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Move CoreTiming::downcount to PowerPC::ppcState.

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This isn't technically the correct place to have the downcount variable, but it is similar to what PPSSPP does to gain a bit of extra speed on ARM.
We access this variable quite a bit, with each exit in a block it is subtracted from.
On ARM this required four instructions to load and store the value, while now it only requires two.

This gives an average of 1FPS gain to most games.
Examples:
Crazy Taxi: 54FPS -> 55FPS
Luigi's Mansion: 20FPS -> 21FPS
Wind Waker(Save Screen): 27FPS -> 28FPS

This seems to average a 6mhz to 16mhz CPU core emulation improvement in the few games I've tested.
This commit is contained in:
Ryan Houdek
2014-06-16 22:47:10 -05:00
parent 177658aed6
commit a40ae6883a
13 changed files with 48 additions and 53 deletions
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23
Source/Core/Core/CoreTiming.cpp
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@ -46,7 +46,7 @@ Common::FifoQueue<BaseEvent, false> tsQueue;
// event pools
Event *eventPool = nullptr;
int downcount, slicelength;
int slicelength;
int maxSliceLength = MAX_SLICE_LENGTH;
s64 globalTimer;
@ -113,7 +113,7 @@ void UnregisterAllEvents()
void Init()
{
downcount = maxSliceLength;
PowerPC::ppcState.downcount = maxSliceLength;
slicelength = maxSliceLength;
globalTimer = 0;
idledCycles = 0;
@ -173,7 +173,6 @@ void EventDoState(PointerWrap &p, BaseEvent* ev)
void DoState(PointerWrap &p)
{
std::lock_guard<std::mutex> lk(tsWriteLock);
p.Do(downcount);
p.Do(slicelength);
p.Do(globalTimer);
p.Do(idledCycles);
@ -336,10 +335,10 @@ void SetMaximumSlice(int maximumSliceLength)
void ForceExceptionCheck(int cycles)
{
if (downcount > cycles)
if (PowerPC::ppcState.downcount > cycles)
{
slicelength -= (downcount - cycles); // Account for cycles already executed by adjusting the slicelength
downcount = cycles;
slicelength -= (PowerPC::ppcState.downcount - cycles); // Account for cycles already executed by adjusting the slicelength
PowerPC::ppcState.downcount = cycles;
}
}
@ -390,9 +389,9 @@ void Advance()
{
MoveEvents();
int cyclesExecuted = slicelength - downcount;
int cyclesExecuted = slicelength - PowerPC::ppcState.downcount;
globalTimer += cyclesExecuted;
downcount = slicelength;
PowerPC::ppcState.downcount = slicelength;
while (first)
{
@ -414,14 +413,14 @@ void Advance()
if (!first)
{
WARN_LOG(POWERPC, "WARNING - no events in queue. Setting downcount to 10000");
downcount += 10000;
PowerPC::ppcState.downcount += 10000;
}
else
{
slicelength = (int)(first->time - globalTimer);
if (slicelength > maxSliceLength)
slicelength = maxSliceLength;
downcount = slicelength;
PowerPC::ppcState.downcount = slicelength;
}
if (advanceCallback)
@ -451,8 +450,8 @@ void Idle()
Common::YieldCPU();
}
idledCycles += downcount;
downcount = 0;
idledCycles += PowerPC::ppcState.downcount;
PowerPC::ppcState.downcount = 0;
Advance();
}