/* Test (255,223) RS code * August 1997 Phil Karn */ #include <stdio.h> #include <stdlib.h> #include <time.h> #include "rs32.h" /* uses rs32.c and rs32asm.s */ void fill_eras(int eras_pos[],int n) { int i,j,t,work[NN]; for(i=0;i<NN;i++) work[i] = i; for(j=NN-1;j>0;j--){ i = random() % j; /* not really uniform, I know */ t = work[i]; work[i] = work[j]; work[j] = t; } for(i=0;i<n;i++) eras_pos[i] = work[i]; } /* Return non-zero random number in range 0 - NN (NN power of 2 minus 1) */ int randomnz(void) { int i; while((i = random() & NN) == 0) ; return i; } int main(int argc,char *argv[]) { dtype data[NN]; dtype tdata[NN]; dtype ddata[NN]; int eras_pos[NN]; int i,trials,k; long t; int nerrors,nerase,ntrials,verbose,timetest; int detfails,fails; extern char *optarg; nerrors = nerase = 0; timetest = verbose = 0; ntrials = 100; while((i = getopt(argc,argv,"e:E:n:vt")) != EOF){ switch(i){ case 'e': /* Number of errors per block */ nerrors = atoi(optarg); break; case 'E': /* Number of erasures per block */ nerase = atoi(optarg); break; case 'n': /* Number of trials */ ntrials = atoi(optarg); break; case 'v': /* Be verbose */ verbose = 1; break; case 't': /* Repeatedly decode the same block */ timetest = 1; break; default: printf("usage: %s [-v] [-t] [-e errors] [-E erasures] [-n ntrials]\n",argv[0]); exit(1); } } printf("Reed-Solomon code is (%d,%d) over GF(%d)\n", NN,KK,NN+1); printf("test erasures: %d errors %d\n",nerase,nerrors); if(2*nerrors + nerase > NN-KK) printf("Warning: %d errors and %d erasures exceeds the correction ability of the code\n",nerrors,nerase); time(&t); srandom(t); init_rs(); if(timetest){ printf("Speed timing test (repeated decoding of same block)\n"); for(i=0;i<KK;i++) data[i] = random() & NN; rse32(data,&data[KK]); fill_eras(eras_pos,nerase+nerrors); if(verbose && nerase){ printf("erasing:"); for(i=0;i<nerase;i++) printf(" %d",eras_pos[i]); printf("\n"); } if(verbose && nerrors){ printf("erroring:"); for(i=nerase;i<nerase+nerrors;i++) printf(" %d",eras_pos[i]); printf("\n"); } memcpy(tdata,data,sizeof(data)); for(i=0;i<nerase+nerrors;i++) tdata[eras_pos[i]] ^= randomnz(); for(k=0;k<ntrials;k++){ memcpy(ddata,tdata,sizeof(tdata)); rsd32(ddata,eras_pos,nerase); } exit(0); } fails = detfails = 0; for(trials=0;trials < ntrials;trials++){ unsigned char nparity[32]; if(verbose) printf("Trial %d:",trials); for(i=0;i<KK;i++) data[i] = random() & NN; rse32(data,&data[KK]); #ifdef printparity printf("old parity:"); for(i=0;i<NN-KK;i++) printf(" %02x",data[KK+i]); printf("\n"); #endif fill_eras(eras_pos,nerase+nerrors); if(verbose && nerase){ printf(" erasing:"); for(i=0;i<nerase;i++) printf(" %d",eras_pos[i]); } if(verbose && nerrors){ printf(" erroring:"); for(i=nerase;i<nerase+nerrors;i++) printf(" %d",eras_pos[i]); } if(verbose) printf("\n"); memcpy(ddata,data,sizeof(data)); for(i=0;i<nerase+nerrors;i++) ddata[eras_pos[i]] ^= randomnz(); i = rsd32(ddata,eras_pos,nerase); if(verbose){ printf("errs + erasures corrected: %d\n",i); } if(i == -1){ detfails++; printf("RS decoder detected failure\n"); } else if(memcmp(ddata,data,NN) != 0){ fails++; printf("Undetected decoding failure!\n"); for(i=0;i<NN;i++){ if(ddata[i] != data[i]) printf("[%d] %02x != %02x\n", i,ddata[i],data[i]); } } } printf("Trials: %d decoding failures: %d; not detected by decoder: %d\n", ntrials,detfails,fails); return 0; }
file: /Techref/method/error/rs-255-223-3-pf-qc-1999/rstest_c.htm, 29KB, , updated: 2000/5/10 12:17, local time: 2024/12/23 00:13,
3.12.163.120:LOG IN
|
©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://massmind.org/Techref/method/error/rs-255-223-3-pf-qc-1999/rstest_c.htm"> Colorized Source Code</A> |
Did you find what you needed? |
Welcome to massmind.org! |
Welcome to massmind.org! |
.