diff options
Diffstat (limited to 'gen_ccsds_tal.c')
-rw-r--r-- | gen_ccsds_tal.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/gen_ccsds_tal.c b/gen_ccsds_tal.c new file mode 100644 index 0000000..fc75503 --- /dev/null +++ b/gen_ccsds_tal.c @@ -0,0 +1,53 @@ +/* Conversion lookup tables from conventional alpha to Berlekamp's + * dual-basis representation. Used in the CCSDS version only. + * taltab[] -- convert conventional to dual basis + * tal1tab[] -- convert dual basis to conventional + + * Note: the actual RS encoder/decoder works with the conventional basis. + * So data is converted from dual to conventional basis before either + * encoding or decoding and then converted back. + * + * Copyright 2002 Phil Karn, KA9Q + * May be used under the terms of the GNU Lesser General Public License (LGPL) + */ +#include <stdio.h> +#include <stdlib.h> + +#define DTYPE unsigned char +DTYPE Taltab[256],Tal1tab[256]; + +static DTYPE tal[] = { 0x8d, 0xef, 0xec, 0x86, 0xfa, 0x99, 0xaf, 0x7b }; + +/* Generate conversion lookup tables between conventional alpha representation + * (@**7, @**6, ...@**0) + * and Berlekamp's dual basis representation + * (l0, l1, ...l7) + */ +int main(){ + int i,j,k; + + for(i=0;i<256;i++){/* For each value of input */ + Taltab[i] = 0; + for(j=0;j<8;j++) /* for each column of matrix */ + for(k=0;k<8;k++){ /* for each row of matrix */ + if(i & (1<<k)) + Taltab[i] ^= tal[7-k] & (1<<j); + } + Tal1tab[Taltab[i]] = i; + } + printf("unsigned char Taltab[] = {\n"); + for(i=0;i<256;i++){ + if((i % 16) == 0) + printf("\n"); + printf("0x%02x,",Taltab[i]); + } + printf("\n};\n\nunsigned char Tal1tab[] = {"); + for(i=0;i<256;i++){ + if((i % 16) == 0) + printf("\n"); + printf("0x%02x,",Tal1tab[i]); + } + printf("\n};\n"); + exit(0); +} + |