129 lines
3.2 KiB
C
129 lines
3.2 KiB
C
/* Exercise an RS codec a specified number of times using random
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* data and error patterns
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*
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* Copyright 2002 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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#define FLAG_ERASURE 1 /* Randomly flag 50% of errors as erasures */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#ifdef FIXED
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#include "fixed.h"
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#define EXERCISE exercise_8
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#elif defined(CCSDS)
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#include "fixed.h"
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#include "ccsds.h"
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#define EXERCISE exercise_ccsds
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#elif defined(BIGSYM)
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#include "int.h"
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#define EXERCISE exercise_int
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#else
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#include "char.h"
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#define EXERCISE exercise_char
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#endif
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#ifdef FIXED
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#define PRINTPARM printf("(255,223):");
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#elif defined(CCSDS)
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#define PRINTPARM printf("CCSDS (255,223):");
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#else
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#define PRINTPARM printf("(%d,%d):",rs->nn,rs->nn-rs->nroots);
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#endif
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/* Exercise the RS codec passed as an argument */
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int EXERCISE(
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#if !defined(CCSDS) && !defined(FIXED)
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void *p,
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#endif
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int trials)
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{
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#if !defined(CCSDS) && !defined(FIXED)
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struct rs *rs = (struct rs *)p;
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#endif
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data_t block[NN], tblock[NN];
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int i;
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int errors;
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int errlocs[NN];
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int derrlocs[NROOTS];
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int derrors;
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int errval, errloc;
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int erasures;
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int decoder_errors = 0;
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while (trials-- != 0) {
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/* Test up to the error correction capacity of the code */
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for (errors = 0; errors <= NROOTS / 2; errors++) {
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/* Load block with random data and encode */
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for (i = 0; i < NN - NROOTS; i++) {
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block[i] = random() & NN;
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}
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#if defined(CCSDS) || defined(FIXED)
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ENCODE_RS(&block[0], &block[NN - NROOTS], 0);
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#else
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ENCODE_RS(rs, &block[0], &block[NN - NROOTS]);
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#endif
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/* Make temp copy, seed with errors */
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memcpy(tblock, block, sizeof(tblock));
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memset(errlocs, 0, sizeof(errlocs));
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memset(derrlocs, 0, sizeof(derrlocs));
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erasures = 0;
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for (i = 0; i < errors; i++) {
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do {
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errval = random() & NN;
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}
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while (errval == 0); /* Error value must be nonzero */
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do {
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errloc = random() % NN;
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}
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while (errlocs[errloc] != 0); /* Must not choose the same location twice */
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errlocs[errloc] = 1;
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#if FLAG_ERASURE
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if (random() & 1) { /* 50-50 chance */
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derrlocs[erasures++] = errloc;
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}
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#endif
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tblock[errloc] ^= errval;
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}
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/* Decode the errored block */
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#if defined(CCSDS) || defined(FIXED)
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derrors = DECODE_RS(tblock, derrlocs, erasures, 0);
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#else
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derrors = DECODE_RS(rs, tblock, derrlocs, erasures);
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#endif
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if (derrors != errors) {
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PRINTPARM
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printf(" decoder says %d errors, true number is %d\n", derrors, errors);
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decoder_errors++;
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}
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for (i = 0; i < derrors; i++) {
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if (errlocs[derrlocs[i]] == 0) {
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PRINTPARM
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printf(" decoder indicates error in location %d without error\n", derrlocs[i]);
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decoder_errors++;
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}
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}
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if (memcmp(tblock, block, sizeof(tblock)) != 0) {
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PRINTPARM
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printf(" uncorrected errors! output ^ input:");
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decoder_errors++;
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for (i = 0; i < NN; i++) {
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printf(" %02x", tblock[i] ^ block[i]);
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}
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printf("\n");
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}
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}
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}
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return decoder_errors;
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}
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