asterisk/codecs/lpc10/README

Tue Aug 20 16:19:51 CDT 1996
Andy Fingerhut (jaf@arl.wustl.edu)

In release 1.4, there are quite a few hand modifications to the C code
that was automatically created from the Fortran code with f2c.  They
are all summarized in change log comments at the beginning of the
changed files.  All of the original files from f2c were checked in to
RCS before modification, so it is possible to see exactly what changes
were made, for the extremely curious.  That precaution was also for my
benefit, in case I ever recompile the Fortran sources, and want to
make similar changes to that new C source code.

Below is the README file for this directory included with the 1.3
release of the LPC-10 package.  A few parts of it are a little out of
date, but it is correct for the most part.


Sun Jul  7 15:30:31 CDT 1996
Andy Fingerhut (jaf@arl.wustl.edu)

To create the LPC-10 library, copy the appropriate makefile to the
proper name for easy use, e.g., for Unix, copy makefile.unx to the
file "Makefile".  The file makefile.dos has been used with some
version of the 'nmake' utility that comes with the Microsoft C
compiler (the same one used for Nautilus v1.5a, which I believe
specifies Microsoft C version 7.0 or later).

Then edit the file lpc10.h in the directory above.  It should already
be set up to work properly on any Unix compiler for which "int" is 32
bits and "short" is 16 bits, and under the Microsoft C compiler
configured so that "long" is 32 bits and "int" is 16 bits.  There must
be a typedef for the two types INT32 and INT16 in that file.  You
should choose types that compile to those sizes using your compiler,
because there are places in the LPC-10 code that expect INT16's to
have exactly 16 bits (at least, I *think* they must be no larger), and
INT32's to have exactly 32 bits.


A few notes on how these files were created
-------------------------------------------

(This section is mostly for my benefit, so I can remember what I did.
You don't need to read it if you just want to use this package.  It
might be useful to read it if you change the Fortran sources and want
to recreate a usable library of C sources.  -- Andy)

These C sources were created automatically from the Fortran sources
using f2c, for the most part.  Listed below are the extra
modifications that were made after this automatic conversion.  Many of
them were made so that it was not necessary to install f2c in order to
use this LPC-10 coder.

1.

Put all of those files that were necessary for only the coder, rather
than an application that uses the coder, into this subdirectory called
lpc10.

2.

Copied f2c.h from the f2c distribution into this subdirectory.  Some
modifications were made to the "typedef" statements in this file, to
explicitly indicate the sizes (in bits) that different integer types
should be.  The types INT32 and INT16 must be defined in a file called
lpc10.h in the directory above.  Created the file f2clib.c, containing
only the functions pow_ii(), r_sign(), and i_nint() from the f2c
library.

3.

The f2c output originally had a file called contrl_com.c, that defined
a small structure containing a few variables that were used in many
different functions of the LPC10 code.  Every file containing
functions that used it defined it as "extern", while contrl_com.c
actually allocated storage for the structure.  Bill Dorsey, one of the
lead developers of Nautilus, said that the Microsoft C compiler had
problems either compiling this file, or linking it with all of the
other compiled files, so he just eliminated that file and removed the
"extern" keyword from the one of the files that declared it that way.
The file chosen (arbitrarily) was analys.c.

4.

Copied the makefiles for Unix and Microsoft C from the Nautilus v1.5a
distribution into the lpc10 directory.  Modified them to take out
references to Nautilus.  These makefiles don't create an executable,
but a library of compiled functions called liblpc10.a (Unix) or
LPC10.LIB (DOS).  This library can be used when linking an executable
that calls the functions lpcini_(), lpcenc_(), and lpcdec_().