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M17: CRC16 code cleanup
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parent
22539b331f
commit
a035c42762
@ -9,23 +9,28 @@
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namespace modemm17
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namespace modemm17
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{
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{
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template <uint16_t Poly = 0x5935, uint16_t Init = 0xFFFF>
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struct CRC16
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struct CRC16
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{
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{
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static constexpr uint16_t MASK = 0xFFFF;
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static const uint16_t MASK = 0xFFFF;
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static constexpr uint16_t LSB = 0x0001;
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static const uint16_t LSB = 0x0001;
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static constexpr uint16_t MSB = 0x8000;
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static const uint16_t MSB = 0x8000;
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uint16_t reg_ = Init;
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CRC16(uint16_t poly = 0x5935, uint16_t init = 0xFFFF) :
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poly_(poly),
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init_(init)
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{
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reg_ = init_;
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}
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void reset()
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void reset()
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{
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{
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reg_ = Init;
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reg_ = init_;
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for (size_t i = 0; i != 16; ++i)
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for (size_t i = 0; i != 16; ++i)
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{
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{
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auto bit = reg_ & LSB;
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auto bit = reg_ & LSB;
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if (bit) reg_ ^= Poly;
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if (bit) reg_ ^= poly_;
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reg_ >>= 1;
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reg_ >>= 1;
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if (bit) reg_ |= MSB;
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if (bit) reg_ |= MSB;
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}
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}
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@ -44,7 +49,7 @@ struct CRC16
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{
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{
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auto msb = reg & MSB;
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auto msb = reg & MSB;
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reg = ((reg << 1) & MASK) | ((byte >> (7 - i)) & LSB);
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reg = ((reg << 1) & MASK) | ((byte >> (7 - i)) & LSB);
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if (msb) reg ^= Poly;
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if (msb) reg ^= poly_;
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}
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}
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return reg & MASK;
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return reg & MASK;
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}
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}
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@ -56,7 +61,7 @@ struct CRC16
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{
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{
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auto msb = reg & MSB;
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auto msb = reg & MSB;
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reg = ((reg << 1) & MASK);
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reg = ((reg << 1) & MASK);
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if (msb) reg ^= Poly;
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if (msb) reg ^= poly_;
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}
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}
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return reg;
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return reg;
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}
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}
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@ -67,6 +72,11 @@ struct CRC16
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std::array<uint8_t, 2> result{uint8_t((crc >> 8) & 0xFF), uint8_t(crc & 0xFF)};
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std::array<uint8_t, 2> result{uint8_t((crc >> 8) & 0xFF), uint8_t(crc & 0xFF)};
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return result;
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return result;
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}
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}
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private:
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uint16_t poly_;
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uint16_t init_;
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uint16_t reg_;
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};
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};
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} // modemm17
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} // modemm17
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@ -45,7 +45,7 @@ struct M17FrameDecoder
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PolynomialInterleaver<45, 92, 368> interleaver_;
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PolynomialInterleaver<45, 92, 368> interleaver_;
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Trellis<4,2> trellis_{makeTrellis<4, 2>({031,027})};
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Trellis<4,2> trellis_{makeTrellis<4, 2>({031,027})};
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Viterbi<decltype(trellis_), 4> viterbi_{trellis_};
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Viterbi<decltype(trellis_), 4> viterbi_{trellis_};
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CRC16<0x5935, 0xFFFF> crc_;
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CRC16 crc_;
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enum class State { LSF, STREAM, BASIC_PACKET, FULL_PACKET, BERT };
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enum class State { LSF, STREAM, BASIC_PACKET, FULL_PACKET, BERT };
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enum class SyncWordType { LSF, STREAM, PACKET, BERT };
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enum class SyncWordType { LSF, STREAM, PACKET, BERT };
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@ -106,6 +106,7 @@ struct M17FrameDecoder
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uint8_t lich_segments{0}; ///< one bit per received LICH fragment.
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uint8_t lich_segments{0}; ///< one bit per received LICH fragment.
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M17FrameDecoder(callback_t callback) :
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M17FrameDecoder(callback_t callback) :
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crc_(0x5935, 0xFFFF),
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callback_(callback)
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callback_(callback)
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{}
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{}
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@ -51,7 +51,7 @@ public:
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static const std::array<uint8_t, 2> BERT_SYNC_WORD;
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static const std::array<uint8_t, 2> BERT_SYNC_WORD;
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static const std::array<uint8_t, 2> EOT_SYNC;
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static const std::array<uint8_t, 2> EOT_SYNC;
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static constexpr int8_t bits_to_symbol(uint8_t bits)
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static int8_t bits_to_symbol(uint8_t bits)
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{
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{
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switch (bits)
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switch (bits)
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{
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{
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@ -120,7 +120,7 @@ public:
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M17Randomizer<368> randomizer;
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M17Randomizer<368> randomizer;
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PolynomialInterleaver<45, 92, 368> interleaver;
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PolynomialInterleaver<45, 92, 368> interleaver;
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CRC16<0x5935, 0xFFFF> crc;
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CRC16 crc(0x5935, 0xFFFF);
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auto rit = std::copy(dest_.begin(), dest_.end(), lsf.begin());
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auto rit = std::copy(dest_.begin(), dest_.end(), lsf.begin());
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std::copy(source_.begin(), source_.end(), rit);
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std::copy(source_.begin(), source_.end(), rit);
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@ -457,7 +457,8 @@ public:
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source_(encode_callsign(source)),
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source_(encode_callsign(source)),
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dest_(encode_callsign(dest)),
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dest_(encode_callsign(dest)),
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can_(10),
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can_(10),
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rrc(makeFirFilter(rrc_taps))
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rrc(makeFirFilter(rrc_taps)),
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crc_(0x5935, 0xFFFF)
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{
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{
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gnss_.fill(0);
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gnss_.fill(0);
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gnss_on_ = false;
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gnss_on_ = false;
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@ -511,7 +512,7 @@ private:
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uint8_t can_;
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uint8_t can_;
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BaseFirFilter<150> rrc;
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BaseFirFilter<150> rrc;
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static const std::array<float, 150> rrc_taps;
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static const std::array<float, 150> rrc_taps;
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CRC16<0x5935, 0xFFFF> crc_;
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CRC16 crc_;
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static LinkSetupFrame::encoded_call_t encode_callsign(std::string callsign)
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static LinkSetupFrame::encoded_call_t encode_callsign(std::string callsign)
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{
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{
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@ -321,7 +321,7 @@ bool M17DemodProcessor::decode_packet(modemm17::M17FrameDecoder::packet_buffer_t
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qDebug() << "M17DemodProcessor::decode_packet: last chunk size:" << packet_size << " packet size:" << m_currentPacket.size();
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qDebug() << "M17DemodProcessor::decode_packet: last chunk size:" << packet_size << " packet size:" << m_currentPacket.size();
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}
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}
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modemm17::CRC16<0x5935, 0xFFFF> crc16;
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modemm17::CRC16 crc16(0x5935, 0xFFFF);
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crc16.reset();
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crc16.reset();
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for (std::vector<uint8_t>::const_iterator it = m_currentPacket.begin(); it != m_currentPacket.end() - 2; ++it) {
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for (std::vector<uint8_t>::const_iterator it = m_currentPacket.begin(); it != m_currentPacket.end() - 2; ++it) {
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