spent a lot of time working out I need -O2 on this version to match The Ocatve/Mpdeco...

git-svn-id: https://svn.code.sf.net/p/freetel/code@2861 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/codec2-dev/src/ldpc_dec.c b/codec2-dev/src/ldpc_dec.c
index 912e5e7f74c217449c172460096038704e018c31..70af95a9f29438974c6d12572dd23d196386bbfd 100644 (file)
--- a/codec2-dev/src/ldpc_dec.c
+++ b/codec2-dev/src/ldpc_dec.c
@@ -14,7 +14,12 @@
 \r
   Build:\r
 \r
-    $ gcc -o ldpc_dec ldpc_dec.c mpdecode_core.c -Wall -lm -g\r
+    $ gcc -O2 -o ldpc_dec ldpc_dec.c mpdecode_core.c -Wall -lm -g\r
+\r
+  Note: -O2 option was required to get identical results to MpDecode,\r
+  which is also compiled with -O2.  Without it the number of bit errors\r
+  between C and Octave was different, especially when the code did\r
+  not converge and hit max_iters.\r
 \r
   TODO:\r
   [ ] C cmd line encoder\r
@@ -76,28 +81,20 @@ int main(int argc, char *argv[])
         fprintf(stderr, "Codeword length: %d\n",  CodeLength);\r
         fprintf(stderr, "Parity Bits....: %d\n",  NumberParityBits);\r
 \r
-        num_runs = 100; num_ok = 0;\r
+        num_runs = 1; num_ok = 0;\r
 \r
         for(r=0; r<num_runs; r++) {\r
 \r
             run_ldpc_decoder(DecodedBits, ParityCheckCount, input);\r
 \r
-            /* Check output. Bill has modified decoded to write number of parity checks that are correct\r
-               to the BitErrors array.  So if decoding is correct the final BitErrors entry will have \r
-               NumberParityBits */\r
-\r
-            /* find output bit row where decoding has finished */\r
+            /* Check output by comparing every output iteration */\r
 \r
             int ok = 0;\r
-            for (i=0;i<max_iter;i++) {\r
-                if (ParityCheckCount[i] == NumberParityBits) {\r
-                    for (j=0;j<CodeLength;j++) {\r
-                        if (output[i + j*max_iter] == DecodedBits[i+j*max_iter])                    \r
+            for (i=0;i<max_iter*CodeLength;i++) {\r
+                if (output[i] == DecodedBits[i])                    \r
                             ok++;\r
-                    }\r
-                }\r
             }\r
-            if (ok == CodeLength)\r
+            if (ok == max_iter*CodeLength)\r
                 num_ok++;            \r
         }\r
 \r
@@ -130,22 +127,30 @@ int main(int argc, char *argv[])
         double *input_double  =  calloc(CodeLength, sizeof(double));\r
 \r
         while(fread(input_double, sizeof(double), CodeLength, fin) == CodeLength) {\r
+ \r
             run_ldpc_decoder(DecodedBits, ParityCheckCount, input_double);\r
+            \r
+            /* extract output bits from ouput iteration that solved all parity equations, or failing that\r
+               the last iteration. */\r
 \r
-            /* default is all zeros - just in case we don't get a decode */\r
-\r
-            memset(out_char, sizeof(out_char), 0);\r
-\r
-            /* extract output bits from ouput iteration that solved all paritry equations */\r
-\r
+            int converged = 0;\r
+            int iter = 0;\r
             for (i=0;i<max_iter;i++) {\r
-                if (ParityCheckCount[i] == NumberParityBits) {\r
+                if (converged == 0)\r
+                    iter++;\r
+                if ((ParityCheckCount[i] == NumberParityBits)) {\r
                     for (j=0; j<CodeLength; j++) {\r
-                        out_char[j] = DecodedBits[i+j*max_iter];                  \r
+                        out_char[j] = DecodedBits[i+j*max_iter];\r
                     }\r
+                    converged = 1;\r
+                }               \r
+            }\r
+            if (converged == 0) {\r
+                for (j=0; j<CodeLength; j++) {\r
+                    out_char[j] = DecodedBits[max_iter-1+j*max_iter];\r
                 }\r
             }\r
-\r
+            //printf("%4d ", iter);\r
             fwrite(out_char, sizeof(char), CodeLength, fout);\r
         }\r
 \r
@@ -194,25 +199,6 @@ void run_ldpc_decoder(int DecodedBits[], int ParityCheckCount[], double input[])
     max_row_weight = MAX_ROW_WEIGHT;\r
     max_col_weight = MAX_COL_WEIGHT;\r
        \r
-#ifdef TT\r
-    /* check H_rows[] */\r
-\r
-    int length;\r
-    int gd = 0, bd = 0;\r
-    length = NumberRowsHcols*max_col_weight;\r
-    for (i=0;i<length;i++) {\r
-        if (H_cols[i] == H_cols2[i])\r
-            gd++;\r
-        else {\r
-            bd++;\r
-            printf("%d H_cols: %f H_cols2: %f\n", i, H_cols[i], H_cols2[i]);\r
-        }\r
-        if (bd == 10)\r
-            exit(0);\r
-    }\r
-    printf("gd: %d bd: %d\n", gd, bd);\r
-#endif\r
-\r
     c_nodes = calloc( NumberParityBits, sizeof( struct c_node ) );\r
     v_nodes = calloc( CodeLength, sizeof( struct v_node));\r
        \r
@@ -227,6 +213,13 @@ void run_ldpc_decoder(int DecodedBits[], int ParityCheckCount[], double input[])
     int DataLength = CodeLength - NumberParityBits;\r
     int *data_int = calloc( DataLength, sizeof(int) );\r
        \r
+    /* need to clear these on each call */\r
+\r
+    for(i=0; i<max_iter; i++)\r
+        ParityCheckCount[i] = 0;\r
+     for(i=0; i<max_iter*CodeLength; i++)\r
+         DecodedBits[i] = 0;\r
+\r
     /* Call function to do the actual decoding */\r
 \r
     if ( dec_type == 1) {\r