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Update interrupt timing

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This commit is contained in:
Adrian Conlon committed 2026-05-12 15:23:45 +01:00
1 parent 75a07ceea0
commit 96eaf1b22f
1 file changed
+36 -16
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MC6809/MC6809.cs
+36 -16
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@@ -514,19 +514,23 @@ namespace MC6809
this.DP = 0;
this.CC = SetBit(this.CC, StatusBits.IF); // Disable IRQ
this.CC = SetBit(this.CC, StatusBits.FF); // Disable FIRQ
this.GetPagedInto(0xff, RESET_vector, this.EA);
this.Jump(this.EA);
this.Bus.Address.Assign(RESET_vector, 0xff);
this.SwallowSpin(3);
this.GetPagedInto(this.PC);
this.SwallowRead();
}
protected override void HandleINT()
{
base.HandleINT();
this.SwallowCurrent(2);
this.LowerBA();
this.RaiseBS();
this.SaveEntireRegisterState();
this.CC = SetBit(this.CC, StatusBits.IF); // Disable IRQ
this.GetPagedInto(0xff, IRQ_vector, this.EA);
this.Jump(this.EA);
this.SwallowRead();
this.GetPagedInto(0xff, IRQ_vector, this.PC);
this.SwallowRead();
}
private void HandleHALT()
@@ -537,26 +541,30 @@ namespace MC6809
private void HandleNMI()
{
this.SwallowCurrent(2);
this.RaiseNMI();
this.LowerBA();
this.RaiseBS();
this.SaveEntireRegisterState();
this.CC = SetBit(this.CC, StatusBits.IF); // Disable IRQ
this.CC = SetBit(this.CC, StatusBits.FF); // Disable FIRQ
this.GetPagedInto(0xff, NMI_vector, this.EA);
this.Jump(this.EA);
this.SwallowRead();
this.GetPagedInto(0xff, NMI_vector, this.PC);
this.SwallowRead();
}
private void HandleFIRQ()
{
this.SwallowCurrent(2);
this.RaiseFIRQ();
this.LowerBA();
this.RaiseBS();
this.SavePartialRegisterState();
this.CC = SetBit(this.CC, StatusBits.IF); // Disable IRQ
this.CC = SetBit(this.CC, StatusBits.FF); // Disable FIRQ
this.GetPagedInto(0xff, FIRQ_vector, this.EA);
this.Jump(this.EA);
this.SwallowRead();
this.GetPagedInto(0xff, FIRQ_vector, this.PC);
this.SwallowRead();
}
#endregion
@@ -939,9 +947,16 @@ namespace MC6809
this.SaveRegisterState();
}
private void SaveRegisterState() => this.PSH(this.S, this.E ? (byte)Mask.Eight : (byte)0b10000001);
private void SaveRegisterState()
{
this.SwallowRead();
this.PSH(this.S, this.E ? (byte)Mask.Eight : (byte)0b10000001);
}
private void RestoreRegisterState() => this.PUL(this.S, this.E ? (byte)Mask.Eight : (byte)0b10000001);
private void RestoreRegisterState()
{
this.PUL(this.S, this.E ? (byte)Mask.Eight : (byte)0b10000001);
}
private void PSHS() => this.PSH(this.S);
private void PSHU() => this.PSH(this.U);
@@ -1206,6 +1221,14 @@ namespace MC6809
private void SwallowEffectiveAddress() => _ = this.MemoryRead(this.EA);
private void SwallowSpin(int ticks = 1)
{
for (int i = 0; i < ticks; i++)
{
this.MemoryRead();
}
}
#endregion
#region Instruction execution
@@ -1371,7 +1394,7 @@ namespace MC6809
case 0x73: this.ExtendedByte(); this.COM(); Debug.Assert(this.Cycles == 7); break; // COM (extended)
// CWAI
case 0x3c: this.SwallowCurrent(); this.CWAI(); break; // CWAI (inherent) - cycles omitted: halts before full interrupt response
case 0x3c: this.ImmediateByte(); this.CWAI(); break; // CWAI (immediate) - cycles omitted: halts before full interrupt response
// DAA
case 0x19: this.SwallowCurrent(); this.DAA(); Debug.Assert(this.Cycles == 2); break; // DAA (inherent)
@@ -1861,9 +1884,10 @@ namespace MC6809
private void CWAI()
{
this.SwallowRead();
this.CC &= this.Bus.Data;
this.SwallowCurrent();
this.SaveEntireRegisterState();
this.SwallowRead();
this.Halt();
}
@@ -2097,7 +2121,6 @@ namespace MC6809
private void SWI()
{
this.SwallowRead();
this.SaveEntireRegisterState();
this.CC = SetBit(this.CC, StatusBits.IF); // Disable IRQ
this.CC = SetBit(this.CC, StatusBits.FF); // Disable FIRQ
@@ -2110,7 +2133,6 @@ namespace MC6809
private void SWI2()
{
this.SwallowRead();
this.SaveEntireRegisterState();
this.SwallowRead();
this.GetPagedInto(0xff, SWI2_vector, this.EA);
@@ -2120,8 +2142,6 @@ namespace MC6809
private void SWI3()
{
this.SwallowRead();
this.SaveEntireRegisterState();
this.SwallowRead();
this.GetPagedInto(0xff, SWI3_vector, this.EA);