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code quality improvement suggested by @uklotzde
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m0dB authored and m0dB committed Jan 1, 2024
1 parent ebac022 commit 6f95b1b
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Showing 2 changed files with 117 additions and 90 deletions.
203 changes: 113 additions & 90 deletions src/waveform/vsyncthread.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -36,107 +36,130 @@ void VSyncThread::run() {
m_timer.start();

//qDebug() << "VSyncThread::run()";
if (m_vSyncMode == ST_FREE) {
while (m_bDoRendering) {
// for benchmark only!
switch (m_vSyncMode) {
case ST_FREE:
runFree();
break;
case ST_PLL:
runPLL();
break;
case ST_TIMER:
runTimer();
break;
default:
assert(false);
break;
}
}

void VSyncThread::runFree() {
assert(m_vSyncMode == ST_FREE);
while (m_bDoRendering) {
// for benchmark only!

// renders the waveform, Possible delayed due to anti tearing
emit vsyncRender();
m_semaVsyncSlot.acquire();

// renders the waveform, Possible delayed due to anti tearing
emit vsyncRender();
m_semaVsyncSlot.acquire();
emit vsyncSwap(); // swaps the new waveform to front
m_semaVsyncSlot.acquire();

m_sinceLastSwap = m_timer.restart();
m_waitToSwapMicros = 1000;
usleep(1000);
}
}

emit vsyncSwap(); // swaps the new waveform to front
m_semaVsyncSlot.acquire();
void VSyncThread::runPLL() {
assert(m_vSyncMode == ST_PLL);
qint64 offset = 0;
qint64 nextSwapMicros = 0;
while (m_bDoRendering) {
// Use a phase-locked-loop on the QOpenGLWindow::frameSwapped signal
// to determine when the vsync occurs

m_sinceLastSwap = m_timer.restart();
m_waitToSwapMicros = 1000;
usleep(1000);
qint64 pllPhaseOut;
qint64 pllDeltaOut;
qint64 now;

{
std::scoped_lock lock(m_pllMutex);
// last estimated vsync
pllPhaseOut = std::llround(m_pllPhaseOut);
// estimated frame interval
pllDeltaOut = std::llround(m_pllDeltaOut);
now = m_pllTimer.elapsed().toIntegerMicros();
}
if (pllPhaseOut > nextSwapMicros) {
nextSwapMicros = pllPhaseOut;
}
if (nextSwapMicros == pllPhaseOut) {
nextSwapMicros += pllDeltaOut;
}
} else if (m_vSyncMode == ST_PLL) {
qint64 offset = 0;
qint64 nextSwapMicros = 0;
while (m_bDoRendering) {
// Use a phase-locked-loop on the QOpenGLWindow::frameSwapped signal
// to determine when the vsync occurs

qint64 pllPhaseOut;
qint64 pllDeltaOut;
qint64 now;

{
std::scoped_lock lock(m_pllMutex);
// last estimated vsync
pllPhaseOut = std::llround(m_pllPhaseOut);
// estimated frame interval
pllDeltaOut = std::llround(m_pllDeltaOut);
now = m_pllTimer.elapsed().toIntegerMicros();
}
if (pllPhaseOut > nextSwapMicros) {
nextSwapMicros = pllPhaseOut;
}
if (nextSwapMicros == pllPhaseOut) {
nextSwapMicros += pllDeltaOut;
}

// sleep an integer number of frames extra to approximate the
// selected framerate (eg 10,15,20,30)
const auto skippedFrames = (m_syncIntervalTimeMicros - pllDeltaOut / 2) / pllDeltaOut;
qint64 sleepForSkippedFrames = skippedFrames * pllDeltaOut;
// sleep an integer number of frames extra to approximate the
// selected framerate (eg 10,15,20,30)
const auto skippedFrames = (m_syncIntervalTimeMicros - pllDeltaOut / 2) / pllDeltaOut;
qint64 sleepForSkippedFrames = skippedFrames * pllDeltaOut;

qint64 sleepUntilSwap = (nextSwapMicros + offset - now) % pllDeltaOut;
if (sleepUntilSwap < 0) {
sleepUntilSwap += pllDeltaOut;
}
usleep(sleepUntilSwap + sleepForSkippedFrames);

m_sinceLastSwap = m_timer.restart();
m_waitToSwapMicros = pllDeltaOut + sleepForSkippedFrames;

// Signal to swap the gl widgets (waveforms, spinnies, vumeters)
// and render them for the next swap
emit vsyncSwapAndRender();
m_semaVsyncSlot.acquire();
if (m_sinceLastSwap.toIntegerMicros() > sleepForSkippedFrames + pllDeltaOut * 3 / 2) {
m_droppedFrames++;
// Adjusting the offset on each frame drop ends up at
// an offset with no frame drops
offset = (offset + 2000) % pllDeltaOut;
}
qint64 sleepUntilSwap = (nextSwapMicros + offset - now) % pllDeltaOut;
if (sleepUntilSwap < 0) {
sleepUntilSwap += pllDeltaOut;
}
} else { // if (m_vSyncMode == ST_TIMER) {
while (m_bDoRendering) {
emit vsyncRender(); // renders the new waveform.

// wait until rendering was scheduled. It might be delayed due a
// pending swap (depends one driver vSync settings)
m_semaVsyncSlot.acquire();

// qDebug() << "ST_TIMER " << lastMicros << restMicros;
int remainingForSwap = m_waitToSwapMicros -
static_cast<int>(m_timer.elapsed().toIntegerMicros());
// waiting for interval by sleep
if (remainingForSwap > 100) {
usleep(remainingForSwap);
}
usleep(sleepUntilSwap + sleepForSkippedFrames);

m_sinceLastSwap = m_timer.restart();
m_waitToSwapMicros = pllDeltaOut + sleepForSkippedFrames;

// Signal to swap the gl widgets (waveforms, spinnies, vumeters)
// and render them for the next swap
emit vsyncSwapAndRender();
m_semaVsyncSlot.acquire();
if (m_sinceLastSwap.toIntegerMicros() > sleepForSkippedFrames + pllDeltaOut * 3 / 2) {
m_droppedFrames++;
// Adjusting the offset on each frame drop ends up at
// an offset with no frame drops
offset = (offset + 2000) % pllDeltaOut;
}
}
}

// swaps the new waveform to front in case of gl-wf
emit vsyncSwap();
void VSyncThread::runTimer() {
assert(m_vSyncMode == ST_TIMER);

// wait until swap occurred. It might be delayed due to driver vSync
// settings.
m_semaVsyncSlot.acquire();
while (m_bDoRendering) {
emit vsyncRender(); // renders the new waveform.

// <- Assume we are VSynced here ->
m_sinceLastSwap = m_timer.restart();
int lastSwapTime = static_cast<int>(m_sinceLastSwap.toIntegerMicros());
if (remainingForSwap < 0) {
// Our swapping call was already delayed
// The real swap might happens on the following VSync, depending on driver settings
m_droppedFrames++; // Count as Real Time Error
}
// try to stay in right intervals
m_waitToSwapMicros = m_syncIntervalTimeMicros +
((m_waitToSwapMicros - lastSwapTime) % m_syncIntervalTimeMicros);
// wait until rendering was scheduled. It might be delayed due a
// pending swap (depends one driver vSync settings)
m_semaVsyncSlot.acquire();

// qDebug() << "ST_TIMER " << lastMicros << restMicros;
int remainingForSwap = m_waitToSwapMicros -
static_cast<int>(m_timer.elapsed().toIntegerMicros());
// waiting for interval by sleep
if (remainingForSwap > 100) {
usleep(remainingForSwap);
}

// swaps the new waveform to front in case of gl-wf
emit vsyncSwap();

// wait until swap occurred. It might be delayed due to driver vSync
// settings.
m_semaVsyncSlot.acquire();

// <- Assume we are VSynced here ->
m_sinceLastSwap = m_timer.restart();
int lastSwapTime = static_cast<int>(m_sinceLastSwap.toIntegerMicros());
if (remainingForSwap < 0) {
// Our swapping call was already delayed
// The real swap might happens on the following VSync, depending on driver settings
m_droppedFrames++; // Count as Real Time Error
}
// try to stay in right intervals
m_waitToSwapMicros = m_syncIntervalTimeMicros +
((m_waitToSwapMicros - lastSwapTime) % m_syncIntervalTimeMicros);
}
}

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4 changes: 4 additions & 0 deletions src/waveform/vsyncthread.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,10 @@ class VSyncThread : public QThread {
void vsyncSwap();

private:
void runFree();
void runPLL();
void runTimer();

bool m_bDoRendering;
bool m_vSyncTypeChanged;
int m_syncIntervalTimeMicros;
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