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Properly emulate interrupt flag behavior of INITM read on wraparound.

This commit is contained in:
Christian Speckner 2017-03-19 22:25:16 +01:00
parent 471db61254
commit 317169c59a
2 changed files with 11 additions and 2 deletions
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12
src/emucore/M6532.cxx
View File

@ -30,7 +30,7 @@ M6532::M6532(const Console& console, const Settings& settings)
: myConsole(console), : myConsole(console),
mySettings(settings), mySettings(settings),
myTimer(0), mySubTimer(0), myDivider(1), myTimer(0), mySubTimer(0), myDivider(1),
myTimerWrapped(false), mySetTimerCycle(0), myLastCycle(0), myTimerWrapped(false), myWrappedThisCycle(false), mySetTimerCycle(0), myLastCycle(0),
myDDRA(0), myDDRB(0), myOutA(0), myOutB(0), myDDRA(0), myDDRB(0), myOutA(0), myOutB(0),
myInterruptFlag(false), myInterruptFlag(false),
myEdgeDetectPositive(false) myEdgeDetectPositive(false)
@ -51,6 +51,8 @@ void M6532::reset()
myDivider = 1024; myDivider = 1024;
mySubTimer = 0; mySubTimer = 0;
myTimerWrapped = false; myTimerWrapped = false;
myWrappedThisCycle = false;
mySetTimerCycle = 0; mySetTimerCycle = 0;
myLastCycle = mySystem->cycles(); myLastCycle = mySystem->cycles();
@ -109,6 +111,11 @@ void M6532::updateEmulation()
uInt32 cycles = mySystem->cycles() - myLastCycle; uInt32 cycles = mySystem->cycles() - myLastCycle;
uInt32 subTimer = mySubTimer; uInt32 subTimer = mySubTimer;
// Guard against further state changes if the debugger alread forwarded emulation
// state (in particular myWrappedThisCycle)
if (cycles == 0) return;
myWrappedThisCycle = false;
mySubTimer = (cycles + mySubTimer) % myDivider; mySubTimer = (cycles + mySubTimer) % myDivider;
if(!myTimerWrapped) if(!myTimerWrapped)
@ -118,6 +125,7 @@ void M6532::updateEmulation()
if(timerTicks > myTimer) if(timerTicks > myTimer)
{ {
cycles -= ((myTimer + 1) * myDivider - subTimer); cycles -= ((myTimer + 1) * myDivider - subTimer);
myWrappedThisCycle = cycles == 0;
myTimer = 0xFF; myTimer = 0xFF;
myTimerWrapped = true; myTimerWrapped = true;
myInterruptFlag |= TimerBit; myInterruptFlag |= TimerBit;
@ -201,7 +209,7 @@ uInt8 M6532::peek(uInt16 addr)
case 0x06: case 0x06:
{ {
// Timer Flag is always cleared when accessing INTIM // Timer Flag is always cleared when accessing INTIM
myInterruptFlag &= ~TimerBit; if (!myWrappedThisCycle) myInterruptFlag &= ~TimerBit;
myTimerWrapped = false; myTimerWrapped = false;
return myTimer; return myTimer;
} }

1
src/emucore/M6532.hxx
View File

@ -175,6 +175,7 @@ class M6532 : public Device
// Has the timer wrapped? // Has the timer wrapped?
bool myTimerWrapped; bool myTimerWrapped;
bool myWrappedThisCycle;
// Cycle when the timer set. Debugging only. // Cycle when the timer set. Debugging only.
Int32 mySetTimerCycle; Int32 mySetTimerCycle;