1 /* Exercise an RS codec a specified number of times using random
2 * data and error patterns
3 *
4 * Copyright 2002 Phil Karn, KA9Q
5 * May be used under the terms of the GNU General Public License (GPL)
6 */
7 #define FLAG_ERASURE 1 /* Randomly flag 50% of errors as erasures */
8
9 #include <stdio.h>
10 #include <stdlib.h>
11
12 #ifdef FIXED
13 #include "fixed.h"
14 #define EXERCISE exercise_8
15 #elif defined(CCSDS)
16 #include "fixed.h"
17 #include "ccsds.h"
18 #define EXERCISE exercise_ccsds
19 #elif defined(BIGSYM)
20 #include "int.h"
21 #define EXERCISE exercise_int
22 #else
23 #include "char.h"
24 #define EXERCISE exercise_char
25 #endif
26
27 #ifdef FIXED
28 #define PRINTPARM printf("(255,223):");
29 #elif defined(CCSDS)
30 #define PRINTPARM printf("CCSDS (255,223):");
31 #else
32 #define PRINTPARM printf("(%d,%d):",rs->nn,rs->nn-rs->nroots);
33 #endif
34
35 /* Exercise the RS codec passed as an argument */
EXERCISE(void * p,int trials)36 int EXERCISE(
37 #if !defined(CCSDS) && !defined(FIXED)
38 void *p,
39 #endif
40 int trials){
41 #if !defined(CCSDS) && !defined(FIXED)
42 struct rs *rs = (struct rs *)p;
43 #endif
44 DTYPE block[NN],tblock[NN];
45 int i;
46 int errors;
47 int errlocs[NN];
48 int derrlocs[NROOTS];
49 int derrors;
50 int errval,errloc;
51 int erasures;
52 int decoder_errors = 0;
53
54 while(trials-- != 0){
55 /* Test up to the error correction capacity of the code */
56 for(errors=0;errors <= NROOTS/2;errors++){
57
58 /* Load block with random data and encode */
59 for(i=0;i<NN-NROOTS;i++)
60 block[i] = random() & NN;
61
62 #if defined(CCSDS) || defined(FIXED)
63 ENCODE_RS(&block[0],&block[NN-NROOTS],0);
64 #else
65 ENCODE_RS(rs,&block[0],&block[NN-NROOTS]);
66 #endif
67
68 /* Make temp copy, seed with errors */
69 memcpy(tblock,block,sizeof(tblock));
70 memset(errlocs,0,sizeof(errlocs));
71 memset(derrlocs,0,sizeof(derrlocs));
72 erasures=0;
73 for(i=0;i<errors;i++){
74 do {
75 errval = random() & NN;
76 } while(errval == 0); /* Error value must be nonzero */
77
78 do {
79 errloc = random() % NN;
80 } while(errlocs[errloc] != 0); /* Must not choose the same location twice */
81
82 errlocs[errloc] = 1;
83
84 #if FLAG_ERASURE
85 if(random() & 1) /* 50-50 chance */
86 derrlocs[erasures++] = errloc;
87 #endif
88 tblock[errloc] ^= errval;
89 }
90
91 /* Decode the errored block */
92 #if defined(CCSDS) || defined(FIXED)
93 derrors = DECODE_RS(tblock,derrlocs,erasures,0);
94 #else
95 derrors = DECODE_RS(rs,tblock,derrlocs,erasures);
96 #endif
97
98 if(derrors != errors){
99 PRINTPARM
100 printf(" decoder says %d errors, true number is %d\n",derrors,errors);
101 decoder_errors++;
102 }
103 for(i=0;i<derrors;i++){
104 if(errlocs[derrlocs[i]] == 0){
105 PRINTPARM
106 printf(" decoder indicates error in location %d without error\n",derrlocs[i]);
107 decoder_errors++;
108 }
109 }
110 if(memcmp(tblock,block,sizeof(tblock)) != 0){
111 PRINTPARM
112 printf(" uncorrected errors! output ^ input:");
113 decoder_errors++;
114 for(i=0;i<NN;i++)
115 printf(" %02x",tblock[i] ^ block[i]);
116 printf("\n");
117 }
118 }
119 }
120 return decoder_errors;
121 }
122