GNU Radio 3.5.1 C++ API
gr_additive_scrambler_bb.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2008,2010 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 #ifndef INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H
00023 #define INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H
00024 
00025 #include <gr_core_api.h>
00026 #include <gr_sync_block.h>
00027 #include "gri_lfsr.h"
00028 
00029 class gr_additive_scrambler_bb;
00030 typedef boost::shared_ptr<gr_additive_scrambler_bb> gr_additive_scrambler_bb_sptr;
00031 
00032 GR_CORE_API gr_additive_scrambler_bb_sptr gr_make_additive_scrambler_bb(int mask, int seed, int len, int count=0);
00033 
00034 /*!
00035  * Scramble an input stream using an LFSR.  This block works on the LSB only
00036  * of the input data stream, i.e., on an "unpacked binary" stream, and 
00037  * produces the same format on its output.
00038  * 
00039  * \param mask     Polynomial mask for LFSR
00040  * \param seed     Initial shift register contents
00041  * \param len      Shift register length
00042  * \param count    Number of bits after which shift register is reset, 0=never
00043  *
00044  * The scrambler works by XORing the incoming bit stream by the output of
00045  * the LFSR.  Optionally, after 'count' bits have been processed, the shift
00046  * register is reset to the seed value.  This allows processing fixed length
00047  * vectors of samples.
00048  * 
00049  * \ingroup coding_blk
00050  */
00051 
00052 class GR_CORE_API gr_additive_scrambler_bb : public gr_sync_block
00053 {
00054   friend GR_CORE_API gr_additive_scrambler_bb_sptr gr_make_additive_scrambler_bb(int mask, int seed, int len, int count);
00055 
00056   gri_lfsr d_lfsr;
00057   int      d_count;
00058   int      d_bits;
00059 
00060   gr_additive_scrambler_bb(int mask, int seed, int len, int count);
00061 
00062 public:
00063   int work(int noutput_items,
00064            gr_vector_const_void_star &input_items,
00065            gr_vector_void_star &output_items);
00066 };
00067 
00068 #endif /* INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H */