Bill Yi | 4e213d5 | 2015-06-23 13:53:11 -0700 | [diff] [blame] | 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 | } |