blob: 32e528f88653e90829b420c42d5ddbd7aaa52052 [file] [log] [blame]
 /* Fast Reed-Solomon encoder for (255,223) CCSDS code on PowerPC G4/G5 using Altivec instructions * Copyright 2004, Phil Karn KA9Q * May be used under the terms of the GNU Lesser General Public License (LGPL) */ #include #include #include "fixed.h" /* Lookup table for feedback multiplications * These are the low half of the coefficients. Since the generator polynomial is * palindromic, we form it by reversing these on the fly */ static union { vector unsigned char v; unsigned char c[16]; } table[256]; static vector unsigned char reverse = (vector unsigned char)(0,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1); static vector unsigned char shift_right = (vector unsigned char)(15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30); extern data_t CCSDS_alpha_to[]; extern data_t CCSDS_index_of[]; extern data_t CCSDS_poly[]; void rs_init_av(){ int i,j; /* The PowerPC is big-endian, so the low-order byte of each vector contains the highest order term in the polynomial */ for(j=0;j<16;j++){ table[0].c[j] = 0; for(i=1;i<256;i++){ table[i].c[16-j-1] = CCSDS_alpha_to[MODNN(CCSDS_poly[j+1] + CCSDS_index_of[i])]; } } #if 0 for(i=0;i<256;i++){ printf("table[%3d] = %3vu\n",i,table[i].v); } #endif } void encode_rs_av(unsigned char *data,unsigned char *parity,int pad){ union { vector unsigned char v[2]; unsigned char c[32]; } shift_register; int i; shift_register.v[0] = (vector unsigned char)(0); shift_register.v[1] = (vector unsigned char)(0); for(i=0;i