mirror of
https://github.com/MoleskiCoder/EightBitNet.git
synced 2025-11-04 07:16:02 +00:00
1341 lines
65 KiB
C#
1341 lines
65 KiB
C#
// <copyright file="M6502.cs" company="Adrian Conlon">
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// Copyright (c) Adrian Conlon. All rights reserved.
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// </copyright>
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namespace EightBit
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{
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public class M6502(Bus bus) : LittleEndianProcessor(bus)
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{
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private readonly Register16 intermediate = new();
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#region Instruction execution events
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public event EventHandler<EventArgs>? ExecutingInstruction;
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public event EventHandler<EventArgs>? ExecutedInstruction;
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protected virtual void OnExecutedInstruction() => this.ExecutedInstruction?.Invoke(this, EventArgs.Empty);
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protected virtual void OnExecutingInstruction() => this.ExecutingInstruction?.Invoke(this, EventArgs.Empty);
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#endregion
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#region Pin controls
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#region NMI pin
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public ref PinLevel NMI => ref this.nmiLine;
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private PinLevel nmiLine = PinLevel.Low;
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public event EventHandler<EventArgs>? RaisingNMI;
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public event EventHandler<EventArgs>? RaisedNMI;
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public event EventHandler<EventArgs>? LoweringNMI;
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public event EventHandler<EventArgs>? LoweredNMI;
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protected virtual void OnRaisingNMI() => this.RaisingNMI?.Invoke(this, EventArgs.Empty);
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protected virtual void OnRaisedNMI() => this.RaisedNMI?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweringNMI() => this.LoweringNMI?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweredNMI() => this.LoweredNMI?.Invoke(this, EventArgs.Empty);
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1030:Use events where appropriate", Justification = "The word 'raise' is used in an electrical sense")]
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public virtual void RaiseNMI()
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{
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if (this.NMI.Lowered())
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{
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this.OnRaisingNMI();
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this.NMI.Raise();
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this.OnRaisedNMI();
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}
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}
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public virtual void LowerNMI()
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{
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if (this.NMI.Raised())
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{
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this.OnLoweringNMI();
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this.NMI.Lower();
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this.OnLoweredNMI();
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}
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}
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#endregion
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#region SO pin
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public ref PinLevel SO => ref this.soLine;
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private PinLevel soLine = PinLevel.Low;
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public event EventHandler<EventArgs>? RaisingSO;
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public event EventHandler<EventArgs>? RaisedSO;
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public event EventHandler<EventArgs>? LoweringSO;
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public event EventHandler<EventArgs>? LoweredSO;
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protected virtual void OnRaisingSO() => this.RaisingSO?.Invoke(this, EventArgs.Empty);
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protected virtual void OnRaisedSO() => this.RaisedSO?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweringSO() => this.LoweringSO?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweredSO() => this.LoweredSO?.Invoke(this, EventArgs.Empty);
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1030:Use events where appropriate", Justification = "The word 'raise' is used in an electrical sense")]
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public virtual void RaiseSO()
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{
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if (this.SO.Lowered())
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{
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this.OnRaisingSO();
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this.SO.Raise();
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this.OnRaisedSO();
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}
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}
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public virtual void LowerSO()
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{
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if (this.SO.Raised())
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{
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this.OnLoweringSO();
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this.SO.Lower();
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this.OnLoweredSO();
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}
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}
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#endregion
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#region SYNC pin
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public ref PinLevel SYNC => ref this.syncLine;
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private PinLevel syncLine = PinLevel.Low;
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public event EventHandler<EventArgs>? RaisingSYNC;
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public event EventHandler<EventArgs>? RaisedSYNC;
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public event EventHandler<EventArgs>? LoweringSYNC;
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public event EventHandler<EventArgs>? LoweredSYNC;
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protected virtual void OnRaisingSYNC() => this.RaisingSYNC?.Invoke(this, EventArgs.Empty);
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protected virtual void OnRaisedSYNC() => this.RaisedSYNC?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweringSYNC() => this.LoweringSYNC?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweredSYNC() => this.LoweredSYNC?.Invoke(this, EventArgs.Empty);
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1030:Use events where appropriate", Justification = "The word 'raise' is used in an electrical sense")]
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protected virtual void RaiseSYNC()
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{
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this.OnRaisingSYNC();
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this.SYNC.Raise();
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this.OnRaisedSYNC();
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}
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protected virtual void LowerSYNC()
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{
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this.OnLoweringSYNC();
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this.SYNC.Lower();
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this.OnLoweredSYNC();
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}
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#endregion
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#region RDY pin
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public ref PinLevel RDY => ref this.rdyLine;
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private PinLevel rdyLine = PinLevel.Low;
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public event EventHandler<EventArgs>? RaisingRDY;
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public event EventHandler<EventArgs>? RaisedRDY;
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public event EventHandler<EventArgs>? LoweringRDY;
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public event EventHandler<EventArgs>? LoweredRDY;
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protected virtual void OnRaisingRDY() => this.RaisingRDY?.Invoke(this, EventArgs.Empty);
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protected virtual void OnRaisedRDY() => this.RaisedRDY?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweringRDY() => this.LoweringRDY?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweredRDY() => this.LoweredRDY?.Invoke(this, EventArgs.Empty);
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1030:Use events where appropriate", Justification = "The word 'raise' is used in an electrical sense")]
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public virtual void RaiseRDY()
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{
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if (this.RDY.Lowered())
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{
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this.OnRaisingRDY();
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this.RDY.Raise();
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this.OnRaisedRDY();
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}
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}
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public virtual void LowerRDY()
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{
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if (this.RDY.Raised())
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{
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this.OnLoweringRDY();
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this.RDY.Lower();
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this.OnLoweredRDY();
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}
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}
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#endregion
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#region RW pin
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public ref PinLevel RW => ref this.rwLine;
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private PinLevel rwLine = PinLevel.Low;
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public event EventHandler<EventArgs>? RaisingRW;
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public event EventHandler<EventArgs>? RaisedRW;
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public event EventHandler<EventArgs>? LoweringRW;
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public event EventHandler<EventArgs>? LoweredRW;
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protected virtual void OnRaisingRW() => this.RaisingRW?.Invoke(this, EventArgs.Empty);
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protected virtual void OnRaisedRW() => this.RaisedRW?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweringRW() => this.LoweringRW?.Invoke(this, EventArgs.Empty);
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protected virtual void OnLoweredRW() => this.LoweredRW?.Invoke(this, EventArgs.Empty);
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[System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1030:Use events where appropriate", Justification = "The word 'raise' is used in an electrical sense")]
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public virtual void RaiseRW()
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{
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if (this.RW.Lowered())
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{
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this.OnRaisingRW();
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this.RW.Raise();
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this.OnRaisedRW();
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}
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}
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public virtual void LowerRW()
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{
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if (this.RW.Raised())
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{
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this.OnLoweringRW();
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this.RW.Lower();
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this.OnLoweredRW();
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}
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}
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#endregion
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protected override void OnRaisedPOWER()
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{
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this.X = (byte)Bits.Bit7;
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this.Y = 0;
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this.A = 0;
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this.P = (byte)StatusBits.RF;
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this.S = (byte)Mask.Eight;
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this.LowerSYNC();
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this.LowerRW();
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base.OnRaisedPOWER();
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}
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#endregion
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#region Interrupts
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private const byte IRQvector = 0xfe; // IRQ vector
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private const byte RSTvector = 0xfc; // RST vector
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private const byte NMIvector = 0xfa; // NMI vector
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enum InterruptSource { hardware, software };
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enum InterruptType { reset, non_reset };
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private void Interrupt(byte vector, InterruptSource source = InterruptSource.hardware, InterruptType type = InterruptType.non_reset)
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{
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if (type == InterruptType.reset)
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{
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this.DummyPush();
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this.DummyPush();
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this.DummyPush();
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}
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else
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{
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this.PushWord(this.PC);
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this.Push((byte)(this.P | (source == InterruptSource.hardware ? 0 : (byte)StatusBits.BF)));
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}
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this.SetFlag(StatusBits.IF); // Disable IRQ
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this.Jump(this.GetWordPaged(0xff, vector).Word);
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}
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#region Interrupt etc. handlers
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protected override sealed void HandleRESET()
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{
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this.RaiseRESET();
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this.Interrupt(RSTvector, InterruptSource.hardware, InterruptType.reset);
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}
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protected override sealed void HandleINT()
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{
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this.RaiseINT();
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this.Interrupt(IRQvector);
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}
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private void HandleNMI()
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{
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this.RaiseNMI();
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this.Interrupt(NMIvector);
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}
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private void HandleSO()
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{
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this.RaiseSO();
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this.SetFlag(StatusBits.VF);
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}
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#endregion
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#endregion
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#region Registers
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public byte X { get; set; }
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public byte Y { get; set; }
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public byte A { get; set; }
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public byte S { get; set; }
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public byte P { get; set; }
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#endregion
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#region Processor state helpers
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private int InterruptMasked => this.P & (byte)StatusBits.IF;
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private int Decimal => this.P & (byte)StatusBits.DF;
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private int Negative => NegativeTest(this.P);
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private int Zero => ZeroTest(this.P);
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private int Overflow => OverflowTest(this.P);
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private int Carry => CarryTest(this.P);
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private static int NegativeTest(byte data) => data & (byte)StatusBits.NF;
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private static int ZeroTest(byte data) => data & (byte)StatusBits.ZF;
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private static int OverflowTest(byte data) => data & (byte)StatusBits.VF;
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private static int CarryTest(byte data) => data & (byte)StatusBits.CF;
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#endregion
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#region Bit/state twiddling
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#region Bit twiddling
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private static byte SetBit(byte f, StatusBits flag) => SetBit(f, (byte)flag);
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private static byte SetBit(byte f, StatusBits flag, int condition) => SetBit(f, (byte)flag, condition);
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private static byte SetBit(byte f, StatusBits flag, bool condition) => SetBit(f, (byte)flag, condition);
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private static byte ClearBit(byte f, StatusBits flag) => ClearBit(f, (byte)flag);
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private static byte ClearBit(byte f, StatusBits flag, int condition) => ClearBit(f, (byte)flag, condition);
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#endregion
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#region State flag twiddling
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private void SetFlag(StatusBits flag)
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{
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this.P = SetBit(this.P, flag);
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}
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private void SetFlag(StatusBits which, int condition)
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{
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this.P = SetBit(this.P, which, condition);
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}
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private void SetFlag(StatusBits which, bool condition)
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{
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this.P = SetBit(this.P, which, condition);
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}
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private void ResetFlag(StatusBits which)
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{
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this.P = ClearBit(this.P, which);
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}
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private void ResetFlag(StatusBits which, int condition)
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{
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this.P = ClearBit(this.P, which, condition);
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}
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#endregion
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#endregion
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#region Cycle wastage
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private void Swallow() => this.MemoryRead(this.PC);
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private void SwallowStack() => this.MemoryRead(this.S, 1);
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private void SwallowFetch() => this.FetchByte();
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#endregion
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#region Core instruction dispatching
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public override void Execute()
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{
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switch (this.OpCode)
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{
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case 0x00: this.SwallowFetch(); this.Interrupt(IRQvector, InterruptSource.software); break; // BRK (implied)
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case 0x01: this.AM_IndexedIndirectX(); this.OrR(); break; // ORA (indexed indirect X)
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case 0x02: this.Jam(); break; // *JAM
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case 0x03: this.AM_IndexedIndirectX(); this.SLO(); break; // *SLO (indexed indirect X)
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case 0x04: this.AM_ZeroPage(); break; // *NOP (zero page)
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case 0x05: this.AM_ZeroPage(); this.OrR(); break; // ORA (zero page)
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case 0x06: this.AM_ZeroPage(); this.ModifyWrite(this.ASL()); break; // ASL (zero page)
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case 0x07: this.AM_ZeroPage(); this.SLO(); break; // *SLO (zero page)
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case 0x08: this.Swallow(); this.PHP(); break; // PHP (implied)
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case 0x09: this.AM_Immediate(); this.OrR(); break; // ORA (immediate)
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case 0x0a: this.Swallow(); A = this.ASL(A); break; // ASL A (implied)
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case 0x0b: this.AM_Immediate(); this.ANC(); break; // *ANC (immediate)
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case 0x0c: this.AM_Absolute(); break; // *NOP (absolute)
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case 0x0d: this.AM_Absolute(); this.OrR(); break; // ORA (absolute)
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case 0x0e: this.AM_Absolute(); this.ModifyWrite(this.ASL()); break; // ASL (absolute)
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case 0x0f: this.AM_Absolute(); this.SLO(); break; // *SLO (absolute)
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case 0x10: this.BranchNot(this.Negative); break; // BPL (relative)
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case 0x11: this.AM_IndirectIndexedY(); this.OrR(); break; // ORA (indirect indexed Y)
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case 0x12: this.Jam(); break; // *JAM
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case 0x13: this.Address_IndirectIndexedY(); this.FixupR(); this.SLO(); break; // *SLO (indirect indexed Y)
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case 0x14: this.AM_ZeroPageX(); break; // *NOP (zero page, X)
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case 0x15: this.AM_ZeroPageX(); this.OrR(); break; // ORA (zero page, X)
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case 0x16: this.AM_ZeroPageX(); this.ModifyWrite(this.ASL()); break; // ASL (zero page, X)
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case 0x17: this.AM_ZeroPageX(); this.SLO(); break; // *SLO (zero page, X)
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case 0x18: this.Swallow(); this.ResetFlag(StatusBits.CF); break; // CLC (implied)
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case 0x19: this.AM_AbsoluteY(); this.OrR(); break; // ORA (absolute, Y)
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case 0x1a: this.Swallow(); break; // *NOP (implied)
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case 0x1b: this.Address_AbsoluteY(); this.FixupR(); this.SLO(); break; // *SLO (absolute, Y)
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case 0x1c: this.Address_AbsoluteX(); this.MaybeFixupR(); break; // *NOP (absolute, X)
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case 0x1d: this.AM_AbsoluteX(); this.OrR(); break; // ORA (absolute, X)
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case 0x1e: this.Address_AbsoluteX(); this.FixupR(); this.ModifyWrite(this.ASL()); break; // ASL (absolute, X)
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case 0x1f: this.Address_AbsoluteX(); this.FixupR(); this.SLO(); break; // *SLO (absolute, X)
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case 0x20: this.JSR(); break; // JSR (absolute)
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case 0x21: this.AM_IndexedIndirectX(); this.AndR(); break; // AND (indexed indirect X)
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case 0x22: this.Jam(); break; // *JAM
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case 0x23: this.AM_IndexedIndirectX(); this.RLA(); ; break; // *RLA (indexed indirect X)
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case 0x24: this.AM_ZeroPage(); this.BIT(); break; // BIT (zero page)
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case 0x25: this.AM_ZeroPage(); this.AndR(); break; // AND (zero page)
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case 0x26: this.AM_ZeroPage(); this.ModifyWrite(this.ROL()); break; // ROL (zero page)
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case 0x27: this.AM_ZeroPage(); this.RLA(); ; break; // *RLA (zero page)
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case 0x28: this.Swallow(); this.PLP(); break; // PLP (implied)
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case 0x29: this.AM_Immediate(); this.AndR(); break; // AND (immediate)
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case 0x2a: this.Swallow(); this.A = this.ROL(this.A); break; // ROL A (implied)
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case 0x2b: this.AM_Immediate(); this.ANC(); break; // *ANC (immediate)
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case 0x2c: this.AM_Absolute(); this.BIT(); break; // BIT (absolute)
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case 0x2d: this.AM_Absolute(); this.AndR(); break; // AND (absolute)
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case 0x2e: this.AM_Absolute(); this.ModifyWrite(this.ROL()); break; // ROL (absolute)
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case 0x2f: this.AM_Absolute(); this.RLA(); break; // *RLA (absolute)
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case 0x30: this.Branch(this.Negative); break; // BMI (relative)
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case 0x31: this.AM_IndirectIndexedY(); this.AndR(); break; // AND (indirect indexed Y)
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case 0x32: this.Jam(); break; // *JAM
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case 0x33: this.Address_IndirectIndexedY(); this.FixupR(); this.RLA(); break; // *RLA (indirect indexed Y)
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case 0x34: this.AM_ZeroPageX(); break; // *NOP (zero page, X)
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case 0x35: this.AM_ZeroPageX(); this.AndR(); break; // AND (zero page, X)
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case 0x36: this.AM_ZeroPageX(); this.ModifyWrite(this.ROL()); break; // ROL (zero page, X)
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case 0x37: this.AM_ZeroPageX(); this.RLA(); ; break; // *RLA (zero page, X)
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case 0x38: this.Swallow(); this.SetFlag(StatusBits.CF); break; // SEC (implied)
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case 0x39: this.AM_AbsoluteY(); this.AndR(); break; // AND (absolute, Y)
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case 0x3a: this.Swallow(); break; // *NOP (implied)
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case 0x3b: this.Address_AbsoluteY(); this.FixupR(); this.RLA(); break; // *RLA (absolute, Y)
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case 0x3c: this.Address_AbsoluteX(); this.MaybeFixupR(); break; // *NOP (absolute, X)
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case 0x3d: this.AM_AbsoluteX(); this.AndR(); break; // AND (absolute, X)
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case 0x3e: this.Address_AbsoluteX(); this.FixupR(); this.ModifyWrite(this.ROL()); break; // ROL (absolute, X)
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case 0x3f: this.Address_AbsoluteX(); this.FixupR(); this.RLA(); break; // *RLA (absolute, X)
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case 0x40: this.Swallow(); this.RTI(); break; // RTI (implied)
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case 0x41: this.AM_IndexedIndirectX(); this.EorR(); break; // EOR (indexed indirect X)
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case 0x42: this.Jam(); break; // *JAM
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case 0x43: this.AM_IndexedIndirectX(); this.SRE(); break; // *SRE (indexed indirect X)
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case 0x44: this.AM_ZeroPage(); break; // *NOP (zero page)
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case 0x45: this.AM_ZeroPage(); this.EorR(); break; // EOR (zero page)
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case 0x46: this.AM_ZeroPage(); this.ModifyWrite(this.LSR()); break; // LSR (zero page)
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case 0x47: this.AM_ZeroPage(); this.SRE(); break; // *SRE (zero page)
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case 0x48: this.Swallow(); this.Push(this.A); break; // PHA (implied)
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case 0x49: this.AM_Immediate(); this.EorR(); break; // EOR (immediate)
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case 0x4a: this.Swallow(); this.A = this.LSR(this.A); break; // LSR A (implied)
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case 0x4b: this.AM_Immediate(); this.ASR(); break; // *ASR (immediate)
|
|
case 0x4c: this.Address_Absolute(); this.Jump(this.Bus.Address.Word); break; // JMP (absolute)
|
|
case 0x4d: this.AM_Absolute(); this.EorR(); break; // EOR (absolute)
|
|
case 0x4e: this.AM_Absolute(); this.ModifyWrite(this.LSR()); break; // LSR (absolute)
|
|
case 0x4f: this.AM_Absolute(); this.SRE(); break; // *SRE (absolute)
|
|
|
|
case 0x50: this.BranchNot(this.Overflow); break; // BVC (relative)
|
|
case 0x51: this.AM_IndirectIndexedY(); this.EorR(); break; // EOR (indirect indexed Y)
|
|
case 0x52: this.Jam(); break; // *JAM
|
|
case 0x53: this.Address_IndirectIndexedY(); this.FixupR(); this.SRE(); break; // *SRE (indirect indexed Y)
|
|
case 0x54: this.AM_ZeroPageX(); break; // *NOP (zero page, X)
|
|
case 0x55: this.AM_ZeroPageX(); this.EorR(); break; // EOR (zero page, X)
|
|
case 0x56: this.AM_ZeroPageX(); this.ModifyWrite(this.LSR()); break; // LSR (zero page, X)
|
|
case 0x57: this.AM_ZeroPageX(); this.SRE(); break; // *SRE (zero page, X)
|
|
case 0x58: this.Swallow(); this.ResetFlag(StatusBits.IF); break; // CLI (implied)
|
|
case 0x59: this.AM_AbsoluteY(); this.EorR(); break; // EOR (absolute, Y)
|
|
case 0x5a: this.Swallow(); break; // *NOP (implied)
|
|
case 0x5b: this.Address_AbsoluteY(); this.FixupR(); this.SRE(); break; // *SRE (absolute, Y)
|
|
case 0x5c: this.Address_AbsoluteX(); this.MaybeFixupR(); break; // *NOP (absolute, X)
|
|
case 0x5d: this.AM_AbsoluteX(); this.EorR(); break; // EOR (absolute, X)
|
|
case 0x5e: this.Address_AbsoluteX(); this.FixupR(); this.ModifyWrite(this.LSR()); break; // LSR (absolute, X)
|
|
case 0x5f: this.Address_AbsoluteX(); this.FixupR(); this.SRE(); break; // *SRE (absolute, X)
|
|
|
|
case 0x60: this.Swallow(); this.RTS(); break; // RTS (implied)
|
|
case 0x61: this.AM_IndexedIndirectX(); this.ADC(); break; // ADC (indexed indirect X)
|
|
case 0x62: this.Jam(); break; // *JAM
|
|
case 0x63: this.AM_IndexedIndirectX(); this.RRA(); break; // *RRA (indexed indirect X)
|
|
case 0x64: this.AM_ZeroPage(); break; // *NOP (zero page)
|
|
case 0x65: this.AM_ZeroPage(); this.ADC(); break; // ADC (zero page)
|
|
case 0x66: this.AM_ZeroPage(); this.ModifyWrite(this.ROR()); break; // ROR (zero page)
|
|
case 0x67: this.AM_ZeroPage(); this.RRA(); break; // *RRA (zero page)
|
|
case 0x68: this.Swallow(); this.SwallowStack(); this.A = this.Through(this.Pop()); break; // PLA (implied)
|
|
case 0x69: this.AM_Immediate(); this.ADC(); break; // ADC (immediate)
|
|
case 0x6a: this.Swallow(); this.A = this.ROR(this.A); break; // ROR A (implied)
|
|
case 0x6b: this.AM_Immediate(); this.ARR(); break; // *ARR (immediate)
|
|
case 0x6c: this.Address_Indirect(); this.Jump(this.Bus.Address.Word); break; // JMP (indirect)
|
|
case 0x6d: this.AM_Absolute(); this.ADC(); break; // ADC (absolute)
|
|
case 0x6e: this.AM_Absolute(); this.ModifyWrite(this.ROR()); break; // ROR (absolute)
|
|
case 0x6f: this.AM_Absolute(); this.RRA(); break; // *RRA (absolute)
|
|
|
|
case 0x70: this.Branch(this.Overflow); break; // BVS (relative)
|
|
case 0x71: this.AM_IndirectIndexedY(); this.ADC(); break; // ADC (indirect indexed Y)
|
|
case 0x72: this.Jam(); break; // *JAM
|
|
case 0x73: this.Address_IndirectIndexedY(); this.FixupR(); this.RRA(); break; // *RRA (indirect indexed Y)
|
|
case 0x74: this.AM_ZeroPageX(); break; // *NOP (zero page, X)
|
|
case 0x75: this.AM_ZeroPageX(); this.ADC(); break; // ADC (zero page, X)
|
|
case 0x76: this.AM_ZeroPageX(); this.ModifyWrite(this.ROR()); break; // ROR (zero page, X)
|
|
case 0x77: this.AM_ZeroPageX(); this.RRA(); break; // *RRA (zero page, X)
|
|
case 0x78: this.Swallow(); this.SetFlag(StatusBits.IF); break; // SEI (implied)
|
|
case 0x79: this.AM_AbsoluteY(); this.ADC(); break; // ADC (absolute, Y)
|
|
case 0x7a: this.Swallow(); break; // *NOP (implied)
|
|
case 0x7b: this.Address_AbsoluteY(); this.FixupR(); this.RRA(); break; // *RRA (absolute, Y)
|
|
case 0x7c: this.Address_AbsoluteX(); this.MaybeFixupR(); break; // *NOP (absolute, X)
|
|
case 0x7d: this.AM_AbsoluteX(); this.ADC(); break; // ADC (absolute, X)
|
|
case 0x7e: this.Address_AbsoluteX(); this.FixupR(); this.ModifyWrite(this.ROR()); break; // ROR (absolute, X)
|
|
case 0x7f: this.Address_AbsoluteX(); this.FixupR(); this.RRA(); break; // *RRA (absolute, X)
|
|
|
|
case 0x80: this.AM_Immediate(); break; // *NOP (immediate)
|
|
case 0x81: this.Address_IndexedIndirectX(); this.MemoryWrite(A); break; // STA (indexed indirect X)
|
|
case 0x82: this.AM_Immediate(); break; // *NOP (immediate)
|
|
case 0x83: this.Address_IndexedIndirectX(); this.MemoryWrite((byte)(this.A & this.X)); break; // *SAX (indexed indirect X)
|
|
case 0x84: this.Address_ZeroPage(); this.MemoryWrite(this.Y); break; // STY (zero page)
|
|
case 0x85: this.Address_ZeroPage(); this.MemoryWrite(this.A); break; // STA (zero page)
|
|
case 0x86: this.Address_ZeroPage(); this.MemoryWrite(this.X); break; // STX (zero page)
|
|
case 0x87: this.Address_ZeroPage(); this.MemoryWrite((byte)(this.A & this.X)); break; // *SAX (zero page)
|
|
case 0x88: this.Swallow(); this.Y = this.DEC(this.Y); break; // DEY (implied)
|
|
case 0x89: this.AM_Immediate(); break; // *NOP (immediate)
|
|
case 0x8a: this.Swallow(); this.A = this.Through(this.X); break; // TXA (implied)
|
|
case 0x8b: this.AM_Immediate(); this.ANE(); break; // *ANE (immediate)
|
|
case 0x8c: this.Address_Absolute(); this.MemoryWrite(this.Y); break; // STY (absolute)
|
|
case 0x8d: this.Address_Absolute(); this.MemoryWrite(this.A); break; // STA (absolute)
|
|
case 0x8e: this.Address_Absolute(); this.MemoryWrite(this.X); break; // STX (absolute)
|
|
case 0x8f: this.Address_Absolute(); this.MemoryWrite((byte)(this.A & this.X)); break; // *SAX (absolute)
|
|
|
|
case 0x90: this.BranchNot(this.Carry); break; // BCC (relative)
|
|
case 0x91: this.Address_IndirectIndexedY(); this.Fixup(); this.MemoryWrite(this.A); break; // STA (indirect indexed Y)
|
|
case 0x92: this.Jam(); break; // *JAM
|
|
case 0x93: this.Address_IndirectIndexedY(); this.Fixup(); this.SHA(); break; // *SHA (indirect indexed, Y)
|
|
case 0x94: this.Address_ZeroPageX(); this.MemoryWrite(this.Y); break; // STY (zero page, X)
|
|
case 0x95: this.Address_ZeroPageX(); this.MemoryWrite(this.A); break; // STA (zero page, X)
|
|
case 0x96: this.Address_ZeroPageY(); this.MemoryWrite(this.X); break; // STX (zero page, Y)
|
|
case 0x97: this.Address_ZeroPageY(); this.MemoryWrite((byte)(this.A & this.X)); break; // *SAX (zero page, Y)
|
|
case 0x98: this.Swallow(); this.A = this.Through(this.Y); break; // TYA (implied)
|
|
case 0x99: this.Address_AbsoluteY(); this.Fixup(); this.MemoryWrite(this.A); break; // STA (absolute, Y)
|
|
case 0x9a: this.Swallow(); this.S = this.X; break; // TXS (implied)
|
|
case 0x9b: this.Address_AbsoluteY(); this.Fixup(); this.TAS(); break; // *TAS (absolute, Y)
|
|
case 0x9c: this.Address_AbsoluteX(); this.Fixup(); this.SYA(); break; // *SYA (absolute, X)
|
|
case 0x9d: this.Address_AbsoluteX(); this.Fixup(); this.MemoryWrite(this.A); break; // STA (absolute, X)
|
|
case 0x9e: this.Address_AbsoluteY(); this.Fixup(); this.SXA(); break; // *SXA (absolute, Y)
|
|
case 0x9f: this.Address_AbsoluteY(); this.Fixup(); this.SHA(); break; // *SHA (absolute, Y)
|
|
|
|
case 0xa0: this.AM_Immediate(); this.Y = this.Through(); break; // LDY (immediate)
|
|
case 0xa1: this.AM_IndexedIndirectX(); this.A = this.Through(); break; // LDA (indexed indirect X)
|
|
case 0xa2: this.AM_Immediate(); this.X = this.Through(); break; // LDX (immediate)
|
|
case 0xa3: this.AM_IndexedIndirectX(); this.A = this.X = this.Through(); break; // *LAX (indexed indirect X)
|
|
case 0xa4: this.AM_ZeroPage(); this.Y = this.Through(); break; // LDY (zero page)
|
|
case 0xa5: this.AM_ZeroPage(); this.A = this.Through(); break; // LDA (zero page)
|
|
case 0xa6: this.AM_ZeroPage(); this.X = this.Through(); break; // LDX (zero page)
|
|
case 0xa7: this.AM_ZeroPage(); this.A = this.X = this.Through(); break; // *LAX (zero page)
|
|
case 0xa8: this.Swallow(); this.Y = Through(this.A); break; // TAY (implied)
|
|
case 0xa9: this.AM_Immediate(); this.A = this.Through(); break; // LDA (immediate)
|
|
case 0xaa: this.Swallow(); this.X = this.Through(this.A); break; // TAX (implied)
|
|
case 0xab: this.AM_Immediate(); this.ATX(); break; // *ATX (immediate)
|
|
case 0xac: this.AM_Absolute(); this.Y = this.Through(); break; // LDY (absolute)
|
|
case 0xad: this.AM_Absolute(); this.A = this.Through(); break; // LDA (absolute)
|
|
case 0xae: this.AM_Absolute(); this.X = this.Through(); break; // LDX (absolute)
|
|
case 0xaf: this.AM_Absolute(); this.A = this.X = this.Through(); break; // *LAX (absolute)
|
|
|
|
case 0xb0: this.Branch(this.Carry); break; // BCS (relative)
|
|
case 0xb1: this.AM_IndirectIndexedY(); this.A = this.Through(); break; // LDA (indirect indexed Y)
|
|
case 0xb2: this.Jam(); break; // *JAM
|
|
case 0xb3: this.AM_IndirectIndexedY(); this.A = this.X = this.Through(); break; // *LAX (indirect indexed Y)
|
|
case 0xb4: this.AM_ZeroPageX(); this.Y = this.Through(); break; // LDY (zero page, X)
|
|
case 0xb5: this.AM_ZeroPageX(); this.A = this.Through(); break; // LDA (zero page, X)
|
|
case 0xb6: this.AM_ZeroPageY(); this.X = this.Through(); break; // LDX (zero page, Y)
|
|
case 0xb7: this.AM_ZeroPageY(); this.A = this.X = this.Through(); break; // *LAX (zero page, Y)
|
|
case 0xb8: this.Swallow(); this.ResetFlag(StatusBits.VF); break; // CLV (implied)
|
|
case 0xb9: this.AM_AbsoluteY(); this.A = this.Through(); break; // LDA (absolute, Y)
|
|
case 0xba: this.Swallow(); this.X = this.Through(this.S); break; // TSX (implied)
|
|
case 0xbb: this.Address_AbsoluteY(); this.MaybeFixup(); this.LAS(); break; // *LAS (absolute, Y)
|
|
case 0xbc: this.AM_AbsoluteX(); this.Y = this.Through(); break; // LDY (absolute, X)
|
|
case 0xbd: this.AM_AbsoluteX(); this.A = this.Through(); break; // LDA (absolute, X)
|
|
case 0xbe: this.AM_AbsoluteY(); this.X = this.Through(); break; // LDX (absolute, Y)
|
|
case 0xbf: this.AM_AbsoluteY(); this.A = this.X = this.Through(); break; // *LAX (absolute, Y)
|
|
|
|
case 0xc0: this.AM_Immediate(); this.CMP(this.Y); break; // CPY (immediate)
|
|
case 0xc1: this.AM_IndexedIndirectX(); this.CMP(this.A); break; // CMP (indexed indirect X)
|
|
case 0xc2: this.AM_Immediate(); break; // *NOP (immediate)
|
|
case 0xc3: this.AM_IndexedIndirectX(); this.DCP(); break; // *DCP (indexed indirect X)
|
|
case 0xc4: this.AM_ZeroPage(); this.CMP(this.Y); break; // CPY (zero page)
|
|
case 0xc5: this.AM_ZeroPage(); this.CMP(this.A); break; // CMP (zero page)
|
|
case 0xc6: this.AM_ZeroPage(); this.ModifyWrite(this.DEC()); break; // DEC (zero page)
|
|
case 0xc7: this.AM_ZeroPage(); this.DCP(); break; // *DCP (zero page)
|
|
case 0xc8: this.Swallow(); this.Y = this.INC(this.Y); break; // INY (implied)
|
|
case 0xc9: this.AM_Immediate(); this.CMP(this.A); break; // CMP (immediate)
|
|
case 0xca: this.Swallow(); this.X = this.DEC(this.X); break; // DEX (implied)
|
|
case 0xcb: this.AM_Immediate(); this.AXS(); break; // *AXS (immediate)
|
|
case 0xcc: this.AM_Absolute(); this.CMP(this.Y); break; // CPY (absolute)
|
|
case 0xcd: this.AM_Absolute(); this.CMP(this.A); break; // CMP (absolute)
|
|
case 0xce: this.AM_Absolute(); this.ModifyWrite(this.DEC()); break; // DEC (absolute)
|
|
case 0xcf: this.AM_Absolute(); this.DCP(); break; // *DCP (absolute)
|
|
|
|
case 0xd0: this.BranchNot(this.Zero); break; // BNE (relative)
|
|
case 0xd1: this.AM_IndirectIndexedY(); this.CMP(this.A); break; // CMP (indirect indexed Y)
|
|
case 0xd2: this.Jam(); break; // *JAM
|
|
case 0xd3: this.Address_IndirectIndexedY(); this.FixupR(); this.DCP(); break; // *DCP (indirect indexed Y)
|
|
case 0xd4: this.AM_ZeroPageX(); break; // *NOP (zero page, X)
|
|
case 0xd5: this.AM_ZeroPageX(); this.CMP(this.A); break; // CMP (zero page, X)
|
|
case 0xd6: this.AM_ZeroPageX(); this.ModifyWrite(this.DEC()); break; // DEC (zero page, X)
|
|
case 0xd7: this.AM_ZeroPageX(); this.DCP(); break; // *DCP (zero page, X)
|
|
case 0xd8: this.Swallow(); this.ResetFlag(StatusBits.DF); break; // CLD (implied)
|
|
case 0xd9: this.AM_AbsoluteY(); this.CMP(this.A); break; // CMP (absolute, Y)
|
|
case 0xda: this.Swallow(); break; // *NOP (implied)
|
|
case 0xdb: this.Address_AbsoluteY(); this.FixupR(); this.DCP(); break; // *DCP (absolute, Y)
|
|
case 0xdc: this.Address_AbsoluteX(); this.MaybeFixupR(); break; // *NOP (absolute, X)
|
|
case 0xdd: this.AM_AbsoluteX(); this.CMP(this.A); break; // CMP (absolute, X)
|
|
case 0xde: this.Address_AbsoluteX(); this.FixupR(); this.ModifyWrite(this.DEC()); break; // DEC (absolute, X)
|
|
case 0xdf: this.Address_AbsoluteX(); this.FixupR(); this.DCP(); break; // *DCP (absolute, X)
|
|
|
|
case 0xe0: this.AM_Immediate(); this.CMP(this.X); break; // CPX (immediate)
|
|
case 0xe1: this.AM_IndexedIndirectX(); this.SBC(); break; // SBC (indexed indirect X)
|
|
case 0xe2: this.AM_Immediate(); break; // *NOP (immediate)
|
|
case 0xe3: this.AM_IndexedIndirectX(); this.ISB(); break; // *ISB (indexed indirect X)
|
|
case 0xe4: this.AM_ZeroPage(); this.CMP(this.X); break; // CPX (zero page)
|
|
case 0xe5: this.AM_ZeroPage(); this.SBC(); break; // SBC (zero page)
|
|
case 0xe6: this.AM_ZeroPage(); this.ModifyWrite(INC()); break; // INC (zero page)
|
|
case 0xe7: this.AM_ZeroPage(); this.ISB(); break; // *ISB (zero page)
|
|
case 0xe8: this.Swallow(); this.X = this.INC(this.X); break; // INX (implied)
|
|
case 0xe9: this.AM_Immediate(); this.SBC(); break; // SBC (immediate)
|
|
case 0xea: this.Swallow(); break; // NOP (implied)
|
|
case 0xeb: this.AM_Immediate(); this.SBC(); break; // *SBC (immediate)
|
|
case 0xec: this.AM_Absolute(); this.CMP(this.X); break; // CPX (absolute)
|
|
case 0xed: this.AM_Absolute(); this.SBC(); break; // SBC (absolute)
|
|
case 0xee: this.AM_Absolute(); this.ModifyWrite(this.INC()); break; // INC (absolute)
|
|
case 0xef: this.AM_Absolute(); this.ISB(); break; // *ISB (absolute)
|
|
|
|
case 0xf0: this.Branch(this.Zero); break; // BEQ (relative)
|
|
case 0xf1: this.AM_IndirectIndexedY(); this.SBC(); break; // SBC (indirect indexed Y)
|
|
case 0xf2: this.Jam(); break; // *JAM
|
|
case 0xf3: this.Address_IndirectIndexedY(); this.FixupR(); this.ISB(); break; // *ISB (indirect indexed Y)
|
|
case 0xf4: this.AM_ZeroPageX(); break; // *NOP (zero page, X)
|
|
case 0xf5: this.AM_ZeroPageX(); this.SBC(); break; // SBC (zero page, X)
|
|
case 0xf6: this.AM_ZeroPageX(); this.ModifyWrite(this.INC()); break; // INC (zero page, X)
|
|
case 0xf7: this.AM_ZeroPageX(); this.ISB(); break; // *ISB (zero page, X)
|
|
case 0xf8: this.Swallow(); this.SetFlag(StatusBits.DF); break; // SED (implied)
|
|
case 0xf9: this.AM_AbsoluteY(); this.SBC(); break; // SBC (absolute, Y)
|
|
case 0xfa: this.Swallow(); break; // *NOP (implied)
|
|
case 0xfb: this.Address_AbsoluteY(); this.FixupR(); this.ISB(); break; // *ISB (absolute, Y)
|
|
case 0xfc: this.Address_AbsoluteX(); this.MaybeFixupR(); break; // *NOP (absolute, X)
|
|
case 0xfd: this.AM_AbsoluteX(); this.SBC(); break; // SBC (absolute, X)
|
|
case 0xfe: this.Address_AbsoluteX(); this.FixupR(); this.ModifyWrite(this.INC()); break; // INC (absolute, X)
|
|
case 0xff: this.Address_AbsoluteX(); this.FixupR(); this.ISB(); break; // *ISB (absolute, X)
|
|
}
|
|
}
|
|
|
|
public override int Step()
|
|
{
|
|
this.ResetCycles();
|
|
this.OnExecutingInstruction();
|
|
if (this.Powered)
|
|
{
|
|
this.Tick();
|
|
if (this.SO.Lowered())
|
|
{
|
|
this.HandleSO();
|
|
}
|
|
|
|
if (this.RDY.Raised())
|
|
{
|
|
this.FetchInstruction();
|
|
if (this.RESET.Lowered())
|
|
{
|
|
this.HandleRESET();
|
|
}
|
|
else if (this.NMI.Lowered())
|
|
{
|
|
this.HandleNMI();
|
|
}
|
|
else if (this.INT.Lowered() && (this.InterruptMasked == 0))
|
|
{
|
|
this.HandleINT();
|
|
}
|
|
else
|
|
{
|
|
this.Execute();
|
|
}
|
|
}
|
|
}
|
|
|
|
this.OnExecutedInstruction();
|
|
return this.Cycles;
|
|
}
|
|
|
|
private void FetchInstruction()
|
|
{
|
|
// Instruction fetch beginning
|
|
this.LowerSYNC();
|
|
|
|
System.Diagnostics.Debug.Assert(this.Cycles == 1, "An extra cycle has occurred");
|
|
|
|
// Can't use fetchByte, since that would add an extra tick.
|
|
this.Address_Immediate();
|
|
this.OpCode = this.ReadFromBus();
|
|
|
|
System.Diagnostics.Debug.Assert(this.Cycles == 1, "BUS read has introduced stray cycles");
|
|
|
|
// Instruction fetch has now completed
|
|
this.RaiseSYNC();
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Bus/Memory access
|
|
|
|
protected override sealed void BusWrite()
|
|
{
|
|
this.Tick();
|
|
this.WriteToBus();
|
|
}
|
|
|
|
protected override sealed byte BusRead()
|
|
{
|
|
this.Tick();
|
|
return this.ReadFromBus();
|
|
}
|
|
|
|
private byte ReadFromBus()
|
|
{
|
|
this.RaiseRW();
|
|
return base.BusRead();
|
|
}
|
|
|
|
private void WriteToBus()
|
|
{
|
|
this.LowerRW();
|
|
base.BusWrite();
|
|
}
|
|
|
|
private void ModifyWrite(byte data)
|
|
{
|
|
// The read will have already taken place...
|
|
this.MemoryWrite();
|
|
this.MemoryWrite(data);
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Stack access
|
|
|
|
protected override byte Pop()
|
|
{
|
|
this.RaiseStack();
|
|
return this.MemoryRead();
|
|
}
|
|
|
|
protected override void Push(byte value)
|
|
{
|
|
this.LowerStack();
|
|
this.MemoryWrite(value);
|
|
}
|
|
|
|
private void UpdateStack(byte position)
|
|
{
|
|
this.Bus.Address.Low = position;
|
|
this.Bus.Address.High = 1;
|
|
}
|
|
|
|
private void LowerStack() => this.UpdateStack(this.S--);
|
|
|
|
private void RaiseStack() => this.UpdateStack(++this.S);
|
|
|
|
private void DummyPush()
|
|
{
|
|
this.LowerStack();
|
|
this.Tick(); // In place of the memory write
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Addressing modes
|
|
|
|
#region Address page fixup
|
|
|
|
private byte fixedPage;
|
|
|
|
private void MaybeFixup()
|
|
{
|
|
if (this.Bus.Address.High != this.fixedPage)
|
|
{
|
|
this.Fixup();
|
|
}
|
|
}
|
|
|
|
private void Fixup()
|
|
{
|
|
this.MemoryRead();
|
|
this.Bus.Address.High = this.fixedPage;
|
|
}
|
|
|
|
private void MaybeFixupR()
|
|
{
|
|
this.MaybeFixup();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
private void FixupR()
|
|
{
|
|
this.Fixup();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Address resolution
|
|
|
|
private void NoteFixedAddress(int address)
|
|
{
|
|
this.NoteFixedAddress((ushort)address);
|
|
}
|
|
|
|
private void NoteFixedAddress(ushort address)
|
|
{
|
|
this.intermediate.Word = address;
|
|
this.fixedPage = this.intermediate.High;
|
|
this.Bus.Address.Low = this.intermediate.Low;
|
|
}
|
|
|
|
private void Address_Immediate() => this.Bus.Address.Word = this.PC.Word++;
|
|
|
|
private void Address_Absolute() => this.Bus.Address.Word = this.FetchWord().Word;
|
|
|
|
private void Address_ZeroPage()
|
|
{
|
|
this.Bus.Address.Low = this.FetchByte();
|
|
this.Bus.Address.High = 0;
|
|
}
|
|
|
|
private void Address_ZeroPageIndirect()
|
|
{
|
|
this.Address_ZeroPage();
|
|
this.Bus.Address.Word = this.GetWordPaged().Word;
|
|
}
|
|
|
|
private void Address_Indirect()
|
|
{
|
|
this.Address_Absolute();
|
|
this.Bus.Address.Word = this.GetWordPaged().Word;
|
|
}
|
|
|
|
private void Address_ZeroPageWithIndex(byte index)
|
|
{
|
|
this.AM_ZeroPage();
|
|
this.Bus.Address.Low += index;
|
|
}
|
|
|
|
private void Address_ZeroPageX() => this.Address_ZeroPageWithIndex(this.X);
|
|
|
|
private void Address_ZeroPageY() => this.Address_ZeroPageWithIndex(this.Y);
|
|
|
|
private void Address_AbsoluteWithIndex(byte index)
|
|
{
|
|
this.Address_Absolute();
|
|
this.NoteFixedAddress(this.Bus.Address.Word + index);
|
|
}
|
|
|
|
private void Address_AbsoluteX() => this.Address_AbsoluteWithIndex(X);
|
|
|
|
private void Address_AbsoluteY() => this.Address_AbsoluteWithIndex(Y);
|
|
|
|
private void Address_IndexedIndirectX()
|
|
{
|
|
this.Address_ZeroPageX();
|
|
this.Bus.Address.Word = this.GetWordPaged().Word;
|
|
}
|
|
|
|
private void Address_IndirectIndexedY()
|
|
{
|
|
this.Address_ZeroPageIndirect();
|
|
this.NoteFixedAddress(this.Bus.Address.Word + Y);
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Address and read
|
|
|
|
private void AM_Immediate()
|
|
{
|
|
this.Address_Immediate();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
private void AM_Absolute()
|
|
{
|
|
this.Address_Absolute();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
private void AM_ZeroPage()
|
|
{
|
|
this.Address_ZeroPage();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
private void AM_ZeroPageX()
|
|
{
|
|
this.Address_ZeroPageX();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
private void AM_ZeroPageY()
|
|
{
|
|
this.Address_ZeroPageY();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
private void AM_IndexedIndirectX()
|
|
{
|
|
this.Address_IndexedIndirectX();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
private void AM_AbsoluteX()
|
|
{
|
|
this.Address_AbsoluteX();
|
|
this.MaybeFixupR();
|
|
}
|
|
|
|
private void AM_AbsoluteY()
|
|
{
|
|
this.Address_AbsoluteY();
|
|
this.MaybeFixupR();
|
|
}
|
|
|
|
private void AM_IndirectIndexedY()
|
|
{
|
|
this.Address_IndirectIndexedY();
|
|
this.MaybeFixupR();
|
|
}
|
|
|
|
#endregion
|
|
|
|
#endregion
|
|
|
|
#region Branching
|
|
|
|
private void BranchNot(int condition) => this.Branch(condition == 0);
|
|
|
|
private void Branch(int condition) => this.Branch(condition != 0);
|
|
|
|
private void Branch(bool condition)
|
|
{
|
|
this.AM_Immediate();
|
|
if (condition)
|
|
{
|
|
var relative = (sbyte)this.Bus.Data;
|
|
this.Swallow();
|
|
this.NoteFixedAddress(this.PC.Word + relative);
|
|
this.MaybeFixup();
|
|
this.Jump(this.Bus.Address.Word);
|
|
}
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Data flag adjustment
|
|
|
|
private void AdjustZero(byte datum) => this.ResetFlag(StatusBits.ZF, datum);
|
|
|
|
private void AdjustNegative(byte datum) => this.SetFlag(StatusBits.NF, NegativeTest(datum));
|
|
|
|
private void AdjustNZ(byte datum)
|
|
{
|
|
this.AdjustZero(datum);
|
|
this.AdjustNegative(datum);
|
|
}
|
|
|
|
private byte Through() => this.Through(this.Bus.Data);
|
|
|
|
private byte Through(int data) => this.Through((byte)data);
|
|
|
|
private byte Through(byte data)
|
|
{
|
|
this.AdjustNZ(data);
|
|
return data;
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Instruction implementations
|
|
|
|
#region Instructions with BCD effects
|
|
|
|
private void AdjustOverflow_add(byte operand)
|
|
{
|
|
var data = Bus.Data;
|
|
var intermediate = this.intermediate.Low;
|
|
this.SetFlag(StatusBits.VF, NegativeTest((byte)(~(operand ^ data) & (operand ^ intermediate))));
|
|
}
|
|
|
|
private void AdjustOverflow_subtract(byte operand)
|
|
{
|
|
var data = Bus.Data;
|
|
var intermediate = this.intermediate.Low;
|
|
this.SetFlag(StatusBits.VF, NegativeTest((byte)((operand ^ data) & (operand ^ intermediate))));
|
|
}
|
|
|
|
#region Addition/subtraction
|
|
|
|
#region Subtraction
|
|
|
|
private void SBC()
|
|
{
|
|
var operand = this.A;
|
|
A = this.SUB(operand, CarryTest((byte)~this.P));
|
|
|
|
this.AdjustOverflow_subtract(operand);
|
|
this.AdjustNZ(this.intermediate.Low);
|
|
this.ResetFlag(StatusBits.CF, this.intermediate.High);
|
|
}
|
|
|
|
private byte SUB(byte operand, int borrow) => this.Decimal != 0 ? SUB_d(operand, borrow) : SUB_b(operand, borrow);
|
|
|
|
private byte SUB_b(byte operand, int borrow = 0)
|
|
{
|
|
var data = Bus.Data;
|
|
this.intermediate.Word = (ushort)(operand - data - borrow);
|
|
return this.intermediate.Low;
|
|
}
|
|
|
|
private byte SUB_d(byte operand, int borrow)
|
|
{
|
|
_ = this.SUB_b(operand, borrow);
|
|
|
|
var data = this.Bus.Data;
|
|
var low = (byte)(LowNibble(operand) - LowNibble(data) - borrow);
|
|
var lowNegative = NegativeTest(low);
|
|
if (lowNegative != 0)
|
|
{
|
|
low -= 6;
|
|
}
|
|
|
|
var high = (byte)(HighNibble(operand) - HighNibble(data) - (lowNegative >> 7));
|
|
var highNegative = NegativeTest(high);
|
|
if (highNegative != 0)
|
|
{
|
|
high -= 6;
|
|
}
|
|
|
|
return (byte)(PromoteNibble(high) | LowNibble(low));
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Addition
|
|
|
|
private void ADC()
|
|
{
|
|
if (this.Decimal != 0)
|
|
this.ADC_d();
|
|
else
|
|
this.ADC_b();
|
|
}
|
|
|
|
private void ADC_b()
|
|
{
|
|
var operand = A;
|
|
var data = Bus.Data;
|
|
this.intermediate.Word = (ushort)(operand + data + this.Carry);
|
|
|
|
this.AdjustOverflow_add(operand);
|
|
this.SetFlag(StatusBits.CF, CarryTest(this.intermediate.High));
|
|
|
|
this.AdjustNZ(intermediate.Low);
|
|
|
|
this.A = intermediate.Low;
|
|
}
|
|
|
|
private void ADC_d()
|
|
{
|
|
var operand = this.A;
|
|
var data = this.Bus.Data;
|
|
|
|
var low = (ushort)(LowerNibble(operand) + LowerNibble(data) + this.Carry);
|
|
this.intermediate.Word = (ushort)(HigherNibble(operand) + HigherNibble(data));
|
|
|
|
this.AdjustZero(LowByte((ushort)(low + this.intermediate.Word)));
|
|
|
|
if (low > 0x09)
|
|
{
|
|
this.intermediate.Word += 0x10;
|
|
low += 0x06;
|
|
}
|
|
|
|
this.AdjustNegative(this.intermediate.Low);
|
|
this.AdjustOverflow_add(operand);
|
|
|
|
if (this.intermediate.Word > 0x90)
|
|
this.intermediate.Word += 0x60;
|
|
|
|
this.SetFlag(StatusBits.CF, this.intermediate.High);
|
|
|
|
this.A = (byte)(LowerNibble(LowByte(low)) | HigherNibble(this.intermediate.Low));
|
|
}
|
|
|
|
#endregion
|
|
|
|
#endregion
|
|
|
|
#region ARR (undocument instruction)
|
|
|
|
private void ARR()
|
|
{
|
|
var value = this.Bus.Data;
|
|
if (this.Decimal != 0)
|
|
this.ARR_d(value);
|
|
else
|
|
this.ARR_b(value);
|
|
}
|
|
|
|
private void ARR_d(byte value)
|
|
{
|
|
// With thanks to https://github.com/TomHarte/CLK
|
|
// What a very strange instruction ARR is...
|
|
|
|
this.A &= value;
|
|
var unshiftedA = this.A;
|
|
this.A = this.Through((this.A >> 1) | (this.Carry << 7));
|
|
this.SetFlag(StatusBits.VF, OverflowTest((byte)(this.A ^ (this.A << 1))));
|
|
|
|
if (LowerNibble(unshiftedA) + (unshiftedA & 0x1) > 5)
|
|
this.A = (byte)(LowerNibble((byte)(this.A + 6)) | HigherNibble(this.A));
|
|
|
|
this.SetFlag(StatusBits.CF, HigherNibble(unshiftedA) + (unshiftedA & 0x10) > 0x50);
|
|
|
|
if (this.Carry != 0)
|
|
this.A += 0x60;
|
|
}
|
|
|
|
private void ARR_b(byte value)
|
|
{
|
|
this.A &= value;
|
|
this.A = this.Through((this.A >> 1) | (this.Carry << 7));
|
|
this.SetFlag(StatusBits.CF, OverflowTest(this.A));
|
|
this.SetFlag(StatusBits.VF, OverflowTest((byte)(this.A ^ (this.A << 1))));
|
|
}
|
|
|
|
#endregion
|
|
|
|
#endregion
|
|
|
|
#region Bitwise operations
|
|
|
|
private void OrR() => this.A = this.Through(this.A | this.Bus.Data);
|
|
|
|
private void AndR() => this.A = this.Through(this.A & this.Bus.Data);
|
|
|
|
private void EorR() => this.A = this.Through(this.A ^ this.Bus.Data);
|
|
|
|
private void BIT()
|
|
{
|
|
var data = this.Bus.Data;
|
|
this.SetFlag(StatusBits.VF, OverflowTest(data));
|
|
this.AdjustZero((byte)(this.A & data));
|
|
this.AdjustNegative(data);
|
|
}
|
|
|
|
#endregion
|
|
|
|
private void CMP(byte first)
|
|
{
|
|
var second = Bus.Data;
|
|
this.intermediate.Word = (ushort)(first - second);
|
|
AdjustNZ(this.intermediate.Low);
|
|
ResetFlag(StatusBits.CF, this.intermediate.High);
|
|
}
|
|
|
|
#region Increment/decrement
|
|
|
|
private byte DEC() => this.DEC(this.Bus.Data);
|
|
|
|
private byte DEC(byte value) => this.Through(value - 1);
|
|
|
|
private byte INC() => this.INC(this.Bus.Data);
|
|
|
|
private byte INC(byte value) => this.Through(value + 1);
|
|
|
|
#endregion
|
|
|
|
#region Stack operations
|
|
|
|
private void JSR()
|
|
{
|
|
this.intermediate.Low = this.FetchByte();
|
|
this.SwallowStack();
|
|
this.PushWord(this.PC);
|
|
this.intermediate.High = this.FetchByte();
|
|
this.PC.Word = this.intermediate.Word;
|
|
}
|
|
|
|
private void PHP() => this.Push(SetBit(this.P, StatusBits.BF));
|
|
|
|
private void PLP()
|
|
{
|
|
this.SwallowStack();
|
|
this.P = ClearBit(SetBit(this.Pop(), StatusBits.RF), StatusBits.BF);
|
|
}
|
|
|
|
private void RTI()
|
|
{
|
|
this.PLP();
|
|
this.Return();
|
|
}
|
|
|
|
private void RTS()
|
|
{
|
|
this.SwallowStack();
|
|
this.Return();
|
|
this.SwallowFetch();
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Shift/rotate operations
|
|
|
|
#region Shift
|
|
|
|
private byte ASL() => this.ASL(this.Bus.Data);
|
|
|
|
private byte ASL(byte value)
|
|
{
|
|
this.SetFlag(StatusBits.CF, NegativeTest(value));
|
|
return this.Through(value << 1);
|
|
}
|
|
|
|
private byte LSR() => this.LSR(this.Bus.Data);
|
|
|
|
private byte LSR(byte value)
|
|
{
|
|
this.SetFlag(StatusBits.CF, CarryTest(value));
|
|
return this.Through(value >> 1);
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Rotate
|
|
|
|
private byte ROL() => this.ROL(this.Bus.Data);
|
|
|
|
private byte ROL(byte value)
|
|
{
|
|
var carryIn = this.Carry;
|
|
return this.Through(this.ASL(value) | carryIn);
|
|
}
|
|
|
|
private byte ROR() => this.ROR(this.Bus.Data);
|
|
|
|
private byte ROR(byte value)
|
|
{
|
|
var carryIn = this.Carry;
|
|
return this.Through(this.LSR(value) | (carryIn << 7));
|
|
}
|
|
|
|
#endregion
|
|
|
|
#endregion
|
|
|
|
#region Undocumented instructions
|
|
|
|
#region Undocumented instructions with fixup effects
|
|
|
|
private void StoreFixupEffect(byte data)
|
|
{
|
|
var fixedAddress = (byte)(this.Bus.Address.High + 1);
|
|
this.MemoryWrite((byte)(data & fixedAddress));
|
|
}
|
|
|
|
private void SHA() => this.StoreFixupEffect((byte)(this.A & this.X));
|
|
|
|
private void SYA() => this.StoreFixupEffect(this.Y);
|
|
|
|
private void SXA() => this.StoreFixupEffect(this.X);
|
|
|
|
#endregion
|
|
|
|
private void ANC()
|
|
{
|
|
this.AndR();
|
|
this.SetFlag(StatusBits.CF, NegativeTest(this.A));
|
|
}
|
|
|
|
private void AXS()
|
|
{
|
|
this.X = this.Through(this.SUB_b((byte)(this.A & this.X)));
|
|
this.ResetFlag(StatusBits.CF, this.intermediate.High);
|
|
}
|
|
|
|
private void Jam()
|
|
{
|
|
this.Bus.Address.Word = this.PC.Word--;
|
|
this.MemoryRead();
|
|
this.MemoryRead();
|
|
}
|
|
|
|
|
|
private void TAS()
|
|
{
|
|
this.S = (byte)(this.A & this.X);
|
|
this.SHA();
|
|
}
|
|
|
|
private void LAS() => this.A = this.X = this.S = this.Through(this.MemoryRead() & this.S);
|
|
|
|
private void ANE() => this.A = this.Through((this.A | 0xee) & this.X & this.Bus.Data);
|
|
|
|
private void ATX() => this.A = this.X = this.Through((this.A | 0xee) & this.Bus.Data);
|
|
|
|
private void ASR()
|
|
{
|
|
this.AndR();
|
|
this.A = this.LSR(this.A);
|
|
}
|
|
|
|
private void ISB()
|
|
{
|
|
this.ModifyWrite(this.INC());
|
|
this.SBC();
|
|
}
|
|
|
|
private void RLA()
|
|
{
|
|
this.ModifyWrite(this.ROL());
|
|
this.AndR();
|
|
}
|
|
|
|
private void RRA()
|
|
{
|
|
this.ModifyWrite(this.ROR());
|
|
this.ADC();
|
|
}
|
|
|
|
private void SLO()
|
|
{
|
|
this.ModifyWrite(this.ASL());
|
|
this.OrR();
|
|
}
|
|
|
|
private void SRE()
|
|
{
|
|
this.ModifyWrite(this.LSR());
|
|
this.EorR();
|
|
}
|
|
|
|
private void DCP()
|
|
{
|
|
this.ModifyWrite(this.DEC());
|
|
this.CMP(this.A);
|
|
}
|
|
|
|
#endregion
|
|
|
|
#endregion
|
|
}
|
|
} |