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MB/6522: IER doesn't start/stop timers

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This commit is contained in:
tomcw 2020-03-07 18:08:50 +00:00
parent ef4ee4ed16
commit c204783816
1 changed files with 1 additions and 14 deletions
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15
source/Mockingboard.cpp
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@ -471,27 +471,14 @@ static void SY6522_Write(BYTE nDevice, BYTE nReg, BYTE nValue)
// Clear those bits which are set in the lower 7 bits.
nValue ^= 0x7F;
pMB->sy6522.IER &= nValue;
UpdateIFR(pMB, 0);
// Check if active timer has been disabled:
if (((pMB->sy6522.IER & IxR_TIMER1) == 0) && pMB->bTimer1Active)
StopTimer1(pMB);
if (((pMB->sy6522.IER & IxR_TIMER2) == 0) && pMB->bTimer2Active)
StopTimer2(pMB);
}
else
{
// Set those bits which are set in the lower 7 bits.
nValue &= 0x7F;
pMB->sy6522.IER |= nValue;
UpdateIFR(pMB, 0);
// Check if a timer interrupt has been enabled (regardless of if there's an active timer or not): GH#567
// . NB. Not Timer2 - only TIMER2H can make it active (GH#765)
if (pMB->sy6522.IER & IxR_TIMER1)
StartTimer1(pMB);
}
UpdateIFR(pMB, 0);
break;
case 0x0f: // ORA_NO_HS
break;