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digital_additive_scrambler_bb.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2008,2010,2012 Free Software Foundation, Inc.
4  *
5  * This file is part of GNU Radio
6  *
7  * GNU Radio is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 3, or (at your option)
10  * any later version.
11  *
12  * GNU Radio is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with GNU Radio; see the file COPYING. If not, write to
19  * the Free Software Foundation, Inc., 51 Franklin Street,
20  * Boston, MA 02110-1301, USA.
21  */
22 #ifndef INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H
23 #define INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H
24 
25 #include <digital_api.h>
26 #include <gr_sync_block.h>
27 #include <analog/lfsr.h>
28 
31 
33 digital_make_additive_scrambler_bb(int mask, int seed,
34  int len, int count=0);
35 
36 /*!
37  * Scramble an input stream using an LFSR. This block works on the LSB only
38  * of the input data stream, i.e., on an "unpacked binary" stream, and
39  * produces the same format on its output.
40  *
41  * \param mask Polynomial mask for LFSR
42  * \param seed Initial shift register contents
43  * \param len Shift register length
44  * \param count Number of bits after which shift register is reset, 0=never
45  *
46  * The scrambler works by XORing the incoming bit stream by the output of
47  * the LFSR. Optionally, after 'count' bits have been processed, the shift
48  * register is reset to the seed value. This allows processing fixed length
49  * vectors of samples.
50  *
51  * \ingroup coding_blk
52  */
53 
55 {
57  digital_make_additive_scrambler_bb(int mask, int seed,
58  int len, int count);
59 
60  gr::analog::lfsr d_lfsr;
61  int d_count;
62  int d_bits;
63 
64  digital_additive_scrambler_bb(int mask, int seed,
65  int len, int count);
66 
67 public:
68  int work(int noutput_items,
69  gr_vector_const_void_star &input_items,
70  gr_vector_void_star &output_items);
71 };
72 
73 #endif /* INCLUDED_GR_ADDITIVE_SCRAMBLER_BB_H */