Refactor frame synchronization

src/gba/gba-thread.c

@@ -28,6 +28,7 @@ static void* _GBAThreadRun(void* context) {
 
 	GBAInit(&gba);
 	threadContext->gba = &gba;
+	gba.sync = &threadContext->sync;
 	pthread_setspecific(contextKey, threadContext);
 	if (threadContext->renderer) {
 		GBAVideoAssociateRenderer(&gba.video, threadContext->renderer);
@@ -65,9 +66,9 @@ static void* _GBAThreadRun(void* context) {
 	gba.keySource = &threadContext->activeKeys;
 
 	threadContext->started = 1;
-	pthread_mutex_lock(&threadContext->mutex);
+	pthread_mutex_lock(&threadContext->startMutex);
-	pthread_cond_broadcast(&threadContext->cond);
+	pthread_cond_broadcast(&threadContext->startCond);
-	pthread_mutex_unlock(&threadContext->mutex);
+	pthread_mutex_unlock(&threadContext->startMutex);
 
 	if (threadContext->useDebugger) {
 		ARMDebuggerRun(&debugger);
@@ -85,32 +86,80 @@ static void* _GBAThreadRun(void* context) {
 
 int GBAThreadStart(struct GBAThread* threadContext) {
 	// TODO: error check
-	{
+	pthread_mutex_init(&threadContext->startMutex, 0);
-		pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+	pthread_cond_init(&threadContext->startCond, 0);
-		threadContext->mutex = mutex;
-		pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
-		threadContext->cond = cond;
-	}
-	pthread_mutex_init(&threadContext->mutex, 0);
-	pthread_cond_init(&threadContext->cond, 0);
 
-	pthread_mutex_lock(&threadContext->mutex);
+	pthread_mutex_init(&threadContext->sync.videoFrameMutex, 0);
+	pthread_cond_init(&threadContext->sync.videoFrameAvailableCond, 0);
+	pthread_cond_init(&threadContext->sync.videoFrameRequiredCond, 0);
+
+	pthread_mutex_lock(&threadContext->startMutex);
 	threadContext->activeKeys = 0;
 	threadContext->started = 0;
 	pthread_create(&threadContext->thread, 0, _GBAThreadRun, threadContext);
-	pthread_cond_wait(&threadContext->cond, &threadContext->mutex);
+	pthread_cond_wait(&threadContext->startCond, &threadContext->startMutex);
-	pthread_mutex_unlock(&threadContext->mutex);
+	pthread_mutex_unlock(&threadContext->startMutex);
 
 	return 0;
 }
 
 void GBAThreadJoin(struct GBAThread* threadContext) {
+	pthread_mutex_lock(&threadContext->sync.videoFrameMutex);
+	threadContext->sync.videoFrameWait = 0;
+	pthread_cond_broadcast(&threadContext->sync.videoFrameRequiredCond);
+	pthread_mutex_unlock(&threadContext->sync.videoFrameMutex);
+
 	pthread_join(threadContext->thread, 0);
 
-	pthread_mutex_destroy(&threadContext->mutex);
+	pthread_mutex_destroy(&threadContext->startMutex);
-	pthread_cond_destroy(&threadContext->cond);
+	pthread_cond_destroy(&threadContext->startCond);
+
+	pthread_mutex_destroy(&threadContext->sync.videoFrameMutex);
+	pthread_cond_broadcast(&threadContext->sync.videoFrameAvailableCond);
+	pthread_cond_destroy(&threadContext->sync.videoFrameAvailableCond);
+	pthread_cond_broadcast(&threadContext->sync.videoFrameRequiredCond);
+	pthread_cond_destroy(&threadContext->sync.videoFrameRequiredCond);
 }
 
 struct GBAThread* GBAThreadGetContext(void) {
 	return pthread_getspecific(contextKey);
 }
+
+void GBASyncPostFrame(struct GBASync* sync) {
+	if (!sync) {
+		return;
+	}
+
+	pthread_mutex_lock(&sync->videoFrameMutex);
+	++sync->videoFramePending;
+	--sync->videoFrameSkip;
+	pthread_cond_broadcast(&sync->videoFrameAvailableCond);
+	if (sync->videoFrameWait) {
+		pthread_cond_wait(&sync->videoFrameRequiredCond, &sync->videoFrameMutex);
+	}
+	pthread_mutex_unlock(&sync->videoFrameMutex);
+}
+
+void GBASyncWaitFrameStart(struct GBASync* sync, int frameskip) {
+	if (!sync) {
+		return;
+	}
+
+	pthread_mutex_lock(&sync->videoFrameMutex);
+	pthread_cond_broadcast(&sync->videoFrameRequiredCond);
+	pthread_cond_wait(&sync->videoFrameAvailableCond, &sync->videoFrameMutex);
+	sync->videoFramePending = 0;
+	sync->videoFrameSkip = frameskip;
+}
+
+void GBASyncWaitFrameEnd(struct GBASync* sync) {
+	if (!sync) {
+		return;
+	}
+
+	pthread_mutex_unlock(&sync->videoFrameMutex);
+}
+
+int GBASyncDrawingFrame(struct GBASync* sync) {
+	return sync->videoFrameSkip <= 0;
+}

src/gba/gba-thread.h

@@ -15,15 +15,31 @@ struct GBAThread {
 	int fd;
 	const char* fname;
 	int activeKeys;
+	int frameskip;
 
 	// Threading state
-	pthread_mutex_t mutex;
-	pthread_cond_t cond;
 	pthread_t thread;
+
+	pthread_mutex_t startMutex;
+	pthread_cond_t startCond;
+
+	struct GBASync {
+		int videoFramePending;
+		int videoFrameWait;
+		int videoFrameSkip;
+		pthread_mutex_t videoFrameMutex;
+		pthread_cond_t videoFrameAvailableCond;
+		pthread_cond_t videoFrameRequiredCond;
+	} sync;
 };
 
 int GBAThreadStart(struct GBAThread* threadContext);
 void GBAThreadJoin(struct GBAThread* threadContext);
 struct GBAThread* GBAThreadGetContext(void);
 
+void GBASyncPostFrame(struct GBASync* sync);
+void GBASyncWaitFrameStart(struct GBASync* sync, int frameskip);
+void GBASyncWaitFrameEnd(struct GBASync* sync);
+int GBASyncDrawingFrame(struct GBASync* sync);
+
 #endif

src/gba/gba-video.c

@@ -2,6 +2,7 @@
 
 #include "gba.h"
 #include "gba-io.h"
+#include "gba-thread.h"
 
 #include <limits.h>
 #include <string.h>
@@ -79,13 +80,15 @@ int32_t GBAVideoProcessEvents(struct GBAVideo* video, int32_t cycles) {
 			switch (video->vcount) {
 			case VIDEO_VERTICAL_PIXELS:
 				video->inVblank = 1;
-				video->renderer->finishFrame(video->renderer);
+				if (GBASyncDrawingFrame(video->p->sync)) {
+					video->renderer->finishFrame(video->renderer);
+				}
 				video->nextVblankIRQ = video->nextEvent + VIDEO_TOTAL_LENGTH;
 				GBAMemoryRunVblankDMAs(&video->p->memory);
 				if (video->vblankIRQ) {
 					GBARaiseIRQ(video->p, IRQ_VBLANK);
 				}
-				//video->vblankCallback();
+				GBASyncPostFrame(video->p->sync);
 				break;
 			case VIDEO_VERTICAL_TOTAL_PIXELS - 1:
 				video->inVblank = 0;
@@ -102,7 +105,7 @@ int32_t GBAVideoProcessEvents(struct GBAVideo* video, int32_t cycles) {
 				video->nextVcounterIRQ += VIDEO_TOTAL_LENGTH;
 			}
 
-			if (video->vcount < VIDEO_VERTICAL_PIXELS) {
+			if (video->vcount < VIDEO_VERTICAL_PIXELS && GBASyncDrawingFrame(video->p->sync)) {
 				video->renderer->drawScanline(video->renderer, video->vcount);
 			}
 		} else {

src/gba/gba-video.h

@@ -168,10 +168,6 @@ struct GBAVideoRenderer {
 	uint16_t* palette;
 	uint16_t* vram;
 	union GBAOAM* oam;
-
-	int framesPending;
-	int frameskip;
-	int turbo;
 };
 
 struct GBAVideo {

src/gba/gba.h

@@ -66,6 +66,8 @@ struct GBA {
 	struct GBAVideo video;
 	struct GBAAudio audio;
 
+	struct GBASync* sync;
+
 	struct ARMDebugger* debugger;
 
 	int timersEnabled;

src/gba/renderers/video-software.c

@@ -48,18 +48,6 @@ void GBAVideoSoftwareRendererCreate(struct GBAVideoSoftwareRenderer* renderer) {
 	renderer->d.writePalette = GBAVideoSoftwareRendererWritePalette;
 	renderer->d.drawScanline = GBAVideoSoftwareRendererDrawScanline;
 	renderer->d.finishFrame = GBAVideoSoftwareRendererFinishFrame;
-
-	renderer->d.turbo = 0;
-	renderer->d.framesPending = 0;
-	renderer->d.frameskip = 0;
-
-	{
-		pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
-		renderer->mutex = mutex;
-		pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
-		renderer->upCond = cond;
-		renderer->downCond = cond;
-	}
 }
 
 static void GBAVideoSoftwareRendererInit(struct GBAVideoRenderer* renderer) {
@@ -110,22 +98,10 @@ static void GBAVideoSoftwareRendererInit(struct GBAVideoRenderer* renderer) {
 		bg->sx = 0;
 		bg->sy = 0;
 	}
-
-	pthread_mutex_init(&softwareRenderer->mutex, 0);
-	pthread_cond_init(&softwareRenderer->upCond, 0);
-	pthread_cond_init(&softwareRenderer->downCond, 0);
 }
 
 static void GBAVideoSoftwareRendererDeinit(struct GBAVideoRenderer* renderer) {
 	struct GBAVideoSoftwareRenderer* softwareRenderer = (struct GBAVideoSoftwareRenderer*) renderer;
-
-	pthread_mutex_lock(&softwareRenderer->mutex);
-	pthread_cond_broadcast(&softwareRenderer->upCond);
-	pthread_mutex_unlock(&softwareRenderer->mutex);
-
-	pthread_mutex_destroy(&softwareRenderer->mutex);
-	pthread_cond_destroy(&softwareRenderer->upCond);
-	pthread_cond_destroy(&softwareRenderer->downCond);
 }
 
 static uint16_t GBAVideoSoftwareRendererWriteVideoRegister(struct GBAVideoRenderer* renderer, uint32_t address, uint16_t value) {
@@ -362,9 +338,7 @@ static void GBAVideoSoftwareRendererWritePalette(struct GBAVideoRenderer* render
 
 static void GBAVideoSoftwareRendererDrawScanline(struct GBAVideoRenderer* renderer, int y) {
 	struct GBAVideoSoftwareRenderer* softwareRenderer = (struct GBAVideoSoftwareRenderer*) renderer;
-	if (renderer->frameskip > 0) {
+
-		return;
-	}
 	color_t* row = &softwareRenderer->outputBuffer[softwareRenderer->outputBufferStride * y];
 	if (softwareRenderer->dispcnt.forcedBlank) {
 		int x;
@@ -437,18 +411,6 @@ static void GBAVideoSoftwareRendererDrawScanline(struct GBAVideoRenderer* render
 static void GBAVideoSoftwareRendererFinishFrame(struct GBAVideoRenderer* renderer) {
 	struct GBAVideoSoftwareRenderer* softwareRenderer = (struct GBAVideoSoftwareRenderer*) renderer;
 
-	pthread_mutex_lock(&softwareRenderer->mutex);
-	if (renderer->frameskip > 0) {
-		--renderer->frameskip;
-	} else {
-		renderer->framesPending++;
-		pthread_cond_broadcast(&softwareRenderer->upCond);
-		if (!renderer->turbo) {
-			pthread_cond_wait(&softwareRenderer->downCond, &softwareRenderer->mutex);
-		}
-	}
-	pthread_mutex_unlock(&softwareRenderer->mutex);
-
 	softwareRenderer->bg[2].sx = softwareRenderer->bg[2].refx;
 	softwareRenderer->bg[2].sy = softwareRenderer->bg[2].refy;
 	softwareRenderer->bg[3].sx = softwareRenderer->bg[3].refx;

src/gba/renderers/video-software.h

@@ -135,10 +135,6 @@ struct GBAVideoSoftwareRenderer {
 	int end;
 
 	uint32_t enabledBitmap[4];
-
-	pthread_mutex_t mutex;
-	pthread_cond_t upCond;
-	pthread_cond_t downCond;
 };
 
 void GBAVideoSoftwareRendererCreate(struct GBAVideoSoftwareRenderer* renderer);

src/gl-main.c

@@ -71,6 +71,7 @@ int main(int argc, char** argv) {
 	context.fname = fname;
 	context.useDebugger = 1;
 	context.renderer = &renderer.d.d;
+	context.frameskip = 0;
 	GBAThreadStart(&context);
 	renderer.audio.audio = &context.gba->audio;
 
@@ -130,30 +131,21 @@ static void _GBASDLRunloop(struct GBAThread* context, struct GLSoftwareRenderer*
 	glLoadIdentity();
 	glOrtho(0, 240, 160, 0, 0, 1);
 	while (context->started && (!context->debugger || context->debugger->state != DEBUGGER_EXITING)) {
-		pthread_mutex_lock(&renderer->d.mutex);
+		GBASyncWaitFrameStart(&context->sync, context->frameskip);
-		if (renderer->d.d.framesPending) {
+		glBindTexture(GL_TEXTURE_2D, renderer->tex);
-			renderer->d.d.framesPending = 0;
-			pthread_mutex_unlock(&renderer->d.mutex);
-			glBindTexture(GL_TEXTURE_2D, renderer->tex);
 #ifdef COLOR_16_BIT
-			glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, renderer->d.outputBuffer);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, renderer->d.outputBuffer);
 #else
-			glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0, GL_RGBA, GL_UNSIGNED_BYTE, renderer->d.outputBuffer);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0, GL_RGBA, GL_UNSIGNED_BYTE, renderer->d.outputBuffer);
 #endif
-			glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+		glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 
-			SDL_GL_SwapBuffers();
+		SDL_GL_SwapBuffers();
 
-			while (SDL_PollEvent(&event)) {
+		while (SDL_PollEvent(&event)) {
-				GBASDLHandleEvent(context, &event);
+			GBASDLHandleEvent(context, &event);
-			}
-			pthread_mutex_lock(&renderer->d.mutex);
-			pthread_cond_broadcast(&renderer->d.downCond);
-		} else {
-			pthread_cond_broadcast(&renderer->d.downCond);
-			pthread_cond_wait(&renderer->d.upCond, &renderer->d.mutex);
 		}
-		pthread_mutex_unlock(&renderer->d.mutex);
+		GBASyncWaitFrameEnd(&context->sync);
 	}
 }
 

src/sdl/sdl-events.c

@@ -52,7 +52,7 @@ static void _GBASDLHandleKeypress(struct GBAThread* context, const struct SDL_Ke
 		key = GBA_KEY_RIGHT;
 		break;
 	case SDLK_TAB:
-		context->renderer->turbo = !context->renderer->turbo;
+		context->sync.videoFrameWait = !context->sync.videoFrameWait;
 		return;
 	default:
 		return;