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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 <GrAtscDerandomizer.h>
// typedefs for fundamental i/o types
typedef atsc_mpeg_packet_no_sync iType;
typedef atsc_mpeg_packet oType;
static const int NUMBER_OF_OUTPUTS = 1; // # of output streams (almost always one)
GrAtscDerandomizer::GrAtscDerandomizer ()
: VrHistoryProc<iType,oType> (NUMBER_OF_OUTPUTS)
{
// 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're one-to-one input-to-output so set it to 1.
history = 1;
// any other init here.
}
GrAtscDerandomizer::~GrAtscDerandomizer ()
{
// 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
GrAtscDerandomizer::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 contents of the LFSR in the randomizer, 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];
// We must produce output.size units of output.
for (unsigned int i = 0; i < output.size; i++){
assert (in[i].pli.regular_seg_p ());
if (in[i].pli.first_regular_seg_p ())
rand.reset ();
rand.derandomize (out[i], in[i]);
// take a look at the transport error bit in the pipeline info
// and set bit as required
if (in[i].pli.transport_error_p ())
out[i].data[1] |= MPEG_TRANSPORT_ERROR_BIT;
else
out[i].data[1] &= ~MPEG_TRANSPORT_ERROR_BIT;
}
// 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;
}
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