Core: Fix audio sync breaking when interrupted

CHANGES

@@ -34,6 +34,7 @@ Bugfixes:
  - GBA Savedata: Fix savedata modified time updating when read-only
  - GB Video: Fix enabling window when LY > WY (fixes mgba.io/i/409)
  - GBA Video: Start timing mid-scanline when skipping BIOS
+ - Core: Fix audio sync breaking when interrupted
 Misc:
  - GBA Timer: Use global cycles for timers
  - GBA: Extend oddly-sized ROMs to full address space (fixes mgba.io/i/722)

include/mgba/core/sync.h

@@ -33,7 +33,8 @@ bool mCoreSyncWaitFrameStart(struct mCoreSync* sync);
 void mCoreSyncWaitFrameEnd(struct mCoreSync* sync);
 void mCoreSyncSetVideoSync(struct mCoreSync* sync, bool wait);
 
-void mCoreSyncProduceAudio(struct mCoreSync* sync, bool wait);
+struct blip_t;
+bool mCoreSyncProduceAudio(struct mCoreSync* sync, const struct blip_t*, size_t samples);
 void mCoreSyncLockAudio(struct mCoreSync* sync);
 void mCoreSyncUnlockAudio(struct mCoreSync* sync);
 void mCoreSyncConsumeAudio(struct mCoreSync* sync);

src/core/sync.c

@@ -5,6 +5,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include <mgba/core/sync.h>
 
+#include <mgba/core/blip_buf.h>
+
 static void _changeVideoSync(struct mCoreSync* sync, bool frameOn) {
 	// Make sure the video thread can process events while the GBA thread is paused
 	MutexLock(&sync->videoFrameMutex);
@@ -76,16 +78,20 @@ void mCoreSyncSetVideoSync(struct mCoreSync* sync, bool wait) {
 	_changeVideoSync(sync, wait);
 }
 
-void mCoreSyncProduceAudio(struct mCoreSync* sync, bool wait) {
+bool mCoreSyncProduceAudio(struct mCoreSync* sync, const struct blip_t* buf, size_t samples) {
 	if (!sync) {
-		return;
+		return true;
 	}
 
-	if (sync->audioWait && wait) {
-		// TODO loop properly in event of spurious wakeups
+	size_t produced = blip_samples_avail(buf);
+	size_t producedNew = produced;
+	while (sync->audioWait && producedNew >= samples) {
 		ConditionWait(&sync->audioRequiredCond, &sync->audioBufferMutex);
+		produced = producedNew;
+		producedNew = blip_samples_avail(buf);
 	}
 	MutexUnlock(&sync->audioBufferMutex);
+	return producedNew != produced;
 }
 
 void mCoreSyncLockAudio(struct mCoreSync* sync) {

src/core/thread.c

@@ -5,6 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include <mgba/core/thread.h>
 
+#include <mgba/core/blip_buf.h>
 #include <mgba/core/core.h>
 #include <mgba/core/serialize.h>
 #include <mgba-util/patch.h>
@@ -219,6 +220,11 @@ static THREAD_ENTRY _mCoreThreadRun(void* context) {
 			deferred = impl->state;
 			while (impl->state >= THREAD_WAITING && impl->state <= THREAD_MAX_WAITING) {
 				ConditionWait(&impl->stateCond, &impl->stateMutex);
+
+				if (impl->sync.audioWait) {
+					mCoreSyncLockAudio(&impl->sync);
+					mCoreSyncProduceAudio(&impl->sync, core->getAudioChannel(core, 0), core->getAudioBufferSize(core));
+				}
 			}
 		}
 		MutexUnlock(&impl->stateMutex);

src/gb/audio.c

@@ -667,7 +667,10 @@ static void _sample(struct mTiming* timing, void* user, uint32_t cyclesLate) {
 		audio->p->stream->postAudioFrame(audio->p->stream, sampleLeft, sampleRight);
 	}
 	bool wait = produced >= audio->samples;
-	mCoreSyncProduceAudio(audio->p->sync, wait);
+	if (!mCoreSyncProduceAudio(audio->p->sync, audio->left, audio->samples)) {
+		// Interrupted
+		audio->p->earlyExit = true;
+	}
 
 	if (wait && audio->p->stream && audio->p->stream->postAudioBuffer) {
 		audio->p->stream->postAudioBuffer(audio->p->stream, audio->left, audio->right);

src/gba/audio.c

@@ -307,7 +307,10 @@ static void _sample(struct mTiming* timing, void* user, uint32_t cyclesLate) {
 		audio->p->stream->postAudioFrame(audio->p->stream, sampleLeft, sampleRight);
 	}
 	bool wait = produced >= audio->samples;
-	mCoreSyncProduceAudio(audio->p->sync, wait);
+	if (!mCoreSyncProduceAudio(audio->p->sync, audio->psg.left, audio->samples)) {
+		// Interrupted
+		audio->p->earlyExit = true;
+	}
 
 	if (wait && audio->p->stream && audio->p->stream->postAudioBuffer) {
 		audio->p->stream->postAudioBuffer(audio->p->stream, audio->psg.left, audio->psg.right);