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133 lines
5.0 KiB
133 lines
5.0 KiB
/*
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* Copyright (C) 2009-2015 by Jonathan Naylor G4KLX
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef SoundCardController_H
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#define SoundCardController_H
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#include "SoundCardReaderWriter.h"
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#include "DStarGMSKDemodulator.h"
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#include "DStarGMSKModulator.h"
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#include "AudioCallback.h"
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#include "RingBuffer.h"
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#include "Modem.h"
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#include "Utils.h"
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#include "StdCompat.h"
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#include <string>
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#include <cstdint>
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enum DSRSCC_STATE {
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DSRSCCS_NONE,
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DSRSCCS_HEADER,
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DSRSCCS_DATA
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};
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/*
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* CSoundCardController - D-Star modem using a sound card as the RF interface.
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*
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* Implements both CModem (repeater-facing) and IAudioCallback (audio I/O facing).
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* The sound card carries the baseband GMSK signal: the discriminator output of the
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* radio feeds the RX input, and the TX output drives the radio's microphone input.
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*
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* Audio path (IAudioCallback):
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* readCallback() - called by CSoundCardReaderWriter with captured float samples.
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* Appends to m_rxAudio ring buffer; entry() drains it.
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* writeCallback() - called when the audio output device needs a new block.
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* Drains m_txAudio into the provided output buffer.
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*
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* Demodulation (entry() thread, processes m_rxAudio bit by bit):
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* m_demodulator converts float samples to a recovered bit stream.
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* A 32-bit shift register (m_patternBuffer) is used to detect the D-Star
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* frame sync pattern (FRAME_SYNC_DATA) and data sync (DATA_SYNC_DATA).
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* State machine (m_rxState): NONE -> HEADER -> DATA
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* processNone(): hunts for the frame sync pattern (up to MAX_SYNC_BITS).
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* processHeader(): accumulates FEC_SECTION_LENGTH_BITS (660) bits, then calls
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* rxHeader() which runs the Viterbi decoder and validates
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* the CCITT checksum before queuing a DSMTT_HEADER record.
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* processData(): accumulates DV_FRAME_LENGTH_BITS per frame; detects end
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* pattern and data sync for sequence tracking.
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*
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* Modulation (writeCallback()):
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* writeHeader() / writeData() push into m_txAudio.
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* The modulator (m_modulator) converts binary frames to float samples.
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* txDelay pads silence before the first header bit; txTail pads after EOT.
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*
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* FEC and interleaving:
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* The header section is rate-1/2 convolutional coded + interleaved.
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* Viterbi decoding state is held in m_pathMetric, m_pathMemory0-3, m_fecOutput.
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* countBits() uses a 4-bit lookup table (NIBBLE_BITS) for Hamming weight.
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*/
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class CSoundCardController : public CModem, public IAudioCallback {
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public:
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CSoundCardController(const std::string& rxDevice, const std::string& txDevice, bool rxInvert, bool txInvert, float rxLevel, float txLevel, unsigned int txDelay, unsigned int txTail);
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virtual ~CSoundCardController();
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virtual bool start();
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virtual unsigned int getSpace();
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virtual bool isTXReady();
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virtual bool isTX();
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virtual bool writeHeader(const CHeaderData& header);
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virtual bool writeData(const unsigned char* data, unsigned int length, bool end);
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virtual void readCallback(const float* input, unsigned int n, int id);
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virtual void writeCallback(float* output, int& n, int id);
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private:
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void entry();
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CSoundCardReaderWriter m_sound;
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float m_rxLevel;
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float m_txLevel;
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unsigned int m_txDelay;
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unsigned int m_txTail;
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CRingBuffer<float> m_txAudio;
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CRingBuffer<float> m_rxAudio;
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DSRSCC_STATE m_rxState;
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uint32_t m_patternBuffer;
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CDStarGMSKDemodulator m_demodulator;
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CDStarGMSKModulator m_modulator;
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unsigned char* m_rxBuffer;
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unsigned int m_rxBufferBits;
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unsigned int m_dataBits;
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unsigned int m_mar;
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int* m_pathMetric;
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unsigned int* m_pathMemory0;
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unsigned int* m_pathMemory1;
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unsigned int* m_pathMemory2;
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unsigned int* m_pathMemory3;
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unsigned char* m_fecOutput;
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void processNone(bool bit);
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void processHeader(bool bit);
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void processData(bool bit);
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bool rxHeader(unsigned char* in, unsigned char* out);
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void acs(int* metric);
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void viterbiDecode(int* data);
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void traceBack();
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void txHeader(const unsigned char* in, unsigned char* out);
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void writeBits(unsigned char c);
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unsigned int countBits(uint32_t num);
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};
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#endif
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