841 lines
32 KiB
C#
841 lines
32 KiB
C#
// <copyright file="Intel8080.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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using System;
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public class Intel8080 : IntelProcessor
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{
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private readonly Register16 af = new Register16();
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private readonly InputOutput ports;
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private bool interruptEnable = false;
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public Intel8080(Bus bus, InputOutput ports)
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: base(bus) => this.ports = ports;
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public event EventHandler<EventArgs> ExecutingInstruction;
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public event EventHandler<EventArgs> ExecutedInstruction;
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public override Register16 AF
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{
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get
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{
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this.af.Low = (byte)((this.af.Low | (byte)Bits.Bit1) & (int)~(Bits.Bit5 | Bits.Bit3));
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return this.af;
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}
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}
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public override Register16 BC { get; } = new Register16((int)Mask.Sixteen);
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public override Register16 DE { get; } = new Register16((int)Mask.Sixteen);
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public override Register16 HL { get; } = new Register16((int)Mask.Sixteen);
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public override int Execute()
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{
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var decoded = this.GetDecodedOpCode(this.OpCode);
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var x = decoded.X;
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var y = decoded.Y;
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var z = decoded.Z;
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var p = decoded.P;
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var q = decoded.Q;
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this.Execute(x, y, z, p, q);
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return this.Cycles;
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}
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public override int Step()
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{
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this.ResetCycles();
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this.OnExecutingInstruction();
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if (this.Powered)
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{
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if (this.RESET.Lowered())
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{
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this.HandleRESET();
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}
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else if (this.INT.Lowered())
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{
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this.HandleINT();
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}
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else if (this.HALT.Lowered())
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{
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this.Execute(0); // NOP
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}
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else
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{
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this.Execute(this.FetchByte());
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}
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}
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this.OnExecutedInstruction();
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return this.Cycles;
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}
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protected virtual void OnExecutingInstruction() => this.ExecutingInstruction?.Invoke(this, EventArgs.Empty);
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protected virtual void OnExecutedInstruction() => this.ExecutedInstruction?.Invoke(this, EventArgs.Empty);
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protected override void HandleRESET()
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{
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base.HandleRESET();
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this.DisableInterrupts();
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this.Tick(3);
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}
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protected override void HandleINT()
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{
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base.HandleINT();
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this.RaiseHALT();
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if (this.interruptEnable)
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{
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this.DisableInterrupts();
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this.Execute(this.Bus.Data);
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this.Tick(3);
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}
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}
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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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private static byte AdjustSign(byte input, byte value) => SetBit(input, StatusBits.SF, value & (byte)StatusBits.SF);
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private static byte AdjustZero(byte input, byte value) => ClearBit(input, StatusBits.ZF, value);
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private static byte AdjustParity(byte input, byte value) => SetBit(input, StatusBits.PF, EvenParity(value));
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private static byte AdjustSZ(byte input, byte value)
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{
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input = AdjustSign(input, value);
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return AdjustZero(input, value);
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}
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private static byte AdjustSZP(byte input, byte value)
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{
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input = AdjustSZ(input, value);
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return AdjustParity(input, value);
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}
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private static byte AdjustAuxiliaryCarryAdd(byte input, byte before, byte value, int calculation) => SetBit(input, StatusBits.AC, CalculateHalfCarryAdd(before, value, calculation));
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private static byte AdjustAuxiliaryCarrySub(byte input, byte before, byte value, int calculation) => ClearBit(input, StatusBits.AC, CalculateHalfCarrySub(before, value, calculation));
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private void DisableInterrupts() => this.interruptEnable = false;
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private void EnableInterrupts() => this.interruptEnable = true;
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private byte R(int r)
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{
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switch (r)
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{
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case 0:
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return this.B;
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case 1:
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return this.C;
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case 2:
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return this.D;
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case 3:
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return this.E;
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case 4:
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return this.H;
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case 5:
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return this.L;
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case 6:
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return this.MemoryRead(this.HL.Word);
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case 7:
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return this.A;
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default:
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throw new ArgumentOutOfRangeException(nameof(r));
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}
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}
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private void R(int r, byte value)
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{
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switch (r)
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{
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case 0:
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this.B = value;
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break;
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case 1:
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this.C = value;
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break;
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case 2:
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this.D = value;
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break;
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case 3:
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this.E = value;
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break;
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case 4:
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this.H = value;
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break;
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case 5:
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this.L = value;
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break;
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case 6:
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this.MemoryWrite(this.HL.Word, value);
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break;
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case 7:
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this.A = value;
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break;
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default:
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throw new ArgumentOutOfRangeException(nameof(r));
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}
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}
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private Register16 RP(int rp)
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{
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switch (rp)
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{
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case 0:
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return this.BC;
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case 1:
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return this.DE;
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case 2:
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return this.HL;
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case 3:
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return this.SP;
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default:
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throw new ArgumentOutOfRangeException(nameof(rp));
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}
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}
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private Register16 RP2(int rp)
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{
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switch (rp)
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{
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case 0:
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return this.BC;
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case 1:
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return this.DE;
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case 2:
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return this.HL;
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case 3:
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return this.AF;
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default:
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throw new ArgumentOutOfRangeException(nameof(rp));
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}
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}
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private void Execute(int x, int y, int z, int p, int q)
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{
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switch (x)
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{
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case 0:
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switch (z)
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{
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case 0: // Relative jumps and assorted ops
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switch (y)
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{
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case 0: // NOP
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this.Tick(4);
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break;
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}
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break;
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case 1: // 16-bit load immediate/add
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switch (q)
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{
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case 0: // LD rp,nn
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this.RP(p).Word = this.FetchWord().Word;
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this.Tick(10);
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break;
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case 1: // ADD HL,rp
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this.Add(this.RP(p));
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this.Tick(11);
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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case 2: // Indirect loading
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switch (q)
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{
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case 0:
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switch (p)
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{
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case 0: // LD (BC),A
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this.MemoryWrite(this.BC, this.A);
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this.Tick(7);
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break;
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case 1: // LD (DE),A
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this.MemoryWrite(this.DE, this.A);
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this.Tick(7);
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break;
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case 2: // LD (nn),HL
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this.Bus.Address.Word = this.FetchWord().Word;
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this.SetWord(this.HL);
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this.Tick(16);
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break;
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case 3: // LD (nn),A
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this.Bus.Address.Word = this.FetchWord().Word;
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this.MemoryWrite(this.A);
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this.Tick(13);
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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case 1:
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switch (p)
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{
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case 0: // LD A,(BC)
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this.A = this.MemoryRead(this.BC);
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this.Tick(7);
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break;
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case 1: // LD A,(DE)
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this.A = this.MemoryRead(this.DE);
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this.Tick(7);
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break;
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case 2: // LD HL,(nn)
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this.Bus.Address.Word = this.FetchWord().Word;
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this.HL.Word = this.GetWord().Word;
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this.Tick(16);
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break;
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case 3: // LD A,(nn)
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this.Bus.Address.Word = this.FetchWord().Word;
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this.A = this.MemoryRead();
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this.Tick(13);
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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case 3: // 16-bit INC/DEC
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switch (q)
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{
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case 0: // INC rp
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++this.RP(p).Word;
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break;
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case 1: // DEC rp
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--this.RP(p).Word;
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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this.Tick(6);
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break;
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case 4: // 8-bit INC
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this.R(y, this.Increment(this.R(y)));
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this.Tick(4);
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break;
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case 5: // 8-bit DEC
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this.R(y, this.Decrement(this.R(y)));
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this.Tick(4);
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if (y == 6)
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{
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this.Tick(7);
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}
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break;
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case 6: // 8-bit load immediate
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this.R(y, this.FetchByte());
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this.Tick(7);
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if (y == 6)
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{
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this.Tick(3);
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}
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break;
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case 7: // Assorted operations on accumulator/flags
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switch (y)
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{
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case 0:
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this.A = this.RLC(this.A);
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break;
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case 1:
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this.A = this.RRC(this.A);
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break;
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case 2:
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this.A = this.RL(this.A);
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break;
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case 3:
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this.A = this.RR(this.A);
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break;
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case 4:
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this.DAA();
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break;
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case 5:
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this.CMA();
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break;
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case 6:
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this.STC();
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break;
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case 7:
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this.CMC();
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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this.Tick(4);
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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case 1: // 8-bit loading
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if (z == 6 && y == 6)
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{
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this.LowerHALT(); // Exception (replaces LD (HL), (HL))
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}
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else
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{
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this.R(y, this.R(z));
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if ((y == 6) || (z == 6))
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{
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this.Tick(3); // M operations
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}
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}
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this.Tick(4);
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break;
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case 2: // Operate on accumulator and register/memory location
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switch (y)
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{
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case 0: // ADD A,r
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this.Add(this.R(z));
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break;
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case 1: // ADC A,r
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this.ADC(this.R(z));
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break;
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case 2: // SUB r
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this.SUB(this.R(z));
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break;
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case 3: // SBC A,r
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this.SBB(this.R(z));
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break;
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case 4: // AND r
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this.AndR(this.R(z));
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break;
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case 5: // XOR r
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this.XorR(this.R(z));
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break;
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case 6: // OR r
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this.OrR(this.R(z));
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break;
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case 7: // CP r
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this.Compare(this.R(z));
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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this.Tick(4);
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if (z == 6)
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{
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this.Tick(3);
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}
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break;
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case 3:
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switch (z)
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{
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case 0: // Conditional return
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if (this.ReturnConditionalFlag(y))
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{
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this.Tick(6);
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}
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this.Tick(5);
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break;
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case 1: // POP & various ops
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switch (q)
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{
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case 0: // POP rp2[p]
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this.RP2(p).Word = this.PopWord().Word;
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this.Tick(10);
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break;
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case 1:
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switch (p)
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{
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case 0: // RET
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this.Return();
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this.Tick(10);
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break;
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case 2: // JP HL
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this.Jump(this.HL.Word);
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this.Tick(4);
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break;
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case 3: // LD SP,HL
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this.SP.Word = this.HL.Word;
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this.Tick(4);
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break;
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}
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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case 2: // Conditional jump
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this.JumpConditionalFlag(y);
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this.Tick(10);
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break;
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case 3: // Assorted operations
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switch (y)
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{
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case 0: // JP nn
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this.Jump(this.FetchWord().Word);
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this.Tick(10);
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break;
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case 2: // OUT (n),A
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this.WritePort(this.FetchByte());
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this.Tick(11);
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break;
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case 3: // IN A,(n)
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this.A = this.ReadPort(this.FetchByte());
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this.Tick(11);
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break;
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case 4: // EX (SP),HL
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this.XHTL(this.HL);
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this.Tick(19);
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break;
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case 5: // EX DE,HL
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(this.DE.Word, this.HL.Word) = (this.HL.Word, this.DE.Word);
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this.Tick(4);
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break;
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case 6: // DI
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this.DisableInterrupts();
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this.Tick(4);
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break;
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case 7: // EI
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this.EnableInterrupts();
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this.Tick(4);
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break;
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}
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break;
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case 4: // Conditional call: CALL cc[y], nn
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if (this.CallConditionalFlag(y))
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{
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this.Tick(7);
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}
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this.Tick(10);
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break;
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case 5: // PUSH & various ops
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switch (q)
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{
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case 0: // PUSH rp2[p]
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this.PushWord(this.RP2(p));
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this.Tick(11);
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break;
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case 1:
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switch (p)
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{
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case 0: // CALL nn
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this.Call(this.FetchWord().Word);
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this.Tick(17);
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break;
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}
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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case 6: // Operate on accumulator and immediate operand: alu[y] n
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switch (y)
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{
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case 0: // ADD A,n
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this.Add(this.FetchByte());
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break;
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case 1: // ADC A,n
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this.ADC(this.FetchByte());
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break;
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case 2: // SUB n
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this.SUB(this.FetchByte());
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break;
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case 3: // SBC A,n
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this.SBB(this.FetchByte());
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break;
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case 4: // AND n
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this.AndR(this.FetchByte());
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break;
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case 5: // XOR n
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this.XorR(this.FetchByte());
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break;
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case 6: // OR n
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this.OrR(this.FetchByte());
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break;
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case 7: // CP n
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this.Compare(this.FetchByte());
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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this.Tick(7);
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break;
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case 7: // Restart: RST y * 8
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this.Restart((byte)(y << 3));
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this.Tick(11);
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break;
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default:
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throw new NotSupportedException("Invalid operation mode");
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}
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break;
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}
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}
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private byte Increment(byte operand)
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{
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this.F = AdjustSZP(this.F, ++operand);
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this.F = ClearBit(this.F, StatusBits.AC, LowNibble(operand));
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return operand;
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}
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private byte Decrement(byte operand)
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|
{
|
|
this.F = AdjustSZP(this.F, --operand);
|
|
this.F = SetBit(this.F, StatusBits.AC, LowNibble(operand) != (byte)Mask.Four);
|
|
return operand;
|
|
}
|
|
|
|
private bool JumpConditionalFlag(int flag)
|
|
{
|
|
switch (flag)
|
|
{
|
|
case 0: // NZ
|
|
return this.JumpConditional((this.F & (byte)StatusBits.ZF) == 0);
|
|
case 1: // Z
|
|
return this.JumpConditional((this.F & (byte)StatusBits.ZF) != 0);
|
|
case 2: // NC
|
|
return this.JumpConditional((this.F & (byte)StatusBits.CF) == 0);
|
|
case 3: // C
|
|
return this.JumpConditional((this.F & (byte)StatusBits.CF) != 0);
|
|
case 4: // PO
|
|
return this.JumpConditional((this.F & (byte)StatusBits.PF) == 0);
|
|
case 5: // PE
|
|
return this.JumpConditional((this.F & (byte)StatusBits.PF) != 0);
|
|
case 6: // P
|
|
return this.JumpConditional((this.F & (byte)StatusBits.SF) == 0);
|
|
case 7: // M
|
|
return this.JumpConditional((this.F & (byte)StatusBits.SF) != 0);
|
|
default:
|
|
throw new ArgumentOutOfRangeException(nameof(flag));
|
|
}
|
|
}
|
|
|
|
private bool ReturnConditionalFlag(int flag)
|
|
{
|
|
switch (flag)
|
|
{
|
|
case 0: // NZ
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.ZF) == 0);
|
|
case 1: // Z
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.ZF) != 0);
|
|
case 2: // NC
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.CF) == 0);
|
|
case 3: // C
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.CF) != 0);
|
|
case 4: // PO
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.PF) == 0);
|
|
case 5: // PE
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.PF) != 0);
|
|
case 6: // P
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.SF) == 0);
|
|
case 7: // M
|
|
return this.ReturnConditional((this.F & (byte)StatusBits.SF) != 0);
|
|
default:
|
|
throw new ArgumentOutOfRangeException(nameof(flag));
|
|
}
|
|
}
|
|
|
|
private bool CallConditionalFlag(int flag)
|
|
{
|
|
switch (flag)
|
|
{
|
|
case 0: // NZ
|
|
return this.CallConditional((this.F & (byte)StatusBits.ZF) == 0);
|
|
case 1: // Z
|
|
return this.CallConditional((this.F & (byte)StatusBits.ZF) != 0);
|
|
case 2: // NC
|
|
return this.CallConditional((this.F & (byte)StatusBits.CF) == 0);
|
|
case 3: // C
|
|
return this.CallConditional((this.F & (byte)StatusBits.CF) != 0);
|
|
case 4: // PO
|
|
return this.CallConditional((this.F & (byte)StatusBits.PF) == 0);
|
|
case 5: // PE
|
|
return this.CallConditional((this.F & (byte)StatusBits.PF) != 0);
|
|
case 6: // P
|
|
return this.CallConditional((this.F & (byte)StatusBits.SF) == 0);
|
|
case 7: // M
|
|
return this.CallConditional((this.F & (byte)StatusBits.SF) != 0);
|
|
default:
|
|
throw new ArgumentOutOfRangeException(nameof(flag));
|
|
}
|
|
}
|
|
|
|
private void Add(Register16 value)
|
|
{
|
|
var result = this.HL.Word + value.Word;
|
|
this.HL.Word = (ushort)result;
|
|
this.F = SetBit(this.F, StatusBits.CF, result & (int)Bits.Bit16);
|
|
}
|
|
|
|
private void Add(byte value, int carry = 0)
|
|
{
|
|
this.MEMPTR.Word = (ushort)(this.A + value + carry);
|
|
|
|
this.F = AdjustAuxiliaryCarryAdd(this.F, this.A, value, this.MEMPTR.Low);
|
|
|
|
this.A = this.MEMPTR.Low;
|
|
|
|
this.F = SetBit(this.F, StatusBits.CF, this.MEMPTR.High & (byte)StatusBits.CF);
|
|
this.F = AdjustSZP(this.F, this.A);
|
|
}
|
|
|
|
private void ADC(byte value) => this.Add(value, this.F & (byte)StatusBits.CF);
|
|
|
|
private byte Subtract(byte operand, byte value, int carry = 0)
|
|
{
|
|
this.MEMPTR.Word = (ushort)(operand - value - carry);
|
|
|
|
this.F = AdjustAuxiliaryCarrySub(this.F, operand, value, this.MEMPTR.Word);
|
|
|
|
var result = this.MEMPTR.Low;
|
|
|
|
this.F = SetBit(this.F, StatusBits.CF, this.MEMPTR.High & (byte)StatusBits.CF);
|
|
this.F = AdjustSZP(this.F, result);
|
|
|
|
return result;
|
|
}
|
|
|
|
private void SUB(byte value, int carry = 0) => this.A = this.Subtract(this.A, value, carry);
|
|
|
|
private void SBB(byte value) => this.SUB(value, this.F & (byte)StatusBits.CF);
|
|
|
|
private void AndR(byte value)
|
|
{
|
|
this.F = SetBit(this.F, StatusBits.AC, (this.A | value) & (int)Bits.Bit3);
|
|
this.F = ClearBit(this.F, StatusBits.CF);
|
|
this.F = AdjustSZP(this.F, this.A &= value);
|
|
}
|
|
|
|
private void XorR(byte value)
|
|
{
|
|
this.F = ClearBit(this.F, StatusBits.AC | StatusBits.CF);
|
|
this.F = AdjustSZP(this.F, this.A ^= value);
|
|
}
|
|
|
|
private void OrR(byte value)
|
|
{
|
|
this.F = ClearBit(this.F, StatusBits.AC | StatusBits.CF);
|
|
this.F = AdjustSZP(this.F, this.A |= value);
|
|
}
|
|
|
|
private void Compare(byte value) => this.Subtract(this.A, value);
|
|
|
|
private byte RLC(byte operand)
|
|
{
|
|
var carry = operand & (byte)Bits.Bit7;
|
|
this.F = SetBit(this.F, StatusBits.CF, carry);
|
|
return (byte)((operand << 1) | (carry >> 7));
|
|
}
|
|
|
|
private byte RRC(byte operand)
|
|
{
|
|
var carry = operand & (byte)Bits.Bit0;
|
|
this.F = SetBit(this.F, StatusBits.CF, carry);
|
|
return (byte)((operand >> 1) | (carry << 7));
|
|
}
|
|
|
|
private byte RL(byte operand)
|
|
{
|
|
var carry = this.F & (byte)StatusBits.CF;
|
|
this.F = SetBit(this.F, StatusBits.CF, operand & (byte)Bits.Bit7);
|
|
return (byte)((operand << 1) | carry);
|
|
}
|
|
|
|
private byte RR(byte operand)
|
|
{
|
|
var carry = this.F & (byte)StatusBits.CF;
|
|
this.F = SetBit(this.F, StatusBits.CF, operand & (byte)Bits.Bit0);
|
|
return (byte)((operand >> 1) | (carry << 7));
|
|
}
|
|
|
|
private void DAA()
|
|
{
|
|
var before = this.A;
|
|
var carry = (this.F & (byte)StatusBits.CF) != 0;
|
|
byte addition = 0;
|
|
if (((this.F & (byte)StatusBits.AC) != 0) || (LowNibble(before) > (byte)9))
|
|
{
|
|
addition = 0x6;
|
|
}
|
|
|
|
if (((this.F & (byte)StatusBits.CF) != 0) || HighNibble(before) > 9 || (HighNibble(before) >= 9 && LowNibble(before) > 9))
|
|
{
|
|
addition |= 0x60;
|
|
carry = true;
|
|
}
|
|
|
|
this.Add(addition);
|
|
this.F = SetBit(this.F, StatusBits.CF, carry);
|
|
}
|
|
|
|
private void CMA() => this.A = (byte)~this.A;
|
|
|
|
private void STC() => this.F = SetBit(this.F, StatusBits.CF);
|
|
|
|
private void CMC() => this.F = ClearBit(this.F, StatusBits.CF, this.F & (byte)StatusBits.CF);
|
|
|
|
private void XHTL(Register16 exchange)
|
|
{
|
|
this.MEMPTR.Low = this.MemoryRead(this.SP.Word);
|
|
++this.Bus.Address.Word;
|
|
this.MEMPTR.High = this.MemoryRead();
|
|
this.MemoryWrite(exchange.High);
|
|
exchange.High = this.MEMPTR.High;
|
|
--this.Bus.Address.Word;
|
|
this.MemoryWrite(exchange.Low);
|
|
exchange.Low = this.MEMPTR.Low;
|
|
}
|
|
|
|
private void WritePort(byte port)
|
|
{
|
|
this.Bus.Address.Word = new Register16(port, this.A).Word;
|
|
this.Bus.Data = this.A;
|
|
this.WritePort();
|
|
}
|
|
|
|
private void WritePort() => this.ports.Write(this.Bus.Address.Low, this.Bus.Data);
|
|
|
|
private byte ReadPort(byte port)
|
|
{
|
|
this.Bus.Address.Word = new Register16(port, this.A).Word;
|
|
return this.ReadPort();
|
|
}
|
|
|
|
private byte ReadPort() => this.Bus.Data = this.ports.Read(this.Bus.Address.Low);
|
|
}
|
|
} |