74 lines
3.9 KiB
C
74 lines
3.9 KiB
C
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#ifndef P25P1_HDU_H_9f95c3a5072842e8aaf94444e1452d20
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#define P25P1_HDU_H_9f95c3a5072842e8aaf94444e1452d20
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#include "p25p1_heuristics.h"
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/**
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* Reads a dibit (two bits) from the stream of data. Takes into account the periodic occurrence of status
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* bits that show up every 36 dibits. Status bits are discarded.
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* \param opts A pointer the the DSD options.
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* \param state A pointer the the DSD state structure.
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* \param output A pointer to be filled with the dibit read. Two bytes used for each dibit.
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* \param status_count Variable used to keep track of the status symbols in the dibit stream. There is one
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* status every 36 dibits. With this counter we can skip the status.
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* \param analog_signal A pointer with the actual analog value read from the input signal and that has been
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* interpreted as the dibit we are returning in output.
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* \param did_read_status Address were a boolean is returned. This is set to true when one status symbol was
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* read (and skipped). This indicates that the sequence on dibits has been broken and is used by the P25
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* heuristics.
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*/
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int read_dibit (dsd_opts* opts, dsd_state* state, char* output, int* status_count, int* analog_signal,
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int* did_read_status);
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/**
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* Reads a number of dibits and stores its value together with the actual analog value that has been
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* intrepreted as the dibit into an AnalogSignal structure. This is used later in the P25 heuristics module
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* to improve the accuracy of the digitizer.
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* \param opts A pointer the the DSD options.
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* \param state A pointer the the DSD state structure.
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* \param output A pointer to be filled with the dibits read.
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* \param count The number of bits to read (remember: 1 dibit = 2 bits).
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* \param status_count Variable used to keep track of the status symbols in the dibit stream. There is one
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* status every 36 dibits. With this counter we can skip the status.
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* \param analog_signal_array The pointer to the start of a sequence of AnalogSignal structures. The
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* information is updated for each dibit read.
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* \param analog_signal_index The actual index into the AnalogSignal array. This is increased here wich each
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* dibit read.
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*/
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void read_dibit_update_analog_data (dsd_opts* opts, dsd_state* state, char* buffer, unsigned int count,
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int* status_count, AnalogSignal* analog_signal_array, int* analog_signal_index);
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/**
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* Reads a word, made up of length bits or length/2 dibits. Also keeps track of the status dibits.
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*/
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void read_word (dsd_opts* opts, dsd_state* state, char* word, unsigned int length, int* status_count,
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AnalogSignal* analog_signal_array, int* analog_signal_index);
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/**
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* Reads 4 bits from the stream of data. Those are the parity bits that follow each hex word.
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*/
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void read_hamm_parity (dsd_opts* opts, dsd_state* state, char* parity, int* status_count,
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AnalogSignal* analog_signal_array, int* analog_signal_index);
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/**
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* Reads 12 bits from the stream of data. Those are the extended Golay parity bits that follow a word of data.
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*/
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void read_golay24_parity (dsd_opts* opts, dsd_state* state, char* parity, int* status_count, AnalogSignal* analog_signal_array, int* analog_signal_index);
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/**
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* Reads bits from the data stream that should all be zeros. This is valuable information for the
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* heuristics module and we update it.
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* \param opts A pointer the the DSD options.
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* \param state A pointer the the DSD state structure.
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* \param analog_signal_array The pointer to the start of a sequence of AnalogSignal structures.
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* \param length Number of bits to read.
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* \param status_count Variable used to keep track of the status symbols in the dibit stream.
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* \param new_sequence Bool used to update the sequence_broken value of the first AnalogSignal element.
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*/
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void read_zeros(dsd_opts* opts, dsd_state* state, AnalogSignal* analog_signal_array, unsigned int length,
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int* status_count, int new_sequence);
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#endif // P25P1_HDU_H_9f95c3a5072842e8aaf94444e1452d20
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