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15 * GNU General Public License for more details.
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23 #ifndef INCLUDED_GR_CORRELATE_ACCESS_CODE_BB_H
24 #define INCLUDED_GR_CORRELATE_ACCESS_CODE_BB_H
26 #include <gr_sync_block.h>
29 class gr_correlate_access_code_bb;
30 typedef boost::shared_ptr<gr_correlate_access_code_bb> gr_correlate_access_code_bb_sptr;
33 * \param access_code is represented with 1 byte per bit, e.g., "010101010111000100"
34 * \param threshold maximum number of bits that may be wrong
36 gr_correlate_access_code_bb_sptr
37 gr_make_correlate_access_code_bb (const std::string &access_code, int threshold);
40 * \brief Examine input for specified access code, one bit at a time.
43 * input: stream of bits, 1 bit per input byte (data in LSB)
44 * output: stream of bits, 2 bits per output byte (data in LSB, flag in next higher bit)
46 * Each output byte contains two valid bits, the data bit, and the
47 * flag bit. The LSB (bit 0) is the data bit, and is the original
48 * input data, delayed 64 bits. Bit 1 is the
49 * flag bit and is 1 if the corresponding data bit is the first data
50 * bit following the access code. Otherwise the flag bit is 0.
52 class gr_correlate_access_code_bb : public gr_sync_block
54 friend gr_correlate_access_code_bb_sptr
55 gr_make_correlate_access_code_bb (const std::string &access_code, int threshold);
57 unsigned long long d_access_code; // access code to locate start of packet
58 // access code is left justified in the word
59 unsigned long long d_data_reg; // used to look for access_code
60 unsigned long long d_flag_reg; // keep track of decisions
61 unsigned long long d_flag_bit; // mask containing 1 bit which is location of new flag
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
67 gr_correlate_access_code_bb(const std::string &access_code, int threshold);
70 ~gr_correlate_access_code_bb();
72 int work(int noutput_items,
73 gr_vector_const_void_star &input_items,
74 gr_vector_void_star &output_items);
78 * \param access_code is represented with 1 byte per bit, e.g., "010101010111000100"
80 bool set_access_code (const std::string &access_code);
83 #endif /* INCLUDED_GR_CORRELATE_ACCESS_CODE_BB_H */