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Resurrect the Register16 class. This (or something *very* much like it) is going to be necessary to add a Z80 emulator (reference access to the high/low parts of 16-bit registers).

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon
2019-02-14 23:01:31 +00:00
parent b61d884679
commit 63db46a7bc
12 changed files with 336 additions and 195 deletions
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59
EightBit/Processor.cs
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@@ -10,6 +10,7 @@ namespace EightBit
{
private PinLevel resetLine;
private PinLevel intLine;
private Register16 pc;
protected Processor(Bus memory)
{
@@ -32,12 +33,12 @@ namespace EightBit
public event EventHandler<EventArgs> LoweredINT;
public ushort PC { get; set; }
public Bus Bus { get; }
protected byte OpCode { get; set; }
public ref Register16 PC() => ref this.pc;
public ref PinLevel RESET() => ref this.resetLine;
public ref PinLevel INT() => ref this.intLine;
@@ -63,11 +64,9 @@ namespace EightBit
return this.Execute();
}
public abstract ushort PeekWord(ushort address);
public abstract Register16 PeekWord(ushort address);
public abstract void PokeWord(ushort address, ushort value);
public ushort PeekWord(byte low, byte high) => this.PeekWord((ushort)(Chip.PromoteByte(high) | low));
public abstract void PokeWord(ushort address, Register16 value);
public virtual void RaiseRESET()
{
@@ -117,11 +116,16 @@ namespace EightBit
protected virtual void HandleINT() => this.RaiseINT();
protected void BusWrite(byte low, byte high, byte data) => this.BusWrite(Chip.MakeWord(low, high), data);
protected void BusWrite(byte low, byte high, byte data)
{
this.Bus.Address().Low = low;
this.Bus.Address().High = high;
this.BusWrite(data);
}
protected void BusWrite(ushort address, byte data)
{
this.Bus.Address = address;
this.Bus.Address().Word = address;
this.BusWrite(data);
}
@@ -133,56 +137,61 @@ namespace EightBit
protected virtual void BusWrite() => this.Bus.Write(); // N.B. Should be the only real call into the "Bus.Write" code.
protected byte BusRead(byte low, byte high) => this.BusRead(Chip.MakeWord(low, high));
protected byte BusRead(byte low, byte high)
{
this.Bus.Address().Low = low;
this.Bus.Address().High = high;
return this.BusRead();
}
protected byte BusRead(ushort address)
{
this.Bus.Address = address;
this.Bus.Address().Word = address;
return this.BusRead();
}
protected virtual byte BusRead() => this.Bus.Read(); // N.B. Should be the only real call into the "Bus.Read" code.
protected byte FetchByte() => this.BusRead(this.PC++);
protected byte FetchByte() => this.BusRead(this.PC().Word++);
protected abstract ushort GetWord();
protected abstract Register16 GetWord();
protected abstract void SetWord(ushort value);
protected abstract void SetWord(Register16 value);
protected abstract ushort GetWordPaged(byte page, byte offset);
protected abstract Register16 GetWordPaged(byte page, byte offset);
protected abstract void SetWordPaged(byte page, byte offset, ushort value);
protected abstract void SetWordPaged(byte page, byte offset, Register16 value);
protected abstract ushort FetchWord();
protected abstract Register16 FetchWord();
protected abstract void Push(byte value);
protected abstract byte Pop();
protected abstract void PushWord(ushort value);
protected abstract void PushWord(Register16 value);
protected abstract ushort PopWord();
protected abstract Register16 PopWord();
protected ushort GetWord(ushort address)
protected Register16 GetWord(ushort address)
{
this.Bus.Address = address;
this.Bus.Address().Word = address;
return this.GetWord();
}
protected void SetWord(ushort address, ushort value)
protected void SetWord(ushort address, Register16 value)
{
this.Bus.Address = address;
this.Bus.Address().Word = address;
this.SetWord(value);
}
protected void Jump(ushort destination) => this.PC = destination;
protected void Jump(ushort destination) => this.PC().Word = destination;
protected void Call(ushort destination)
{
this.PushWord(this.PC);
this.PushWord(this.PC());
this.Jump(destination);
}
protected virtual void Return() => this.Jump(this.PopWord());
protected virtual void Return() => this.Jump(this.PopWord().Word);
}
}