65 lines
1.8 KiB
C
65 lines
1.8 KiB
C
/* dvdisaster: Additional error correction for optical media.
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* Copyright (C) 2004-2015 Carsten Gnoerlich.
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*
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* Email: carsten@dvdisaster.org -or- cgnoerlich@fsfe.org
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* Project homepage: http://www.dvdisaster.org
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*
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* This file is part of dvdisaster.
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*
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* dvdisaster is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* dvdisaster is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with dvdisaster. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "dvdisaster.h"
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#include "galois-inlines.h"
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/***
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*** Reed-Solomon decoding (work in progress; incomplete)
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***/
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/*
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* Test and report the error syndrome.
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*/
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int TestErrorSyndromes(ReedSolomonTables *rt, unsigned char *data)
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{ int syndrome[rt->nroots];
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int syn_error;
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int i,j;
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/*** Form the syndromes: Evaluate data(x) at roots of g(x) */
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for(i=0; i<rt->nroots; i++)
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syndrome[i] = data[0];
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for(j=1; j<GF_FIELDMAX; j++)
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for(i=0; i<rt->nroots; i++)
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if(syndrome[i] == 0)
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syndrome[i] = data[j];
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else syndrome[i] = data[j] ^ rt->synLut[(i<<8) + syndrome[i]];
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#if 0
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else syndrome[i] = data[j] ^ gt->alphaTo[mod_fieldmax(gt->indexOf[syndrome[i]]
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+ (rt->fcr+i)*rt->primElem)];
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#endif
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/*** Check for nonzero condition. */
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syn_error = 0;
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for(i=0; i<rt->nroots; i++)
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syn_error |= syndrome[i];
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/*** If the syndrome is zero, everything is fine. */
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return syn_error;
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}
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