

•	Immediate form long jumps and calls are 'lcall/ljmp $section, $offset' in AT&T syntax; the Intel syntax is 'call/jmp far section:offset'.  Also, the far return instruction is 'lret $stack-adjust' in AT&T syntax; Intel syntax is 'ret far stack-adjust'.

•	The AT&T assembler does not provide support for multiple section programs.  Unix style systems expect all programs to be single sections.


Opcode Naming
Node: i386-Opcodes, Next: i386-Regs, Prev: i386-Syntax, Up: i386-Dependent

Opcode Naming

Opcode names are suffixed with one character modifiers which specify the size of operands.  The letters 'b', 'w', and 'l' specify byte, word, and long operands.  If no suffix is specified by an instruction and it contains no memory operands then as tries to fill in the missing suffix based on the destination register operand (the last one by convention).  Thus, 'mov %ax, %bx' is equivalent to 'movw %ax, %bx'; also, 'mov $1, %bx' is equivalent to 'movw $1, %bx'.  Note that this is incompatible with the AT&T Unix assembler which assumes that a missing opcode suffix implies long operand size.  (This incompatibility does not affect compiler output since compilers always explicitly specify the opcode suffix.)

Almost all opcodes have the same names in AT&T and Intel format.  There are a few exceptions.  The sign extend and zero extend instructions need two sizes to specify them.  They need a size to sign/zero extend from and a size to zero extend to.  This is accomplished by using two opcode suffixes in AT&T syntax.  Base names for sign extend and zero extend are 'movs...' and 'movz...' in AT&T syntax ('movsx' and 'movzx' in Intel syntax).  The opcode suffixes are tacked on to this base name, the from suffix before the to suffix.  Thus, 'movsbl %al, %edx' is AT&T syntax for "move sign extend from %al to %edx."  Possible suffixes, thus, are 'bl' (from byte to long), 'bw' (from byte to word), and 'wl' (from word to long).

The Intel-syntax conversion instructions

•	'cbw' -- sign-extend byte in '%al' to word in '%ax',

•	'cwde' -- sign-extend word in '%ax' to long in '%eax',

•	'cwd' -- sign-extend word in '%ax' to long in '%dx:%ax',

•	'cdq' -- sign-extend dword in '%eax' to quad in '%edx:%eax',

are called 'cbtw', 'cwtl', 'cwtd', and 'cltd' in AT&T naming.  as accepts either naming for these instructions.

Far call/jump instructions are 'lcall' and 'ljmp' in AT&T syntax, but are 'call far' and 'jump far' in Intel convention.


Register Naming
Node: i386-Regs, Next: i386-prefixes, Prev: i386-Opcodes, Up: i386-Dependent

Register Naming

Register operands are always prefixes with '%'.  The 80386 registers consist of

•	the 8 32-bit registers '%eax' (the accumulator), '%ebx', '%ecx', '%edx', '%edi', '%esi', '%ebp' (the frame pointer), and '%esp' (the stack pointer).

•	the 8 16-bit low-ends of these: '%ax', '%bx', '%cx', '%dx', '%di', '%si', '%bp', and '%sp'.

•	the 8 8-bit registers: '%ah', '%al', '%bh', '%bl', '%ch', '%cl', '%dh', and '%dl' (These are the high-bytes and low-bytes of '%ax', '%bx', '%cx', and '%dx')

•	the 6 section registers '%cs' (code section), '%ds' (data section), '%ss' (stack section), '%es', '%fs', and '%gs'.

•	the 3 processor control registers '%cr0', '%cr2', and '%cr3'.

•	the 6 debug registers '%db0', '%db1', '%db2', '%db3', '%db6', and '%db7'.

•	the 2 test registers '%tr6' and '%tr7'.

•	the 8 floating point register stack '%st' or equivalently '%st(0)', '%st(1)', '%st(2)', '%st(3)', '%st(4)', '%st(5)', '%st(6)', and '%st(7)'.


Opcode Prefixes
Node: i386-prefixes, Next: i386-Memory, Prev: i386-Regs, Up: i386-Dependent

Opcode Prefixes

Opcode prefixes are used to modify the following opcode.  They are used to repeat string instructions, to provide section overrides, to perform bus lock operations, and to give operand and address size (16-bit operands are specified in an instruction by prefixing what would normally be 32-bit operands with a "operand size" opcode prefix).  Opcode prefixes are usually given as single-line instructions with no operands, and must directly precede the instruction they act upon.  For example, the 'scas' (scan string) instruction is repeated with:

        repne
        scas

Here is a list of opcode prefixes:

•	Section override prefixes 'cs', 'ds', 'ss', 'es', 'fs', 'gs'.  These are automatically added by specifying using the section:memory-operand form for memory references.

•	Operand/Address size prefixes 'data16' and 'addr16' change 32-bit operands/addresses into 16-bit operands/addresses.  Note that 16-bit addressing modes (i.e. 8086 and 80286 addressing modes) are not supported (yet).

•	The bus lock prefix 'lock' inhibits interrupts during execution of the instruction it precedes.  (This is only valid with certain instructions; see a 80386 manual for details).

•	The wait for coprocessor prefix 'wait' waits for the coprocessor to complete the current instruction.  This should never be needed for the 80386/80387 combination.

•	The 'rep', 'repe', and 'repne' prefixes are added to string instructions to make them repeat '%ecx' times.


Memory References
Node: i386-Memory, Next: i386-jumps, Prev: i386-prefixes, Up: i386-Dependent

Memory References

An Intel syntax indirect memory reference of the form

section:[base + index*scale + disp]

is translated into the AT&T syntax

section:disp(base, index, scale)

where base and index are the optional 32-bit base and index registers, disp is the optional displacement, and scale, taking the values 1, 2, 4, and 8, multiplies index to calculate the address of the operand.  If no scale is specified, scale is taken to be 1.  section specifies the optional section register for the memory operand, and may override the default section register (see a 80386 manual for section register defaults). Note that section overrides in AT&T syntax must have be preceded by a '%'.  If you specify a section override which coincides with the default section register, as does not output any section register override prefixes to assemble the given instruction.  Thus, section overrides can be specified to emphasize which section register is used for a given memory operand.

Here are some examples of Intel and AT&T style memory references:

AT&T: '-4(%ebp)', Intel:  '[ebp - 4]'

base is '%ebp'; disp is '-4'. section is missing, and the default section is used ('%ss' for addressing with '%ebp' as the base register).  index, scale are both missing.

AT&T: 'foo(,%eax,4)', Intel: '[foo + eax*4]'

index is '%eax' (scaled by a scale 4); disp is 'foo'.  All other fields are missing.  The section register here defaults to '%ds'.

AT&T: 'foo(,1)'; Intel '[foo]'

This uses the value pointed to by 'foo' as a memory operand.  Note that base and index are both missing, but there is only one ','.  This is a syntactic exception.

AT&T: '%gs:foo'; Intel 'gs:foo'

This selects the contents of the variable 'foo' with section register section being '%gs'.

Absolute (as opposed to PC relative) call and jump operands must be prefixed with '*'.  If no '*' is specified, as always chooses PC relative addressing for jump/call labels.

Any instruction that has a memory operand must specify its size (byte, word, or long) with an opcode suffix ('b', 'w', or 'l', respectively).


Handling of Jump Instructions
Node: i386-jumps, Next: i386-Float, Prev: i386-Memory, Up: i386-Dependent

Handling of Jump Instructions

Jump instructions are always optimized to use the smallest possible displacements.  This is accomplished by using byte (8-bit) displacement jumps whenever the target is sufficiently close.  If a byte displacement is insufficient a long (32-bit) displacement is used.  We do not support word (16-bit) displacement jumps (i.e. prefixing the jump instruction with the 'addr16' opcode prefix), since the 80386 insists upon masking '%eip' to 16 bits after the word displacement is added.

Note that the 'jcxz', 'jecxz', 'loop', 'loopz', 'loope', 'loopnz' and 'loopne' instructions only come in byte displacements, so that if you use these instructions (gcc does not use them) you may get an error message (and incorrect code).  The AT&T 80386 assembler tries to get around this problem by expanding 'jcxz foo' to

         jcxz cx_zero
         jmp cx_nonzero
cx_zero: jmp foo
cx_nonzero:


Floating Point
Node: i386-Float, Next: i386-Notes, Prev: i386-jumps, Up: i386-Dependent

Floating Point

All 80387 floating point types except packed BCD are supported.  (BCD support may be added without much difficulty).  These data types are 16-, 32-, and 64- bit integers, and single (32-bit), double (64-bit), and extended (80-bit) precision floating point.  Each supported type has an opcode suffix and a constructor associated with it.  Opcode suffixes specify operand's data types.  Constructors build these data types into memory.

•	Floating point constructors are '.float' or '.single', '.double', and '.tfloat' for 32-, 64-, and 80-bit formats.  These correspond to opcode suffixes 's', 'l', and 't'.  't' stands for temporary real, and that the 80387 only supports this format via the 'fldt' (load temporary real to stack top) and 'fstpt' (store temporary real and pop stack) instructions.

•	Integer constructors are '.word', '.long' or '.int', and '.quad' for the 16-, 32-, and 64-bit integer formats.  The corresponding opcode suffixes are 's' (single), 'l' (long), and 'q' (quad).  As with the temporary real format the 64-bit 'q' format is only present in the 'fildq' (load quad integer to stack top) and 'fistpq' (store quad integer and pop stack) instructions.

Register to register operations do not require opcode suffixes, so that 'fst %st, %st(1)' is equivalent to 'fstl %st, %st(1)'.

Since the 80387 automatically synchronizes with the 80386 'fwait' instructions are almost never needed (this is not the case for the 80286/80287 and 8086/8087 combinations).  Therefore, as suppresses the 'fwait' instruction whenever it is implicitly selected by one of the 'fn...' instructions.  For example, 'fsave' and 'fnsave' are treated identically.  In general, all the 'fn...'  instructions are made equivalent to 'f...' instructions.  If 'fwait' is desired it must be explicitly coded.


Notes
Node: i386-Notes, Next: , Prev: i386-Float, Up: i386-Dependent

Notes

There is some trickery concerning the 'mul' and 'imul' instructions that deserves mention.  The 16-, 32-, and 64-bit expanding multiplies (base opcode '0xf6'; extension 4 for 'mul' and 5 for 'imul') can be output only in the one operand form.  Thus, 'imul %ebx, %eax' does not select the expanding multiply; the expanding multiply would clobber the '%edx' register, and this would confuse gcc output.  Use 'imul %ebx' to get the 64-bit product in '%edx:%eax'.

We have added a two operand form of 'imul' when the first operand is an immediate mode expression and the second operand is a register.  This is just a shorthand, so that, multiplying '%eax' by 69, for example, can be done with 'imul $69, %eax' rather than 'imul $69, %eax, %eax'.


Z8000 Dependent Features
Node: Z8000-Dependent, Next: MIPS-Dependent, Prev: Sparc-Dependent, Up: Machine Dependencies

Z8000 Dependent Features

The Z8000 as supports both members of the Z8000 family: the unsegmented Z8002, with 16 bit addresses, and the segmented Z8001 with 24 bit addresses.

When the assembler is in unsegmented mode (specified with the unsegm directive), an address takes up one word (16 bit) sized register.  When the assembler is in segmented mode (specified with the segm directive), a 24-bit address takes up a long (32 bit) register.  See Assembler Directives for the Z8000, for a list of other Z8000 specific assembler directives.

* Menu:

Z8000 Options	No special command-line options for Z8000

Z8000 Syntax	Assembler syntax for the Z8000

Z8000 Directives	Special directives for the Z8000

Z8000 Opcodes	Opcodes


Options
Node: Z8000 Options, Next: Z8000 Syntax, Prev: , Up: Z8000-Dependent

Options

as has no additional command-line options for the Zilog Z8000 family.


Syntax
Node: Z8000 Syntax, Next: Z8000 Directives, Prev: Z8000 Options, Up: Z8000-Dependent

Syntax

* Menu:

Z8000-Chars	Special Characters

Z8000-Regs	Register Names

Z8000-Addressing	Addressing Modes


Special Characters
Node: Z8000-Chars, Next: Z8000-Regs, Prev: , Up: Z8000 Syntax

Special Characters

'!' is the line comment character.

You can use ';' instead of a newline to separate statements.


Register Names
Node: Z8000-Regs, Next: Z8000-Addressing, Prev: Z8000-Chars, Up: Z8000 Syntax

Register Names

The Z8000 has sixteen 16 bit registers, numbered 0 to 15.  You can refer to different sized groups of registers by register number, with the prefix 'r' for 16 bit registers, 'rr' for 32 bit registers and 'rq' for 64 bit registers.  You can also refer to the contents of the first eight (of the sixteen 16 bit registers) by bytes.  They are named 'rnh' and 'rnl'.

byte registers

r0l r0h r1h r1l r2h r2l r3h r3l
r4h r4l r5h r5l r6h r6l r7h r7l

word registers

r0 r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11 r12 r13 r14 r15

long word registers

rr0 rr2 rr4 rr6 rr8 rr10 rr12 rr14

quad word registers

rq0 rq4 rq8 rq12


Addressing Modes
Node: Z8000-Addressing, Next: , Prev: Z8000-Regs, Up: Z8000 Syntax

Addressing Modes

as understands the following addressing modes for the Z8000:

rn

Register direct

@rn

Indirect register

addr

Direct: the 16 bit or 24 bit address (depending on whether the assembler is in segmented or unsegmented mode) of the operand is in the instruction.

address(rn)

Indexed: the 16 or 24 bit address is added to the 16 bit register to produce the final address in memory of the operand.

rn(#imm)

Base Address: the 16 or 24 bit register is added to the 16 bit sign extended immediate displacement to produce the final address in memory of the operand.

rn(rm)

Base Index: the 16 or 24 bit register rn is added to the sign extended 16 bit index register rm to produce the final address in memory of the operand.

#xx

Immediate data xx.


Assembler Directives for the Z8000
Node: Z8000 Directives, Next: Z8000 Opcodes, Prev: Z8000 Syntax, Up: Z8000-Dependent

Assembler Directives for the Z8000

The Z8000 port of as includes these additional assembler directives, for compatibility with other Z8000 assemblers.  As shown, these do not begin with '.' (unlike the ordinary as directives).

segm

Generates code for the segmented Z8001.

unsegm

Generates code for the unsegmented Z8002.

name

Synonym for .file

global

Synonum for .global

wval

Synonym for .word

lval

Synonym for .long

bval

Synonym for .byte

sval

Assemble a string.  sval expects one string literal, delimited by single quotes.  It assembles each byte of the string into consecutive addresses.  You can use the escape sequence '%xx' (where xx represents a two-digit hexadecimal number) to represent the character whose ASCII value is xx.  Use this feature to describe single quote and other characters that may not appear in string literals as themselves.  For example, the C statement 'char *a = "he said \"it's 50% off\"";' is represented in Z8000 assembly language (shown with the assembler output in hex at the left) as

68652073    sval    'he said %22it%27s 50%25 off%22%00'
61696420
22697427
73203530
25206F66
662200

rsect

synonym for .section

block

synonym for .space

even

synonym for .align 1


Opcodes
Node: Z8000 Opcodes, Next: , Prev: Z8000 Directives, Up: Z8000-Dependent

Opcodes

For detailed information on the Z8000 machine instruction set, see `Z8000 Technical Manual'.

The following table summarizes the opcodes and their arguments:

            rs   16 bit source register
            rd   16 bit destination register
            rbs   8 bit source register
            rbd   8 bit destination register
            rrs   32 bit source register
            rrd   32 bit destination register
            rqs   64 bit source register
            rqd   64 bit destination register
            addr 16/24 bit address
            imm  immediate data

adc rd,rs               clrb addr               cpsir @rd,@rs,rr,cc
adcb rbd,rbs            clrb addr(rd)           cpsirb @rd,@rs,rr,cc
add rd,@rs              clrb rbd                dab rbd
add rd,addr             com @rd                 dbjnz rbd,disp7
add rd,addr(rs)         com addr                dec @rd,imm4m1
add rd,imm16            com addr(rd)            dec addr(rd),imm4m1
add rd,rs               com rd                  dec addr,imm4m1
addb rbd,@rs            comb @rd                dec rd,imm4m1
addb rbd,addr           comb addr               decb @rd,imm4m1
addb rbd,addr(rs)       comb addr(rd)           decb addr(rd),imm4m1
addb rbd,imm8           comb rbd                decb addr,imm4m1
addb rbd,rbs            comflg flags            decb rbd,imm4m1
addl rrd,@rs            cp @rd,imm16            di i2
addl rrd,addr           cp addr(rd),imm16       div rrd,@rs
addl rrd,addr(rs)       cp addr,imm16           div rrd,addr
addl rrd,imm32          cp rd,@rs               div rrd,addr(rs)
addl rrd,rrs            cp rd,addr              div rrd,imm16
and rd,@rs              cp rd,addr(rs)          div rrd,rs
and rd,addr             cp rd,imm16             divl rqd,@rs
and rd,addr(rs)         cp rd,rs                divl rqd,addr
and rd,imm16            cpb @rd,imm8            divl rqd,addr(rs)
and rd,rs               cpb addr(rd),imm8       divl rqd,imm32
andb rbd,@rs            cpb addr,imm8           divl rqd,rrs
andb rbd,addr           cpb rbd,@rs             djnz rd,disp7
andb rbd,addr(rs)       cpb rbd,addr            ei i2
andb rbd,imm8           cpb rbd,addr(rs)        ex rd,@rs
andb rbd,rbs            cpb rbd,imm8            ex rd,addr
bit @rd,imm4            cpb rbd,rbs             ex rd,addr(rs)
bit addr(rd),imm4       cpd rd,@rs,rr,cc        ex rd,rs
bit addr,imm4           cpdb rbd,@rs,rr,cc      exb rbd,@rs
bit rd,imm4             cpdr rd,@rs,rr,cc       exb rbd,addr
bit rd,rs               cpdrb rbd,@rs,rr,cc     exb rbd,addr(rs)
bitb @rd,imm4           cpi rd,@rs,rr,cc        exb rbd,rbs
bitb addr(rd),imm4      cpib rbd,@rs,rr,cc      ext0e imm8
bitb addr,imm4          cpir rd,@rs,rr,cc       ext0f imm8
bitb rbd,imm4           cpirb rbd,@rs,rr,cc     ext8e imm8
bitb rbd,rs             cpl rrd,@rs             ext8f imm8
bpt                     cpl rrd,addr            exts rrd
call @rd                cpl rrd,addr(rs)        extsb rd
call addr               cpl rrd,imm32           extsl rqd
call addr(rd)           cpl rrd,rrs             halt
calr disp12             cpsd @rd,@rs,rr,cc      in rd,@rs
clr @rd                 cpsdb @rd,@rs,rr,cc     in rd,imm16
clr addr                cpsdr @rd,@rs,rr,cc     inb rbd,@rs
clr addr(rd)            cpsdrb @rd,@rs,rr,cc    inb rbd,imm16
clr rd                  cpsi @rd,@rs,rr,cc      inc @rd,imm4m1
clrb @rd                cpsib @rd,@rs,rr,cc     inc addr(rd),imm4m1
inc addr,imm4m1         ldb rbd,rs(rx)          mult rrd,addr(rs)
inc rd,imm4m1           ldb rd(imm16),rbs       mult rrd,imm16
incb @rd,imm4m1         ldb rd(rx),rbs          mult rrd,rs
incb addr(rd),imm4m1    ldctl ctrl,rs           multl rqd,@rs
incb addr,imm4m1        ldctl rd,ctrl           multl rqd,addr
incb rbd,imm4m1         ldd @rs,@rd,rr          multl rqd,addr(rs)
ind @rd,@rs,ra          lddb @rs,@rd,rr         multl rqd,imm32
indb @rd,@rs,rba        lddr @rs,@rd,rr         multl rqd,rrs
inib @rd,@rs,ra         lddrb @rs,@rd,rr        neg @rd
inibr @rd,@rs,ra        ldi @rd,@rs,rr          neg addr
iret                    ldib @rd,@rs,rr         neg addr(rd)
jp cc,@rd               ldir @rd,@rs,rr         neg rd
jp cc,addr              ldirb @rd,@rs,rr        negb @rd
jp cc,addr(rd)          ldk rd,imm4             negb addr
jr cc,disp8             ldl @rd,rrs             negb addr(rd)
ld @rd,imm16            ldl addr(rd),rrs        negb rbd
ld @rd,rs               ldl addr,rrs            nop
ld addr(rd),imm16       ldl rd(imm16),rrs       or rd,@rs
ld addr(rd),rs          ldl rd(rx),rrs          or rd,addr
ld addr,imm16           ldl rrd,@rs             or rd,addr(rs)
ld addr,rs              ldl rrd,addr            or rd,imm16
ld rd(imm16),rs         ldl rrd,addr(rs)        or rd,rs
ld rd(rx),rs            ldl rrd,imm32           orb rbd,@rs
ld rd,@rs               ldl rrd,rrs             orb rbd,addr
ld rd,addr              ldl rrd,rs(imm16)       orb rbd,addr(rs)
ld rd,addr(rs)          ldl rrd,rs(rx)          orb rbd,imm8
ld rd,imm16             ldm @rd,rs,n            orb rbd,rbs
ld rd,rs                ldm addr(rd),rs,n       out @rd,rs
ld rd,rs(imm16)         ldm addr,rs,n           out imm16,rs
ld rd,rs(rx)            ldm rd,@rs,n            outb @rd,rbs
lda rd,addr             ldm rd,addr(rs),n       outb imm16,rbs
lda rd,addr(rs)         ldm rd,addr,n           outd @rd,@rs,ra
lda rd,rs(imm16)        ldps @rs                outdb @rd,@rs,rba
lda rd,rs(rx)           ldps addr               outib @rd,@rs,ra
ldar rd,disp16          ldps addr(rs)           outibr @rd,@rs,ra
ldb @rd,imm8            ldr disp16,rs           pop @rd,@rs
ldb @rd,rbs             ldr rd,disp16           pop addr(rd),@rs
ldb addr(rd),imm8       ldrb disp16,rbs         pop addr,@rs
ldb addr(rd),rbs        ldrb rbd,disp16         pop rd,@rs
ldb addr,imm8           ldrl disp16,rrs         popl @rd,@rs
ldb addr,rbs            ldrl rrd,disp16         popl addr(rd),@rs
ldb rbd,@rs             mbit                    popl addr,@rs
ldb rbd,addr            mreq rd                 popl rrd,@rs
ldb rbd,addr(rs)        mres                    push @rd,@rs
ldb rbd,imm8            mset                    push @rd,addr
ldb rbd,rbs             mult rrd,@rs            push @rd,addr(rs)
ldb rbd,rs(imm16)       mult rrd,addr           push @rd,imm16
push @rd,rs             set addr,imm4           subl rrd,imm32
pushl @rd,@rs           set rd,imm4             subl rrd,rrs
pushl @rd,addr          set rd,rs               tcc cc,rd
pushl @rd,addr(rs)      setb @rd,imm4           tccb cc,rbd
pushl @rd,rrs           setb addr(rd),imm4      test @rd
res @rd,imm4            setb addr,imm4          test addr
res addr(rd),imm4       setb rbd,imm4           test addr(rd)
res addr,imm4           setb rbd,rs             test rd
res rd,imm4             setflg imm4             testb @rd
res rd,rs               sinb rbd,imm16          testb addr
resb @rd,imm4           sinb rd,imm16           testb addr(rd)
resb addr(rd),imm4      sind @rd,@rs,ra         testb rbd
resb addr,imm4          sindb @rd,@rs,rba       testl @rd
resb rbd,imm4           sinib @rd,@rs,ra        testl addr
resb rbd,rs             sinibr @rd,@rs,ra       testl addr(rd)
resflg imm4             sla rd,imm8             testl rrd
ret cc                  slab rbd,imm8           trdb @rd,@rs,rba
rl rd,imm1or2           slal rrd,imm8           trdrb @rd,@rs,rba
rlb rbd,imm1or2         sll rd,imm8             trib @rd,@rs,rbr
rlc rd,imm1or2          sllb rbd,imm8           trirb @rd,@rs,rbr
rlcb rbd,imm1or2        slll rrd,imm8           trtdrb @ra,@rb,rbr
rldb rbb,rba            sout imm16,rs           trtib @ra,@rb,rr
rr rd,imm1or2           soutb imm16,rbs         trtirb @ra,@rb,rbr
rrb rbd,imm1or2         soutd @rd,@rs,ra        trtrb @ra,@rb,rbr
rrc rd,imm1or2          soutdb @rd,@rs,rba      tset @rd
rrcb rbd,imm1or2        soutib @rd,@rs,ra       tset addr
rrdb rbb,rba            soutibr @rd,@rs,ra      tset addr(rd)
rsvd36                  sra rd,imm8             tset rd
rsvd38                  srab rbd,imm8           tsetb @rd
rsvd78                  sral rrd,imm8           tsetb addr
rsvd7e                  srl rd,imm8             tsetb addr(rd)
rsvd9d                  srlb rbd,imm8           tsetb rbd
rsvd9f                  srll rrd,imm8           xor rd,@rs
rsvdb9                  sub rd,@rs              xor rd,addr
rsvdbf                  sub rd,addr             xor rd,addr(rs)
sbc rd,rs               sub rd,addr(rs)         xor rd,imm16
sbcb rbd,rbs            sub rd,imm16            xor rd,rs
sc imm8                 sub rd,rs               xorb rbd,@rs
sda rd,rs               subb rbd,@rs            xorb rbd,addr
sdab rbd,rs             subb rbd,addr           xorb rbd,addr(rs)
sdal rrd,rs             subb rbd,addr(rs)       xorb rbd,imm8
sdl rd,rs               subb rbd,imm8           xorb rbd,rbs
sdlb rbd,rs             subb rbd,rbs            xorb rbd,rbs
sdll rrd,rs             subl rrd,@rs
set @rd,imm4            subl rrd,addr
set addr(rd),imm4       subl rrd,addr(rs)


MIPS Dependent Features
Node: MIPS-Dependent, Next: i386-Dependent, Prev: Z8000-Dependent, Up: Machine Dependencies

MIPS Dependent Features

GNU as for MIPS architectures supports the MIPS R2000, R3000, R4000 and R6000 processors.  For information about the MIPS instruction set, see `MIPS RISC Architecture', by Kane and Heindrich (Prentice-Hall).  For an overview of MIPS assembly conventions, see "Appendix D: Assembly Language Programming" in the same work.

* Menu:

MIPS Opts	Assembler options

MIPS Object	ECOFF object code

MIPS Stabs	Directives for debugging information

MIPS ISA	Directives to override the ISA level


Assembler options
Node: MIPS Opts, Next: MIPS Object, Prev: , Up: MIPS-Dependent

Assembler options

The MIPS configurations of GNU as support these special options:

-G num

This option sets the largest size of an object that can be referenced implicitly with the gp register.  It is only accepted for targets that use ECOFF format.  The default value is 8.

-EB

-EL

Any MIPS configuration of as can select big-endian or little-endian output at run time (unlike the other GNU development tools, which must be configured for one or the other).  Use '-EB' to select big-endian output, and '-EL' for little-endian.

-mips1

-mips2

-mips3

Generate code for a particular MIPS Instruction Set Architecture level.  '-mips1' corresponds to the R2000 and R3000 processors, '-mips2' to the R6000 processor, and '-mips3' to the R4000 processor.  You can also switch instruction sets during the assembly; see See Directives to override the ISA level.

-nocpp

This option is ignored.  It is accepted for command-line compatibility with other assemblers, which use it to turn off C style preprocessing.  With GNU as, there is no need for '-nocpp', because the GNU assembler itself never runs the C preprocessor.

--trap

--no-break

{No Value For "\li720{}AS"} automatically macro expands certain division and multiplication instructions to check for overflow and division by zero.  This option causes as to generate code to take a trap exception rather than a break exception when an error is detected.  The trap instructions are only supported at Instruction Set Architecture level 2 and higher.

--break

--no-trap

Generate code to take a break exception rather than a trap exception when an error is detected.  This is the default.


MIPS ECOFF object code
Node: MIPS Object, Next: MIPS Stabs, Prev: MIPS Opts, Up: MIPS-Dependent

MIPS ECOFF object code

Assembling for a MIPS ECOFF target supports some additional sections besides the usual .text, .data and .bss.  The additional sections are .rdata, used for read-only data, .sdata, used for small data, and .sbss, used for small common objects.

When assembling for ECOFF, the assembler uses the $gp ($28) register to form the address of a "small object".  Any object in the .sdata or .sbss sections is considered "small" in this sense.  For external objects, or for objects in the .bss section, you can use the gcc '-G' option to control the size of objects addressed via $gp; the default value is 8, meaning that a reference to any object eight bytes or smaller uses $gp.  Passing '-G 0' to as prevents it from using the $gp register on the basis of object size (but the assembler uses $gp for objects in .sdata or sbss in any case).  The size of an object in the .bss section is set by the .comm or .lcomm directive that defines it.  The size of an external object may be set with the .extern directive.  For example, '.extern sym,4' declares that the object at sym is 4 bytes in length, whie leaving sym otherwise undefined.

Using small ECOFF objects requires linker support, and assumes that the $gp register is correctly initialized (normally done automatically by the startup code).  MIPS ECOFF assembly code must not modify the $gp register.


Directives for debugging information
Node: MIPS Stabs, Next: MIPS ISA, Prev: MIPS Object, Up: MIPS-Dependent

Directives for debugging information

MIPS ECOFF as supports several directives used for generating debugging information which are not support by traditional MIPS assemblers.  These are .def, .endef, .dim, .file, .scl, .size, .tag, .type, .val, .stabd, .stabn, and .stabs.  The debugging information generated by the three .stab directives can only be read by GDB, not by traditional MIPS debuggers (this enhancement is required to fully support C++ debugging).  These directives are primarily used by compilers, not assembly language programmers!


Directives to override the ISA level
Node: MIPS ISA, Next: , Prev: MIPS Stabs, Up: MIPS-Dependent

Directives to override the ISA level

GNU as supports an additional directive to change the MIPS Instruction Set Architecture level on the fly: .set mipsn.  n should be a number from 0 to 3.  A value from 1 to 3 makes the assembler accept instructions for the corresponding ISA level, from that point on in the assembly.  .set mipsn affects not only which instructions are permitted, but also how certain macros are expanded.  .set mips0 restores the ISA level to its original level: either the level you selected with command line options, or the default for your configuration.  You can use this feature to permit specific R4000 instructions while assembling in 32 bit mode.  Use this directive with care!

Traditional MIPS assemblers do not support this directive.


Acknowledgements
Node: Acknowledgements, Next: Index, Prev: Machine Dependencies, Up: Top

Acknowledgements

If you have contributed to as and your name isn't listed here, it is not meant as a slight.  We just don't know about it.  Send mail to the maintainer, and we'll correct the situation.  Currently (January 1994), the maintainer is Ken Raeburn (email address raeburn@cygnus.com).

Dean Elsner wrote the original GNU assembler for the VAX.(1)

Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug information and the 68k series machines, most of the preprocessing pass, and extensive changes in 'messages.c', 'input-file.c', 'write.c'.

K. Richard Pixley maintained GAS for a while, adding various enhancements and many bug fixes, including merging support for several processors, breaking GAS up to handle multiple object file format back ends (including heavy rewrite, testing, an integration of the coff and b.out back ends), adding configuration including heavy testing and verification of cross assemblers and file splits and renaming, converted GAS to strictly ANSI C including full prototypes, added support for m680[34]0 and cpu32, did considerable work on i960 including a COFF port (including considerable amounts of reverse engineering), a SPARC opcode file rewrite, DECstation, rs6000, and hp300hpux host ports, updated "know" assertions and made them work, much other reorganization, cleanup, and lint.

Ken Raeburn wrote the high-level BFD interface code to replace most of the code in format-specific I/O modules.

The original VMS support was contributed by David L. Kashtan.  Eric Youngdale has done much work with it since.

The Intel 80386 machine description was written by Eliot Dresselhaus.

Minh Tran-Le at IntelliCorp contributed some AIX 386 support.

The Motorola 88k machine description was contributed by Devon Bowen of Buffalo University and Torbjorn Granlund of the Swedish Institute of Computer Science.

Keith Knowles at the Open Software Foundation wrote the original MIPS back end ('tc-mips.c', 'tc-mips.h'), and contributed Rose format support (which hasn't been merged in yet).  Ralph Campbell worked with the MIPS code to support a.out format.

Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k, tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by Steve Chamberlain of Cygnus Support.  Steve also modified the COFF back end to use BFD for some low-level operations, for use with the H8/300 and AMD 29k targets.

John Gilmore built the AMD 29000 support, added .include support, and simplified the configuration of which versions accept which directives.  He updated the 68k machine description so that Motorola's opcodes always produced fixed-size instructions (e.g. jsr), while synthetic instructions remained shrinkable (jbsr).  John fixed many bugs, including true tested cross-compilation support, and one bug in relaxation that took a week and required the proverbial one-bit fix.

Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix), added support for MIPS ECOFF and ELF targets, and made a few other minor patches.

Steve Chamberlain made as able to generate listings.

Hewlett-Packard contributed support for the HP9000/300.

Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM) along with a fairly extensive HPPA testsuite (for both SOM and ELF object formats).  This work was supported by both the Center for Software Science at the University of Utah and Cygnus Support.

Support for ELF format files has been worked on by Mark Eichin of Cygnus Support (original, incomplete implementation for SPARC), Pete Hoogenboom and Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc, and some initial 64-bit support).

Several engineers at Cygnus Support have also provided many small bug fixes and configuration enhancements.

Many others have contributed large or small bugfixes and enhancements.  If you have contributed significant work and are not mentioned on this list, and want to be, let us know.  Some of the history has been lost; we are not intentionally leaving anyone out.


Any more details?


Index
Node: Index, Next: , Prev: Acknowledgements, Up: Top

Index

#:	See Comments.

#APP:	See Preprocessing.

#NO_APP:	See Preprocessing.

-:	See Command Line.

-statistics:	See statistics.

-a:	See a.

-ad:	See a.

-ah:	See a.

-al:	See a.

-an:	See a.

-as:	See a.

-Asparclite:	See Sparc-Opts.

-Av6:	See Sparc-Opts.

-Av8:	See Sparc-Opts.

-D:	See D.

-f:	See f.

-I path:	See I.

-K:	See K.

-L:	See L.

-o:	See o.

-R:	See R.

-v:	See v.

-version:	See v.

-W:	See W.

.o:	See Object.

K support:	See AMD29K-Dependent.

$ in symbol names <1>:	See SH-Chars.

$ in symbol names:	See H8/500-Chars.

-+ option, VAX/VMS:	See Vax-Opts.

-A options, i960:	See Options-i960.

-b option, i960:	See Options-i960.

-D, ignored on VAX:	See Vax-Opts.

-d, VAX option:	See Vax-Opts.

-EB option (MIPS):	See MIPS Opts.

-EL option (MIPS):	See MIPS Opts.

-G option (MIPS):	See MIPS Opts.

-h option, VAX/VMS:	See Vax-Opts.

-J, ignored on VAX:	See Vax-Opts.

-l option, M680x0:	See M68K-Opts.

-m68000 and related options:	See M68K-Opts.

-no-relax option, i960:	See Options-i960.

-nocpp ignored (MIPS):	See MIPS Opts.

-S, ignored on VAX:	See Vax-Opts.

-t, ignored on VAX:	See Vax-Opts.

-V, redundant on VAX:	See Vax-Opts.

.param on HPPA:	See HPPA Directives.

.set mipsn:	See MIPS ISA.

. (symbol):	See Dot.

: (label):	See Statements.

as version:	See v.

a.out symbol attributes:	See a.out Symbols.

abort directive:	See Abort.

ABORT directive:	See ABORT.

align directive:	See Align.

app-file directive:	See App-File.

ascii directive:	See Ascii.

asciz directive:	See Asciz.

block directive, AMD 29K:	See AMD29K Directives.

bss directive, i960:	See Directives-i960.

byte directive:	See Byte.

callj, i960 pseudo-opcode:	See callj-i960.

common directive, SPARC:	See Sparc-Directives.

comm directive:	See Comm.

cputype directive, AMD 29K:	See AMD29K Directives.

data1 directive, M680x0:	See M68K-Directives.

data2 directive, M680x0:	See M68K-Directives.

data directive:	See Data.

def directive:	See Def.

desc directive:	See Desc.

dfloat directive, VAX:	See VAX-directives.

dim directive:	See Dim.

double directive:	See Double.

double directive, i386:	See i386-Float.

double directive, M680x0:	See M68K-Float.

double directive, VAX:	See VAX-float.

eject directive:	See Eject.

else directive:	See Else.

endef directive:	See Endef.

endif directive:	See Endif.

equ directive:	See Equ.

even directive, M680x0:	See M68K-Directives.

extended directive, i960:	See Directives-i960.

extern directive:	See Extern.

ffloat directive, VAX:	See VAX-directives.

file directive:	See File.

file directive, AMD 29K:	See AMD29K Directives.

fill directive:	See Fill.

float directive:	See Float.

float directive, i386:	See i386-Float.

float directive, M680x0:	See M68K-Float.

float directive, VAX:	See VAX-float.

fwait instruction, i386:	See i386-Float.

gbr960, i960 postprocessor:	See Options-i960.

gfloat directive, VAX:	See VAX-directives.

global directive:	See Global.

gp register, MIPS:	See MIPS Object.

half directive, SPARC:	See Sparc-Directives.

hfloat directive, VAX:	See VAX-directives.

hword directive:	See hword.

ident directive:	See Ident.

ifdef directive:	See If.

ifndef directive:	See If.

ifnotdef directive:	See If.

if directive:	See If.

imul instruction, i386:	See i386-Notes.

include directive:	See Include.

include directive search path:	See I.

int directive:	See Int.

int directive, H8/300:	See H8/300 Directives.

int directive, H8/500:	See H8/500 Directives.

int directive, i386:	See i386-Float.

int directive, SH:	See SH Directives.

lcomm directive:	See Lcomm.

leafproc directive, i960:	See Directives-i960.

lflags directive (ignored):	See Lflags.

line directive:	See Line.

line directive, AMD 29K:	See AMD29K Directives.

list directive:	See List.

ln directive:	See Ln.

long directive:	See Long.

long directive, i386:	See i386-Float.

mul instruction, i386:	See i386-Notes.

nolist directive:	See Nolist.

octa directive:	See Octa.

org directive:	See Org.

proc directive, SPARC:	See Sparc-Directives.

psize directive:	See Psize.

quad directive:	See Quad.

quad directive, i386:	See i386-Float.

reserve directive, SPARC:	See Sparc-Directives.

sbttl directive:	See Sbttl.

scl directive:	See Scl.

section directive:	See Section.

sect directive, AMD 29K:	See AMD29K Directives.

seg directive, SPARC:	See Sparc-Directives.

set directive:	See Set.

short directive:	See Short.

single directive:	See Single.

single directive, i386:	See i386-Float.

size directive:	See Size.

skip directive, M680x0:	See M68K-Directives.

skip directive, SPARC:	See Sparc-Directives.

space directive:	See Space.

stabx directives:	See Stab.

stabd directive:	See Stab.

stabn directive:	See Stab.

stabs directive:	See Stab.

string directive:	See String.

string directive on HPPA:	See HPPA Directives.

sysproc directive, i960:	See Directives-i960.

tag directive:	See Tag.

text directive:	See Text.

tfloat directive, i386:	See i386-Float.

title directive:	See Title.

type directive:	See Type.

use directive, AMD 29K:	See AMD29K Directives.

val directive:	See Val.

word directive:	See Word.

word directive, H8/300:	See H8/300 Directives.

word directive, H8/500:	See H8/500 Directives.

word directive, i386:	See i386-Float.

word directive, SH:	See SH Directives.

word directive, SPARC:	See Sparc-Directives.

\" (doublequote character):	See Strings.

\ddd (octal character code):	See Strings.

\xdd (hex character code):	See Strings.

\b (backspace character):	See Strings.

\f (formfeed character):	See Strings.

\n (newline character):	See Strings.

\r (carriage return character):	See Strings.

\t (tab):	See Strings.

\\ (\ character):	See Strings.

mit:	See M68K-Syntax.

a.out:	See Object.

absolute section:	See Ld Sections.

addition, permitted arguments:	See Infix Ops.

addresses:	See Expressions.

addresses, format of:	See Secs Background.

addressing modes, H8/300:	See H8/300-Addressing.

addressing modes, H8/500:	See H8/500-Addressing.

addressing modes, M680x0 <1>:	See M68K-Syntax.

addressing modes, M680x0:	See M68K-Moto-Syntax.

addressing modes, SH:	See SH-Addressing.

addressing modes, Z8000:	See Z8000-Addressing.

advancing location counter:	See Org.

altered difference tables:	See Word.

alternate syntax for the 680x0:	See M68K-Moto-Syntax.

AMD 29K floating point (ieee):	See AMD29K Floating Point.

AMD 29K identifiers:	See AMD29K-Chars.

AMD 29K line comment character:	See AMD29K-Chars.

AMD 29K line separator:	See AMD29K-Chars.

AMD 29K machine directives:	See AMD29K Directives.

AMD 29K opcodes:	See AMD29K Opcodes.

AMD 29K options (none):	See AMD29K Options.

AMD 29K protected registers:	See AMD29K-Regs.

AMD 29K register names:	See AMD29K-Regs.

AMD 29K special purpose registers:	See AMD29K-Regs.

AMD 29K statement separator:	See AMD29K-Chars.

AMD 29K support:	See AMD29K-Dependent.

architecture options, i960:	See Options-i960.

architecture options, M680x0:	See M68K-Opts.

architectures, SPARC:	See Sparc-Opts.

arguments for addition:	See Infix Ops.

arguments for subtraction:	See Infix Ops.

arguments in expressions:	See Arguments.

arithmetic functions:	See Operators.

arithmetic operands:	See Arguments.

assembler internal logic error:	See As Sections.

assembler, and linker:	See Secs Background.

assembly listings, enabling:	See a.

assigning values to symbols <1>:	See Equ.

assigning values to symbols:	See Setting Symbols.

attributes, symbol:	See Symbol Attributes.

auxiliary attributes, COFF symbols:	See COFF Symbols.

auxiliary symbol information, COFF:	See Dim.

Av7:	See Sparc-Opts.

backslash (\\):	See Strings.

backspace (\b):	See Strings.

big endian output, MIPS:	See Overview.

big-endian output, MIPS:	See MIPS Opts.

bignums:	See Bignums.

binary integers:	See Integers.

bitfields, not supported on VAX:	See VAX-no.

block:	See Z8000 Directives.

branch improvement, M680x0:	See M68K-Branch.

branch improvement, VAX:	See VAX-branch.

branch recording, i960:	See Options-i960.

branch statistics table, i960:	See Options-i960.

bss section <1>:	See Ld Sections.

bss section:	See bss.

bus lock prefixes, i386:	See i386-prefixes.

bval:	See Z8000 Directives.

call instructions, i386:	See i386-Opcodes.

carriage return (\r):	See Strings.

character constants:	See Characters.

character escape codes:	See Strings.

character, single:	See Chars.

characters used in symbols:	See Symbol Intro.

COFF auxiliary symbol information:	See Dim.

COFF named section:	See Section.

COFF structure debugging:	See Tag.

COFF symbol attributes:	See COFF Symbols.

COFF symbol descriptor:	See Desc.

COFF symbol storage class:	See Scl.

COFF symbol type:	See Type.

COFF symbols, debugging:	See Def.

COFF value attribute:	See Val.

command line conventions:	See Command Line.

command-line options ignored, VAX:	See Vax-Opts.

comments:	See Comments.

comments, M680x0:	See M68K-Chars.

comments, removed by preprocessor:	See Preprocessing.

common variable storage:	See bss.

compare and jump expansions, i960:	See Compare-and-branch-i960.

compare/branch instructions, i960:	See Compare-and-branch-i960.

conditional assembly:	See If.

constant, single character:	See Chars.

constants:	See Constants.

constants, bignum:	See Bignums.

constants, character:	See Characters.

constants, converted by preprocessor:	See Preprocessing.

constants, floating point:	See Flonums.

constants, integer:	See Integers.

constants, number:	See Numbers.

constants, string:	See Strings.

continuing statements:	See Statements.

conversion instructions, i386:	See i386-Opcodes.

coprocessor wait, i386:	See i386-prefixes.

current address:	See Dot.

current address, advancing:	See Org.

data and text sections, joining:	See R.

data section:	See Ld Sections.

debuggers, and symbol order:	See Symbols.

debugging COFF symbols:	See Def.

decimal integers:	See Integers.

deprecated directives:	See Deprecated.

descriptor, of a.out symbol:	See Symbol Desc.

difference tables altered:	See Word.

difference tables, warning:	See K.

directives and instructions:	See Statements.

directives, M680x0:	See M68K-Directives.

directives, machine independent:	See Pseudo Ops.

directives, Z8000:	See Z8000 Directives.

displacement sizing character, VAX:	See VAX-operands.

dot (symbol):	See Dot.

doublequote (\"):	See Strings.

ECOFF sections:	See MIPS Object.

eight-byte integer:	See Quad.

empty expressions:	See Empty Exprs.

endianness, MIPS:	See Overview.

EOF, newline must precede:	See Statements.

error messsages:	See Errors.

errors, continuing after:	See Z.

escape codes, character:	See Strings.

even:	See Z8000 Directives.

expr (internal section):	See As Sections.

expression arguments:	See Arguments.

expressions:	See Expressions.

expressions, empty:	See Empty Exprs.

expressions, integer:	See Integer Exprs.

faster processing (-f):	See f.

file name, logical <1>:	See File.

file name, logical:	See App-File.

files, including:	See Include.

files, input:	See Input Files.

filling memory:	See Space.

floating point numbers:	See Flonums.

floating point numbers (double):	See Double.

floating point numbers (single) <1>:	See Float.

floating point numbers (single):	See Single.

floating point, AMD 29K (ieee):	See AMD29K Floating Point.

floating point, H8/300 (ieee):	See H8/300 Floating Point.

floating point, H8/500 (ieee):	See H8/500 Floating Point.

floating point, HPPA (ieee):	See HPPA Floating Point.

floating point, i386:	See i386-Float.

floating point, i960 (ieee):	See Floating Point-i960.

floating point, M680x0:	See M68K-Float.

floating point, SH (ieee):	See SH Floating Point.

floating point, SPARC (ieee):	See Sparc-Float.

floating point, VAX:	See VAX-float.

flonums:	See Flonums.

format of error messages:	See Errors.

format of warning messages:	See Errors.

formfeed (\f):	See Strings.

functions, in expressions:	See Operators.

global:	See Z8000 Directives.

grouping data:	See Sub-Sections.

H8/300 addressing modes:	See H8/300-Addressing.

H8/300 floating point (ieee):	See H8/300 Floating Point.

H8/300 line comment character:	See H8/300-Chars.

H8/300 line separator:	See H8/300-Chars.

H8/300 machine directives (none):	See H8/300 Directives.

H8/300 opcode summary:	See H8/300 Opcodes.

H8/300 options (none):	See H8/300 Options.

H8/300 registers:	See H8/300-Regs.

H8/300 size suffixes:	See H8/300 Opcodes.

H8/300 support:	See H8/300-Dependent.

H8/300H, assembling for:	See H8/300 Directives.

H8/500 addressing modes:	See H8/500-Addressing.

H8/500 floating point (ieee):	See H8/500 Floating Point.

H8/500 line comment character:	See H8/500-Chars.

H8/500 line separator:	See H8/500-Chars.

H8/500 machine directives (none):	See H8/500 Directives.

H8/500 opcode summary:	See H8/500 Opcodes.

H8/500 options (none):	See H8/500 Options.

H8/500 registers:	See H8/500-Regs.

H8/500 support:	See H8/500-Dependent.

hex character code (\xdd):	See Strings.

hexadecimal integers:	See Integers.

HPPA directives not supported:	See HPPA Directives.

HPPA floating point (ieee):	See HPPA Floating Point.

HPPA Syntax:	See HPPA Options.

HPPA-only directives:	See HPPA Directives.

i386 fwait instruction:	See i386-Float.

i386 mul, imul instructions:	See i386-Notes.

i386 conversion instructions:	See i386-Opcodes.

i386 floating point:	See i386-Float.

i386 immediate operands:	See i386-Syntax.

i386 jump optimization:	See i386-jumps.

i386 jump, call, return:	See i386-Syntax.

i386 jump/call operands:	See i386-Syntax.

i386 memory references:	See i386-Memory.

i386 opcode naming:	See i386-Opcodes.

i386 opcode prefixes:	See i386-prefixes.

i386 options (none):	See i386-Options.

i386 register operands:	See i386-Syntax.

i386 registers:	See i386-Regs.

i386 sections:	See i386-Syntax.

i386 size suffixes:	See i386-Syntax.

i386 source, destination operands:	See i386-Syntax.

i386 support:	See i386-Dependent.

i386 syntax compatibility:	See i386-Syntax.

i80306 support:	See i386-Dependent.

i960 callj pseudo-opcode:	See callj-i960.

i960 architecture options:	See Options-i960.

i960 branch recording:	See Options-i960.

i960 compare and jump expansions:	See Compare-and-branch-i960.

i960 compare/branch instructions:	See Compare-and-branch-i960.

i960 floating point (ieee):	See Floating Point-i960.

i960 machine directives:	See Directives-i960.

i960 opcodes:	See Opcodes for i960.

i960 options:	See Options-i960.

i960 support:	See i960-Dependent.

identifiers, AMD 29K:	See AMD29K-Chars.

immediate character, M680x0:	See M68K-Chars.

immediate character, VAX:	See VAX-operands.

immediate operands, i386:	See i386-Syntax.

indirect character, VAX:	See VAX-operands.

infix operators:	See Infix Ops.

inhibiting interrupts, i386:	See i386-prefixes.

input:	See Input Files.

input file linenumbers:	See Input Files.

instruction set, M680x0:	See M68K-opcodes.

instruction summary, H8/300:	See H8/300 Opcodes.

instruction summary, H8/500:	See H8/500 Opcodes.

instruction summary, SH:	See SH Opcodes.

instruction summary, Z8000:	See Z8000 Opcodes.

instructions and directives:	See Statements.

integer expressions:	See Integer Exprs.

integer, 16-byte:	See Octa.

integer, 8-byte:	See Quad.

integers:	See Integers.

integers, 16-bit:	See hword.

integers, 32-bit:	See Int.

integers, binary:	See Integers.

integers, decimal:	See Integers.

integers, hexadecimal:	See Integers.

integers, octal:	See Integers.

integers, one byte:	See Byte.

internal as sections:	See As Sections.

invocation summary:	See Overview.

joining text and data sections:	See R.

jump instructions, i386:	See i386-Opcodes.

jump optimization, i386:	See i386-jumps.

jump/call operands, i386:	See i386-Syntax.

label (:):	See Statements.

labels:	See Labels.

ld:	See Object.

length of symbols:	See Symbol Intro.

line comment character:	See Comments.

line comment character, AMD 29K:	See AMD29K-Chars.

line comment character, H8/300:	See H8/300-Chars.

line comment character, H8/500:	See H8/500-Chars.

line comment character, M680x0:	See M68K-Chars.

line comment character, SH:	See SH-Chars.

line comment character, Z8000:	See Z8000-Chars.

line numbers, in input files:	See Input Files.

line numbers, in warnings/errors:	See Errors.

line separator character:	See Statements.

line separator, AMD 29K:	See AMD29K-Chars.

line separator, H8/300:	See H8/300-Chars.

line separator, H8/500:	See H8/500-Chars.

line separator, SH:	See SH-Chars.

line separator, Z8000:	See Z8000-Chars.

lines starting with #:	See Comments.

linker:	See Object.

linker, and assembler:	See Secs Background.

listing control, turning off:	See Nolist.

listing control, turning on:	See List.

listing control: new page:	See Eject.

listing control: paper size:	See Psize.

listing control: subtitle:	See Sbttl.

listing control: title line:	See Title.

listings, enabling:	See a.

little endian output, MIPS:	See Overview.

little-endian output, MIPS:	See MIPS Opts.

local common symbols:	See Lcomm.

local labels, retaining in output:	See L.

local symbol names:	See Symbol Names.

location counter:	See Dot.

location counter, advancing:	See Org.

logical file name <1>:	See File.

logical file name:	See App-File.

logical line number:	See Line.

logical line numbers:	See Comments.

lval:	See Z8000 Directives.

M680x0 addressing modes <1>:	See M68K-Syntax.

M680x0 addressing modes:	See M68K-Moto-Syntax.

M680x0 architecture options:	See M68K-Opts.

M680x0 branch improvement:	See M68K-Branch.

M680x0 directives:	See M68K-Directives.

M680x0 floating point:	See M68K-Float.

M680x0 immediate character:	See M68K-Chars.

M680x0 line comment character:	See M68K-Chars.

M680x0 opcodes:	See M68K-opcodes.

M680x0 options:	See M68K-Opts.

M680x0 pseudo-opcodes:	See M68K-Branch.

M680x0 size modifiers:	See M68K-Syntax.

M680x0 support:	See M68K-Dependent.

M680x0 syntax <1>:	See M68K-Moto-Syntax.

M680x0 syntax:	See M68K-Syntax.

machine dependencies:	See Machine Dependencies.

machine directives, AMD 29K:	See AMD29K Directives.

machine directives, H8/300 (none):	See H8/300 Directives.

machine directives, H8/500 (none):	See H8/500 Directives.

machine directives, i960:	See Directives-i960.

machine directives, SH (none):	See SH Directives.

machine directives, SPARC:	See Sparc-Directives.

machine directives, VAX:	See VAX-directives.

machine independent directives:	See Pseudo Ops.

machine instructions (not covered):	See Manual.

machine-independent syntax:	See Syntax.

manual, structure and purpose:	See Manual.

memory references, i386:	See i386-Memory.

merging text and data sections:	See R.

messages from as:	See Errors.

minus, permitted arguments:	See Infix Ops.

MIPS architecture options:	See MIPS Opts.

MIPS big-endian output:	See MIPS Opts.

MIPS debugging directives:	See MIPS Stabs.

MIPS ECOFF sections:	See MIPS Object.

MIPS endianness:	See Overview.

MIPS ISA:	See Overview.

MIPS ISA override:	See MIPS ISA.

MIPS little-endian output:	See MIPS Opts.

MIPS R2000:	See MIPS-Dependent.

MIPS R3000:	See MIPS-Dependent.

MIPS R4000:	See MIPS-Dependent.

MIPS R6000:	See MIPS-Dependent.

mnemonics for opcodes, VAX:	See VAX-opcodes.

mnemonics, H8/300:	See H8/300 Opcodes.

mnemonics, H8/500:	See H8/500 Opcodes.

mnemonics, SH:	See SH Opcodes.

mnemonics, Z8000:	See Z8000 Opcodes.

Motorola syntax for the 680x0:	See M68K-Moto-Syntax.

multi-line statements:	See Statements.

name:	See Z8000 Directives.

named section (COFF):	See Section.

named sections:	See Ld Sections.

names, symbol:	See Symbol Names.

naming object file:	See o.

new page, in listings:	See Eject.

newline (\n):	See Strings.

newline, required at file end:	See Statements.

null-terminated strings:	See Asciz.

number constants:	See Numbers.

numbered subsections:	See Sub-Sections.

numbers, 16-bit:	See hword.

numeric values:	See Expressions.

object file:	See Object.

object file format:	See Object Formats.

object file name:	See o.

object file, after errors:	See Z.

obsolescent directives:	See Deprecated.

octal character code (\ddd):	See Strings.

octal integers:	See Integers.

opcode mnemonics, VAX:	See VAX-opcodes.

opcode naming, i386:	See i386-Opcodes.

opcode prefixes, i386:	See i386-prefixes.

opcode suffixes, i386:	See i386-Syntax.

opcode summary, H8/300:	See H8/300 Opcodes.

opcode summary, H8/500:	See H8/500 Opcodes.

opcode summary, SH:	See SH Opcodes.

opcode summary, Z8000:	See Z8000 Opcodes.

opcodes for AMD 29K:	See AMD29K Opcodes.

opcodes, i960:	See Opcodes for i960.

opcodes, M680x0:	See M68K-opcodes.

operand delimiters, i386:	See i386-Syntax.

operand notation, VAX:	See VAX-operands.

operands in expressions:	See Arguments.

operator precedence:	See Infix Ops.

operators, in expressions:	See Operators.

operators, permitted arguments:	See Infix Ops.

option summary:	See Overview.

options for AMD29K (none):	See AMD29K Options.

options for i386 (none):	See i386-Options.

options for SPARC:	See Sparc-Opts.

options for VAX/VMS:	See Vax-Opts.

options, all versions of as:	See Invoking.

options, command line:	See Command Line.

options, H8/300 (none):	See H8/300 Options.

options, H8/500 (none):	See H8/500 Options.

options, i960:	See Options-i960.

options, M680x0:	See M68K-Opts.

options, SH (none):	See SH Options.

options, Z8000:	See Z8000 Options.

other attribute, of a.out symbol:	See Symbol Other.

output file:	See Object.

padding the location counter:	See Align.

page, in listings:	See Eject.

paper size, for listings:	See Psize.

paths for .include:	See I.

patterns, writing in memory:	See Fill.

plus, permitted arguments:	See Infix Ops.

precedence of operators:	See Infix Ops.

precision, floating point:	See Flonums.

prefix operators:	See Prefix Ops.

prefixes, i386:	See i386-prefixes.

preprocessing:	See Preprocessing.

preprocessing, turning on and off:	See Preprocessing.

primary attributes, COFF symbols:	See COFF Symbols.

protected registers, AMD 29K:	See AMD29K-Regs.

pseudo-opcodes, M680x0:	See M68K-Branch.

pseudo-ops for branch, VAX:	See VAX-branch.

pseudo-ops, machine independent:	See Pseudo Ops.

purpose of gnu as:	See GNU Assembler.

register names, AMD 29K:	See AMD29K-Regs.

register names, H8/300:	See H8/300-Regs.

register names, VAX:	See VAX-operands.

register operands, i386:	See i386-Syntax.

registers, H8/500:	See H8/500-Regs.

registers, i386:	See i386-Regs.

registers, SH:	See SH-Regs.

registers, Z8000:	See Z8000-Regs.

relocation:	See Sections.

relocation example:	See Ld Sections.

repeat prefixes, i386:	See i386-prefixes.

return instructions, i386:	See i386-Syntax.

rsect:	See Z8000 Directives.

search path for .include:	See I.

section override prefixes, i386:	See i386-prefixes.

section-relative addressing:	See Secs Background.

sections:	See Sections.

sections in messages, internal:	See As Sections.

sections, i386:	See i386-Syntax.

sections, named:	See Ld Sections.

segm:	See Z8000 Directives.

SH addressing modes:	See SH-Addressing.

SH floating point (ieee):	See SH Floating Point.

SH line comment character:	See SH-Chars.

SH line separator:	See SH-Chars.

SH machine directives (none):	See SH Directives.

SH opcode summary:	See SH Opcodes.

SH options (none):	See SH Options.

SH registers:	See SH-Regs.

SH support:	See SH-Dependent.

single character constant:	See Chars.

sixteen bit integers:	See hword.

sixteen byte integer:	See Octa.

size modifiers, M680x0:	See M68K-Syntax.

size prefixes, i386:	See i386-prefixes.

size suffixes, H8/300:	See H8/300 Opcodes.

sizes operands, i386:	See i386-Syntax.

small objects, MIPS ECOFF:	See MIPS Object.

SOM symbol attributes:	See SOM Symbols.

source program:	See Input Files.

source, destination operands; i386:	See i386-Syntax.

space used, maximum for assembly:	See statistics.

SPARC architectures:	See Sparc-Opts.

SPARC floating point (ieee):	See Sparc-Float.

SPARC machine directives:	See Sparc-Directives.

SPARC options:	See Sparc-Opts.

SPARC support:	See Sparc-Dependent.

special characters, M680x0:	See M68K-Chars.

special purpose registers, AMD 29K:	See AMD29K-Regs.

standard as sections:	See Secs Background.

standard input, as input file:	See Command Line.

statement on multiple lines:	See Statements.

statement separator character:	See Statements.

statement separator, AMD 29K:	See AMD29K-Chars.

statement separator, H8/300:	See H8/300-Chars.

statement separator, H8/500:	See H8/500-Chars.

statement separator, SH:	See SH-Chars.

statement separator, Z8000:	See Z8000-Chars.

statements, structure of:	See Statements.

statistics, about assembly:	See statistics.

stopping the assembly:	See Abort.

string constants:	See Strings.

string literals:	See Ascii.

string, copying to object file:	See String.

structure debugging, COFF:	See Tag.

subexpressions:	See Arguments.

subtitles for listings:	See Sbttl.

subtraction, permitted arguments:	See Infix Ops.

summary of options:	See Overview.

support:	See HPPA-Dependent.

supporting files, including:	See Include.

suppressing warnings:	See W.

sval:	See Z8000 Directives.

symbol attributes:	See Symbol Attributes.

symbol attributes, a.out:	See a.out Symbols.

symbol attributes, COFF:	See COFF Symbols.

symbol attributes, SOM:	See SOM Symbols.

symbol descriptor, COFF:	See Desc.

symbol names:	See Symbol Names.

symbol names, $ in <1>:	See SH-Chars.

symbol names, $ in:	See H8/500-Chars.

symbol names, local:	See Symbol Names.

symbol names, temporary:	See Symbol Names.

symbol storage class (COFF):	See Scl.

symbol type:	See Symbol Type.

symbol type, COFF:	See Type.

symbol value:	See Symbol Value.

symbol value, setting:	See Set.

symbol values, assigning:	See Setting Symbols.

symbol, common:	See Comm.

symbol, making visible to linker:	See Global.

symbolic debuggers, information for:	See Stab.

symbols:	See Symbols.

symbols with lowercase, VAX/VMS:	See Vax-Opts.

symbols, assigning values to:	See Equ.

symbols, local common:	See Lcomm.

syntax compatibility, i386:	See i386-Syntax.

syntax, M680x0 <1>:	See M68K-Moto-Syntax.

syntax, M680x0:	See M68K-Syntax.

syntax, machine-independent:	See Syntax.

tab (\t):	See Strings.

temporary symbol names:	See Symbol Names.

text and data sections, joining:	See R.

text section:	See Ld Sections.

time, total for assembly:	See statistics.

trusted compiler:	See f.

turning preprocessing on and off:	See Preprocessing.

type of a symbol:	See Symbol Type.

undefined section:	See Ld Sections.

unsegm:	See Z8000 Directives.

value attribute, COFF:	See Val.

value of a symbol:	See Symbol Value.

VAX bitfields not supported:	See VAX-no.

VAX branch improvement:	See VAX-branch.

VAX command-line options ignored:	See Vax-Opts.

VAX displacement sizing character:	See VAX-operands.

VAX floating point:	See VAX-float.

VAX immediate character:	See VAX-operands.

VAX indirect character:	See VAX-operands.

VAX machine directives:	See VAX-directives.

VAX opcode mnemonics:	See VAX-opcodes.

VAX operand notation:	See VAX-operands.

VAX register names:	See VAX-operands.

VAX support:	See Vax-Dependent.

Vax-11 C compatibility:	See Vax-Opts.

VAX/VMS options:	See Vax-Opts.

version of as:	See v.

VMS (VAX) options:	See Vax-Opts.

warning for altered difference tables:	See K.

warning messages:	See Errors.

warnings, suppressing:	See W.

whitespace:	See Whitespace.

whitespace, removed by preprocessor:	See Preprocessing.

wide floating point directives, VAX:	See VAX-directives.

writing patterns in memory:	See Fill.

wval:	See Z8000 Directives.

Z800 addressing modes:	See Z8000-Addressing.

Z8000 directives:	See Z8000 Directives.

Z8000 line comment character:	See Z8000-Chars.

Z8000 line separator:	See Z8000-Chars.

Z8000 opcode summary:	See Z8000 Opcodes.

Z8000 options:	See Z8000 Options.

Z8000 registers:	See Z8000-Regs.

Z8000 support:	See Z8000-Dependent.

zero-terminated strings:	See Asciz.