ALL RIGHTS RESERVED. Note: Directions for using this system are included below and in the sample Pascal programs of the a:\samples directory. This is a subset of ISO Standard Pascal, with some useful C extensions. Many programs in college-level Pascal textbooks will run on it without major change. A full ISO standard version of the enclosed Pascal translator and p-code interpreter, together with the complete C source code, is available for $30 from the Austin Code Works (whose address is at the end of this file). A companion ISO standard Pascal to C translator system, together with C source code, is also available from Austin Code Works. The Pascal to C translator is based on the p-code interpreter, and it generates optimizable C code that runs almost as fast as programs compiled directly from C code. Advanced versions of these systems, extended or custom-tailored for efficient operation on your own system, can be commissioned from the author at the address given at the end of this file. As a demonstration of this, the "primes.exe" program in the \samples directory of this diskette was compiled from the "\samples\primes.pas" program after a Pascal to C translation. ================================================================== DISCLAIMER: These programs are provided to the public domain as a service to programmers. They may be copied freely and distributed for edu- cational purposes with the following restrictions: 1. Persons or organizations wishing to use these programs for commercial resale, or to incorporate these programs into their own systems for commercial resale, whether in whole or in part, must first obtain written permission from the author. 2. Charges for reproduced copies must be limited to cost (disks, postage and handling). 3. Any modifications to the programs from the originally dis- tributed version must be clearly indicated. Such modifications should retain the genealogy of the program. 4. All documentation and notices supplied with these programs must be included in any reproduced versions. 5. All warranties connected with these programs are dis- claimed. In particular, the author assumes no responsibility that the programs will operate as documented, nor is the author respon- sible for direct, indirect, or consequential damages. Any and all risk associated with using these programs, in whole or in part, is the user's. ================================================================== NOTES ON USING THE TRANSLATOR: The "A:\P_PASCAL\DO.BAT" file gives a simple description of the calling sequences for translating and executing a Pascal program. A more elaborate explanation of the command line calling sequences and special features of the translator and interpreter is given below. FEATURES AND RESTRICTIONS This is a "Portable Pascal" system, with some C extensions. Modern college-level standard Pascal programming textbooks, such as "Oh! Pascal", by Cooper and Clancy, give examples of Pascal source programs that will run on this system. The C extensions, such as C-style file inclusion during translation, the "system" call, and masking and shifting operations, appear as examples in the demon- stration programs of the a:\samples directory on this diskette. This Pascal in C implementation limits sets to 64 members and str- ing constants to no more than 80 characters apiece. Any mix of up- per and lower case identifiers and reserved words can be used, but identifiers are stored internally in an eight-letter format. European ascii alphabet letters may be used in identifiers. At present, the predeclared constant "maxint" has a value of 32767, which means that any long arithmetic must be done using REAL num- bers. Standard Pascal functions "RESET" and "REWRITE" are not im- plemented in Portable Pascal, and there in this public-domain ver- sion of the system of two external textfiles that, when used, must be listed as parameters in the program header and should not be declared within the program. The system available from Austin Code Works is a standard Pascal with full Pascal data and text files. Additional minor restrictions: procedures may not be passed as pa- rameters. The "packed" and "unpacked" keywords may be used, but they have no effect at present; instead, all character and boolean arrays are automatically stored as packed character arrays. Pack and unpack are not implemented, but an example of "do it yourself" packing and unpacking using the shifting and masking operators is included in the "a:\samples" directory ("truefalse.pas"). See the yesno.pas program in the a:\samples directory for examples of string assignment and comparison (full standard Pascal version). A "SYSTEM(packed_char_array)" function identical in behavior to the C version of "system(char *)" is implemented. If you use a Pascal packed char array instead of a string constant as argument to the "system" function, be sure to intialize your array properly with a blank string constant of the correct size. The external Pascal file names are limited to eight letters and must appear in the first line "program xxxxx(a, b, ...);" statement. (The file name may also apear in the command line with a Unix or Dos path prefix.) The standard P-Pascal prr and prd files are no longer predeclared as external textfiles. Prr and prd can be listed as program parameters or other names can be used instesad. "Text" and "File" can not be used in variable or type declarations in Portable Pascal. External files are automatically declared as text files by the system. A version of this system removing many of these restrictions is available from the Austin Code Works, along with the complete C source code, for a nominal fee. (See the address at end of this file.) The standard Pascal "NEW" and "DISPOSE" procedures are available for acquiring individual data nodes and returning them to the Pas- cal heap. In addition, "MARK" and "RELEASE" are available for use in returning entire blocks of data to the heap, rather than in- dividual nodes. Programs can be written using only "NEW" and "DISPOSE", without mention of "MARK" and "RELEASE". Or, "NEW" (and optionally, "DISPOSE") can be used in combination with "MARK" and "RELEASE". However, while "NEW" and "DISPOSE" are relatively well-behaved operations, "MARK" and "RELEASE" have to be used carefully as paired operations that have side-effects. One of these side effects is that all data nodes acquired by "NEW" after a "MARK" operation are automatically disposed of by the call on "RELEASE". Furthermore, calls on "MARK" and "RELEASE" are only defined if they are paired so each call on "MARK" is balanced by a corresponding call on "RELEASE". (The a:\samples listtest.pas and newtest.pas programs are examples of their use.) The PC-SIG "Near arrays" version of the Pascal p-code interpreter has approximately 1900 words of Pascal heap data available for "NEW" and "DISPOSE". Some small source program examples are included in the "samples" directory on this diskette. They illustrate the general form of programs accepted by the translator and the required translator options directives to precede programs. TRANSLATOR OPTIONS: The Pascal program examples in the a:\samples file illustrate the use of translator options. In particular, "pi.pas" shows how to turn the translator listing on and off during translation of that program. All programs contain one or more lists of translator op- tions of the form: (*$ ... *) where the " ... " in the middle is some sequence of the following options separated by commas: c+ causes p-code to be written to the ".pcd" file. If c+ does not appear, or if c- or c is written, the source program will be checked for correctness, but not trans- lated. d+ causes the translator to put range checks into the p- code translation of the program. These checks are use- ful for debugging programs, but also cause programs to run slowly. They are partly responsible for Pascal's re- putation as a slow programming language. The default op- tion is d-, for omitting these checks to improve program speed and to pass "flexible dimension" arrays to sub- programs. The d+ option can be turned off within your program by following it with a d- option at the desired point in the program. i+ causes the file whose quoted name follows to be read by the translator: i. e., {$i+'a:\samples\vpack.p'} includes the vpack.p file at that point in the program. The file source code has to be to be correct for that point in the program where its insertion occurs. Up to seven levels of file inclusion from any source file are allowed by the system. (For an example of how to use the i+ option, see the 'a:\samples\factorial.pas' file.) l+ causes the program to be listed to the "stdout" file (the monitor screen). The listing can be re-directed from the screen to the line printer using the ">" redi- rection operator on the command line. l+ is the default option (the listing will appear if l+ is omitted). To turn off the listing, use l-. Programs will translate several times faster with the screen listing disabled. o+ causes the translator to route its translation of the source program to the stdout file, causing each execut- able source statement to be followed by the p-code that it generates (the ".pcd" file will be empty as a result, but must still be mentioned on the translator's command line). Default option is o-. t+ causes the translator to write out its internal tables listing declared constants, procedures, and functions at the end of the translation pass. Its use is to discover what the translator believes the program variables and procedures to be. Default option is t-. ================================================================= CALLING THE TRANSLATOR AND INTERPRETER UNDER DOS: For the translator: ================================================================== translator your_source_code.pas p_code_output.pcd or translator con p_code_output.pcd ================================================================== Note that the .pcd file extension for the output p-code file in the example is necessary to interface properly with both the in- terpreter and the C code generator programs. The command lines above illustrate how source programs can be typed in from the keyboard if "con" is used as an argument on the translator command line; but editing is limited to the current line only. Refer to the DOS manual description of the "copy con output_file" command for information about how to use the console keyboard for program input to the translator. In particular, "control-Z" or ^Z is used as the end of file mark to terminate source programs. Files external to the program are named in standard Pascal style on the "Program xxxxx(Input, Output, File1, File2);" line of your Pascal program. These external files are names of up to eight letters each (the same as Pascal identifiers), and they match file names (preceded by optional operating system pathnames) that ap- pear on the command line of your program. Thus, for example, Program Fileptrs(Input, Output, Prr); .... .... END. can be called by a command line sequence of the form: interpreter fileptrs.pcd c:\xxx\prr or interpreter fileptrs.pcd a:\yyy\zzzz.prr or even interpreter fileptrs.pcd prr depending on the file path designation that you, the user, find convenient to use. Translator listings are sent to the screen, unless DOS I/O redirection is used: ================================================================== translator source.pas object.pcd > lpt1 (* parallel printer *) or translator source.pas object.pcd > com1 (* serial printer *) or translator source.pas object.pcd > a:listing.asc ================================================================== NOTES ON USING THE INTERPRETER: Interpreter command line with optional files in brackets: ================================================================== interpreter p_code_input.pcd [path1][file1] [path2][file2] ================================================================== The interpreter also has available the standard Pascal Input and Output files, known in the C language as stdin and stdout. So programs translated for the interpreter can access Input (stdin), Output (stdout) and up to two external Portable Pascal text files. See the a:\samples directory for examples of how to use files. Note that the interpreter has some limitations, most important of which is that sets can have up to 64 members. This is a relative- ly complete Pascal otherwise. It is intended as a teaching system, with the p-code interpreter to be used by students in compiler courses. Thus, the p-code output from the translator is in ascii format, so that it can be inspected and compared with the source code and used in conjunction with the source code to p-code cross-reference generated in the translator listings. Translator error messages use the error number format that appears in the Pascal User Manual listed below and in some C compilers as well: Jensen, K. and Wirth, N. Pascal User Manual and Report. Springer Publishing Co., 1974. The full listings and executable files for the expanded version of this system or for the Pascal to C translator are available at a nominal price (presently $30) from: Austin Code Works 11100 Leafwood Lane Austin, Texas 78750-3409 USA Author's address for correspondence: Victor Schneider 291 Summit Avenue Brighton, MA 02146 USA