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Refactor 6809 processor for readability

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This commit is contained in:
Adrian Conlon committed 2026-05-07 17:11:42 +01:00
1 parent 95b801b72f
commit 224fe74e09
1 file changed
+34 -82
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MC6809/MC6809.cs
+34 -82
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@@ -570,11 +570,7 @@ namespace MC6809
protected override void Push(byte value) => this.PushS(value);
private void Push(Register16 stack, byte value)
{
stack.Decrement();
this.MemoryWrite(stack, value);
}
private void Push(Register16 stack, byte value) => this.MemoryWrite(stack.Decrement(), value);
private void PushS(byte value) => this.Push(this.S, value);
@@ -652,24 +648,26 @@ namespace MC6809
{
case 0b0000: // ,R+
this.Tick(2);
this.Intermediate.Word = r.Word++;
this.Intermediate.Assign(r);
r.Word++;
break;
case 0b0001: // ,R++
this.Tick(3);
this.Intermediate.Word = r.Word;
this.Intermediate.Assign(r);
r.Word += 2;
break;
case 0b0010: // ,-R
this.Tick(2);
this.Intermediate.Word = --r.Word;
--r.Word;
this.Intermediate.Assign(r);
break;
case 0b0011: // ,--R
this.Tick(3);
r.Word -= 2;
this.Intermediate.Word = r.Word;
this.Intermediate.Assign(r);
break;
case 0b0100: // ,R
this.Intermediate.Word = r.Word;
this.Intermediate.Assign(r);
break;
case 0b0101: // B,R
this.Tick();
@@ -769,8 +767,10 @@ namespace MC6809
#region Load/store 8 or 16-bit data
private void LDA() => this.A = this.Through(this.Bus.Data);
private void LDB() => this.B = this.Through(this.Bus.Data);
private void LDA() => this.Assign(ref this.A);
private void LDB() => this.Assign(ref this.B);
private void Assign(ref byte destination) => destination = this.Through(this.Bus.Data);
private byte Through(byte data)
{
@@ -779,40 +779,19 @@ namespace MC6809
return data;
}
private void LDD()
{
this.Through(this.Intermediate);
this.D.Assign(this.Intermediate);
}
private void LDD() => this.Assign(this.D);
private void LDS() => this.Assign(this.S);
private void LDU() => this.Assign(this.U);
private void LDX() => this.Assign(this.X);
private void LDY() => this.Assign(this.Y);
private void LDS()
{
this.Through(this.Intermediate);
this.S.Assign(this.Intermediate);
}
private void Assign(Register16 destination) => destination.Assign(this.Through(this.Intermediate));
private void LDU()
{
this.Through(this.Intermediate);
this.U.Assign(this.Intermediate);
}
private void LDX()
{
this.Through(this.Intermediate);
this.X.Assign(this.Intermediate);
}
private void LDY()
{
this.Through(this.Intermediate);
this.Y.Assign(this.Intermediate);
}
private void Through(Register16 data)
private Register16 Through(Register16 data)
{
this.CC = ClearBit(this.CC, StatusBits.VF);
this.CC = this.AdjustNZ(data);
return data;
}
private void STA() => this.Store(this.A);
@@ -820,35 +799,13 @@ namespace MC6809
private void Store(byte data) => this.MemoryWrite(this.Intermediate, this.Through(data));
private void STD()
{
this.Through(this.D);
this.SetWord(this.Intermediate, this.D);
}
private void STD() => this.Store(this.D);
private void STU() => this.Store(this.U);
private void STS() => this.Store(this.S);
private void STX() => this.Store(this.X);
private void STY() => this.Store(this.Y);
private void STU()
{
this.Through(this.U);
this.SetWord(this.Intermediate, this.U);
}
private void STS()
{
this.Through(this.S);
this.SetWord(this.Intermediate, this.S);
}
private void STX()
{
this.Through(this.X);
this.SetWord(this.Intermediate, this.X);
}
private void STY()
{
this.Through(this.Y);
this.SetWord(this.Intermediate, this.Y);
}
private void Store(Register16 data) => this.SetWord(this.Intermediate, this.Through(data));
#endregion
@@ -1041,13 +998,13 @@ namespace MC6809
if ((data & (byte)Bits.Bit4) != 0)
{
this.Tick(2);
this.X.Word = this.PopWord(stack).Word;
this.X.Assign(this.PopWord(stack));
}
if ((data & (byte)Bits.Bit5) != 0)
{
this.Tick(2);
this.Y.Word = this.PopWord(stack).Word;
this.Y.Assign(this.PopWord(stack));
}
if ((data & (byte)Bits.Bit6) != 0)
@@ -1055,13 +1012,13 @@ namespace MC6809
this.Tick(2);
// Pulling from the S stack means we must be pulling U
(ReferenceEquals(stack, this.S) ? this.U : this.S).Word = this.PopWord(stack).Word;
(ReferenceEquals(stack, this.S) ? this.U : this.S).Assign(this.PopWord(stack));
}
if ((data & (byte)Bits.Bit7) != 0)
{
this.Tick(2);
this.PC.Word = this.PopWord(stack).Word;
this.PC.Assign(this.PopWord(stack));
}
}
@@ -1157,13 +1114,11 @@ namespace MC6809
var sourceRegister = this.ReferenceTransfer16(sourceSpecifier);
if (destinationType == 0)
{
var destinationRegister = this.ReferenceTransfer16(destinationSpecifier);
destinationRegister.Word = sourceRegister.Word;
this.ReferenceTransfer16(destinationSpecifier).Assign(sourceRegister);
}
else
{
ref var destinationRegister = ref this.ReferenceTransfer8(destinationSpecifier);
destinationRegister = sourceRegister.Low;
this.ReferenceTransfer8(destinationSpecifier) = sourceRegister.Low;
}
}
else
@@ -1171,14 +1126,11 @@ namespace MC6809
ref var sourceRegister = ref this.ReferenceTransfer8(sourceSpecifier);
if (destinationType == 0)
{
var destinationRegister = this.ReferenceTransfer16(destinationSpecifier);
destinationRegister.Low = sourceRegister;
destinationRegister.High = (byte)Mask.Eight;
this.ReferenceTransfer16(destinationSpecifier).Assign(sourceRegister, (byte)Mask.Eight);
}
else
{
ref var destinationRegister = ref this.ReferenceTransfer8(destinationSpecifier);
destinationRegister = sourceRegister;
this.ReferenceTransfer8(destinationSpecifier) = sourceRegister;
}
}
}