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Tidy IO page access

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This commit is contained in:
Adrian Conlon
2025-03-28 14:50:53 +00:00
parent fa48a64cac
commit 87abbaa75e
2 changed files with 14 additions and 8 deletions
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8
LR35902/IoRegisters.cs
View File

@@ -8,7 +8,11 @@ namespace LR35902
public sealed class IoRegisters : Ram
{
public const int BASE = 0xFF00;
public const byte BasePage = 0xFF;
private static readonly ushort _base = Chip.PromoteByte(BasePage);
public static ushort BASE => _base;
// Port/Mode Registers
public const int P1 = 0x0; // R/W Mask5
@@ -343,7 +347,7 @@ namespace LR35902
private void Bus_ReadingByte(object? sender, EventArgs e)
{
var address = this.bus.Address.Word;
var io = address is >= BASE and < 0xff80;
var io = address >= BASE && address < 0xff80;
if (io)
{
var port = (ushort)(address - BASE);

14
LR35902/LR35902.cs
View File

@@ -45,10 +45,12 @@ namespace LR35902
public bool IME { get; set; }
private static readonly Register16 _addressIE = new(IoRegisters.IE, IoRegisters.BasePage);
public byte IE
{
get => this.Bus.Peek(IoRegisters.BASE + IoRegisters.IE);
set => this.Bus.Poke(IoRegisters.BASE + IoRegisters.IE, value);
get => this.Bus.Peek(_addressIE);
set => this.Bus.Poke(_addressIE, value);
}
public byte IF
@@ -689,7 +691,7 @@ namespace LR35902
break;
case 4: // GB: LD (FF00 + n),A
this.MemoryWrite((ushort)(IoRegisters.BASE + this.FetchByte()), this.A);
this.MemoryWrite(this.FetchByte(), IoRegisters.BasePage, this.A);
break;
case 5:
@@ -707,7 +709,7 @@ namespace LR35902
break;
case 6: // GB: LD A,(FF00 + n)
this.A = this.MemoryRead((ushort)(IoRegisters.BASE + this.FetchByte()));
this.A = this.MemoryRead(this.FetchByte(), IoRegisters.BasePage);
break;
case 7:
@@ -772,7 +774,7 @@ namespace LR35902
_ = this.JumpConditionalFlag(y);
break;
case 4: // GB: LD (FF00 + C),A
this.MemoryWrite((ushort)(IoRegisters.BASE + this.C), this.A);
this.MemoryWrite(this.C, IoRegisters.BasePage, this.A);
break;
case 5: // GB: LD (nn),A
this.MEMPTR.Assign(this.FetchWord());
@@ -780,7 +782,7 @@ namespace LR35902
this.MemoryWrite(this.A);
break;
case 6: // GB: LD A,(FF00 + C)
this.A = this.MemoryRead((ushort)(IoRegisters.BASE + this.C));
this.A = this.MemoryRead(this.C, IoRegisters.BasePage);
break;
case 7: // GB: LD A,(nn)
this.MEMPTR.Assign(this.FetchWord());