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/*
*
* $Id: ecc.c,v 1.2 2002/09/09 13:29:52 germeier Exp $
*
* Library for USB MPIO-*
*
* Markus Germeier (mager@tzi.de)
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* */
#include "ecc.h"
#include "debug.h"
BYTE get_bit(BYTE, int);
/* TODO: fix correctable errors */
inline BYTE
get_bit(BYTE d, int offset)
{
return ((d >> offset) & 0x01 );
}
int
mpio_ecc_256_gen(BYTE *data, BYTE *ecc)
{
BYTE p1, p1_;
BYTE p2, p2_;
BYTE p4, p4_;
BYTE p08, p08_;
BYTE p16, p16_;
BYTE p32, p32_;
BYTE p64, p64_;
BYTE p0128, p0128_;
BYTE p0256, p0256_;
BYTE p0512, p0512_;
BYTE p1024, p1024_;
int i, j;
/* init */
p1=p1_=0;
p2=p2_=0;
p4=p4_=0;
p08=p08_=0;
p16=p16_=0;
p32=p32_=0;
p64=p64_=0;
p0128=p0128_=0;
p0256=p0256_=0;
p0512=p0512_=0;
p1024=p1024_=0;
/* vertical */
for (i=0; i<256; i++) {
/* p1, p1_ */
p1 ^= (get_bit(data[i], 7) ^
get_bit(data[i], 5) ^
get_bit(data[i], 3) ^
get_bit(data[i], 1));
p1_^= (get_bit(data[i], 6) ^
get_bit(data[i], 4) ^
get_bit(data[i], 2) ^
get_bit(data[i], 0));
/* p2, p2_ */
p2 ^= (get_bit(data[i], 7) ^
get_bit(data[i], 6) ^
get_bit(data[i], 3) ^
get_bit(data[i], 2));
p2_^= (get_bit(data[i], 5) ^
get_bit(data[i], 4) ^
get_bit(data[i], 1) ^
get_bit(data[i], 0));
/* p4, p4_ */
p4 ^= (get_bit(data[i], 7) ^
get_bit(data[i], 6) ^
get_bit(data[i], 5) ^
get_bit(data[i], 4));
p4_^= (get_bit(data[i], 3) ^
get_bit(data[i], 2) ^
get_bit(data[i], 1) ^
get_bit(data[i], 0));
}
/* horizontal */
for (i=0; i<8; i++) {
for (j=0; j<256; j++) {
/* p08, p08_ */
if ((j & 0x01) == 0)
p08_^= get_bit(data[j], i);
if ((j & 0x01) == 1)
p08 ^= get_bit(data[j], i);
/* p16, p16_ */
if (((j/2) & 0x01) == 0)
p16_^= get_bit(data[j], i);
if (((j/2) & 0x01) == 1)
p16^= get_bit(data[j], i);
/* p32, p32_ */
if (((j/4) & 0x01) == 0)
p32_^= get_bit(data[j], i);
if (((j/4) & 0x01) == 1)
p32^= get_bit(data[j], i);
/* p64, p64_ */
if (((j/8) & 0x01) == 0)
p64_^= get_bit(data[j], i);
if (((j/8) & 0x01) == 1)
p64^= get_bit(data[j], i);
/* p0128, p0128_ */
if (((j/16) & 0x01) == 0)
p0128_^= get_bit(data[j], i);
if (((j/16) & 0x01) == 1)
p0128 ^= get_bit(data[j], i);
/* p0256, p0256_ */
if (((j/32) & 0x01) == 0)
p0256_^= get_bit(data[j], i);
if (((j/32) & 0x01) == 1)
p0256^= get_bit(data[j], i);
/* p0512, p0512_ */
if (((j/64) & 0x01) == 0)
p0512_^= get_bit(data[j], i);
if (((j/64) & 0x01) == 1)
p0512^= get_bit(data[j], i);
/* p1024, p1024_ */
if (((j/128) & 0x01) == 0)
p1024_^= get_bit(data[j], i);
if (((j/128) & 0x01) == 1)
p1024^= get_bit(data[j], i);
}
}
ecc[0]=~((p64 << 7) | (p64_ << 6) |
(p32 << 5) | (p32_ << 4) |
(p16 << 3) | (p16_ << 2) |
(p08 << 1) | (p08_ << 0));
ecc[1]=~((p1024 << 7) | (p1024_ << 6) |
(p0512 << 5) | (p0512_ << 4) |
(p0256 << 3) | (p0256_ << 2) |
(p0128 << 1) | (p0128_ << 0));
ecc[2]=~((p4 << 7) | (p4_ << 6) |
(p2 << 5) | (p2_ << 4) |
(p1 << 3) | (p1_ << 2));
return 0;
}
int
mpio_ecc_256_check(BYTE *data, BYTE *ecc)
{
BYTE own_ecc[3];
mpio_ecc_256_gen(data, own_ecc);
if ((own_ecc[0]^ecc[0])|
(own_ecc[1]^ecc[1])|
(own_ecc[2]^ecc[2])) {
debug("ECC %2x %2x %2x vs. %2x %2x %2x\n",
ecc[0], ecc[1], ecc[2], own_ecc[0], own_ecc[1], own_ecc[2]);
debugn(2, "ECC Error detected\n");
debugn(2, "ECC Correction code not in place yet, Sorry\n");
debugn(3, "got ECC: %2x %2x %2x\n", ecc[0], ecc[1], ecc[2]);
debugn(3, "calc. ECC: %2x %2x %2x\n", own_ecc[0], own_ecc[1], own_ecc[2]);
return 1;
}
return 0;
}
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