1 /* Reed-Solomon encoder 2 * Copyright 2002, Phil Karn, KA9Q 3 * May be used under the terms of the GNU Lesser General Public License (LGPL) 4 */ 5 #include <string.h> 6 7 #ifdef FIXED 8 #include "fixed.h" 9 #elif defined(BIGSYM) 10 #include "int.h" 11 #else 12 #include "char.h" 13 #endif 14 15 void ENCODE_RS( 16 #ifdef FIXED 17 data_t *data, data_t *bb,int pad){ 18 #else 19 void *p,data_t *data, data_t *bb){ 20 struct rs *rs = (struct rs *)p; 21 #endif 22 int i, j; 23 data_t feedback; 24 25 #ifdef FIXED 26 /* Check pad parameter for validity */ 27 if(pad < 0 || pad >= NN) 28 return; 29 #endif 30 31 memset(bb,0,NROOTS*sizeof(data_t)); 32 33 for(i=0;i<NN-NROOTS-PAD;i++){ 34 feedback = INDEX_OF[data[i] ^ bb[0]]; 35 if(feedback != A0){ /* feedback term is non-zero */ 36 #ifdef UNNORMALIZED 37 /* This line is unnecessary when GENPOLY[NROOTS] is unity, as it must 38 * always be for the polynomials constructed by init_rs() 39 */ 40 feedback = MODNN(NN - GENPOLY[NROOTS] + feedback); 41 #endif 42 for(j=1;j<NROOTS;j++) 43 bb[j] ^= ALPHA_TO[MODNN(feedback + GENPOLY[NROOTS-j])]; 44 } 45 /* Shift */ 46 memmove(&bb[0],&bb[1],sizeof(data_t)*(NROOTS-1)); 47 if(feedback != A0) 48 bb[NROOTS-1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])]; 49 else 50 bb[NROOTS-1] = 0; 51 } 52 } 53
