136 lines
3.3 KiB
C++
136 lines
3.3 KiB
C++
#include "hdlcAfskRx.h"
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HdlcAfskRx::HdlcAfskRx(HdlcFrameBuffer* rxBuffer) {
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_rxBuffer = rxBuffer;
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}
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void HdlcAfskRx::decodeSample(byte sampleVal) {
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int intAnVal = sampleVal - 127;
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_rxFilter[0][0] = _rxFilter[0][1];
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_rxFilter[0][1] = (_rxAnSamples[_histAnSampleIndex] * intAnVal) >> 2;
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_rxFilter[1][0] = _rxFilter[1][1];
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_rxFilter[1][1] = _rxFilter[0][0] + _rxFilter[0][1] + (_rxFilter[1][0] >> 1);
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_rxAnSamples[_rxAnSampleIndex] = intAnVal;
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_histAnSampleIndex++;
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if (_histAnSampleIndex > MAX_RX_AN_SAMPLE_INDEX) {
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_histAnSampleIndex = 0;
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}
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_rxAnSampleIndex++;
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if (_rxAnSampleIndex > MAX_RX_AN_SAMPLE_INDEX) {
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_rxAnSampleIndex = 0;
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}
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_spaceMarkSamples <<= 1;
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_spaceMarkSamples |= (_rxFilter[1][1] > 0) ? 1 : 0;
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if (
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(
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( (_spaceMarkSamples)^(_spaceMarkSamples >> 2) ) & SPACE_MARK_TRANSISION_MASK
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) == SPACE_MARK_TRANSISION_MASK
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) {
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if (_currentPhase < HALF_WINDOW_SAMPLE_COUNT) {
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_currentPhase += 1;
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}
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else {
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_currentPhase -= 1;
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}
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}
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_currentPhase += RX_AN_SAMPLE_COUNT;
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if (_currentPhase >= WINDOW_SAMPLE_COUNT) {
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_currentPhase %= WINDOW_SAMPLE_COUNT;
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byte bits = _spaceMarkSamples & 0x07;
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setNextMark(
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(bits == 0x07 || // 111
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bits == 0x06 || // 110
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bits == 0x05 || // 101
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bits == 0x03) // 011
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);
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}
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}
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void HdlcAfskRx::setNextMark(boolean spaceMark) {
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_prevSpace = _currentSpace;
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_currentSpace = spaceMark;
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boolean flagDetect = false;
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switch (stufState) {
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case STUF_NO_STUF:
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_afskShiftInReg >>= 1;
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_rxBitCount++;
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if (_rxBitCount > 8) {
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_rxBitCount = 1;
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}
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_afskShiftInReg |= (_prevSpace == _currentSpace) ? 0x80 : 0;
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flagDetect = _afskShiftInReg == HDLC_FLAG;
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if ((_afskShiftInReg == STUF1) || (_afskShiftInReg == STUF2)) {
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stufState = STUF_SKIP;
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}
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break;
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case STUF_SKIP:
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_afskShiftInReg |= (_prevSpace == _currentSpace) ? 0x80 : 0;
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stufState = STUF_SKIP_CHECKS;
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break;
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case STUF_SKIP_CHECKS:
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_afskShiftInReg >>= 1;
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_rxBitCount++;
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if (_rxBitCount > 8) {
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_rxBitCount = 1;
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}
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_afskShiftInReg |= (_prevSpace == _currentSpace) ? 0x80 : 0;
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stufState = STUF_NO_STUF;
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break;
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}
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if (stufState == STUF_SKIP) {
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return;
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}
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switch (_frameRxState) {
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case RXST_IDLE:
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if (flagDetect) {
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_rxBitCount = 0;
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_frameRxState = RXST_SYNC1;
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}
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break;
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case RXST_SYNC1:
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if (_rxBitCount > 7) {
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if (flagDetect) {
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_rxBuffer->frameReset();
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_frameRxState = RXST_SYNC2;
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}
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else {
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_frameRxState = RXST_IDLE;
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}
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}
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break;
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case RXST_SYNC2:
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if (_rxBitCount > 7) {
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if (!flagDetect) {
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_frameRxState = RXST_START;
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receiving = true;
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if (!_rxBuffer->push(_afskShiftInReg)) {
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_frameRxState = RXST_IDLE;
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}
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}
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}
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break;
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case RXST_START:
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if (flagDetect) {
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_rxBitCount = 0;
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_frameRxState = RXST_SYNC1;
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receiving = false;
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_rxBuffer->frameEnd();
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}
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else if (_rxBitCount > 7) {
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if (!_rxBuffer->push(_afskShiftInReg)) {
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_frameRxState = RXST_IDLE;
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receiving = false;
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}
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}
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break;
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}
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}
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