X-Git-Url: https://git.gag.com/?p=debian%2Fgnuradio;a=blobdiff_plain;f=gr-atsc%2Fsrc%2Flib%2FGrAtscViterbiDecoder.cc;fp=gr-atsc%2Fsrc%2Flib%2FGrAtscViterbiDecoder.cc;h=98e0a81a5149f212c2e3d129f481277ffb9c087f;hp=0000000000000000000000000000000000000000;hb=8a9ddbb0675f9bfcc6e03b457fba6c79474a3693;hpb=82d471b9b4a8b389b5da44b19c69c36420828382

diff --git a/gr-atsc/src/lib/GrAtscViterbiDecoder.cc b/gr-atsc/src/lib/GrAtscViterbiDecoder.cc
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+++ b/gr-atsc/src/lib/GrAtscViterbiDecoder.cc
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+/* -*- c++ -*- */
+/*
+ * Copyright 2002 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.
+ */
+
+#include <GrAtscViterbiDecoder.h>
+#include <iostream>
+
+// typedefs for fundamental i/o types
+
+typedef atsc_soft_data_segment		iType;
+typedef atsc_mpeg_packet_rs_encoded	oType;
+
+static const int NUMBER_OF_OUTPUTS = 1;	// # of output streams (almost always one)
+
+
+GrAtscViterbiDecoder::GrAtscViterbiDecoder ()
+  : VrHistoryProc<iType,oType> (NUMBER_OF_OUTPUTS), last_start(-1)
+{
+  // 1 + number of extra input elements at which we look.  This is
+  // used by the superclass's forecast routine to get us the correct
+  // range on our inputs.
+  //
+  // We need our input to be aligned on a 12-segment boundary,
+  // to ensure satisfaction, ask for 11 more
+  history = 1 + (atsci_viterbi_decoder::NCODERS - 1);
+
+  // any other init here.
+
+  // Let the bottom end know we must produce output in multiples of 12 segments.  
+  setOutputSize (atsci_viterbi_decoder::NCODERS);
+}
+
+GrAtscViterbiDecoder::~GrAtscViterbiDecoder ()
+{
+  // Anything that isn't automatically cleaned up...
+}
+
+/*
+ * This is the real work horse.  In general this interface can handle
+ * multiple streams of input and output, but we almost always
+ * use a single input and output stream.
+ */
+
+int 
+GrAtscViterbiDecoder::work (VrSampleRange output, void *ao[],
+			    VrSampleRange inputs[], void *ai[])
+{
+  // If we have state that persists across invocations (e.g., we have
+  // instance variables that we modify), we must use the sync method
+  // to indicate to the scheduler that our output must be computed in
+  // order.  This doesn't keep other things from being run in
+  // parallel, it just means that at any given time, there is only a
+  // single thread working this code, and that the scheduler will
+  // ensure that we are asked to produce output that is contiguous and
+  // that will be presented to us in order of increasing time.
+
+  // We have state, the current state of the decoder, hence
+  // we must use sync.
+
+  sync (output.index);
+
+  // construct some nicer i/o pointers to work with.
+
+  iType *in  = ((iType **) ai)[0];
+  oType *out = ((oType **) ao)[0];
+
+
+  assert (output.size % atsci_viterbi_decoder::NCODERS == 0);
+
+  // find the first mod 12 boundary to begin decoding
+  int start;
+  for (start = 0; start < atsci_viterbi_decoder::NCODERS; start++){
+    assert (in[start].pli.regular_seg_p ());
+    if ((in[start].pli.segno () % atsci_viterbi_decoder::NCODERS) == 0)
+      break;
+  }
+
+  if (start == atsci_viterbi_decoder::NCODERS){
+    // we didn't find a mod 12 boundary.  There's some kind of problem
+    // upstream of us (not yet sync'd??)
+    cerr << "!!!GrAtscViterbiDecoder: no mod-12 boundary found\7\n";
+    start = 0;
+  }
+  else if (start != last_start){
+    cerr << "GrAtscViterbiDecoder: new starting offset = " << start
+	 << " output.index = " << output.index << endl;
+    last_start = start;
+  }
+
+  // We must produce output.size units of output.
+
+  for (unsigned int i = 0; i < output.size; i += atsci_viterbi_decoder::NCODERS){
+    // primitive does 12 segments at a time.
+    // pipeline info is handled in the primitive.
+    decoder.decode (&out[i], &in[i + start]);
+  }
+
+#if 0
+  // FIXME paranoid check...
+  for (unsigned int i = 0; i < output.size; i++){
+    plinfo::sanity_check (out[i].pli);
+    assert (out[i].pli.regular_seg_p ());
+  }
+#endif
+
+#if 0
+  cerr << "@@@ GrAtscViterbiDecoder: output.index = " << output.index
+       << " output.size = " << output.size
+       << " sum = " << output.index + output.size << endl;
+#endif
+  
+  // Return the number of units we produced.
+  // Note that for all intents and purposes, it is an error to
+  // produce less than you are asked for.
+
+  return output.size;	
+}