mirror of https://github.com/markqvist/MMDVM.git
405 lines
10 KiB
C++
405 lines
10 KiB
C++
/*
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* Copyright (C) 2009-2017 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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#include "Config.h"
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#include "Globals.h"
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#include "YSFRX.h"
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#include "Utils.h"
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const q15_t SCALING_FACTOR = 18750; // Q15(0.55)
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const uint8_t MAX_SYNC_BIT_START_ERRS = 2U;
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const uint8_t MAX_SYNC_BIT_RUN_ERRS = 4U;
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const uint8_t MAX_SYNC_SYMBOLS_ERRS = 3U;
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const uint8_t BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U};
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#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
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const uint8_t NOAVEPTR = 99U;
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const uint16_t NOENDPTR = 9999U;
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const unsigned int MAX_SYNC_FRAMES = 4U + 1U;
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CYSFRX::CYSFRX() :
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m_state(YSFRXS_NONE),
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m_bitBuffer(),
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m_buffer(),
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m_bitPtr(0U),
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m_dataPtr(0U),
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m_startPtr(NOENDPTR),
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m_endPtr(NOENDPTR),
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m_syncPtr(NOENDPTR),
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m_minSyncPtr(NOENDPTR),
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m_maxSyncPtr(NOENDPTR),
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m_maxCorr(0),
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m_lostCount(0U),
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m_countdown(0U),
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m_centre(),
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m_centreVal(0),
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m_threshold(),
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m_thresholdVal(0),
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m_averagePtr(NOAVEPTR),
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m_rssiAccum(0U),
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m_rssiCount(0U)
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{
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}
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void CYSFRX::reset()
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{
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m_state = YSFRXS_NONE;
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m_dataPtr = 0U;
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m_bitPtr = 0U;
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m_maxCorr = 0;
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m_averagePtr = NOAVEPTR;
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m_startPtr = NOENDPTR;
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m_endPtr = NOENDPTR;
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m_syncPtr = NOENDPTR;
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m_minSyncPtr = NOENDPTR;
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m_maxSyncPtr = NOENDPTR;
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m_centreVal = 0;
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m_thresholdVal = 0;
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m_lostCount = 0U;
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m_countdown = 0U;
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m_rssiAccum = 0U;
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m_rssiCount = 0U;
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}
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void CYSFRX::samples(const q15_t* samples, uint16_t* rssi, uint8_t length)
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{
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for (uint8_t i = 0U; i < length; i++) {
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q15_t sample = samples[i];
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m_rssiAccum += rssi[i];
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m_rssiCount++;
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m_bitBuffer[m_bitPtr] <<= 1;
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if (sample < 0)
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m_bitBuffer[m_bitPtr] |= 0x01U;
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m_buffer[m_dataPtr] = sample;
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switch (m_state) {
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case YSFRXS_DATA:
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processData(sample);
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break;
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default:
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processNone(sample);
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break;
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}
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m_dataPtr++;
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if (m_dataPtr >= YSF_FRAME_LENGTH_SAMPLES)
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m_dataPtr = 0U;
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m_bitPtr++;
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if (m_bitPtr >= YSF_RADIO_SYMBOL_LENGTH)
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m_bitPtr = 0U;
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}
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}
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void CYSFRX::processNone(q15_t sample)
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{
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bool ret = correlateSync();
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if (ret) {
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// On the first sync, start the countdown to the state change
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if (m_countdown == 0U) {
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m_rssiAccum = 0U;
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m_rssiCount = 0U;
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io.setDecode(true);
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io.setADCDetection(true);
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m_averagePtr = NOAVEPTR;
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m_countdown = 5U;
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}
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}
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if (m_countdown > 0U)
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m_countdown--;
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if (m_countdown == 1U) {
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m_minSyncPtr = m_syncPtr + YSF_FRAME_LENGTH_SAMPLES - 1U;
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if (m_minSyncPtr >= YSF_FRAME_LENGTH_SAMPLES)
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m_minSyncPtr -= YSF_FRAME_LENGTH_SAMPLES;
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m_maxSyncPtr = m_syncPtr + 1U;
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if (m_maxSyncPtr >= YSF_FRAME_LENGTH_SAMPLES)
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m_maxSyncPtr -= YSF_FRAME_LENGTH_SAMPLES;
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m_state = YSFRXS_DATA;
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m_countdown = 0U;
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}
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}
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void CYSFRX::processData(q15_t sample)
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{
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if (m_minSyncPtr < m_maxSyncPtr) {
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if (m_dataPtr >= m_minSyncPtr && m_dataPtr <= m_maxSyncPtr)
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correlateSync();
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} else {
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if (m_dataPtr >= m_minSyncPtr || m_dataPtr <= m_maxSyncPtr)
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correlateSync();
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}
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if (m_dataPtr == m_endPtr) {
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// Only update the centre and threshold if they are from a good sync
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if (m_lostCount == MAX_SYNC_FRAMES) {
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m_minSyncPtr = m_syncPtr + YSF_FRAME_LENGTH_SAMPLES - 1U;
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if (m_minSyncPtr >= YSF_FRAME_LENGTH_SAMPLES)
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m_minSyncPtr -= YSF_FRAME_LENGTH_SAMPLES;
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m_maxSyncPtr = m_syncPtr + 1U;
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if (m_maxSyncPtr >= YSF_FRAME_LENGTH_SAMPLES)
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m_maxSyncPtr -= YSF_FRAME_LENGTH_SAMPLES;
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}
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calculateLevels(m_startPtr, YSF_FRAME_LENGTH_SYMBOLS);
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DEBUG4("YSFRX: sync found pos/centre/threshold", m_syncPtr, m_centreVal, m_thresholdVal);
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uint8_t frame[YSF_FRAME_LENGTH_BYTES + 3U];
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samplesToBits(m_startPtr, YSF_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centreVal, m_thresholdVal);
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// We've not seen a data sync for too long, signal RXLOST and change to RX_NONE
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m_lostCount--;
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if (m_lostCount == 0U) {
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DEBUG1("YSFRX: sync timed out, lost lock");
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io.setDecode(false);
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io.setADCDetection(false);
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serial.writeYSFLost();
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m_state = YSFRXS_NONE;
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m_endPtr = NOENDPTR;
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m_averagePtr = NOAVEPTR;
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m_countdown = 0U;
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m_maxCorr = 0;
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} else {
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frame[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
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writeRSSIData(frame);
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m_maxCorr = 0;
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}
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}
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}
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bool CYSFRX::correlateSync()
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{
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if (countBits32((m_bitBuffer[m_bitPtr] & YSF_SYNC_SYMBOLS_MASK) ^ YSF_SYNC_SYMBOLS) <= MAX_SYNC_SYMBOLS_ERRS) {
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uint16_t ptr = m_dataPtr + YSF_FRAME_LENGTH_SAMPLES - YSF_SYNC_LENGTH_SAMPLES + YSF_RADIO_SYMBOL_LENGTH;
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if (ptr >= YSF_FRAME_LENGTH_SAMPLES)
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ptr -= YSF_FRAME_LENGTH_SAMPLES;
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q31_t corr = 0;
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q15_t min = 16000;
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q15_t max = -16000;
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for (uint8_t i = 0U; i < YSF_SYNC_LENGTH_SYMBOLS; i++) {
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q15_t val = m_buffer[ptr];
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if (val > max)
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max = val;
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if (val < min)
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min = val;
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switch (YSF_SYNC_SYMBOLS_VALUES[i]) {
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case +3:
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corr -= (val + val + val);
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break;
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case +1:
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corr -= val;
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break;
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case -1:
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corr += val;
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break;
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default: // -3
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corr += (val + val + val);
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break;
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}
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ptr += YSF_RADIO_SYMBOL_LENGTH;
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if (ptr >= YSF_FRAME_LENGTH_SAMPLES)
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ptr -= YSF_FRAME_LENGTH_SAMPLES;
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}
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if (corr > m_maxCorr) {
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if (m_averagePtr == NOAVEPTR) {
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m_centreVal = (max + min) >> 1;
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q31_t v1 = (max - m_centreVal) * SCALING_FACTOR;
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m_thresholdVal = q15_t(v1 >> 15);
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}
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uint16_t startPtr = m_dataPtr + YSF_FRAME_LENGTH_SAMPLES - YSF_SYNC_LENGTH_SAMPLES + YSF_RADIO_SYMBOL_LENGTH;
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if (startPtr >= YSF_FRAME_LENGTH_SAMPLES)
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startPtr -= YSF_FRAME_LENGTH_SAMPLES;
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uint8_t sync[YSF_SYNC_BYTES_LENGTH];
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samplesToBits(startPtr, YSF_SYNC_LENGTH_SYMBOLS, sync, 0U, m_centreVal, m_thresholdVal);
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uint8_t maxErrs;
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if (m_state == YSFRXS_NONE)
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maxErrs = MAX_SYNC_BIT_START_ERRS;
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else
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maxErrs = MAX_SYNC_BIT_RUN_ERRS;
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uint8_t errs = 0U;
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for (uint8_t i = 0U; i < YSF_SYNC_BYTES_LENGTH; i++)
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errs += countBits8(sync[i] ^ YSF_SYNC_BYTES[i]);
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if (errs <= maxErrs) {
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m_maxCorr = corr;
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m_lostCount = MAX_SYNC_FRAMES;
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m_syncPtr = m_dataPtr;
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m_startPtr = startPtr;
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m_endPtr = m_dataPtr + YSF_FRAME_LENGTH_SAMPLES - YSF_SYNC_LENGTH_SAMPLES - 1U;
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if (m_endPtr >= YSF_FRAME_LENGTH_SAMPLES)
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m_endPtr -= YSF_FRAME_LENGTH_SAMPLES;
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return true;
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}
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}
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}
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return false;
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}
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void CYSFRX::calculateLevels(uint16_t start, uint16_t count)
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{
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q15_t maxPos = -16000;
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q15_t minPos = 16000;
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q15_t maxNeg = 16000;
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q15_t minNeg = -16000;
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for (uint16_t i = 0U; i < count; i++) {
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q15_t sample = m_buffer[start];
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if (sample > 0) {
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if (sample > maxPos)
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maxPos = sample;
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if (sample < minPos)
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minPos = sample;
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} else {
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if (sample < maxNeg)
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maxNeg = sample;
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if (sample > minNeg)
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minNeg = sample;
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}
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start += YSF_RADIO_SYMBOL_LENGTH;
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if (start >= YSF_FRAME_LENGTH_SAMPLES)
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start -= YSF_FRAME_LENGTH_SAMPLES;
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}
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q15_t posThresh = (maxPos + minPos) >> 1;
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q15_t negThresh = (maxNeg + minNeg) >> 1;
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q15_t centre = (posThresh + negThresh) >> 1;
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q15_t threshold = posThresh - centre;
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DEBUG5("YSFRX: pos/neg/centre/threshold", posThresh, negThresh, centre, threshold);
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if (m_averagePtr == NOAVEPTR) {
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for (uint8_t i = 0U; i < 16U; i++) {
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m_centre[i] = centre;
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m_threshold[i] = threshold;
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}
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m_averagePtr = 0U;
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} else {
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m_centre[m_averagePtr] = centre;
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m_threshold[m_averagePtr] = threshold;
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m_averagePtr++;
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if (m_averagePtr >= 16U)
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m_averagePtr = 0U;
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}
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m_centreVal = 0;
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m_thresholdVal = 0;
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for (uint8_t i = 0U; i < 16U; i++) {
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m_centreVal += m_centre[i];
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m_thresholdVal += m_threshold[i];
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}
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m_centreVal >>= 4;
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m_thresholdVal >>= 4;
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}
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void CYSFRX::samplesToBits(uint16_t start, uint16_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold)
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{
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for (uint16_t i = 0U; i < count; i++) {
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q15_t sample = m_buffer[start] - centre;
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if (sample < -threshold) {
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WRITE_BIT1(buffer, offset, false);
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offset++;
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WRITE_BIT1(buffer, offset, true);
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offset++;
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} else if (sample < 0) {
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WRITE_BIT1(buffer, offset, false);
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offset++;
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WRITE_BIT1(buffer, offset, false);
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offset++;
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} else if (sample < threshold) {
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WRITE_BIT1(buffer, offset, true);
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offset++;
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WRITE_BIT1(buffer, offset, false);
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offset++;
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} else {
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WRITE_BIT1(buffer, offset, true);
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offset++;
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WRITE_BIT1(buffer, offset, true);
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offset++;
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}
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start += YSF_RADIO_SYMBOL_LENGTH;
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if (start >= YSF_FRAME_LENGTH_SAMPLES)
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start -= YSF_FRAME_LENGTH_SAMPLES;
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}
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}
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void CYSFRX::writeRSSIData(uint8_t* data)
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{
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#if defined(SEND_RSSI_DATA)
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if (m_rssiCount > 0U) {
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uint16_t rssi = m_rssiAccum / m_rssiCount;
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data[121U] = (rssi >> 8) & 0xFFU;
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data[122U] = (rssi >> 0) & 0xFFU;
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serial.writeYSFData(data, YSF_FRAME_LENGTH_BYTES + 3U);
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} else {
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serial.writeYSFData(data, YSF_FRAME_LENGTH_BYTES + 1U);
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}
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#else
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serial.writeYSFData(data, YSF_FRAME_LENGTH_BYTES + 1U);
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#endif
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m_rssiAccum = 0U;
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m_rssiCount = 0U;
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}
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