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mGBA Game Boy Advance Emulator

src/gba/gba-thread.c (view raw)

  1/* Copyright (c) 2013-2014 Jeffrey Pfau
  2 *
  3 * This Source Code Form is subject to the terms of the Mozilla Public
  4 * License, v. 2.0. If a copy of the MPL was not distributed with this
  5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  6#include "gba-thread.h"
  7
  8#include "arm.h"
  9#include "gba.h"
 10#include "gba-config.h"
 11#include "gba-overrides.h"
 12#include "gba-serialize.h"
 13
 14#include "debugger/debugger.h"
 15
 16#include "util/patch.h"
 17#include "util/png-io.h"
 18#include "util/vfs.h"
 19
 20#include "platform/commandline.h"
 21
 22#include <signal.h>
 23
 24static const float _defaultFPSTarget = 60.f;
 25
 26#ifdef USE_PTHREADS
 27static pthread_key_t _contextKey;
 28static pthread_once_t _contextOnce = PTHREAD_ONCE_INIT;
 29
 30static void _createTLS(void) {
 31	pthread_key_create(&_contextKey, 0);
 32}
 33#elif _WIN32
 34static DWORD _contextKey;
 35static INIT_ONCE _contextOnce = INIT_ONCE_STATIC_INIT;
 36
 37static BOOL CALLBACK _createTLS(PINIT_ONCE once, PVOID param, PVOID* context) {
 38	UNUSED(once);
 39	UNUSED(param);
 40	UNUSED(context);
 41	_contextKey = TlsAlloc();
 42	return TRUE;
 43}
 44#endif
 45
 46#ifndef DISABLE_THREADING
 47static void _changeState(struct GBAThread* threadContext, enum ThreadState newState, bool broadcast) {
 48	MutexLock(&threadContext->stateMutex);
 49	threadContext->state = newState;
 50	if (broadcast) {
 51		ConditionWake(&threadContext->stateCond);
 52	}
 53	MutexUnlock(&threadContext->stateMutex);
 54}
 55
 56static void _waitOnInterrupt(struct GBAThread* threadContext) {
 57	while (threadContext->state == THREAD_INTERRUPTED) {
 58		ConditionWait(&threadContext->stateCond, &threadContext->stateMutex);
 59	}
 60}
 61
 62static void _waitUntilNotState(struct GBAThread* threadContext, enum ThreadState oldState) {
 63	while (threadContext->state == oldState) {
 64		MutexUnlock(&threadContext->stateMutex);
 65
 66		MutexLock(&threadContext->sync.videoFrameMutex);
 67		ConditionWake(&threadContext->sync.videoFrameRequiredCond);
 68		MutexUnlock(&threadContext->sync.videoFrameMutex);
 69
 70		MutexLock(&threadContext->sync.audioBufferMutex);
 71		ConditionWake(&threadContext->sync.audioRequiredCond);
 72		MutexUnlock(&threadContext->sync.audioBufferMutex);
 73
 74		MutexLock(&threadContext->stateMutex);
 75		ConditionWake(&threadContext->stateCond);
 76	}
 77}
 78
 79static void _pauseThread(struct GBAThread* threadContext, bool onThread) {
 80	if (threadContext->debugger && threadContext->debugger->state == DEBUGGER_RUNNING) {
 81		threadContext->debugger->state = DEBUGGER_EXITING;
 82	}
 83	threadContext->state = THREAD_PAUSING;
 84	if (!onThread) {
 85		_waitUntilNotState(threadContext, THREAD_PAUSING);
 86	}
 87}
 88#endif
 89
 90static void _changeVideoSync(struct GBASync* sync, bool frameOn) {
 91	// Make sure the video thread can process events while the GBA thread is paused
 92	MutexLock(&sync->videoFrameMutex);
 93	if (frameOn != sync->videoFrameOn) {
 94		sync->videoFrameOn = frameOn;
 95		ConditionWake(&sync->videoFrameAvailableCond);
 96	}
 97	MutexUnlock(&sync->videoFrameMutex);
 98}
 99
100#ifndef DISABLE_THREADING
101static THREAD_ENTRY _GBAThreadRun(void* context) {
102#ifdef USE_PTHREADS
103	pthread_once(&_contextOnce, _createTLS);
104#else
105	InitOnceExecuteOnce(&_contextOnce, _createTLS, NULL, 0);
106#endif
107
108	struct GBA gba;
109	struct ARMCore cpu;
110	struct Patch patch;
111	struct GBAThread* threadContext = context;
112	struct ARMComponent* components[GBA_COMPONENT_MAX] = {};
113	int numComponents = GBA_COMPONENT_MAX;
114
115#if !defined(_WIN32) && defined(USE_PTHREADS)
116	sigset_t signals;
117	sigemptyset(&signals);
118	pthread_sigmask(SIG_SETMASK, &signals, 0);
119#endif
120
121	GBACreate(&gba);
122	ARMSetComponents(&cpu, &gba.d, numComponents, components);
123	ARMInit(&cpu);
124	gba.sync = &threadContext->sync;
125	threadContext->gba = &gba;
126	gba.logLevel = threadContext->logLevel;
127#ifdef USE_PTHREADS
128	pthread_setspecific(_contextKey, threadContext);
129#else
130	TlsSetValue(_contextKey, threadContext);
131#endif
132
133	if (threadContext->audioBuffers) {
134		GBAAudioResizeBuffer(&gba.audio, threadContext->audioBuffers);
135	} else {
136		threadContext->audioBuffers = GBA_AUDIO_SAMPLES;
137	}
138
139	if (threadContext->renderer) {
140		GBAVideoAssociateRenderer(&gba.video, threadContext->renderer);
141	}
142
143	if (threadContext->rom) {
144		GBALoadROM(&gba, threadContext->rom, threadContext->save, threadContext->fname);
145
146		struct GBACartridgeOverride override;
147		const struct GBACartridge* cart = (const struct GBACartridge*) gba.memory.rom;
148		memcpy(override.id, &cart->id, sizeof(override.id));
149		if (GBAOverrideFind(threadContext->overrides, &override)) {
150			GBAOverrideApply(&gba, &override);
151		}
152
153		if (threadContext->bios && GBAIsBIOS(threadContext->bios)) {
154			GBALoadBIOS(&gba, threadContext->bios);
155		}
156
157		if (threadContext->patch && loadPatch(threadContext->patch, &patch)) {
158			GBAApplyPatch(&gba, &patch);
159		}
160	}
161
162	ARMReset(&cpu);
163	if (threadContext->skipBios) {
164		GBASkipBIOS(&cpu);
165	}
166
167	if (threadContext->debugger) {
168		threadContext->debugger->log = GBADebuggerLogShim;
169		GBAAttachDebugger(&gba, threadContext->debugger);
170		ARMDebuggerEnter(threadContext->debugger, DEBUGGER_ENTER_ATTACHED);
171	}
172
173	GBASIOSetDriverSet(&gba.sio, &threadContext->sioDrivers);
174
175	gba.keySource = &threadContext->activeKeys;
176
177	if (threadContext->startCallback) {
178		threadContext->startCallback(threadContext);
179	}
180
181	_changeState(threadContext, THREAD_RUNNING, true);
182
183	while (threadContext->state < THREAD_EXITING) {
184		if (threadContext->debugger) {
185			struct ARMDebugger* debugger = threadContext->debugger;
186			ARMDebuggerRun(debugger);
187			if (debugger->state == DEBUGGER_SHUTDOWN) {
188				_changeState(threadContext, THREAD_EXITING, false);
189			}
190		} else {
191			while (threadContext->state == THREAD_RUNNING) {
192				ARMRunLoop(&cpu);
193			}
194		}
195
196		int resetScheduled = 0;
197		MutexLock(&threadContext->stateMutex);
198		while (threadContext->state > THREAD_RUNNING && threadContext->state < THREAD_EXITING) {
199			if (threadContext->state == THREAD_PAUSING) {
200				threadContext->state = THREAD_PAUSED;
201				ConditionWake(&threadContext->stateCond);
202			}
203			if (threadContext->state == THREAD_INTERRUPTING) {
204				threadContext->state = THREAD_INTERRUPTED;
205				ConditionWake(&threadContext->stateCond);
206			}
207			if (threadContext->state == THREAD_RESETING) {
208				threadContext->state = THREAD_RUNNING;
209				resetScheduled = 1;
210			}
211			while (threadContext->state == THREAD_PAUSED || threadContext->state == THREAD_INTERRUPTED) {
212				ConditionWait(&threadContext->stateCond, &threadContext->stateMutex);
213			}
214		}
215		MutexUnlock(&threadContext->stateMutex);
216		if (resetScheduled) {
217			ARMReset(&cpu);
218			if (threadContext->skipBios) {
219				GBASkipBIOS(&cpu);
220			}
221		}
222	}
223
224	while (threadContext->state < THREAD_SHUTDOWN) {
225		_changeState(threadContext, THREAD_SHUTDOWN, false);
226	}
227
228	if (threadContext->cleanCallback) {
229		threadContext->cleanCallback(threadContext);
230	}
231
232	threadContext->gba = 0;
233	ARMDeinit(&cpu);
234	GBADestroy(&gba);
235
236	threadContext->sync.videoFrameOn = false;
237	ConditionWake(&threadContext->sync.videoFrameAvailableCond);
238	ConditionWake(&threadContext->sync.audioRequiredCond);
239
240	return 0;
241}
242
243void GBAMapOptionsToContext(const struct GBAOptions* opts, struct GBAThread* threadContext) {
244	threadContext->bios = VFileOpen(opts->bios, O_RDONLY);
245	threadContext->frameskip = opts->frameskip;
246	threadContext->logLevel = opts->logLevel;
247	if (opts->rewindEnable) {
248		threadContext->rewindBufferCapacity = opts->rewindBufferCapacity;
249		threadContext->rewindBufferInterval = opts->rewindBufferInterval;
250	} else {
251		threadContext->rewindBufferCapacity = 0;
252	}
253	threadContext->skipBios = opts->skipBios;
254	threadContext->sync.audioWait = opts->audioSync;
255	threadContext->sync.videoFrameWait = opts->videoSync;
256
257	if (opts->fpsTarget) {
258		threadContext->fpsTarget = opts->fpsTarget;
259	}
260
261	if (opts->audioBuffers) {
262		threadContext->audioBuffers = opts->audioBuffers;
263	}
264}
265
266void GBAMapArgumentsToContext(const struct GBAArguments* args, struct GBAThread* threadContext) {
267	if (args->dirmode) {
268		threadContext->gameDir = VDirOpen(args->fname);
269		threadContext->stateDir = threadContext->gameDir;
270	} else {
271		threadContext->rom = VFileOpen(args->fname, O_RDONLY);
272#if ENABLE_LIBZIP
273		threadContext->gameDir = VDirOpenZip(args->fname, 0);
274#endif
275	}
276	threadContext->fname = args->fname;
277	threadContext->patch = VFileOpen(args->patch, O_RDONLY);
278}
279
280bool GBAThreadStart(struct GBAThread* threadContext) {
281	// TODO: error check
282	threadContext->activeKeys = 0;
283	threadContext->state = THREAD_INITIALIZED;
284	threadContext->sync.videoFrameOn = true;
285	threadContext->sync.videoFrameSkip = 0;
286
287	threadContext->rewindBuffer = 0;
288	int newCapacity = threadContext->rewindBufferCapacity;
289	int newInterval = threadContext->rewindBufferInterval;
290	threadContext->rewindBufferCapacity = 0;
291	threadContext->rewindBufferInterval = 0;
292	GBARewindSettingsChanged(threadContext, newCapacity, newInterval);
293
294	if (!threadContext->fpsTarget) {
295		threadContext->fpsTarget = _defaultFPSTarget;
296	}
297
298	if (threadContext->rom && !GBAIsROM(threadContext->rom)) {
299		threadContext->rom->close(threadContext->rom);
300		threadContext->rom = 0;
301	}
302
303	if (threadContext->gameDir) {
304		threadContext->gameDir->rewind(threadContext->gameDir);
305		struct VDirEntry* dirent = threadContext->gameDir->listNext(threadContext->gameDir);
306		while (dirent) {
307			struct Patch patchTemp;
308			struct VFile* vf = threadContext->gameDir->openFile(threadContext->gameDir, dirent->name(dirent), O_RDONLY);
309			if (!vf) {
310				continue;
311			}
312			if (!threadContext->rom && GBAIsROM(vf)) {
313				threadContext->rom = vf;
314			} else if (!threadContext->patch && loadPatch(vf, &patchTemp)) {
315				threadContext->patch = vf;
316			} else {
317				vf->close(vf);
318			}
319			dirent = threadContext->gameDir->listNext(threadContext->gameDir);
320		}
321
322	}
323
324	if (!threadContext->rom) {
325		threadContext->state = THREAD_SHUTDOWN;
326		return false;
327	}
328
329	threadContext->save = VDirOptionalOpenFile(threadContext->stateDir, threadContext->fname, "sram", ".sav", O_CREAT | O_RDWR);
330
331	MutexInit(&threadContext->stateMutex);
332	ConditionInit(&threadContext->stateCond);
333
334	MutexInit(&threadContext->sync.videoFrameMutex);
335	ConditionInit(&threadContext->sync.videoFrameAvailableCond);
336	ConditionInit(&threadContext->sync.videoFrameRequiredCond);
337	MutexInit(&threadContext->sync.audioBufferMutex);
338	ConditionInit(&threadContext->sync.audioRequiredCond);
339
340	threadContext->interruptDepth = 0;
341
342#ifndef _WIN32
343	sigset_t signals;
344	sigemptyset(&signals);
345	sigaddset(&signals, SIGINT);
346	sigaddset(&signals, SIGTRAP);
347	pthread_sigmask(SIG_BLOCK, &signals, 0);
348#endif
349
350	MutexLock(&threadContext->stateMutex);
351	ThreadCreate(&threadContext->thread, _GBAThreadRun, threadContext);
352	while (threadContext->state < THREAD_RUNNING) {
353		ConditionWait(&threadContext->stateCond, &threadContext->stateMutex);
354	}
355	MutexUnlock(&threadContext->stateMutex);
356
357	return true;
358}
359
360bool GBAThreadHasStarted(struct GBAThread* threadContext) {
361	bool hasStarted;
362	MutexLock(&threadContext->stateMutex);
363	hasStarted = threadContext->state > THREAD_INITIALIZED;
364	MutexUnlock(&threadContext->stateMutex);
365	return hasStarted;
366}
367
368bool GBAThreadHasExited(struct GBAThread* threadContext) {
369	bool hasExited;
370	MutexLock(&threadContext->stateMutex);
371	hasExited = threadContext->state > THREAD_EXITING;
372	MutexUnlock(&threadContext->stateMutex);
373	return hasExited;
374}
375
376bool GBAThreadHasCrashed(struct GBAThread* threadContext) {
377	bool hasExited;
378	MutexLock(&threadContext->stateMutex);
379	hasExited = threadContext->state == THREAD_CRASHED;
380	MutexUnlock(&threadContext->stateMutex);
381	return hasExited;
382}
383
384void GBAThreadEnd(struct GBAThread* threadContext) {
385	MutexLock(&threadContext->stateMutex);
386	if (threadContext->debugger && threadContext->debugger->state == DEBUGGER_RUNNING) {
387		threadContext->debugger->state = DEBUGGER_EXITING;
388	}
389	threadContext->state = THREAD_EXITING;
390	if (threadContext->gba) {
391		threadContext->gba->cpu->halted = false;
392	}
393	ConditionWake(&threadContext->stateCond);
394	MutexUnlock(&threadContext->stateMutex);
395	MutexLock(&threadContext->sync.audioBufferMutex);
396	threadContext->sync.audioWait = 0;
397	ConditionWake(&threadContext->sync.audioRequiredCond);
398	MutexUnlock(&threadContext->sync.audioBufferMutex);
399
400	MutexLock(&threadContext->sync.videoFrameMutex);
401	threadContext->sync.videoFrameWait = false;
402	threadContext->sync.videoFrameOn = false;
403	ConditionWake(&threadContext->sync.videoFrameRequiredCond);
404	ConditionWake(&threadContext->sync.videoFrameAvailableCond);
405	MutexUnlock(&threadContext->sync.videoFrameMutex);
406}
407
408void GBAThreadReset(struct GBAThread* threadContext) {
409	MutexLock(&threadContext->stateMutex);
410	_waitOnInterrupt(threadContext);
411	threadContext->state = THREAD_RESETING;
412	ConditionWake(&threadContext->stateCond);
413	MutexUnlock(&threadContext->stateMutex);
414}
415
416void GBAThreadJoin(struct GBAThread* threadContext) {
417	ThreadJoin(threadContext->thread);
418
419	MutexDeinit(&threadContext->stateMutex);
420	ConditionDeinit(&threadContext->stateCond);
421
422	MutexDeinit(&threadContext->sync.videoFrameMutex);
423	ConditionWake(&threadContext->sync.videoFrameAvailableCond);
424	ConditionDeinit(&threadContext->sync.videoFrameAvailableCond);
425	ConditionWake(&threadContext->sync.videoFrameRequiredCond);
426	ConditionDeinit(&threadContext->sync.videoFrameRequiredCond);
427
428	ConditionWake(&threadContext->sync.audioRequiredCond);
429	ConditionDeinit(&threadContext->sync.audioRequiredCond);
430	MutexDeinit(&threadContext->sync.audioBufferMutex);
431
432	int i;
433	for (i = 0; i < threadContext->rewindBufferCapacity; ++i) {
434		if (threadContext->rewindBuffer[i]) {
435			GBADeallocateState(threadContext->rewindBuffer[i]);
436		}
437	}
438	free(threadContext->rewindBuffer);
439
440	if (threadContext->rom) {
441		threadContext->rom->close(threadContext->rom);
442		threadContext->rom = 0;
443	}
444
445	if (threadContext->save) {
446		threadContext->save->close(threadContext->save);
447		threadContext->save = 0;
448	}
449
450	if (threadContext->bios) {
451		threadContext->bios->close(threadContext->bios);
452		threadContext->bios = 0;
453	}
454
455	if (threadContext->patch) {
456		threadContext->patch->close(threadContext->patch);
457		threadContext->patch = 0;
458	}
459
460	if (threadContext->gameDir) {
461		if (threadContext->stateDir == threadContext->gameDir) {
462			threadContext->stateDir = 0;
463		}
464		threadContext->gameDir->close(threadContext->gameDir);
465		threadContext->gameDir = 0;
466	}
467
468	if (threadContext->stateDir) {
469		threadContext->stateDir->close(threadContext->stateDir);
470		threadContext->stateDir = 0;
471	}
472}
473
474bool GBAThreadIsActive(struct GBAThread* threadContext) {
475	return threadContext->state >= THREAD_RUNNING && threadContext->state < THREAD_EXITING;
476}
477
478void GBAThreadInterrupt(struct GBAThread* threadContext) {
479	MutexLock(&threadContext->stateMutex);
480	++threadContext->interruptDepth;
481	if (threadContext->interruptDepth > 1 || !GBAThreadIsActive(threadContext)) {
482		MutexUnlock(&threadContext->stateMutex);
483		return;
484	}
485	threadContext->savedState = threadContext->state;
486	_waitOnInterrupt(threadContext);
487	threadContext->state = THREAD_INTERRUPTING;
488	threadContext->gba->cpu->nextEvent = 0;
489	if (threadContext->debugger && threadContext->debugger->state == DEBUGGER_RUNNING) {
490		threadContext->debugger->state = DEBUGGER_EXITING;
491	}
492	ConditionWake(&threadContext->stateCond);
493	_waitUntilNotState(threadContext, THREAD_INTERRUPTING);
494	MutexUnlock(&threadContext->stateMutex);
495}
496
497void GBAThreadContinue(struct GBAThread* threadContext) {
498	MutexLock(&threadContext->stateMutex);
499	--threadContext->interruptDepth;
500	if (threadContext->interruptDepth < 1 && GBAThreadIsActive(threadContext)) {
501		threadContext->state = threadContext->savedState;
502		ConditionWake(&threadContext->stateCond);
503	}
504	MutexUnlock(&threadContext->stateMutex);
505}
506
507void GBAThreadPause(struct GBAThread* threadContext) {
508	bool frameOn = true;
509	MutexLock(&threadContext->stateMutex);
510	_waitOnInterrupt(threadContext);
511	if (threadContext->state == THREAD_RUNNING) {
512		_pauseThread(threadContext, false);
513		frameOn = false;
514	}
515	MutexUnlock(&threadContext->stateMutex);
516
517	_changeVideoSync(&threadContext->sync, frameOn);
518}
519
520void GBAThreadUnpause(struct GBAThread* threadContext) {
521	MutexLock(&threadContext->stateMutex);
522	_waitOnInterrupt(threadContext);
523	if (threadContext->state == THREAD_PAUSED || threadContext->state == THREAD_PAUSING) {
524		threadContext->state = THREAD_RUNNING;
525		ConditionWake(&threadContext->stateCond);
526	}
527	MutexUnlock(&threadContext->stateMutex);
528
529	_changeVideoSync(&threadContext->sync, true);
530}
531
532bool GBAThreadIsPaused(struct GBAThread* threadContext) {
533	bool isPaused;
534	MutexLock(&threadContext->stateMutex);
535	_waitOnInterrupt(threadContext);
536	isPaused = threadContext->state == THREAD_PAUSED;
537	MutexUnlock(&threadContext->stateMutex);
538	return isPaused;
539}
540
541void GBAThreadTogglePause(struct GBAThread* threadContext) {
542	bool frameOn = true;
543	MutexLock(&threadContext->stateMutex);
544	_waitOnInterrupt(threadContext);
545	if (threadContext->state == THREAD_PAUSED || threadContext->state == THREAD_PAUSING) {
546		threadContext->state = THREAD_RUNNING;
547		ConditionWake(&threadContext->stateCond);
548	} else if (threadContext->state == THREAD_RUNNING) {
549		_pauseThread(threadContext, false);
550		frameOn = false;
551	}
552	MutexUnlock(&threadContext->stateMutex);
553
554	_changeVideoSync(&threadContext->sync, frameOn);
555}
556
557void GBAThreadPauseFromThread(struct GBAThread* threadContext) {
558	bool frameOn = true;
559	MutexLock(&threadContext->stateMutex);
560	_waitOnInterrupt(threadContext);
561	if (threadContext->state == THREAD_RUNNING) {
562		_pauseThread(threadContext, true);
563		frameOn = false;
564	}
565	MutexUnlock(&threadContext->stateMutex);
566
567	_changeVideoSync(&threadContext->sync, frameOn);
568}
569
570#ifdef USE_PTHREADS
571struct GBAThread* GBAThreadGetContext(void) {
572	pthread_once(&_contextOnce, _createTLS);
573	return pthread_getspecific(_contextKey);
574}
575#elif _WIN32
576struct GBAThread* GBAThreadGetContext(void) {
577	InitOnceExecuteOnce(&_contextOnce, _createTLS, NULL, 0);
578	return TlsGetValue(_contextKey);
579}
580#endif
581
582#ifdef USE_PNG
583void GBAThreadTakeScreenshot(struct GBAThread* threadContext) {
584	unsigned stride;
585	void* pixels = 0;
586	struct VFile* vf = VDirOptionalOpenIncrementFile(threadContext->stateDir, threadContext->gba->activeFile, "screenshot", "-", ".png", O_CREAT | O_TRUNC | O_WRONLY);
587	threadContext->gba->video.renderer->getPixels(threadContext->gba->video.renderer, &stride, &pixels);
588	png_structp png = PNGWriteOpen(vf);
589	png_infop info = PNGWriteHeader(png, VIDEO_HORIZONTAL_PIXELS, VIDEO_VERTICAL_PIXELS);
590	PNGWritePixels(png, VIDEO_HORIZONTAL_PIXELS, VIDEO_VERTICAL_PIXELS, stride, pixels);
591	PNGWriteClose(png, info);
592	vf->close(vf);
593}
594#endif
595
596#else
597struct GBAThread* GBAThreadGetContext(void) {
598	return 0;
599}
600#endif
601
602void GBASyncPostFrame(struct GBASync* sync) {
603	if (!sync) {
604		return;
605	}
606
607	MutexLock(&sync->videoFrameMutex);
608	++sync->videoFramePending;
609	--sync->videoFrameSkip;
610	if (sync->videoFrameSkip < 0) {
611		do {
612			ConditionWake(&sync->videoFrameAvailableCond);
613			if (sync->videoFrameWait) {
614				ConditionWait(&sync->videoFrameRequiredCond, &sync->videoFrameMutex);
615			}
616		} while (sync->videoFrameWait && sync->videoFramePending);
617	}
618	MutexUnlock(&sync->videoFrameMutex);
619}
620
621bool GBASyncWaitFrameStart(struct GBASync* sync, int frameskip) {
622	if (!sync) {
623		return true;
624	}
625
626	MutexLock(&sync->videoFrameMutex);
627	ConditionWake(&sync->videoFrameRequiredCond);
628	if (!sync->videoFrameOn && !sync->videoFramePending) {
629		return false;
630	}
631	if (sync->videoFrameOn) {
632		ConditionWait(&sync->videoFrameAvailableCond, &sync->videoFrameMutex);
633	}
634	sync->videoFramePending = 0;
635	sync->videoFrameSkip = frameskip;
636	return true;
637}
638
639void GBASyncWaitFrameEnd(struct GBASync* sync) {
640	if (!sync) {
641		return;
642	}
643
644	MutexUnlock(&sync->videoFrameMutex);
645}
646
647bool GBASyncDrawingFrame(struct GBASync* sync) {
648	if (!sync) {
649		return true;
650	}
651
652	return sync->videoFrameSkip <= 0;
653}
654
655void GBASyncSuspendDrawing(struct GBASync* sync) {
656	if (!sync) {
657		return;
658	}
659
660	_changeVideoSync(sync, false);
661}
662
663void GBASyncResumeDrawing(struct GBASync* sync) {
664	if (!sync) {
665		return;
666	}
667
668	_changeVideoSync(sync, true);
669}
670
671void GBASyncProduceAudio(struct GBASync* sync, bool wait) {
672	if (!sync) {
673		return;
674	}
675
676	if (sync->audioWait && wait) {
677		// TODO loop properly in event of spurious wakeups
678		ConditionWait(&sync->audioRequiredCond, &sync->audioBufferMutex);
679	}
680	MutexUnlock(&sync->audioBufferMutex);
681}
682
683void GBASyncLockAudio(struct GBASync* sync) {
684	if (!sync) {
685		return;
686	}
687
688	MutexLock(&sync->audioBufferMutex);
689}
690
691void GBASyncUnlockAudio(struct GBASync* sync) {
692	if (!sync) {
693		return;
694	}
695
696	MutexUnlock(&sync->audioBufferMutex);
697}
698
699void GBASyncConsumeAudio(struct GBASync* sync) {
700	if (!sync) {
701		return;
702	}
703
704	ConditionWake(&sync->audioRequiredCond);
705	MutexUnlock(&sync->audioBufferMutex);
706}