GNU Radio 3.5.1 C++ API
gri_glfsr.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2007 Free Software Foundation, Inc.
00004  * 
00005  * This file is part of GNU Radio
00006  * 
00007  * GNU Radio is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 3, or (at your option)
00010  * any later version.
00011  * 
00012  * GNU Radio is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  * 
00017  * You should have received a copy of the GNU General Public License
00018  * along with GNU Radio; see the file COPYING.  If not, write to
00019  * the Free Software Foundation, Inc., 51 Franklin Street,
00020  * Boston, MA 02110-1301, USA.
00021  */
00022 
00023 #ifndef INCLUDED_GRI_GLFSR_H
00024 #define INCLUDED_GRI_GLFSR_H
00025 
00026 #include <gr_core_api.h>
00027 
00028 /*!
00029  * \brief Galois Linear Feedback Shift Register using specified polynomial mask
00030  * \ingroup misc
00031  *
00032  * Generates a maximal length pseudo-random sequence of length 2^degree-1
00033  */
00034 
00035 class GR_CORE_API gri_glfsr
00036 {
00037  private:
00038   int d_shift_register;
00039   int d_mask;
00040 
00041  public:
00042 
00043   gri_glfsr(int mask, int seed) { d_shift_register = seed; d_mask = mask; }
00044   static int glfsr_mask(int degree);
00045 
00046   unsigned char next_bit() {
00047     unsigned char bit = d_shift_register & 1;
00048     d_shift_register >>= 1;
00049     if (bit)
00050       d_shift_register ^= d_mask;
00051     return bit;
00052   }
00053 
00054   int mask() const { return d_mask; }
00055 };
00056 
00057 #endif /* INCLUDED_GRI_GLFSR_H */