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/* -*- c++ -*- */
/*
* Copyright 2008,2010 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_GR_ADDITIVE_SCRAMBLER_BB_H
#define INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H
#include <gr_core_api.h>
#include <gr_sync_block.h>
#include "gri_lfsr.h"
class gr_additive_scrambler_bb;
typedef boost::shared_ptr<gr_additive_scrambler_bb> gr_additive_scrambler_bb_sptr;
GR_CORE_API gr_additive_scrambler_bb_sptr gr_make_additive_scrambler_bb(int mask, int seed, int len, int count=0);
/*!
* Scramble an input stream using an LFSR. This block works on the LSB only
* of the input data stream, i.e., on an "unpacked binary" stream, and
* produces the same format on its output.
*
* \param mask Polynomial mask for LFSR
* \param seed Initial shift register contents
* \param len Shift register length
* \param count Number of bits after which shift register is reset, 0=never
*
* The scrambler works by XORing the incoming bit stream by the output of
* the LFSR. Optionally, after 'count' bits have been processed, the shift
* register is reset to the seed value. This allows processing fixed length
* vectors of samples.
*
* \ingroup coding_blk
*/
class GR_CORE_API gr_additive_scrambler_bb : public gr_sync_block
{
friend GR_CORE_API gr_additive_scrambler_bb_sptr gr_make_additive_scrambler_bb(int mask, int seed, int len, int count);
gri_lfsr d_lfsr;
int d_count;
int d_bits;
gr_additive_scrambler_bb(int mask, int seed, int len, int count);
public:
int work(int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
};
#endif /* INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H */
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