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MB/6522: support for T1 latch in one-shot mode

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tomcw 2021-02-10 20:51:11 +00:00
parent f3b6b8665f
commit 776a48fc01
1 changed files with 9 additions and 6 deletions
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15
source/Mockingboard.cpp
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@ -275,6 +275,8 @@ static void StopTimer2(SY6522_AY8910* pMB)
static void ResetSY6522(SY6522_AY8910* pMB)
{
memset(&pMB->sy6522,0,sizeof(SY6522));
pMB->sy6522.TIMER1_LATCH.w = 0xffff; // Some random value (but pick $ffff so it's deterministic)
// . NB. if it's too small (< ~$0007) then MB detection routines will fail!
StopTimer1(pMB);
StopTimer2(pMB);
@ -2007,7 +2009,7 @@ static BYTE __stdcall MB_Write(WORD PC, WORD nAddr, BYTE bWrite, BYTE nValue, UL
// . RESET -> Mockingboard mode (b#000)
// . $C0C1, then $C0C4 (or $C0C4, then $C0C1) -> Phasor mode (b#101)
// . $C0C2 -> Echo+ mode (b#111)
// . $C0C5 -> remaing in Echo+ mode (b#111)
// . $C0C5 -> remaining in Echo+ mode (b#111)
// So $C0C5 seemingly results in 2 different modes.
//
@ -2216,9 +2218,7 @@ void MB_UpdateCycles(ULONG uExecutedCycles)
SY6522_AY8910* pMB = &g_MB[i];
const bool bTimer1Underflow = CheckTimerUnderflow(pMB->sy6522.TIMER1_COUNTER.w, pMB->sy6522.timer1IrqDelay, nClocks);
const bool bTimer2Underflow = CheckTimerUnderflow(pMB->sy6522.TIMER2_COUNTER.w, pMB->sy6522.timer2IrqDelay, nClocks);
if (pMB->bTimer1Active && bTimer1Underflow)
if (bTimer1Underflow)
{
pMB->sy6522.TIMER1_COUNTER.w += pMB->sy6522.TIMER1_LATCH.w; // GH#651: account for underflowed cycles too
pMB->sy6522.TIMER1_COUNTER.w += kExtraTimerCycles; // GH#652: account for extra 2 cycles
@ -2233,6 +2233,9 @@ void MB_UpdateCycles(ULONG uExecutedCycles)
pMB->sy6522.TIMER1_COUNTER.w = 0;
}
}
// No TIMER2 latch so "after timing out, the counter will continue to decrement"
CheckTimerUnderflow(pMB->sy6522.TIMER2_COUNTER.w, pMB->sy6522.timer2IrqDelay, nClocks);
}
}
@ -2249,6 +2252,8 @@ static int MB_SyncEventCallback(int id, int /*cycles*/, ULONG uExecutedCycles)
UpdateIFR(pMB, 0, IxR_TIMER1);
MB_UpdateCycles(uExecutedCycles);
if ((pMB->sy6522.ACR & RUNMODE) == RM_ONESHOT)
{
// One-shot mode
@ -2257,8 +2262,6 @@ static int MB_SyncEventCallback(int id, int /*cycles*/, ULONG uExecutedCycles)
return 0; // Don't repeat event
}
MB_UpdateCycles(uExecutedCycles);
StartTimer1(pMB);
return pMB->sy6522.TIMER1_COUNTER.w + kExtraTimerCycles;
}