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M17: Demodulator: reduce indentation levels 

Removed some indentation levels in M17Demodulator::update function body,
no functional change.

Signed-off-by: Silvano Seva <silseva@fastwebnet.it>
This commit is contained in:
Silvano Seva 2025-10-27 21:32:42 +01:00
parent 1c50bf8bad
commit 7b633c5bee
1 changed files with 119 additions and 122 deletions
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241
openrtx/src/protocols/M17/M17Demodulator.cpp
View File

@ -235,151 +235,148 @@ bool M17Demodulator::update(const bool invertPhase)
// Read samples from the ADC // Read samples from the ADC
dataBlock_t baseband = inputStream_getData(basebandId); dataBlock_t baseband = inputStream_getData(basebandId);
if(baseband.data != NULL) if(baseband.data == NULL)
return false;
// Process samples
for(size_t i = 0; i < baseband.len; i++)
{ {
// Process samples // Apply DC removal filter
for(size_t i = 0; i < baseband.len; i++) int16_t sample = dsp_dcBlockFilter(&dcBlock, baseband.data[i]);
// Apply RRC on the baseband sample
float elem = static_cast< float >(sample);
if(invertPhase) elem = 0.0f - elem;
sample = static_cast< int16_t >(M17::rrc_24k(elem));
// Update correlator and sample filter for correlation thresholds
correlator.sample(sample);
corrThreshold = sampleFilter(std::abs(sample));
switch(demodState)
{ {
// Apply DC removal filter case DemodState::INIT:
int16_t sample = dsp_dcBlockFilter(&dcBlock, baseband.data[i]);
// Apply RRC on the baseband sample
float elem = static_cast< float >(sample);
if(invertPhase) elem = 0.0f - elem;
sample = static_cast< int16_t >(M17::rrc_24k(elem));
// Update correlator and sample filter for correlation thresholds
correlator.sample(sample);
corrThreshold = sampleFilter(std::abs(sample));
switch(demodState)
{ {
case DemodState::INIT: initCount -= 1;
if(initCount == 0)
demodState = DemodState::UNLOCKED;
}
break;
case DemodState::UNLOCKED:
{
int32_t syncThresh = static_cast< int32_t >(corrThreshold * 33.0f);
int8_t syncStatus = streamSync.update(correlator, syncThresh, -syncThresh);
if(syncStatus != 0)
demodState = DemodState::SYNCED;
}
break;
case DemodState::SYNCED:
{
// Set sampling point and deviation, zero frame symbol count
samplingPoint = streamSync.samplingIndex();
outerDeviation = correlator.maxDeviation(samplingPoint);
frameIndex = 0;
// Quantize the syncword taking data from the correlator
// memory.
for(size_t i = 0; i < SYNCWORD_SAMPLES; i++)
{ {
initCount -= 1; size_t pos = (correlator.index() + i) % SYNCWORD_SAMPLES;
if(initCount == 0) int16_t val = correlator.data()[pos];
demodState = DemodState::UNLOCKED;
if((pos % SAMPLES_PER_SYMBOL) == samplingPoint)
updateFrame(val);
} }
uint8_t hd = hammingDistance((*demodFrame)[0], STREAM_SYNC_WORD[0]);
hd += hammingDistance((*demodFrame)[1], STREAM_SYNC_WORD[1]);
if(hd == 0)
{
locked = true;
demodState = DemodState::LOCKED;
}
else
{
demodState = DemodState::UNLOCKED;
}
}
break;
case DemodState::LOCKED:
{
if(sampleIndex != samplingPoint)
break; break;
case DemodState::UNLOCKED: // Quantize and update frame at each sampling point
{ updateFrame(sample);
int32_t syncThresh = static_cast< int32_t >(corrThreshold * 33.0f);
int8_t syncStatus = streamSync.update(correlator, syncThresh, -syncThresh);
if(syncStatus != 0) // When we have reached almost the end of a frame, switch
demodState = DemodState::SYNCED; // to syncpoint update.
if(frameIndex == (M17_FRAME_SYMBOLS - M17_SYNCWORD_SYMBOLS/2))
{
demodState = DemodState::SYNC_UPDATE;
syncCount = SYNCWORD_SAMPLES * 2;
} }
break; }
break;
case DemodState::SYNCED: case DemodState::SYNC_UPDATE:
{
// Keep filling the ongoing frame!
if(sampleIndex == samplingPoint)
updateFrame(sample);
// Find the new correlation peak
int32_t syncThresh = static_cast< int32_t >(corrThreshold * 33.0f);
int8_t syncStatus = streamSync.update(correlator, syncThresh, -syncThresh);
// Correlation has to coincide with a syncword!
if((syncStatus != 0) && (frameIndex == M17_SYNCWORD_SYMBOLS))
{ {
// Set sampling point and deviation, zero frame symbol count
samplingPoint = streamSync.samplingIndex();
outerDeviation = correlator.maxDeviation(samplingPoint);
frameIndex = 0;
// Quantize the syncword taking data from the correlator
// memory.
for(size_t i = 0; i < SYNCWORD_SAMPLES; i++)
{
size_t pos = (correlator.index() + i) % SYNCWORD_SAMPLES;
int16_t val = correlator.data()[pos];
if((pos % SAMPLES_PER_SYMBOL) == samplingPoint)
updateFrame(val);
}
uint8_t hd = hammingDistance((*demodFrame)[0], STREAM_SYNC_WORD[0]); uint8_t hd = hammingDistance((*demodFrame)[0], STREAM_SYNC_WORD[0]);
hd += hammingDistance((*demodFrame)[1], STREAM_SYNC_WORD[1]); hd += hammingDistance((*demodFrame)[1], STREAM_SYNC_WORD[1]);
if(hd == 0) // Valid sync found: update deviation and sample
// point, then go back to locked state
if(hd <= 1)
{ {
locked = true; outerDeviation = correlator.maxDeviation(samplingPoint);
demodState = DemodState::LOCKED; samplingPoint = streamSync.samplingIndex();
missedSyncs = 0;
demodState = DemodState::LOCKED;
break;
}
}
// No syncword found within the window, increase the count
// of missed syncs and choose where to go. The lock is lost
// after four consecutive sync misses.
if(syncCount == 0)
{
if(missedSyncs >= 4)
{
demodState = DemodState::UNLOCKED;
locked = false;
} }
else else
{ {
demodState = DemodState::UNLOCKED; demodState = DemodState::LOCKED;
} }
missedSyncs += 1;
} }
break;
case DemodState::LOCKED: syncCount -= 1;
{
// Quantize and update frame at each sampling point
if(sampleIndex == samplingPoint)
{
updateFrame(sample);
// When we have reached almost the end of a frame, switch
// to syncpoint update.
if(frameIndex == (M17_FRAME_SYMBOLS - M17_SYNCWORD_SYMBOLS/2))
{
demodState = DemodState::SYNC_UPDATE;
syncCount = SYNCWORD_SAMPLES * 2;
}
}
}
break;
case DemodState::SYNC_UPDATE:
{
// Keep filling the ongoing frame!
if(sampleIndex == samplingPoint)
updateFrame(sample);
// Find the new correlation peak
int32_t syncThresh = static_cast< int32_t >(corrThreshold * 33.0f);
int8_t syncStatus = streamSync.update(correlator, syncThresh, -syncThresh);
if(syncStatus != 0)
{
// Correlation has to coincide with a syncword!
if(frameIndex == M17_SYNCWORD_SYMBOLS)
{
uint8_t hd = hammingDistance((*demodFrame)[0], STREAM_SYNC_WORD[0]);
hd += hammingDistance((*demodFrame)[1], STREAM_SYNC_WORD[1]);
// Valid sync found: update deviation and sample
// point, then go back to locked state
if(hd <= 1)
{
outerDeviation = correlator.maxDeviation(samplingPoint);
samplingPoint = streamSync.samplingIndex();
missedSyncs = 0;
demodState = DemodState::LOCKED;
break;
}
}
}
// No syncword found within the window, increase the count
// of missed syncs and choose where to go. The lock is lost
// after four consecutive sync misses.
if(syncCount == 0)
{
if(missedSyncs >= 4)
{
demodState = DemodState::UNLOCKED;
locked = false;
}
else
{
demodState = DemodState::LOCKED;
}
missedSyncs += 1;
}
syncCount -= 1;
}
break;
} }
break;
sampleCount += 1;
sampleIndex = (sampleIndex + 1) % SAMPLES_PER_SYMBOL;
} }
sampleCount += 1;
sampleIndex = (sampleIndex + 1) % SAMPLES_PER_SYMBOL;
} }
return newFrame; return newFrame;