Bill Yi | 4e213d5 | 2015-06-23 13:53:11 -0700 | [diff] [blame] | 1 | /* Conversion lookup tables from conventional alpha to Berlekamp's |
| 2 | * dual-basis representation. Used in the CCSDS version only. |
| 3 | * taltab[] -- convert conventional to dual basis |
| 4 | * tal1tab[] -- convert dual basis to conventional |
| 5 | |
| 6 | * Note: the actual RS encoder/decoder works with the conventional basis. |
| 7 | * So data is converted from dual to conventional basis before either |
| 8 | * encoding or decoding and then converted back. |
| 9 | * |
| 10 | * Copyright 2002 Phil Karn, KA9Q |
| 11 | * May be used under the terms of the GNU Lesser General Public License (LGPL) |
| 12 | */ |
| 13 | #include <stdio.h> |
| 14 | #include <stdlib.h> |
| 15 | |
| 16 | #define DTYPE unsigned char |
| 17 | DTYPE Taltab[256],Tal1tab[256]; |
| 18 | |
| 19 | static DTYPE tal[] = { 0x8d, 0xef, 0xec, 0x86, 0xfa, 0x99, 0xaf, 0x7b }; |
| 20 | |
| 21 | /* Generate conversion lookup tables between conventional alpha representation |
| 22 | * (@**7, @**6, ...@**0) |
| 23 | * and Berlekamp's dual basis representation |
| 24 | * (l0, l1, ...l7) |
| 25 | */ |
| 26 | int main(){ |
| 27 | int i,j,k; |
| 28 | |
| 29 | for(i=0;i<256;i++){/* For each value of input */ |
| 30 | Taltab[i] = 0; |
| 31 | for(j=0;j<8;j++) /* for each column of matrix */ |
| 32 | for(k=0;k<8;k++){ /* for each row of matrix */ |
| 33 | if(i & (1<<k)) |
| 34 | Taltab[i] ^= tal[7-k] & (1<<j); |
| 35 | } |
| 36 | Tal1tab[Taltab[i]] = i; |
| 37 | } |
| 38 | printf("unsigned char Taltab[] = {\n"); |
| 39 | for(i=0;i<256;i++){ |
| 40 | if((i % 16) == 0) |
| 41 | printf("\n"); |
| 42 | printf("0x%02x,",Taltab[i]); |
| 43 | } |
| 44 | printf("\n};\n\nunsigned char Tal1tab[] = {"); |
| 45 | for(i=0;i<256;i++){ |
| 46 | if((i % 16) == 0) |
| 47 | printf("\n"); |
| 48 | printf("0x%02x,",Tal1tab[i]); |
| 49 | } |
| 50 | printf("\n};\n"); |
| 51 | exit(0); |
| 52 | } |
| 53 | |