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82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
/* Reed-Solomon encoder
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* Copyright 2004, Phil Karn, KA9Q
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* May be used under the terms of the GNU Lesser General Public License (LGPL)
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*/
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#include <string.h>
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#include "fixed.h"
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#ifdef __VEC__
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#include <sys/sysctl.h>
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#endif
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static enum {UNKNOWN=0,MMX,SSE,SSE2,ALTIVEC,PORT} cpu_mode;
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static void encode_rs_8_c(data_t *data, data_t *parity,int pad);
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#if __vec__
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static void encode_rs_8_av(data_t *data, data_t *parity,int pad);
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#endif
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void encode_rs_8(data_t *data, data_t *parity,int pad){
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if(cpu_mode == UNKNOWN){
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cpu_mode = PORT;
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}
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switch(cpu_mode){
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#if __vec__
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case ALTIVEC:
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encode_rs_8_av(data,parity,pad);
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return;
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#endif
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#if __i386__
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case MMX:
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case SSE:
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case SSE2:
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#endif
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default:
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encode_rs_8_c(data,parity,pad);
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return;
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}
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}
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#if __vec__ /* PowerPC G4/G5 Altivec instructions are available */
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static vector unsigned char reverse = (vector unsigned char)(0,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1);
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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);
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/* Lookup table for feedback multiplications
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* These are the low half of the coefficients. Since the generator polynomial is
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* palindromic, we form the other half by reversing this one
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*/
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extern static union { vector unsigned char v; unsigned char c[16]; } table[256];
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static void encode_rs_8_av(data_t *data, data_t *parity,int pad){
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union { vector unsigned char v[2]; unsigned char c[32]; } shift_register;
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int i;
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shift_register.v[0] = (vector unsigned char)(0);
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shift_register.v[1] = (vector unsigned char)(0);
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for(i=0;i<NN-NROOTS-pad;i++){
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vector unsigned char feedback0,feedback1;
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unsigned char f;
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f = data[i] ^ shift_register.c[31];
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feedback1 = table[f].v;
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feedback0 = vec_perm(feedback1,feedback1,reverse);
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/* Shift right one byte */
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shift_register.v[1] = vec_perm(shift_register.v[0],shift_register.v[1],shift_right) ^ feedback1;
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shift_register.v[0] = vec_sro(shift_register.v[0],(vector unsigned char)(8)) ^ feedback0;
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shift_register.c[0] = f;
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}
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for(i=0;i<NROOTS;i++)
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parity[NROOTS-i-1] = shift_register.c[i];
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}
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#endif
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/* Portable C version */
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static void encode_rs_8_c(data_t *data, data_t *parity,int pad){
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#include "encode_rs.h"
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}
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