Imported Upstream version 3.2.2

[debian/gnuradio] / gnuradio-core / src / lib / viterbi / decode.cc

diff --git a/gnuradio-core/src/lib/viterbi/decode.cc b/gnuradio-core/src/lib/viterbi/decode.cc
new file mode 100644 (file)
index 0000000..6580e4d
--- /dev/null
+++ b/gnuradio-core/src/lib/viterbi/decode.cc
@@ -0,0 +1,88 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2008 Free Software Foundation, Inc.
+ * 
+ * This file is part of GNU Radio
+ * 
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ * 
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+/*
+ * This is a minimal example demonstrating how to call the Viterbi decoder
+ * in continuous streaming mode.  It accepts data on stdin and writes to 
+ * stdout.
+ *
+ */
+
+extern "C" {
+#include "viterbi.h"
+}
+
+#include <cstdio>
+#include <cmath>
+
+#define MAXCHUNKSIZE 4096
+#define MAXENCSIZE MAXCHUNKSIZE*16
+
+int main()
+{
+  unsigned char data[MAXCHUNKSIZE];
+  signed char syms[MAXENCSIZE];
+  int count = 0;
+
+  // Initialize metric table
+  int mettab[2][256];
+  int amp = 100;
+  float RATE=0.5;
+  float ebn0 = 12.0;
+  float esn0 = RATE*pow(10.0, ebn0/10);
+  gen_met(mettab, amp, esn0, 0.0, 4);
+
+  // Initialize decoder state
+  struct viterbi_state state0[64];
+  struct viterbi_state state1[64];
+  unsigned char viterbi_in[16];
+  viterbi_chunks_init(state0);  
+
+  while (!feof(stdin)) {
+    unsigned int n = fread(syms, 1, MAXENCSIZE, stdin);
+    unsigned char *out = data;
+    
+    for (unsigned int i = 0; i < n; i++) {
+
+      // FIXME: This implements hard decoding by slicing the input stream
+      unsigned char sym = syms[i] > 0 ? -amp : amp;
+
+      // Write the symbol to the decoder input
+      viterbi_in[count % 4] = sym;
+
+      // Every four symbols, perform the butterfly2 operation
+      if ((count % 4) == 3) {
+        viterbi_butterfly2(viterbi_in, mettab, state0, state1);      
+
+       // Every sixteen symbols, perform the readback operation
+        if ((count > 64) && (count % 16) == 11) {
+          viterbi_get_output(state0, out);
+         fwrite(out++, 1, 1, stdout);
+       }
+      }
+      
+      count++;
+    }    
+  }
+
+  return 0;
+}