juribeparada/MMDVM_HS
1
0
Fork 0
mirror of https://github.com/juribeparada/MMDVM_HS.git synced 2025-12-06 07:12:08 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

Small optimisations of the sync decoding for M17

Browse source
This commit is contained in:
Jonathan Naylor 2021-09-12 21:47:08 +01:00
parent 6fc189793d
commit d408845f82
1 changed files with 10 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

14
M17RX.cpp
View file

@ -69,7 +69,7 @@ void CM17RX::processNone(bool bit)
if (bit) if (bit)
m_bitBuffer |= 0x01U; m_bitBuffer |= 0x01U;
// Fuzzy matching of the link setup sync bit sequence // Exact matching of the link setup sync bit sequence
if (countBits16(m_bitBuffer ^ M17_LINK_SETUP_SYNC_BITS) <= MAX_SYNC_BIT_START_ERRS) { if (countBits16(m_bitBuffer ^ M17_LINK_SETUP_SYNC_BITS) <= MAX_SYNC_BIT_START_ERRS) {
DEBUG1("M17RX: link setup sync found in None"); DEBUG1("M17RX: link setup sync found in None");
for (uint8_t i = 0U; i < M17_SYNC_BYTES_LENGTH; i++) for (uint8_t i = 0U; i < M17_SYNC_BYTES_LENGTH; i++)
@ -80,9 +80,11 @@ void CM17RX::processNone(bool bit)
m_state = M17RXS_LINK_SETUP; m_state = M17RXS_LINK_SETUP;
io.setDecode(true); io.setDecode(true);
return;
} }
// Fuzzy matching of the stream sync bit sequence // Exact matching of the stream sync bit sequence
if (countBits16(m_bitBuffer ^ M17_STREAM_SYNC_BITS) <= MAX_SYNC_BIT_START_ERRS) { if (countBits16(m_bitBuffer ^ M17_STREAM_SYNC_BITS) <= MAX_SYNC_BIT_START_ERRS) {
DEBUG1("M17RX: stream sync found in None"); DEBUG1("M17RX: stream sync found in None");
for (uint8_t i = 0U; i < M17_SYNC_BYTES_LENGTH; i++) for (uint8_t i = 0U; i < M17_SYNC_BYTES_LENGTH; i++)
@ -93,6 +95,8 @@ void CM17RX::processNone(bool bit)
m_state = M17RXS_STREAM; m_state = M17RXS_STREAM;
io.setDecode(true); io.setDecode(true);
return;
} }
} }
@ -108,14 +112,15 @@ void CM17RX::processData(bool bit)
if (m_bufferPtr > M17_FRAME_LENGTH_BITS) if (m_bufferPtr > M17_FRAME_LENGTH_BITS)
reset(); reset();
// Only search for the syncs in the right place +-2 symbols // Only search for the syncs in the right place +-1 bit
if (m_bufferPtr >= (M17_SYNC_LENGTH_BITS - 2U) && m_bufferPtr <= (M17_SYNC_LENGTH_BITS + 2U)) { if (m_bufferPtr >= (M17_SYNC_LENGTH_BITS - 1U) && m_bufferPtr <= (M17_SYNC_LENGTH_BITS + 1U)) {
// Fuzzy matching of the link setup sync bit sequence // Fuzzy matching of the link setup sync bit sequence
if (countBits16(m_bitBuffer ^ M17_LINK_SETUP_SYNC_BITS) <= MAX_SYNC_BIT_RUN_ERRS) { if (countBits16(m_bitBuffer ^ M17_LINK_SETUP_SYNC_BITS) <= MAX_SYNC_BIT_RUN_ERRS) {
DEBUG2("M17RX: found link setup sync, pos", m_bufferPtr - M17_SYNC_LENGTH_BITS); DEBUG2("M17RX: found link setup sync, pos", m_bufferPtr - M17_SYNC_LENGTH_BITS);
m_lostCount = MAX_SYNC_FRAMES; m_lostCount = MAX_SYNC_FRAMES;
m_bufferPtr = M17_SYNC_LENGTH_BITS; m_bufferPtr = M17_SYNC_LENGTH_BITS;
m_state = M17RXS_LINK_SETUP; m_state = M17RXS_LINK_SETUP;
return;
} }
// Fuzzy matching of the stream sync bit sequence // Fuzzy matching of the stream sync bit sequence
@ -124,6 +129,7 @@ void CM17RX::processData(bool bit)
m_lostCount = MAX_SYNC_FRAMES; m_lostCount = MAX_SYNC_FRAMES;
m_bufferPtr = M17_SYNC_LENGTH_BITS; m_bufferPtr = M17_SYNC_LENGTH_BITS;
m_state = M17RXS_STREAM; m_state = M17RXS_STREAM;
return;
} }
// Fuzzy matching of the EOT sync bit sequence // Fuzzy matching of the EOT sync bit sequence