GNU Radio C++ API
gr_correlate_access_code_tag_bb.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2005,2006,2011 Free Software Foundation, Inc.
4  *
5  * This file is part of GNU Radio
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15  * GNU General Public License for more details.
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22 
23 #ifndef INCLUDED_gr_correlate_access_code_tag_bb_H
24 #define INCLUDED_gr_correlate_access_code_tag_bb_H
25 
26 #include <gr_core_api.h>
27 #include <gr_sync_block.h>
28 #include <string>
29 
32 
33 /*!
34  * \param access_code is represented with 1 byte per bit, e.g., "010101010111000100"
35  * \param threshold maximum number of bits that may be wrong
36  * \param tag_name key of the tag inserted into the tag stream
37  */
39 gr_make_correlate_access_code_tag_bb (const std::string &access_code, int threshold,
40  const std::string &tag_name);
41 
42 /*!
43  * \brief Examine input for specified access code, one bit at a time.
44  * \ingroup sync_blk
45  *
46  * input: stream of bits, 1 bit per input byte (data in LSB)
47  * output: unaltered stream of bits (plus tags)
48  *
49  * This block annotates the input stream with tags. The tags have key
50  * name [tag_name], specified in the constructor. Used for searching
51  * an input data stream for preambles, etc.
52  */
54 {
56  gr_make_correlate_access_code_tag_bb (const std::string &access_code, int threshold,
57  const std::string &tag_name);
58  private:
59  unsigned long long d_access_code; // access code to locate start of packet
60  // access code is left justified in the word
61  unsigned long long d_data_reg; // used to look for access_code
62  unsigned long long d_mask; // masks access_code bits (top N bits are set where
63  // N is the number of bits in the access code)
64  unsigned int d_threshold; // how many bits may be wrong in sync vector
65  unsigned int d_len; //the length of the access code
66 
67  pmt::pmt_t d_key, d_me; //d_key is the tag name, d_me is the block name + unique ID
68 
69  protected:
70  gr_correlate_access_code_tag_bb(const std::string &access_code, int threshold,
71  const std::string &tag_name);
72 
73  public:
75 
76  int work(int noutput_items,
77  gr_vector_const_void_star &input_items,
78  gr_vector_void_star &output_items);
79 
80 
81  /*!
82  * \param access_code is represented with 1 byte per bit, e.g., "010101010111000100"
83  */
84  bool set_access_code (const std::string &access_code);
85 };
86 
87 #endif /* INCLUDED_gr_correlate_access_code_tag_bb_H */