GNU Radio 3.4.0 C++ API
gri_glfsr.h
Go to the documentation of this file.
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 /*!
00027  * \brief Galois Linear Feedback Shift Register using specified polynomial mask
00028  * \ingroup misc
00029  *
00030  * Generates a maximal length pseudo-random sequence of length 2^degree-1
00031  */
00032 
00033 class gri_glfsr
00034 {
00035  private:
00036   int d_shift_register;
00037   int d_mask;
00038 
00039  public:
00040 
00041   gri_glfsr(int mask, int seed) { d_shift_register = seed; d_mask = mask; }
00042   static int glfsr_mask(int degree);
00043 
00044   unsigned char next_bit() {
00045     unsigned char bit = d_shift_register & 1;
00046     d_shift_register >>= 1;
00047     if (bit)
00048       d_shift_register ^= d_mask;
00049     return bit;
00050   }
00051 
00052   int mask() const { return d_mask; }
00053 };
00054 
00055 #endif /* INCLUDED_GRI_GLFSR_H */