TR.TTP:		Translate and/or delete characters.

by David Megginson, 1991
Released into the Public Domain

Usage:	tr [-cds] string1 [string2]

INTRODUCTION

Here is my version of tr(1v) for the Atari ST. tr is a pure filter
program (it cannot take files as arguments) which will translate or
delete characters from its standard input and place the result on
its standard output. tr takes three options:

-c	Use the complement of string1 (everything but..)
-d	Delete characters in string1
-s	Squeeze output so that multiple instances of the same
	translate character are compressed into a single instance.

The strings may consist of any characters, a range in the format 
<char1>-<char2>, or an octal value in the form \nnn (you may not use
octal values in a range). Use \ to take - literally. This example will
create a list of words in a file, one on each line:

	tr -cs a-zA-Z '\012' < myfile.txt > wordlist.txt

SPEED

For the sake of speed, I bypass the high-level i/o functions and read
in large chunks of a file at once (this is portable to Unix and MSDOS,
by the way). The default buffer size is 50000 bytes, but you can change
it in the Makefile by adding -DBUFFER_SIZE=<whatever>. The bigger the
buffer, the faster tr, but also the more memory wasted (remember, the
ST is a MULTITASKING machine now, so we can't use Malloc(-1L) to grab
all available memory any more without risking flames).

THOSE PESKY CARRIAGE RETURNS

For some brain-damaged reason (MSDOS,CP/M compatibility, I imagine),
the ST uses "\r\n" to mark the end of a line instead of "\n" like in
Unix. Many of us have recompiled programs to avoid this, but the
problem of compatibility still remains. Use the -DSKIP_CR flag in the
Makefile to handle '\r' correctly in the input file (I have _not_ done
this for the distribution binary). Even with -DSKIP_CR, CR will usually
be stripped from the output file, at least in this version.

WHAT DOES THIS COST?

Nothing, of course. After Eric Smith created MiNT and made it free to
the public, how could I live with myself if I tried to make this
shareware? Besides, I spent only an hour or two on it. Do feel free
to post glowing messages about me to the net, though... :-)

REVISION NUMBER

You can check the revision number of your tr.ttp binaries using the
RCS ident(1) command. If you don't have A. Pratt's excellent port of
RCS for the Atari ST, GET IT!

USING THE SOURCE

This program is in the Public Domain, _not_ under the Gnu licensing
agreement. As a result, you may incorporate it (re-compiled) into
commercial packages without charge, although I would like a little
credit somewhere in the documentation. The source is (I hope) good
ANSI, and you will need an ANSI compiler and ANSI header files to
recompile it (I use the Gnu C compiler and Eric Smith's MiNT library
for GCC on the Atari ST).