GNU Radio 3.7.1 C++ API
glfsr.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2007,2012 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_DIGITAL_GLFSR_H
00024 #define INCLUDED_DIGITAL_GLFSR_H
00025 
00026 #include <gnuradio/digital/api.h>
00027 
00028 namespace gr {
00029   namespace digital {
00030 
00031     /*!
00032      * \brief Galois Linear Feedback Shift Register using specified polynomial mask
00033      * \ingroup waveform_generators_blk
00034      *
00035      * \details
00036      * Generates a maximal length pseudo-random sequence of length 2^degree-1
00037      */
00038     class DIGITAL_API glfsr
00039     {
00040     private:
00041       int d_shift_register;
00042       int d_mask;
00043 
00044     public:
00045       glfsr(int mask, int seed) { d_shift_register = seed; d_mask = mask; }
00046       ~glfsr();
00047 
00048       static int glfsr_mask(int degree);
00049 
00050       unsigned char next_bit()
00051       {
00052         unsigned char bit = d_shift_register & 1;
00053         d_shift_register >>= 1;
00054         if(bit)
00055           d_shift_register ^= d_mask;
00056         return bit;
00057       }
00058 
00059       int mask() const { return d_mask; }
00060     };
00061 
00062   } /* namespace digital */
00063 } /* namespace gr */
00064 
00065 #endif /* INCLUDED_DIGITAL_GLFSR_H */