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Isolate program counter increment/decrement (to be used for HALT processing)

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This commit is contained in:
Adrian Conlon
2025-05-03 23:25:06 +01:00
parent 2501bdfd28
commit cbe871d365
6 changed files with 23 additions and 30 deletions
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6
EightBit/Processor.cs
View File

@@ -220,10 +220,14 @@ namespace EightBit
protected virtual byte BusRead() => this.Bus.Read(); // N.B. Should be the only real call into the "Bus.Read" code. protected virtual byte BusRead() => this.Bus.Read(); // N.B. Should be the only real call into the "Bus.Read" code.
protected virtual void IncrementPC() => ++this.PC.Word;
protected virtual void DecrementPC() => --this.PC.Word;
protected virtual byte FetchByte() protected virtual byte FetchByte()
{ {
this.Bus.Address.Assign(this.PC); this.Bus.Address.Assign(this.PC);
this.PC.Word++; IncrementPC();
return this.MemoryRead(); return this.MemoryRead();
} }

12
Intel8080/Intel8080.cs
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@@ -13,8 +13,6 @@ namespace Intel8080
: base(bus) : base(bus)
{ {
this.ports = ports; this.ports = ports;
this.LoweredHALT += this.Intel8080_LoweredHALT;
this.RaisedHALT += this.Intel8080_RaisedHALT;
} }
private readonly Register16 af = new(); private readonly Register16 af = new();
@@ -91,16 +89,6 @@ namespace Intel8080
} }
} }
private void Intel8080_RaisedHALT(object? sender, EventArgs e)
{
++this.PC.Word; // Release the PC from HALT instruction
}
private void Intel8080_LoweredHALT(object? sender, EventArgs e)
{
--this.PC.Word; // Keep the PC on the HALT instruction (i.e. executing NOP)
}
private int Sign() private int Sign()
{ {

1
LR35902/LR35902.cs
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@@ -669,7 +669,6 @@ namespace LR35902
{ {
this.LowerHALT(); // Exception (replaces LD (HL), (HL)) this.LowerHALT(); // Exception (replaces LD (HL), (HL))
this.TickMachine(2); this.TickMachine(2);
//this.PC.Word++;
} }
else else
{ {

2
M6502/Core.cs
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@@ -664,7 +664,7 @@ namespace M6502
protected void ImmediateAddress() protected void ImmediateAddress()
{ {
this.Bus.Address.Assign(this.PC); this.Bus.Address.Assign(this.PC);
++this.PC.Word; this.IncrementPC();
} }
protected void AbsoluteAddress() => this.FetchWordAddress(); protected void AbsoluteAddress() => this.FetchWordAddress();

2
MC6809/MC6809.cs
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@@ -161,13 +161,11 @@ namespace EightBit
public void Halt() public void Halt()
{ {
--this.PC.Word;
this.LowerHALT(); this.LowerHALT();
} }
public void Proceed() public void Proceed()
{ {
++this.PC.Word;
this.RaiseHALT(); this.RaiseHALT();
} }

30
Z80/Z80.cs
View File

@@ -1021,9 +1021,9 @@ namespace Z80
case 6: // LDIR case 6: // LDIR
if (this.LDIR()) if (this.LDIR())
{ {
--this.PC.Word; this.DecrementPC();
this.MEMPTR.Assign(this.PC); this.MEMPTR.Assign(this.PC);
--this.PC.Word; this.DecrementPC();
} }
this.Tick(5); this.Tick(5);
@@ -1031,9 +1031,9 @@ namespace Z80
case 7: // LDDR case 7: // LDDR
if (this.LDDR()) if (this.LDDR())
{ {
--this.PC.Word; this.DecrementPC();
this.MEMPTR.Assign(this.PC); this.MEMPTR.Assign(this.PC);
--this.PC.Word; this.DecrementPC();
} }
this.Tick(5); this.Tick(5);
@@ -1055,9 +1055,9 @@ namespace Z80
case 6: // CPIR case 6: // CPIR
if (this.CPIR()) if (this.CPIR())
{ {
--this.PC.Word; this.DecrementPC();
this.MEMPTR.Assign(this.PC); this.MEMPTR.Assign(this.PC);
--this.PC.Word; this.DecrementPC();
this.Tick(5); this.Tick(5);
} }
@@ -1065,9 +1065,9 @@ namespace Z80
case 7: // CPDR case 7: // CPDR
if (this.CPDR()) if (this.CPDR())
{ {
--this.PC.Word; this.DecrementPC();
this.MEMPTR.Assign(this.PC); this.MEMPTR.Assign(this.PC);
--this.PC.Word; this.DecrementPC();
this.Tick(3); this.Tick(3);
} }
else else
@@ -1094,7 +1094,8 @@ namespace Z80
case 6: // INIR case 6: // INIR
if (this.INIR()) if (this.INIR())
{ {
this.PC.Word -= 2; this.DecrementPC();
this.DecrementPC();
this.Tick(5); this.Tick(5);
} }
@@ -1102,7 +1103,8 @@ namespace Z80
case 7: // INDR case 7: // INDR
if (this.INDR()) if (this.INDR())
{ {
this.PC.Word -= 2; this.DecrementPC();
this.DecrementPC();
this.Tick(5); this.Tick(5);
} }
@@ -1124,7 +1126,8 @@ namespace Z80
case 6: // OTIR case 6: // OTIR
if (this.OTIR()) if (this.OTIR())
{ {
this.PC.Word -= 2; this.DecrementPC();
this.DecrementPC();
this.Tick(5); this.Tick(5);
} }
@@ -1132,7 +1135,8 @@ namespace Z80
case 7: // OTDR case 7: // OTDR
if (this.OTDR()) if (this.OTDR())
{ {
this.PC.Word -= 2; this.DecrementPC();
this.DecrementPC();
this.Tick(5); this.Tick(5);
} }
@@ -1664,7 +1668,7 @@ namespace Z80
private byte FetchInitialOpCode() private byte FetchInitialOpCode()
{ {
var returned = this.ReadInitialOpCode(); var returned = this.ReadInitialOpCode();
++this.PC.Word; this.IncrementPC();
return returned; return returned;
} }