README.adding_code
1
2(This documentation is related to the development of gf2x)
3
4This lowlevel/ subdirectory is the place where new code may be added to gf2x,
5in particular new code for lowlevel routines, so-called mul1, mul2, mul3,
6and so on. The steps for adding code are:
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8* Choose a file name. Assuming you are coding a new version of mul3, for
9 instance, you might choose to name your file mul3foo.c. The file name
10 must match mul[0-9] because probably some scripts rely on it.
11
12* Write a skeleton for mul3foo.c based on pre-existing files. There are a
13 couple of very important things in writing this file:
14 - The file must be guarded by a #ifndef GF2X_MUL3_H_ / ... / #endif
15 construct. The name of the macro matters.
16 - The file must include gf2x-small.h
17 - The function included must be called gf2x_mul3, and match the
18 expected prototype.
19
20* For inserting this function in the tuning mechanism, edit Makefile.am ;
21 Since the tedious Makefile.am code is now generated by a perl script
22 (albeit not automatically), one just has to add a new line among those
23 starting with #*
24 Then, to regenerate the tedious section of Makefile.am, do:
25 perl -i ./generate-test-list.pl Makefile.am
26 Note that this edits Makefile.am in place, so you'd better quit your
27 text editing section on Makefil.am first.
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29Generated code:
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31It is more complicated to add a new code _generation_ mechanism, and
32requires the following steps.
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34* Assuming the generator code is in C (but it does not matter much), then
35 it must be codded, and a rule for building the _generator_ must be
36 added to Makefile.am. There is not much to it, probably a matter of
37 adding only a simple line to Makefile.am
38
39* Your generator must accept arguments, and output its result to a file
40 whose name matches gen_mul3 (for a mul3 of course). Or possibly write
41 to stdout. Then you have to copy one of the very ugly paragraphs, e.g.
42 the one for tune_gen_mul1_w64k2. The same warnings as above apply.
43
44* The generation rule has to be told to generate-test-list.pl somehow.
45