GNU Radio 3.6.1 C++ API
digital_impl_glfsr.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2007,2012 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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10  * any later version.
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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_IMPL_GLFSR_H
24 #define INCLUDED_DIGITAL_IMPL_GLFSR_H
25 
26 #include <digital_api.h>
27 
28 /*!
29  * \brief Galois Linear Feedback Shift Register using specified polynomial mask
30  * \ingroup misc
31  *
32  * Generates a maximal length pseudo-random sequence of length 2^degree-1
33  */
34 
36 {
37  private:
38  int d_shift_register;
39  int d_mask;
40 
41  public:
42 
43  digital_impl_glfsr(int mask, int seed) { d_shift_register = seed; d_mask = mask; }
44  static int glfsr_mask(int degree);
45 
46  unsigned char next_bit() {
47  unsigned char bit = d_shift_register & 1;
48  d_shift_register >>= 1;
49  if (bit)
50  d_shift_register ^= d_mask;
51  return bit;
52  }
53 
54  int mask() const { return d_mask; }
55 };
56 
57 #endif /* INCLUDED_DIGITAL_IMPL_GLFSR_H */