GNU Radio Manual and C++ API Reference 3.7.14.0
The Free & Open Software Radio Ecosystem
puncture_bb.h
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1/* -*- c++ -*- */
2/*
3 * Copyright 2014 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
6 *
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
10 * any later version.
11 *
12 * GNU Radio is distributed in the hope that it will be useful,
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.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
21 */
22
23#ifndef INCLUDED_FEC_PUNCTURE_BB_H
24#define INCLUDED_FEC_PUNCTURE_BB_H
25
26#include <gnuradio/block.h>
27#include <gnuradio/fec/api.h>
28
29namespace gr {
30namespace fec {
31
32/*!
33 * \brief Puncture a stream of unpacked bits.
34 * \ingroup error_coding_blk
35 *
36 * \details
37 * Puncture a given block of input samples of \p puncsize. The
38 * items produced is based on pattern \p puncpat. Basically, if:
39 *
40 * \code
41 * k = 0
42 * if _puncpat[i] == 1:
43 * out[k++] = input[i]
44 * \endcode
45 *
46 * This block is designed for unpacked bits - that is, every
47 * input sample is a bit, either a 1 or 0. It's possible to use
48 * packed bits as symbols, but the puncturing will be done on
49 * the symbol level, not the bit level.
50 *
51 * \p puncpat is specified as a 32-bit integer that we can
52 * convert into the vector _puncpat used in the algorithm above:
53 *
54 * \code
55 * _puncpat = [0,...]
56 * for i in puncsize:
57 * _puncpat[i] = puncpat >> (puncsize-1-i)
58 * \endcode
59 *
60 * Example:
61 * \code
62 * puncsize = 8
63 * puncpat = 0xEF --> [1,1,1,0,1,1,1,1]
64 * input = [a, b, c, d, e, f, g, h]
65 * output = [a, b, c, e, f, g, h]
66 * \endcode
67 *
68 * The gr.fec Python module provides a read_bitlist function
69 * that can turn a string of a puncture pattern into the correct
70 * integer form. The pattern of 0xEF could be specified as
71 * fec.readbitlist("11101111"). Also, this allows us to use
72 * puncsize=len("11101111") to make sure that our sizes are set
73 * up correctly for the pattern we want.
74 *
75 * The fec.extended_encoder takes in the puncture pattern
76 * directly as a string and uses the readbitlist inside to do
77 * the conversion.
78 *
79 * Note that due to the above concept, the default setting in the
80 * extended encoder of '11' translates into no puncturing.
81 *
82 * The \p delay parameter delays the application of the puncture
83 * pattern. This is equivalent to circularly rotating the \p
84 * puncpat by \p delay. Note that because of the circular shift,
85 * the delay should be between 0 and \p puncsize, but this is
86 * not enforced; the effective delay will simply be \p delay mod
87 * \p puncsize. A negative value here is ignored.
88 */
89class FEC_API puncture_bb : virtual public block
90{
91public:
92 // gr::fec::puncture_bb::sptr
93 typedef boost::shared_ptr<puncture_bb> sptr;
94
95 /*!
96 * \brief Constructs a puncture block for unpacked bits.
97 *
98 * \param puncsize Size of block of bits to puncture
99 * \param puncpat The puncturing pattern
100 * \param delay Delayed the puncturing pattern by shifting it
101 */
102 static sptr make(int puncsize, int puncpat, int delay = 0);
103};
104
105} /* namespace fec */
106} /* namespace gr */
107
108#endif /* INCLUDED_FEC_PUNCTURE_BB_H */
The abstract base class for all 'terminal' processing blocks.
Definition: block.h:66
Puncture a stream of unpacked bits.
Definition: puncture_bb.h:90
static sptr make(int puncsize, int puncpat, int delay=0)
Constructs a puncture block for unpacked bits.
boost::shared_ptr< puncture_bb > sptr
Definition: puncture_bb.h:93
#define FEC_API
Definition: gr-fec/include/gnuradio/fec/api.h:30
Include this header to use the message passing features.
Definition: basic_block.h:45