3 * Copyright 2002 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
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8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2, or (at your option)
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13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
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19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
23 #include <GrAtscRandomizer.h>
25 // typedefs for fundamental i/o types
27 typedef atsc_mpeg_packet iType;
28 typedef atsc_mpeg_packet_no_sync oType;
30 static const int NUMBER_OF_OUTPUTS = 1; // # of output streams (almost always one)
33 GrAtscRandomizer::GrAtscRandomizer ()
34 : VrHistoryProc<iType,oType> (NUMBER_OF_OUTPUTS),
35 field2 (false), segno (0)
37 // 1 + number of extra input elements at which we look. This is
38 // used by the superclass's forecast routine to get us the correct
39 // range on our inputs.
40 // We're one-to-one input-to-output so set it to 1.
43 // any other init here.
46 GrAtscRandomizer::~GrAtscRandomizer ()
48 // Anything that isn't automatically cleaned up...
52 * This is the real work horse. In general this interface can handle
53 * multiple streams of input and output, but we almost always
54 * use a single input and output stream.
58 GrAtscRandomizer::work (VrSampleRange output, void *ao[],
59 VrSampleRange inputs[], void *ai[])
61 // If we have state that persists across invocations (e.g., we have
62 // instance variables that we modify), we must use the sync method
63 // to indicate to the scheduler that our output must be computed in
64 // order. This doesn't keep other things from being run in
65 // parallel, it just means that at any given time, there is only a
66 // single thread working this code, and that the scheduler will
67 // ensure that we are asked to produce output that is contiguous and
68 // that will be presented to us in order of increasing time.
70 // We have state, the current contents of the LFSR in the randomizer, hence
75 // construct some nicer i/o pointers to work with.
77 iType *in = ((iType **) ai)[0];
78 oType *out = ((oType **) ao)[0];
81 // We must produce output.size units of output.
83 for (unsigned int i = 0; i < output.size; i++){
85 // initialize plinfo for downstream
87 // We do this here because the randomizer is effectively
88 // the head of the tx processing chain
90 out[i].pli.set_regular_seg (field2, segno);
97 assert ((in[i].data[1] & MPEG_TRANSPORT_ERROR_BIT) == 0);
99 if (out[i].pli.first_regular_seg_p ())
102 rand.randomize (out[i], in[i]);
105 // Return the number of units we produced.
106 // Note that for all intents and purposes, it is an error to
107 // produce less than you are asked for.