mirror of
https://github.com/MoleskiCoder/EightBitNet.git
synced 2025-01-22 00:32:32 +00:00
303 lines
16 KiB
C#
303 lines
16 KiB
C#
// <copyright file="W65C02.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 W65C02(Bus bus) : M6502Core(bus)
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{
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private bool _stopped;
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private bool _waiting;
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private bool Stopped
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{
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get => this._stopped; set => this._stopped = value;
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}
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private bool Waiting
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{
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get => this._waiting; set => this._waiting = value;
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}
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private bool Paused => this.Stopped || this.Waiting;
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#region Interrupts
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protected override void Interrupt(byte vector, InterruptSource source, InterruptType type)
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{
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base.Interrupt(vector, source, type);
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this.ResetFlag(StatusBits.DF); // Disable decimal mode (Change from M6502)
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}
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#endregion
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#region Core instruction dispatching
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protected override bool MaybeExecute()
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{
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if (base.MaybeExecute())
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{
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return true;
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}
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var cycles = this.Cycles;
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switch (this.OpCode)
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{
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case 0x02: this.SwallowFetch(); break; // NOP
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case 0x03: break; // null
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case 0x04: this.ZeroPageRead(); this.TSB(); break; // TSB zp
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case 0x07: this.ZeroPageRead(); this.RMB(Chip.Bit(0)); break; // RMB0 zp
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case 0x0b: break; // null
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case 0x0c: this.AbsoluteRead(); this.TSB(); break; // TSB a
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case 0x0f: this.ZeroPageRead(); this.BBR(Chip.Bit(0)); break; // BBR0 r
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case 0x12: this.ZeroPageIndirectAddress(); this.OrR(); break; // ORA (zp),y
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case 0x13: break; // null
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case 0x14: this.ZeroPageRead(); this.TRB(); break; // TRB zp
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case 0x17: this.ZeroPageRead(); this.RMB(Chip.Bit(1)); break; // RMB1 zp
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case 0x1a: this.SwallowRead(); this.A = this.INC(this.A); break; // INC A
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case 0x1b: break; // null
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case 0x1c: this.AbsoluteRead(); this.TRB(); break; // TRB a
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case 0x1f: this.ZeroPageRead(); this.BBR(Chip.Bit(1)); break; // BBR1 r
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case 0x22: this.SwallowFetch(); break; // NOP
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case 0x23: break; // null
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case 0x27: this.ZeroPageRead(); this.RMB(Chip.Bit(2)); break; // RMB2 zp
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case 0x2b: break; // null
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case 0x2f: this.ZeroPageRead(); this.BBR(Chip.Bit(2)); break; // BBR2 r
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case 0x32: this.ZeroPageIndirectRead(); this.AndR(); break; // AND (zp)
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case 0x33: break; // null
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case 0x34: break; // BIT zp,x
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case 0x37: this.ZeroPageRead(); this.RMB(Chip.Bit(3)); break; // RMB3 zp
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case 0x3a: this.SwallowRead(); this.A = this.DEC(this.A); break; // DEC A
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case 0x3b: break; // null
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case 0x3c: break; // BIT a,x
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case 0x3f: this.ZeroPageRead(); this.BBR(Chip.Bit(3)); break; // BBR3 r
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case 0x42: this.SwallowFetch(); break; // NOP
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case 0x43: break; // null
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case 0x47: this.ZeroPageRead(); this.RMB(Chip.Bit(4)); break; // RMB4 zp
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case 0x4b: break; // null
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case 0x4f: this.ZeroPageRead(); this.BBR(Chip.Bit(4)); break; // BBR4 r
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case 0x52: this.ZeroPageIndirectRead(); this.EorR(); break; // EOR (zp)
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case 0x53: break; // null
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case 0x57: this.ZeroPageRead(); this.RMB(Chip.Bit(5)); break; // RMB5 zp
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case 0x5a: this.SwallowRead(); this.Push(this.Y); break; // PHY s
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case 0x5b: break; // null
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case 0x5c: break; // null
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case 0x5f: this.ZeroPageRead(); this.BBR(Chip.Bit(5)); break; // BBR5 r
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case 0x62: this.SwallowFetch(); break; // *NOP
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case 0x63: break; // null
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case 0x64: this.ZeroPageAddress(); this.MemoryWrite(0); break; // STZ zp
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case 0x67: this.ZeroPageRead(); this.RMB(Chip.Bit(6)); break; // RMB6 zp
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case 0x6b: break; // null
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case 0x6f: this.ZeroPageRead(); this.BBR(Chip.Bit(6)); break; // BBR6 r
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case 0x72: this.ZeroPageIndirectRead(); this.ADC(); break; // ADC (zp)
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case 0x73: break; // null
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case 0x74: this.ZeroPageXAddress(); this.MemoryWrite(0); break; // STZ zp,x
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case 0x77: this.ZeroPageRead(); this.RMB(Chip.Bit(7)); break; // RMB7 zp
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case 0x7a: this.SwallowRead(); this.SwallowPop(); this.Y = this.Through(this.Pop()); break; // PLY s
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case 0x7b: break; // null
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case 0x7c: break; // JMP (a,x)
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case 0x7f: this.ZeroPageRead(); this.BBR(Chip.Bit(7)); break; // BBR7 r
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case 0x80: Branch(true); break; // BRA r
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case 0x83: break; // null
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case 0x87: this.ZeroPageRead(); this.SMB(Chip.Bit(0)); break; // SMB0 zp
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case 0x89: break; // BIT # (TBC)
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case 0x8b: break; // null
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case 0x8f: this.ZeroPageRead(); this.BBS(Chip.Bit(0)); break; // BBS0 r
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case 0x92: ZeroPageIndirectAddress(); this.MemoryWrite(this.A); break; // STA (zp)
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case 0x93: break; // null
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case 0x97: this.ZeroPageRead(); this.SMB(Chip.Bit(1)); break; // SMB1 zp
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case 0x9b: break; // null
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case 0x9c: this.AbsoluteAddress(); this.MemoryWrite(0); break; // STZ a
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case 0x9e: this.AbsoluteXAddress(); this.MemoryWrite(0); break; // STZ a,x
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case 0x9f: this.ZeroPageRead(); this.BBS(Chip.Bit(1)); break; // BBS1 r
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case 0xa3: break; // null
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case 0xa7: this.ZeroPageRead(); this.SMB(Chip.Bit(2)); break; // SMB2 zp
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case 0xab: break; // null
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case 0xaf: this.ZeroPageRead(); this.BBS(Chip.Bit(2)); break; // BBS2 r
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case 0xb2: ZeroPageIndirectRead(); this.A = this.Through(); break; // LDA (zp)
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case 0xb3: break; // null
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case 0xb7: this.ZeroPageRead(); this.SMB(Chip.Bit(3)); break; // SMB3 zp
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case 0xbb: break; // null
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case 0xbf: this.ZeroPageRead(); this.BBS(Chip.Bit(3)); break; // BBS3 r
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case 0xc3: break; // null
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case 0xc7: this.ZeroPageRead(); this.SMB(Chip.Bit(4)); break; // SMB4 zp
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case 0xcb: this.SwallowRead(); this.Waiting = true; break; // WAI i
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case 0xcf: this.ZeroPageRead(); this.BBS(Chip.Bit(4)); break; // BBS4 r
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case 0xd2: this.ZeroPageIndirectRead(); this.CMP(this.A); break; // CMP (zp)
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case 0xd3: break; // null
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case 0xd7: this.ZeroPageRead(); this.SMB(Chip.Bit(5)); break; // SMB5 zp
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case 0xda: this.SwallowRead(); this.Push(this.X); break; // PHX s
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case 0xdb: this.SwallowRead(); this.Stopped = true; break; // STP i
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case 0xdc: this.SwallowRead(); break; // null
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case 0xdf: this.ZeroPageRead(); this.BBS(Chip.Bit(5)); break; // BBS5 r
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case 0xe3: break; // null
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case 0xe7: this.ZeroPageRead(); this.SMB(Chip.Bit(6)); break; // SMB6 zp
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case 0xeb: break; // null
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case 0xef: this.ZeroPageRead(); this.BBS(Chip.Bit(6)); break; // BBS6 r
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case 0xf2: this.ZeroPageIndirectRead(); this.SBC(); break; // SBC (zp)
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case 0xf3: break; // null
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case 0xf7: this.ZeroPageRead(); this.SMB(Chip.Bit(7)); break; // SMB7 zp
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case 0xfa: this.SwallowRead(); this.SwallowPop(); this.X = this.Through(this.Pop()); break; // PLX s
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case 0xfb: break; // null
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case 0xfc: break; // null
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case 0xff: this.ZeroPageRead(); this.BBS(Chip.Bit(7)); break; // BBS7 r
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}
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return cycles != this.Cycles;
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}
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public override void PoweredStep()
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{
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if (!this.Paused)
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{
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base.PoweredStep();
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}
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}
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protected override void OnLoweredRESET()
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{
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base.OnLoweredRESET();
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this.Stopped = this.Waiting = false;
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}
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protected override void OnLoweredINT()
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{
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base.OnLoweredINT();
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this.Waiting = false;
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}
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protected override void OnLoweredNMI()
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{
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base.OnLoweredNMI();
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this.Waiting = false;
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}
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#endregion
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#region Bus/Memory Access
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protected override void ModifyWrite(byte data)
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{
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// The read will have already taken place...
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this.MemoryRead(); // Modify cycle (Change from M6502)
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this.MemoryWrite(data); // Write cycle
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}
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#endregion
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#region Addressing modes
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#region Address page fixup
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private readonly Register16 lastFetchAddress = new();
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protected override byte FetchByte()
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{
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this.lastFetchAddress.Assign(this.PC);
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return base.FetchByte();
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}
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protected override void Fixup()
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{
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var fixingLow = this.Bus.Address.Low;
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this.MemoryRead(this.lastFetchAddress);
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this.Bus.Address.Assign(fixingLow, this.FixedPage);
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}
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protected override void FixupBranch(sbyte relative)
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{
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this.NoteFixedAddress(this.PC.Word + relative);
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this.lastFetchAddress.Assign(this.Bus.Address); // Effectively negate the use of "lastFetchAddress" for branch fixup usages
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this.MaybeFixup();
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}
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#endregion
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#region Address resolution
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protected void GetAddress()
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{
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this.GetWordPaged();
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if (this.Bus.Address.Low == 0)
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{
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this.Bus.Address.High++;
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}
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this.Bus.Address.Assign(this.Intermediate.Low, this.MemoryRead());
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}
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protected override void IndirectAddress()
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{
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this.AbsoluteAddress();
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this.GetAddress();
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}
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#endregion
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#region Address and read
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private void ZeroPageIndirectRead()
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{
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this.ZeroPageIndirectAddress();
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this.MemoryRead();
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}
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#endregion
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#endregion
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private void RMB(byte flag)
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{
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this.MemoryRead();
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this.Bus.Data &= (byte)~flag;
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this.MemoryWrite();
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}
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private void SMB(byte flag)
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{
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this.MemoryRead();
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this.Bus.Data |= flag;
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this.MemoryWrite();
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}
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private void BBS(byte flag)
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{
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this.MemoryRead();
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this.Branch(this.Bus.Data & flag);
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}
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private void BBR(byte flag)
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{
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this.MemoryRead();
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this.BranchNot(this.Bus.Data & flag);
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}
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private void TSB()
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{
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this.AdjustZero((byte)(this.A & this.Bus.Data));
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this.ModifyWrite((byte)(this.A | this.Bus.Data));
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}
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private void TRB()
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{
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this.AdjustZero((byte)(this.A & this.Bus.Data));
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this.ModifyWrite((byte)(~this.A & this.Bus.Data));
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}
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}
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} |