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Cocoa Port: 

- Throttle execution speed using mach_wait_until() instead of usleep(). This improves execution timing, and reduces screen tearing when running the video at >= 60FPS.
- Improve thread safety when changing the execution speed.
- Do some miscellaneous minor optimizations to the execution loop and frame skip.
This commit is contained in:
rogerman 2012-03-13 01:59:32 +00:00
parent 7ae952f366
commit f6f1678eca
2 changed files with 20 additions and 20 deletions
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4
desmume/src/cocoa/cocoa_core.h
View File

@ -120,5 +120,5 @@ typedef struct
@end
void* RunCoreThread(void *arg);
void CoreFrameSkip(uint64_t timeBudgetMachAbsoluteTime, uint64_t frameStartMachAbsoluteTime, unsigned int *outFramesToSkip);
static void* RunCoreThread(void *arg);
static void CoreFrameSkip(uint64_t timeBudgetMachAbsoluteTime, uint64_t frameStartMachAbsoluteTime, unsigned int *outFramesToSkip);

36
desmume/src/cocoa/cocoa_core.mm
View File

@ -642,23 +642,25 @@ static BOOL isCoreStarted = NO;
@end
void* RunCoreThread(void *arg)
static void* RunCoreThread(void *arg)
{
CoreThreadParam *param = (CoreThreadParam *)arg;
CocoaDSCore *cdsCore = (CocoaDSCore *)param->cdsCore;
NSMutableArray *cdsOutputList = [cdsCore cdsOutputList];
uint64_t startTime = 0;
uint64_t elapsedMachAbsTime;
uint64_t timeBudget = 0; // Need local variable to ensure that param->timeBudgetMachAbsTime is thread-safe.
do
{
startTime = mach_absolute_time();
pthread_mutex_lock(&param->mutexThreadExecute);
timeBudget = param->timeBudgetMachAbsTime;
while (!(param->state == CORESTATE_EXECUTE && execute && !param->exitThread))
{
pthread_cond_wait(&param->condThreadExecute, &param->mutexThreadExecute);
startTime = mach_absolute_time();
timeBudget = param->timeBudgetMachAbsTime;
}
if (param->exitThread)
@ -708,20 +710,15 @@ void* RunCoreThread(void *arg)
// we owe on timeBudget.
if (param->isFrameSkipEnabled)
{
CoreFrameSkip(param->timeBudgetMachAbsTime, startTime, &param->framesToSkip);
CoreFrameSkip(timeBudget, startTime, &param->framesToSkip);
}
// If there is any time left in the loop, go ahead and pad it.
elapsedMachAbsTime = mach_absolute_time() - startTime;
pthread_mutex_unlock(&param->mutexThreadExecute);
if(param->timeBudgetMachAbsTime > elapsedMachAbsTime)
// If there is any time left in the loop, go ahead and pad it.
if(timeBudget > (mach_absolute_time() - startTime))
{
uint64_t padMachAbsTime = param->timeBudgetMachAbsTime - elapsedMachAbsTime;
Nanoseconds padNanoseconds = AbsoluteToNanoseconds(*(AbsoluteTime *)&padMachAbsTime);
useconds_t padMicroseconds = (useconds_t)(*(uint64_t *)&padNanoseconds / 1000);
usleep(padMicroseconds);
mach_wait_until(startTime + timeBudget);
}
} while (!param->exitThread);
@ -729,10 +726,8 @@ void* RunCoreThread(void *arg)
return nil;
}
void CoreFrameSkip(uint64_t timeBudgetMachAbsTime, uint64_t frameStartMachAbsTime, unsigned int *outFramesToSkip)
static void CoreFrameSkip(uint64_t timeBudgetMachAbsTime, uint64_t frameStartMachAbsTime, unsigned int *outFramesToSkip)
{
static unsigned int lastSetFrameSkip = 0;
if (*outFramesToSkip > 0)
{
NDS_SkipNextFrame();
@ -740,13 +735,14 @@ void CoreFrameSkip(uint64_t timeBudgetMachAbsTime, uint64_t frameStartMachAbsTim
}
else
{
unsigned int framesToSkip = 0;
// Calculate the time remaining.
uint64_t elapsed = mach_absolute_time() - frameStartMachAbsTime;
if (elapsed > timeBudgetMachAbsTime)
{
static unsigned int lastSetFrameSkip = 0;
unsigned int framesToSkip = 0;
if (timeBudgetMachAbsTime > 0)
{
framesToSkip = (unsigned int)( (((double)(elapsed - timeBudgetMachAbsTime) * FRAME_SKIP_AGGRESSIVENESS) / (double)timeBudgetMachAbsTime) + FRAME_SKIP_BIAS );
@ -770,8 +766,12 @@ void CoreFrameSkip(uint64_t timeBudgetMachAbsTime, uint64_t frameStartMachAbsTim
framesToSkip = (unsigned int)MAX_FRAME_SKIP;
lastSetFrameSkip = framesToSkip;
}
*outFramesToSkip = framesToSkip;
}
else
{
*outFramesToSkip = 0;
}
*outFramesToSkip = framesToSkip;
}
}