GNU Radio 3.6.5.1 C++ API
gr_additive_scrambler_bb.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2008,2010 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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10  * any later version.
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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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21  */
22 #ifndef INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H
23 #define INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H
24 
25 #include <gr_core_api.h>
26 #include <gr_sync_block.h>
27 #include "gri_lfsr.h"
28 
31 
32 GR_CORE_API gr_additive_scrambler_bb_sptr gr_make_additive_scrambler_bb(int mask, int seed, int len, int count=0);
33 
34 /*!
35  * Scramble an input stream using an LFSR. This block works on the LSB only
36  * of the input data stream, i.e., on an "unpacked binary" stream, and
37  * produces the same format on its output.
38  *
39  * \param mask Polynomial mask for LFSR
40  * \param seed Initial shift register contents
41  * \param len Shift register length
42  * \param count Number of bits after which shift register is reset, 0=never
43  *
44  * The scrambler works by XORing the incoming bit stream by the output of
45  * the LFSR. Optionally, after 'count' bits have been processed, the shift
46  * register is reset to the seed value. This allows processing fixed length
47  * vectors of samples.
48  */
49 
51 {
52  friend GR_CORE_API gr_additive_scrambler_bb_sptr gr_make_additive_scrambler_bb(int mask, int seed, int len, int count);
53 
54  gri_lfsr d_lfsr;
55  int d_count;
56  int d_bits;
57 
58  gr_additive_scrambler_bb(int mask, int seed, int len, int count);
59 
60 public:
61  int work(int noutput_items,
62  gr_vector_const_void_star &input_items,
63  gr_vector_void_star &output_items);
64 };
65 
66 #endif /* INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H */