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48 lines
1.1 KiB
C
48 lines
1.1 KiB
C
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/* Reed-Solomon encoder
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* Copyright 2002, Phil Karn, KA9Q
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* May be used under the terms of the GNU General Public License (GPL)
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*/
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#include <string.h>
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#ifdef FIXED
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#include "fixed.h"
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#elif defined(BIGSYM)
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#include "int.h"
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#else
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#include "char.h"
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#endif
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void ENCODE_RS(
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#ifndef FIXED
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void *p,
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#endif
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DTYPE *data, DTYPE *bb){
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#ifndef FIXED
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struct rs *rs = (struct rs *)p;
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#endif
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int i, j;
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DTYPE feedback;
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memset(bb,0,NROOTS*sizeof(DTYPE));
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for(i=0;i<NN-NROOTS;i++){
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feedback = INDEX_OF[data[i] ^ bb[0]];
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if(feedback != A0){ /* feedback term is non-zero */
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#ifdef UNNORMALIZED
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/* This line is unnecessary when GENPOLY[NROOTS] is unity, as it must
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* always be for the polynomials constructed by init_rs()
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*/
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feedback = MODNN(NN - GENPOLY[NROOTS] + feedback);
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#endif
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for(j=1;j<NROOTS;j++)
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bb[j] ^= ALPHA_TO[MODNN(feedback + GENPOLY[NROOTS-j])];
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}
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/* Shift */
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memmove(&bb[0],&bb[1],sizeof(DTYPE)*(NROOTS-1));
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if(feedback != A0)
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bb[NROOTS-1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])];
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else
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bb[NROOTS-1] = 0;
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}
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}
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