--- /dev/null
+/* -*- 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 <atsci_viterbi_decoder.h>
+#include <assert.h>
+#include <stdio.h>
+#include <cmath>
+#include "atsci_viterbi_mux.cc"
+#include <string.h>
+
+
+/* How many separate Trellis encoders / Viterbi decoders run in parallel */
+static const int NCODERS = 12;
+
+static const float DSEG_SYNC_SYM1 = 5;
+static const float DSEG_SYNC_SYM2 = -5;
+static const float DSEG_SYNC_SYM3 = -5;
+static const float DSEG_SYNC_SYM4 = 5;
+
+atsci_viterbi_decoder::atsci_viterbi_decoder ()
+{
+ debug = true;
+
+ /*
+ * These fifo's handle the alignment problem caused by the
+ * inherent decoding delay of the individual viterbi decoders.
+ * The net result is that this entire block has a pipeline latency
+ * of 12 complete segments.
+ *
+ * If anybody cares, it is possible to do it with less delay, but
+ * this approach is at least somewhat understandable...
+ */
+
+ // the -4 is for the 4 sync symbols
+ int fifo_size = ATSC_DATA_SEGMENT_LENGTH - 4 - viterbi[0].delay ();
+ for (int i = 0; i < NCODERS; i++)
+ fifo[i] = new fifo_t(fifo_size);
+
+ reset ();
+}
+
+atsci_viterbi_decoder::~atsci_viterbi_decoder ()
+{
+ for (int i = 0; i < NCODERS; i++)
+ delete fifo[i];
+}
+
+void
+atsci_viterbi_decoder::reset ()
+{
+ for (int i = 0; i < NCODERS; i++){
+ viterbi[i].reset ();
+ fifo[i]->reset ();
+ }
+}
+
+
+void
+atsci_viterbi_decoder::decode (atsc_mpeg_packet_rs_encoded out[NCODERS],
+ const atsc_soft_data_segment in[NCODERS])
+{
+ unsigned char out_copy[OUTPUT_SIZE];
+ float in_copy[INPUT_SIZE];
+
+ // copy input into continguous temporary buffer
+ for (int i = 0; i < NCODERS; i++){
+ assert (in[i].pli.regular_seg_p ());
+ memcpy (&in_copy[i * INPUT_SIZE/NCODERS],
+ &in[i].data[0],
+ ATSC_DATA_SEGMENT_LENGTH * sizeof (in_copy[0]));
+ }
+
+ memset (out_copy, 0, sizeof (out_copy)); // sanity check
+
+ // do the deed...
+ decode_helper (out_copy, in_copy);
+
+ // copy output from contiguous temp buffer into final output
+ for (int i = 0; i < NCODERS; i++){
+ memcpy (&out[i].data[0],
+ &out_copy[i * OUTPUT_SIZE/NCODERS],
+ ATSC_MPEG_RS_ENCODED_LENGTH * sizeof (out_copy[0]));
+
+
+ // adjust pipeline info to reflect 12 segment delay
+ plinfo::delay (out[i].pli, in[i].pli, NCODERS);
+ }
+}
+
+void
+atsci_viterbi_decoder::decode_helper (unsigned char out[OUTPUT_SIZE],
+ const float symbols_in[INPUT_SIZE])
+{
+ int encoder;
+ unsigned int i;
+ int dbi;
+ int dbwhere;
+ int dbindex;
+ int shift;
+ unsigned char dibit;
+ float symbol;
+
+ /* Memset is not necessary if it's all working... */
+ memset (out, 0, OUTPUT_SIZE);
+
+#define VERBOSE 0
+
+#if 1
+ /* Check for sync symbols in the incoming data stream */
+ /* For now, all we do is complain to stdout. FIXME, pass it back to
+ caller as an error/quality signal. */
+ for (i = 0; i < sync_symbol_indices_max; i++) {
+ int j = sync_symbol_indices[i];
+ if (fabsf (symbols_in[j] - DSEG_SYNC_SYM1) > 1.0)
+ if (VERBOSE) fprintf (stderr, "** Missing dataseg sync 1 at %d, expect %g, got %g.\n",
+ j, DSEG_SYNC_SYM1, symbols_in[j]);
+ j++;
+ if (fabsf (symbols_in[j] - DSEG_SYNC_SYM2) > 1.0)
+ if (VERBOSE) fprintf (stderr, "** Missing dataseg sync 2 at %d, expect %g, got %g.\n",
+ j, DSEG_SYNC_SYM2, symbols_in[j]);
+ j++;
+ if (fabsf (symbols_in[j] - DSEG_SYNC_SYM3) > 1.0)
+ if (VERBOSE) fprintf (stderr, "** Missing dataseg sync 3 at %d, expect %g, got %g.\n",
+ j, DSEG_SYNC_SYM3, symbols_in[j]);
+ j++;
+ if (fabsf (symbols_in[j] - DSEG_SYNC_SYM4) > 1.0)
+ if (VERBOSE) fprintf (stderr, "** Missing dataseg sync 4 at %d, expect %g, got %g.\n",
+ j, DSEG_SYNC_SYM4, symbols_in[j]);
+ }
+#endif
+#undef VERBOSE
+
+ // printf ("@@@ DIBITS @@@\n");
+
+ /* Now run each of the 12 Trellis encoders over their subset of
+ the input symbols */
+ for (encoder = 0; encoder < NCODERS; encoder++) {
+ dbi = 0; /* Reinitialize dibit index for new encoder */
+ fifo_t *dibit_fifo = fifo[encoder];
+
+ /* Feed all the incoming symbols into one encoder;
+ pump them into the relevant dibits. */
+ for (i = 0; i < enco_which_max; i++) {
+ symbol = symbols_in[enco_which_syms[encoder][i]];
+ dibit = dibit_fifo->stuff (viterbi[encoder].decode (symbol));
+ // printf ("%d\n", dibit);
+ /* Store the dibit into the output data segment */
+ dbwhere = enco_which_dibits[encoder][dbi++];
+ dbindex = dbwhere >> 3;
+ shift = dbwhere & 0x7;
+ out[dbindex] =
+ (out[dbindex] & ~(0x03 << shift)) | (dibit << shift);
+ } /* Symbols fed into one encoder */
+ } /* Encoders */
+
+ // fflush (stdout);
+}
projects / debian / gnuradio / blobdiff