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|
#!/usr/bin/perl
#
# Galois field table generator.
#
# Copyright (c) 2006-2010 Miru Limited.
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
use strict;
my $GF_ELEMENT_BYTES = 1;
my $GF_ELEMENT_BITS = 8 * $GF_ELEMENT_BYTES;
my $GF_NO_ELEMENTS = 1 << $GF_ELEMENT_BITS;
my $GF_MAX = $GF_NO_ELEMENTS - 1;
my $GF_GENERATOR = 0x11d;
my @gflog;
my @gfantilog;
my $j = 1;
for (my $i = 0; $i < $GF_MAX; $i++)
{
$gflog[ $j ] = $i;
$gfantilog[ $i ] = $j;
$j <<= 1;
if ($j & $GF_NO_ELEMENTS) {
$j ^= $GF_GENERATOR;
}
}
$gflog[ 0 ] = $GF_MAX;
$gfantilog[ $GF_MAX ] = 0;
print<<MOO;
/* vim:ts=8:sts=8:sw=4:noai:noexpandtab
*
* Galois field tables
*
* Copyright (c) 2006-2010 Miru Limited.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <impl/framework.h>
/* globals */
const pgm_gf8_t pgm_gflog[PGM_GF_NO_ELEMENTS] =
{
MOO
# print out y = log₂(x) table
for (my $i = 0; $i < $GF_NO_ELEMENTS; $i++)
{
print "\t" if ($i % 8 == 0);
print sprintf("0x%2.2x", $gflog[ $i ]);
print ',' unless ($i == $GF_MAX);
print ( (($i % 8) == 7) ? "\n" : ' ' );
}
print<<MOO;
};
const pgm_gf8_t pgm_gfantilog[PGM_GF_NO_ELEMENTS] =
{
MOO
# print out y = antilog₂(x) table, aka pow2(x), 2^^x
for (my $i = 0; $i < $GF_NO_ELEMENTS; $i++)
{
print "\t" if ($i % 8 == 0);
print sprintf("0x%2.2x", $gfantilog[ $i ]);
print ',' unless ($i == $GF_MAX);
print ( (($i % 8) == 7) ? "\n" : ' ' );
}
print<<MOO;
};
#ifdef CONFIG_GALOIS_MUL_LUT
const pgm_gf8_t pgm_gftable[PGM_GF_NO_ELEMENTS * PGM_GF_NO_ELEMENTS] =
{
MOO
sub gfmul {
my($a, $b) = @_;
return 0 if ($a == 0 || $b == 0);
my $sum = $gflog[ $a ] + $gflog[ $b ];
return ($sum >= $GF_MAX) ? $gfantilog[ $sum - $GF_MAX ] : $gfantilog[ $sum ];
}
# print out multiplication table z = x • y
for (my $i = 0; $i < $GF_NO_ELEMENTS; $i++)
{
for (my $j = 0; $j < $GF_NO_ELEMENTS; $j++)
{
print "\t" if ($j % 8 == 0);
print sprintf("0x%2.2x", gfmul( $i, $j ));
print ',' unless ($i == $GF_MAX && $j == $GF_MAX);
print ( (($j % 8) == 7) ? "\n" : ' ' );
}
}
print<<MOO;
};
#endif
/* eof */
MOO
# eof
|
