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additive_scrambler_bb.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2008,2010,2012 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
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12  * GNU Radio is distributed in the hope that it will be useful,
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14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
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22 
23 #ifndef INCLUDED_DIGITAL_ADDITIVE_SCRAMBLER_BB_H
24 #define INCLUDED_DIGITAL_ADDITIVE_SCRAMBLER_BB_H
25 
26 #include <gnuradio/digital/api.h>
27 #include <gnuradio/sync_block.h>
28 
29 namespace gr {
30  namespace digital {
31 
32  /*!
33  * \ingroup coding_blk
34  *
35  * \brief
36  * Scramble an input stream using an LFSR.
37  *
38  * \details
39  * This block scrambles up to 8 bits per byte of the input
40  * data stream, starting at the LSB.
41  *
42  * The scrambler works by XORing the incoming bit stream by the
43  * output of the LFSR. Optionally, after \p count bits have been
44  * processed, the shift register is reset to the \p seed value.
45  * This allows processing fixed length vectors of samples.
46  *
47  * Alternatively, the LFSR can be reset using a reset tag to
48  * scramble variable length vectors. However, it cannot be reset
49  * between bytes.
50  *
51  * For details on configuring the LFSR, see gr::digital::lfsr.
52  */
54  {
55  public:
56  // gr::digital::additive_scrambler_bb::sptr
57  typedef boost::shared_ptr<additive_scrambler_bb> sptr;
58 
59  /*!
60  * \brief Create additive scrambler.
61  *
62  * \param mask Polynomial mask for LFSR
63  * \param seed Initial shift register contents
64  * \param len Shift register length
65  * \param count Number of bytes after which shift register is reset, 0=never
66  * \param bits_per_byte Number of bits per byte
67  * \param reset_tag_key When a tag with this key is detected, the shift register is reset (when this is set, count is ignored!)
68  */
69  static sptr make(int mask, int seed, int len, int count=0, int bits_per_byte=1, const std::string &reset_tag_key="");
70 
71  virtual int mask() const = 0;
72  virtual int seed() const = 0;
73  virtual int len() const = 0;
74  virtual int count() const = 0;
75  virtual int bits_per_byte() = 0;
76  };
77 
78  } /* namespace digital */
79 } /* namespace gr */
80 
81 #endif /* INCLUDED_DIGITAL_ADDITIVE_SCRAMBLER_BB_H */
#define DIGITAL_API
Definition: gr-digital/include/gnuradio/digital/api.h:30
Scramble an input stream using an LFSR.
Definition: additive_scrambler_bb.h:53
Include this header to use the message passing features.
Definition: logger.h:131
synchronous 1:1 input to output with historyOverride work to provide the signal processing implementa...
Definition: sync_block.h:37
boost::shared_ptr< additive_scrambler_bb > sptr
Definition: additive_scrambler_bb.h:57