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How to get started:
Edit the Makefile.
You should configure a few machine-dependencies and what
compiler you want to use.
The code works both with ANSI and K&R-C. Use
-DNeedFunctionPrototypes to compile with, or
-UNeedFunctionPrototypes to compile without, function
prototypes in the header files.
Make addtst
The "add" program that will be compiled and run checks whether
the basic math functions of the gsm library work with your
compiler. If it prints anything to stderr, complain (to us).
Edit inc/config.h.
Local versions of the gsm library and the "compress"-like filters
toast, untoast and tcat will be generated.
If the compilation aborts because of a missing function,
declaration, or header file, see if there's something in
inc/config.h to work around it. If not, complain.
Try it
Grab an audio file from somewhere (raw u-law or Sun .au is fine,
linear 16-bit in host byte order will do), copy it, toast it,
untoast it, and listen to the result.
The GSM-encoded and -decoded audio should have the quality
of a good phone line. If the resulting audio is noisier than
your original, or if you hear compression artifacts, complain;
that's a bug in our software, not a bug in the GSM encoding
standard itself.
You can install the gsm library interface, or the toast binaries,
or both.
Edit the Makefile
Fill in the directories where you want to install the
library, header files, manual pages, and binaries.
Turn off the installation of one half of the distribution
(i.e., gsm library or toast binaries) by not setting the
corresponding directory root Makefile macro.
make install
will install the programs "toast" with two links named
"tcat" and "untoast", and the gsm library "libgsm.a" with
a "gsm.h" header file, and their respective manual pages.
This code was developed on a machine without an integer
multiplication instruction, where we obtained the fastest result by
replacing some of the integer multiplications with floating point
If your machine does multiply integers fast enough,
leave USE_FLOAT_MUL undefined. The results should be the
same in both cases.
On machines with fast floating point arithmetic, defining
both USE_FLOAT_MUL and FAST makes a run-time library
option available that will (in a few crucial places) use
``native'' floating point operations rather than the bit-by-bit
defined ones of the GSM standard. If you use this fast
option, the outcome will not be bitwise identical to the
results prescribed by the standard, but it is compatible with
the standard encoding, and a user is unlikely to notice a
Bug Reports
Please direct bug reports, questions, and comments to and
Good luck,
Jutta Degener,
Carsten Bormann
Copyright 1992, 1993, 1994, by Jutta Degener and Carsten Bormann,
Technische Universitaet Berlin. See the accompanying file "COPYRIGHT"