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/* -*- c++ -*- */
/*
* Copyright 2004 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef INCLUDED_GRI_LFSR_15_1_0_H
#define INCLUDED_GRI_LFSR_15_1_0_H
#include <blocks/api.h>
namespace gr {
namespace blocks {
/*!
* \brief Linear Feedback Shift Register using primitive polynomial x^15 + x + 1
* \ingroup misc
*
* \details
* Generates a maximal length pseudo-random sequence of length
* 2^15 - 1 bits.
*/
class BLOCKS_API lfsr_15_1_0
{
private:
unsigned long d_sr; // shift register
public:
lfsr_15_1_0() { reset(); }
void reset() { d_sr = 0x7fff; }
int next_bit()
{
d_sr = ((((d_sr >> 1) ^ d_sr) & 0x1) << 14) | (d_sr >> 1);
return d_sr & 0x1;
}
int next_byte ()
{
int v = 0;
for(int i = 0; i < 8; i++) {
v >>= 1;
if(next_bit ())
v |= 0x80;
}
return v;
}
};
} /* namespace blocks */
} /* namespace gr */
#endif /* INCLUDED_GRI_LFSR_15_1_0_H */
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