README change

1 files changed, 134 insertions, 0 deletions

diff --git a/gnuradio-core/src/lib/reed-solomon/exercise.c b/gnuradio-core/src/lib/reed-solomon/exercise.c
new file mode 100644
index 000000000..de33a6bff
--- /dev/null
+++ b/gnuradio-core/src/lib/reed-solomon/exercise.c
@@ -0,0 +1,134 @@
+/* Exercise an RS codec a specified number of times using random
+ * data and error patterns
+ *
+ * Copyright 2002 Phil Karn, KA9Q
+ * May be used under the terms of the GNU General Public License (GPL)
+ */
+#define FLAG_ERASURE 1 /* Randomly flag 50% of errors as erasures */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef FIXED
+#include "fixed.h"
+#define EXERCISE exercise_8
+#elif defined(CCSDS)
+#include "fixed.h"
+#include "ccsds.h"
+#define EXERCISE exercise_ccsds
+#elif defined(BIGSYM)
+#include "int.h"
+#define EXERCISE exercise_int
+#else
+#include "char.h"
+#define EXERCISE exercise_char
+#endif
+
+#ifdef FIXED
+#define PRINTPARM printf("(255,223):");
+#elif defined(CCSDS)
+#define PRINTPARM printf("CCSDS (255,223):");
+#else
+#define PRINTPARM printf("(%d,%d):",rs->nn,rs->nn-rs->nroots);
+#endif
+
+/* Exercise the RS codec passed as an argument */
+int EXERCISE(
+#if !defined(CCSDS) && !defined(FIXED)
+void *p,
+#endif
+int trials){
+#if !defined(CCSDS) && !defined(FIXED)
+  struct rs *rs = (struct rs *)p;
+#endif
+#if MAX_ARRAY
+  DTYPE block[MAX_ARRAY],tblock[MAX_ARRAY];
+  unsigned int i;
+  int errors;
+  int errlocs[MAX_ARRAY];
+  int derrlocs[MAX_ARRAY];
+#else
+  DTYPE block[NN],tblock[NN];
+  unsigned int i;
+  int errors;
+  int errlocs[NN];
+  int derrlocs[NROOTS];
+#endif
+  int derrors;
+  int errval,errloc;
+  int erasures;
+  int decoder_errors = 0;
+
+  while(trials-- != 0){
+    /* Test up to the error correction capacity of the code */
+    for(errors=0;(unsigned int)errors <= NROOTS/2;errors++){
+
+      /* Load block with random data and encode */
+      for(i=0;i<NN-NROOTS;i++)
+	block[i] = random() & NN;
+
+#if defined(CCSDS) || defined(FIXED)
+      ENCODE_RS(&block[0],&block[NN-NROOTS]);
+#else
+      ENCODE_RS(rs,&block[0],&block[NN-NROOTS]);
+#endif
+
+      /* Make temp copy, seed with errors */
+      memcpy(tblock,block,sizeof(tblock));
+      memset(errlocs,0,sizeof(errlocs));
+      memset(derrlocs,0,sizeof(derrlocs));
+      erasures=0;
+      for(i=0;i<(unsigned int)errors;i++){
+	do {
+	  errval = random() & NN;
+	} while(errval == 0); /* Error value must be nonzero */
+
+	do {
+	  errloc = random() % NN;
+	} while(errlocs[errloc] != 0); /* Must not choose the same location twice */
+
+	errlocs[errloc] = 1;
+
+#if FLAG_ERASURE
+	if(random() & 1) /* 50-50 chance */
+	  derrlocs[erasures++] = errloc;
+#endif
+	tblock[errloc] ^= errval;
+      }
+
+      /* Decode the errored block */
+#if defined(CCSDS) || defined(FIXED)
+      derrors = DECODE_RS(tblock,derrlocs,erasures);
+#else
+      derrors = DECODE_RS(rs,tblock,derrlocs,erasures);
+#endif
+
+      if(derrors != errors){
+	PRINTPARM
+	printf(" decoder says %d errors, true number is %d\n",derrors,errors);
+	decoder_errors++;
+      }
+      for(i=0;i<(unsigned int)derrors;i++){
+	if(errlocs[derrlocs[i]] == 0){
+	  PRINTPARM
+	  printf(" decoder indicates error in location %d without error\n",i);
+	  decoder_errors++;
+	}
+      }
+      if(memcmp(tblock,block,sizeof(tblock)) != 0){
+	PRINTPARM
+	printf(" uncorrected errors! output ^ input:");
+	decoder_errors++;
+	for(i=0;i<NN;i++)
+	  printf(" %02x",tblock[i] ^ block[i]);
+	printf("\n");
+      }
+    }
+  }
+  return decoder_errors;
+}