mirror of https://github.com/g4klx/MMDVM.git
295 lines
7.9 KiB
C++
295 lines
7.9 KiB
C++
/*
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* Copyright (C) 2009-2017,2020 by Jonathan Naylor G4KLX
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* Copyright (C) 2025 by Rob Williams M1BGT
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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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#if defined(MODE_DMR)
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#include "Globals.h"
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#include "DMRUserRX.h"
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#include "DMRSlotType.h"
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#include "Utils.h"
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const q15_t SCALING_FACTOR = 19505; // Q15(0.60)
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const uint8_t MAX_SYNC_SYMBOLS_ERRS = 2U;
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const uint8_t MAX_SYNC_BYTES_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 uint16_t NOENDPTR = 9999U;
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const uint8_t CONTROL_IDLE = 0x80U;
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const uint8_t CONTROL_DATA = 0x40U;
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const uint8_t cachInterleave[DMR_CACH_LENGTH_BITS] = {
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0, 7, 8, 9, 1, 10, 11, 12, 2, 13, 14,
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15, 3, 16, 4, 17, 18, 19, 5, 20, 21, 22, 6, 23
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};
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extern bool decodeDMRHamming74(uint8_t *received);
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CDMRUserRX::CDMRUserRX() :
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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_endPtr(NOENDPTR),
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m_maxCorr(0),
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m_centre(0),
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m_threshold(0),
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m_colorCode(0U),
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m_slot(false)
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{
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}
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void CDMRUserRX::reset()
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{
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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_threshold = 0;
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m_centre = 0;
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m_slot = false;
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m_endPtr = NOENDPTR;
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}
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void CDMRUserRX::samples(const q15_t* samples, uint8_t length)
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{
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for (uint8_t i = 0U; i < length; i++)
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processSample(samples[i]);
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}
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void CDMRUserRX::processSample(q15_t sample)
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{
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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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bool bsDataSyncFound = countBits32((m_bitBuffer[m_bitPtr] & DMR_SYNC_SYMBOLS_MASK) ^ DMR_BS_DATA_SYNC_SYMBOLS) <= MAX_SYNC_SYMBOLS_ERRS;
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if (
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bsDataSyncFound
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) {
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// Sync pattern found
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// | CACH (24 bits/60 samples) | Payload (98 bits) | Slot type (10 bits) | Sync (DMR_SYNC_LENGTH_SAMPLES) | Slot type Slot type (10 bits) | Payload (98 bits) |
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uint16_t ptr = m_dataPtr + DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES - DMR_SYNC_LENGTH_SAMPLES + DMR_RADIO_SYMBOL_LENGTH;
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if (ptr >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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ptr -= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES;
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// ptr is start of first sync sample
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q31_t corr = 0;
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q15_t max = -16000;
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q15_t min = 16000;
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for (uint8_t i = 0U; i < DMR_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 (DMR_BS_DATA_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 += DMR_RADIO_SYMBOL_LENGTH;
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if (ptr >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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ptr -= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES;
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}
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if (corr > m_maxCorr) {
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q15_t centre = (max + min) >> 1;
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q31_t v1 = (max - centre) * SCALING_FACTOR;
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q15_t threshold = q15_t(v1 >> 15);
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uint8_t sync[DMR_SYNC_BYTES_LENGTH];
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uint16_t ptr = m_dataPtr + DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES - DMR_SYNC_LENGTH_SAMPLES + DMR_RADIO_SYMBOL_LENGTH;
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if (ptr >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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ptr -= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES;
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samplesToBits(ptr, DMR_SYNC_LENGTH_SYMBOLS, sync, 4U, centre, threshold);
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uint8_t errs = 0U;
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for (uint8_t i = 0U; i < DMR_SYNC_BYTES_LENGTH; i++)
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errs += countBits8((sync[i] & DMR_SYNC_BYTES_MASK[i]) ^ DMR_BS_DATA_SYNC_BYTES[i]);
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if (errs <= MAX_SYNC_BYTES_ERRS) {
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//DEBUG3("DMRUserRX: data sync found centre/threshold", centre, threshold);
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m_maxCorr = corr;
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m_centre = centre;
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m_threshold = threshold;
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m_endPtr = m_dataPtr + DMR_SLOT_TYPE_LENGTH_SAMPLES / 2U + DMR_INFO_LENGTH_SAMPLES / 2U - 1U;
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if (m_endPtr >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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m_endPtr -= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES;
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}
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}
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}
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if (m_dataPtr == m_endPtr) {
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uint16_t ptr = m_endPtr + DMR_RADIO_SYMBOL_LENGTH + 1U + DMR_CACH_LENGTH_SAMPLES;
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if (ptr >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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ptr -= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES;
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uint16_t cachePtr = m_endPtr + DMR_RADIO_SYMBOL_LENGTH + 1U;
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if (cachePtr >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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cachePtr -= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES;
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uint8_t frame[DMR_FRAME_LENGTH_BYTES + 1U];
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samplesToBits(ptr, DMR_FRAME_LENGTH_SYMBOLS, frame, 8U, m_centre, m_threshold);
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uint8_t colorCode;
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uint8_t dataType;
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CDMRSlotType slotType;
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slotType.decode(frame + 1U, colorCode, dataType);
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//DEBUG4("At end, cachePtr/ptr/endPtr", cachePtr, ptr, m_endPtr);
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if (colorCode == m_colorCode && dataType != DT_IDLE) {
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// Read the CACH in order to get the time slot
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uint8_t cach[DMR_CACH_LENGTH_BYTES];
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samplesToBits(cachePtr, DMR_CACH_LENGTH_SYMBOLS, cach, 0U, m_centre, m_threshold);
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if(cachCheck(cach))
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{
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frame[0U] = CONTROL_DATA | dataType;
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serial.writeDMRData(m_slot, frame, DMR_FRAME_LENGTH_BYTES + 1U);
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} else {
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DEBUG1("CACH check failed");
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}
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}
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m_endPtr = NOENDPTR;
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m_maxCorr = 0;
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}
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m_dataPtr++;
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if (m_dataPtr >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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m_dataPtr = 0U;
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m_bitPtr++;
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if (m_bitPtr >= DMR_RADIO_SYMBOL_LENGTH)
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m_bitPtr = 0U;
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}
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#define READ_BIT1(p,i) ((p[(i)>>3] & BIT_MASK_TABLE[(i)&7]) >> (7 - ((i)&7)))
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void CDMRUserRX::extractBits(uint8_t* bytes, uint16_t start, uint8_t count_bits, bool* buffer)
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{
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for (uint8_t i = 0U; i < count_bits; i++) {
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buffer[i] = READ_BIT1(bytes, start) == 0x01;
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start++;
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}
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}
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bool CDMRUserRX::cachCheck(uint8_t* cach)
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{
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uint8_t i;
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bool bits[DMR_CACH_LENGTH_BITS];
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extractBits(cach, 0, DMR_CACH_LENGTH_BITS, bits);
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bool cachdata[DMR_CACH_LENGTH_BITS];
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for (i = 0; i < DMR_CACH_LENGTH_BITS; i++)
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{
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cachdata[cachInterleave[i]] = bits[i];
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}
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uint8_t tactBits[7];
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for (i = 0; i < 7; i++)
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{
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tactBits[i] = cachdata[i];
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}
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if(!decodeDMRHamming74(tactBits))
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{
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return false;
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}
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// bool at_continuous = tactBits[0];
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m_slot = tactBits[1]; // TDMA Channel (TC)
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return true;
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}
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void CDMRUserRX::samplesToBits(uint16_t start, uint8_t count, uint8_t* buffer, uint16_t offset, q15_t centre, q15_t threshold)
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{
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for (uint8_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 += DMR_RADIO_SYMBOL_LENGTH;
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if (start >= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES)
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start -= DMR_FRAME_PLUS_CACH_LENGTH_SAMPLES;
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}
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}
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void CDMRUserRX::setColorCode(uint8_t colorCode)
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{
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m_colorCode = colorCode;
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}
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#endif
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