1 files changed, 89 insertions, 0 deletions
diff --git a/gr-fec/lib/decode_ccsds_27_fb_impl.cc b/gr-fec/lib/decode_ccsds_27_fb_impl.cc
new file mode 100644
index 0000000000..87bdc46402
--- /dev/null
+++ b/gr-fec/lib/decode_ccsds_27_fb_impl.cc
@@ -0,0 +1,89 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2012 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "decode_ccsds_27_fb_impl.h"
+#include <gr_io_signature.h>
+
+namespace gr {
+  namespace fec {
+
+    decode_ccsds_27_fb::sptr decode_ccsds_27_fb::make()
+    {
+      return gnuradio::get_initial_sptr(new decode_ccsds_27_fb_impl());
+    }
+
+    decode_ccsds_27_fb_impl::decode_ccsds_27_fb_impl()
+      : gr_sync_decimator("decode_ccsds_27_fb",
+			  gr_make_io_signature (1, 1, sizeof(float)),
+			  gr_make_io_signature (1, 1, sizeof(char)),
+			  2*8)  // Rate 1/2 code, unpacked to packed conversion
+    {
+      float RATE = 0.5;
+      float ebn0 = 12.0;
+      float esn0 = RATE*pow(10.0, ebn0/10.0);
+      
+      gen_met(d_mettab, 100, esn0, 0.0, 256);
+      viterbi_chunks_init(d_state0);
+    }
+
+    int
+    decode_ccsds_27_fb_impl::work(int noutput_items,
+				  gr_vector_const_void_star &input_items,
+				  gr_vector_void_star &output_items)
+    {
+      const float *in = (const float *)input_items[0];
+      unsigned char *out = (unsigned char *)output_items[0];
+      
+      for (int i = 0; i < noutput_items*16; i++) {
+	// Translate and clip [-1.0..1.0] to [28..228]
+	float sample = in[i]*100.0+128.0;
+	if (sample > 255.0)
+	  sample = 255.0;
+	else if (sample < 0.0)
+	  sample = 0.0;
+	unsigned char sym = (unsigned char)(floor(sample));
+	
+	d_viterbi_in[d_count % 4] = sym;
+	if ((d_count % 4) == 3) {
+	  // Every fourth symbol, perform butterfly operation
+	  viterbi_butterfly2(d_viterbi_in, d_mettab, d_state0, d_state1);
+	  
+	  // Every sixteenth symbol, read out a byte
+	  if (d_count % 16 == 11) {
+	    // long metric =
+	    viterbi_get_output(d_state0, out++);
+	    // printf("%li\n", *(out-1), metric);
+	  }
+	}
+	
+	d_count++;
+      }
+      
+      return noutput_items;
+    }
+
+  } /* namespace fec */
+}/* namespace gr */