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Code Issues Projects Releases Wiki Activity

Simplify LR35902 IO register access a little.

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2019-08-12 18:34:17 +01:00
parent 583c5444a0
commit 3c7ca33efe
1 changed files with 20 additions and 13 deletions
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33
LR35902/IoRegisters.cs
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@ -100,11 +100,11 @@ namespace EightBit.GameBoy
public bool BootRomEnabled => !this.BootRomDisabled; public bool BootRomEnabled => !this.BootRomDisabled;
public int TimerClock => this.Peek((ushort)TAC) & (byte)Mask.Mask2; public int TimerClock => this.TimerControl & (byte)Mask.Mask2;
public bool TimerEnabled => !this.TimerDisabled; public bool TimerEnabled => !this.TimerDisabled;
public bool TimerDisabled => (this.Peek((ushort)TAC) & (byte)Bits.Bit2) == 0; public bool TimerDisabled => (this.TimerControl & (byte)Bits.Bit2) == 0;
public int TimerClockTicks public int TimerClockTicks
{ {
@ -126,10 +126,16 @@ namespace EightBit.GameBoy
} }
} }
private ref byte TimerControl => ref this.Reference(TAC);
private ref byte TimerModulo => ref this.Reference(TMA);
private ref byte TimerCounter => ref this.Reference(TIMA);
public void Reset() public void Reset()
{ {
this.Poke((ushort)NR52, 0xf1); this.Poke(NR52, 0xf1);
this.Poke((ushort)LCDC, (byte)(LcdcControl.DisplayBackground | LcdcControl.BackgroundCharacterDataSelection | LcdcControl.LcdEnable)); this.Poke(LCDC, (byte)(LcdcControl.DisplayBackground | LcdcControl.BackgroundCharacterDataSelection | LcdcControl.LcdEnable));
this.divCounter.Word = 0xabcc; this.divCounter.Word = 0xabcc;
this.timerCounter = 0; this.timerCounter = 0;
} }
@ -143,7 +149,7 @@ namespace EightBit.GameBoy
} }
} }
public void TriggerInterrupt(Interrupts cause) => this.Poke((ushort)IF, (byte)(this.Peek((ushort)IF) | (byte)cause)); public void TriggerInterrupt(Interrupts cause) => this.Reference(IF) |= (byte)cause;
public void CheckTimers(int cycles) public void CheckTimers(int cycles)
{ {
@ -154,29 +160,29 @@ namespace EightBit.GameBoy
public void IncrementDIV(int cycles) public void IncrementDIV(int cycles)
{ {
this.divCounter.Word += (ushort)cycles; this.divCounter.Word += (ushort)cycles;
this.Poke((ushort)DIV, this.divCounter.High); this.Poke(DIV, this.divCounter.High);
} }
public void IncrementTIMA() public void IncrementTIMA()
{ {
var updated = this.Peek((ushort)TIMA) + 1; var updated = this.TimerCounter + 1;
if ((updated & (int)Bits.Bit8) != 0) if ((updated & (int)Bits.Bit8) != 0)
{ {
this.TriggerInterrupt(Interrupts.TimerOverflow); this.TriggerInterrupt(Interrupts.TimerOverflow);
updated = this.Peek((ushort)TMA); updated = this.TimerModulo;
} }
this.Poke((ushort)TIMA, Chip.LowByte(updated)); this.TimerCounter = Chip.LowByte(updated);
} }
public void IncrementLY() => this.Poke((ushort)LY, (byte)((this.Peek((ushort)LY) + 1) % GameBoy.Bus.TotalLineCount)); public void IncrementLY() => this.Poke(LY, (byte)((this.Peek(LY) + 1) % GameBoy.Bus.TotalLineCount));
public void ResetLY() => this.Poke((ushort)LY, 0); public void ResetLY() => this.Poke(LY, 0);
public void UpdateLcdStatusMode(LcdStatusMode mode) public void UpdateLcdStatusMode(LcdStatusMode mode)
{ {
var current = this.Peek((ushort)STAT) & unchecked((byte)~Mask.Mask2); var current = this.Peek(STAT) & unchecked((byte)~Mask.Mask2);
this.Poke((ushort)STAT, (byte)(current | (int)mode)); this.Poke(STAT, (byte)(current | (int)mode));
this.OnDisplayStatusModeUpdated(mode); this.OnDisplayStatusModeUpdated(mode);
} }
@ -289,6 +295,7 @@ namespace EightBit.GameBoy
this.timerCounter = this.divCounter.Word = 0; this.timerCounter = this.divCounter.Word = 0;
break; break;
case TIMA: // R/W case TIMA: // R/W
break;
case TMA: // R/W case TMA: // R/W
break; break;
case TAC: // R/W case TAC: // R/W