using System; using System.Text; using System.Windows.Forms; using Core.Cpu; using Core.Memory; namespace Desktop { public partial class DebuggerForm : Form { private readonly Z80 _cpu; private readonly SmsMemoryBus _memoryBus; private readonly ParsonsForm1 _mainForm; public DebuggerForm(Z80 cpu, SmsMemoryBus memoryBus, ParsonsForm1 mainForm) { InitializeComponent(); _cpu = cpu; _memoryBus = memoryBus; _mainForm = mainForm; // Set default memory view address txtMemoryStart.Text = "0000"; UpdateDisplay(); UpdateStackView(); UpdateDisassemblyView(); _mainForm = mainForm; } private void CpuRun_Click(object sender, EventArgs e) { if (_mainForm.IsRunning) { // Stop the machine _mainForm.StopEmulator(); CpuRun.Text = "CPU Run"; // Stop the live UI updates and do one final manual refresh uiUpdateTimer.Stop(); UpdateDisplay(); } else { // Start the machine _mainForm.StartEmulator(); CpuRun.Text = "CPU Stop"; // Start the timer so the debugger screen updates automatically // (Make sure your uiUpdateTimer Interval in the designer is set to something like 100ms) uiUpdateTimer.Start(); } } private void btnStep_Click(object sender, EventArgs e) { try { // Ask the main form to step the WHOLE machine, not just the Z80! //_mainForm.StepEmulator(); UpdateDisplay(); } catch (Exception ex) { MessageBox.Show(ex.Message, "CPU Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } } private void btnSetBreakpoint_Click(object sender, EventArgs e) // Hook this to a button or text changed event { if (ushort.TryParse(txtBreakpoint.Text, System.Globalization.NumberStyles.HexNumber, null, out ushort parsedBp)) { _mainForm.Breakpoint = parsedBp; } else { _mainForm.Breakpoint = null; } } private void btnRefreshMemory_Click(object sender, EventArgs e) { UpdateDisplay(); } public void uiUpdateTimer_Tick(object sender, EventArgs e) { UpdateDisplay(); } // Current Emulator State private void UpdateDisplay() { lblAF.Text = $"AF: {_cpu.AF.Word:X4}"; lblBC.Text = $"BC: {_cpu.BC.Word:X4}"; lblDE.Text = $"DE: {_cpu.DE.Word:X4}"; lblHL.Text = $"HL: {_cpu.HL.Word:X4}"; lblPC.Text = $"PC: {_cpu.PC:X4}"; lblSP.Text = $"SP: {_cpu.SP:X4}"; lblIX.Text = $"IX: {_cpu.IX.Word:X4}"; lblIY.Text = $"IY: {_cpu.IY.Word:X4}"; lblIff1.Text = $"IFF1: {_cpu.IFF1}"; lblIff2.Text = $"IFF2: {_cpu.IFF2}"; lblIE.Text = $"Interrupt Mode: {_cpu.InterruptMode}"; lblFlags.Text = $"Flags: {_cpu.GetFlagsString()}"; lblTStates.Text = $"T-States: {_cpu.TotalTStates}"; lblFrames.Text = $"Frames Rendered: {_mainForm.TotalFrameCount}"; lblFrameTime.Text = $"Frame Time: {((float)_mainForm.FrameTime):F1}ms"; lblFPS.Text = $"FPS: {_mainForm.FramesPerSecond:F2}"; UpdateMemoryView(); UpdateStackView(); UpdateDisassemblyView(); } private void UpdateMemoryView() { int count = 40; // Try to parse the hex string the user typed in if (!ushort.TryParse(txtMemoryStart.Text, System.Globalization.NumberStyles.HexNumber, null, out ushort startAddress)) { txtMemoryView.Text = "Invalid Hex Address!"; return; } StringBuilder sb = new StringBuilder(); // Read 100 bytes (or roughly 6 lines of 16 bytes) for (int line = 0; line < count; line++) { ushort currentAddr = (ushort)(startAddress + (line * 16)); // Print the address header for this line (e.g., "0000: ") sb.Append($"{currentAddr:X4}: "); // Print 16 bytes across for (int i = 0; i < 16; i++) { // Careful not to overflow the 64k address space! if (currentAddr + i <= 0xFFFF) { byte b = _memoryBus.Read((ushort)(currentAddr + i)); sb.Append($"{b:X2} "); } } sb.AppendLine(); } txtMemoryView.Text = sb.ToString(); } private void UpdateStackView() { lstStack.Items.Clear(); int itemsToShow = 5; ushort currentSp = _cpu.SP; for (int i = 0; i < itemsToShow; i++) { // Prevent reading past 0xFFFF if (currentSp >= 0xFFFE) { lstStack.Items.Add($"{currentSp:X4}: [End of Mem]"); break; } // Read the 16-bit value (Little-Endian: Low byte first, then High byte) byte low = _memoryBus.Read(currentSp); byte high = _memoryBus.Read((ushort)(currentSp + 1)); ushort value = (ushort)((high << 8) | low); lstStack.Items.Add($"{currentSp:X4}: {value:X4}"); // Move to the next 16-bit word on the stack currentSp += 2; } } private void UpdateDisassemblyView() { lstDisassembly.Items.Clear(); ushort currentPc = _cpu.PC; int instructionsToShow = 8; for (int i = 0; i < instructionsToShow; i++) { byte opcode = _memoryBus.Read(currentPc); string mnemonic; int instructionLength = 1; // Default to 1 byte cbOp = 0; int opGroup = 0; int targetBit = 0; int regIdx = 0; string[] regNames = { "B", "C", "D", "E", "H", "L", "(HL)", "A" }; string targetReg = ""; switch (opcode) { case 0x00: mnemonic = "NOP"; break; case 0x01: ushort bcVal = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); mnemonic = $"LD BC, 0x{bcVal:X4}"; instructionLength = 3; break; case 0x02: mnemonic = "LD (BC), A"; break; // --- 16-Bit Increments --- case 0x03: mnemonic = "INC BC"; break; case 0x07: mnemonic = "RLCA"; break; case 0x08: mnemonic = "EX AF, AF'"; break; case 0x0A: mnemonic = "LD A, (BC)"; break; case 0x12: mnemonic = "LD (DE), A"; break; case 0x13: mnemonic = "INC DE"; break; case 0x33: mnemonic = "INC SP"; break; // --- 16-Bit Decrements --- case 0x0B: mnemonic = "DEC BC"; break; case 0x3B: mnemonic = "DEC SP"; break; // --- 8-Bit Increments --- case 0x04: mnemonic = "INC B"; break; case 0x0C: mnemonic = "INC C"; break; case 0x14: mnemonic = "INC D"; break; case 0x1C: mnemonic = "INC E"; break; case 0x24: mnemonic = "INC H"; break; case 0x2C: mnemonic = "INC L"; break; case 0x34: mnemonic = "INC (HL)"; break; case 0x3C: mnemonic = "INC A"; break; // --- 8-Bit Decrements --- case 0x05: mnemonic = "DEC B"; break; case 0x0D: mnemonic = "DEC C"; break; case 0x15: mnemonic = "DEC D"; break; case 0x1D: mnemonic = "DEC E"; break; case 0x25: mnemonic = "DEC H"; break; case 0x2D: mnemonic = "DEC L"; break; case 0x35: mnemonic = "DEC (HL)"; break; case 0x3D: mnemonic = "DEC A"; break; case 0x06: byte bImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"LD B, 0x{bImm:X2}"; instructionLength = 2; break; // --- ADD HL, rr --- case 0x09: mnemonic = "ADD HL, BC"; break; case 0x19: mnemonic = "ADD HL, DE"; break; case 0x29: mnemonic = "ADD HL, HL"; break; case 0x39: mnemonic = "ADD HL, SP"; break; case 0x0E: byte cImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"LD C, 0x{cImm:X2}"; instructionLength = 2; break; case 0x0F: mnemonic = "RRCA"; break; case 0x10: sbyte djnzOffset = (sbyte)_memoryBus.Read((ushort)(currentPc + 1)); ushort djnzDest = (ushort)(currentPc + 2 + djnzOffset); mnemonic = $"DJNZ 0x{djnzDest:X4}"; instructionLength = 2; break; case 0x11: // LD DE, nn byte deLow = _memoryBus.Read((ushort)(currentPc + 1)); byte deHigh = _memoryBus.Read((ushort)(currentPc + 2)); mnemonic = $"LD DE, 0x{deHigh:X2}{deLow:X2}"; instructionLength = 3; break; case 0x16: byte dImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"LD D, 0x{dImm:X2}"; instructionLength = 2; break; case 0x17: // RLA mnemonic = "RLA"; instructionLength = 1; break; case 0x18: sbyte dUnconditional = (sbyte)_memoryBus.Read((ushort)(currentPc + 1)); ushort targetAddressUnconditional = (ushort)(currentPc + 2 + dUnconditional); mnemonic = $"JR 0x{targetAddressUnconditional:X4}"; instructionLength = 2; break; case 0x1A: mnemonic = "LD A, (DE)"; break; case 0x1B: mnemonic = "DEC DE"; break; case 0x1E: byte val1E = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"LD E, 0x{val1E:X2}"; instructionLength = 2; break; case 0x1F: mnemonic = $"RRA"; break; case 0x20: sbyte jrOffset = (sbyte)_memoryBus.Read((ushort)(currentPc + 1)); ushort destination = (ushort)(currentPc + 2 + jrOffset); mnemonic = $"JR NZ, 0x{destination:X4}"; instructionLength = 2; break; case 0x21: { ushort hlImm = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); mnemonic = $"LD HL, 0x{hlImm:X4}"; instructionLength = 3; break; } case 0x22: ushort hlAddr = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); mnemonic = $"LD (0x{hlAddr:X4}), HL"; instructionLength = 3; break; case 0x23: mnemonic = "INC HL"; break; case 0x26: byte hImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"LD H, 0x{hImm:X2}"; instructionLength = 2; break; case 0x27: // DAA mnemonic = "DAA"; instructionLength = 1; break; case 0x28: sbyte jrZOffset = (sbyte)_memoryBus.Read((ushort)(currentPc + 1)); ushort jrZDest = (ushort)(currentPc + 2 + jrZOffset); mnemonic = $"JR Z, 0x{jrZDest:X4}"; instructionLength = 2; break; case 0x2A: { ushort addr2A = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); mnemonic = $"LD HL, (0x{addr2A:X4})"; instructionLength = 3; break; } case 0x2B: mnemonic = "DEC HL"; break; case 0x2E: byte lImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"LD L, 0x{lImm:X2}"; instructionLength = 2; break; case 0x2F: mnemonic = "CPL"; break; case 0x30: sbyte jrNcOffset = (sbyte)_memoryBus.Read((ushort)(currentPc + 1)); ushort dest = (ushort)(currentPc + 2 + jrNcOffset); mnemonic = $"JR NC, 0x{dest:X4}"; instructionLength = 2; break; case 0x31: mnemonic = "LD SP, nn"; instructionLength = 3; break; case 0x32: { ushort addr32 = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); mnemonic = $"LD (0x{addr32:X4}), A"; instructionLength = 3; break; } case 0x36: byte memValue = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"LD (HL), 0x{memValue:X2}"; instructionLength = 2; break; case 0x37: mnemonic = "SCF"; break; case 0x38: sbyte dC = (sbyte)_memoryBus.Read((ushort)(currentPc + 1)); ushort targetC = (ushort)(currentPc + 2 + dC); mnemonic = $"JR C, 0x{targetC:X4}"; instructionLength = 2; break; case 0x3A: ushort addr3A = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); mnemonic = $"LD A, (0x{addr3A:X4})"; instructionLength = 3; break; case 0x3E: mnemonic = $"LD A, 0x{_memoryBus.Read((ushort)(currentPc + 1)):X2}"; instructionLength = 2; break; case 0x3F: mnemonic = "CCF"; break; // --- LD B, r --- case 0x40: mnemonic = "LD B, B"; break; case 0x41: mnemonic = "LD B, C"; break; case 0x42: mnemonic = "LD B, D"; break; case 0x43: mnemonic = "LD B, E"; break; case 0x44: mnemonic = "LD B, H"; break; case 0x45: mnemonic = "LD B, L"; break; case 0x46: mnemonic = "LD B, (HL)"; break; case 0x47: mnemonic = "LD B, A"; break; // --- LD C, r --- case 0x48: mnemonic = "LD C, B"; break; case 0x49: mnemonic = "LD C, C"; break; case 0x4A: mnemonic = "LD C, D"; break; case 0x4B: mnemonic = "LD C, E"; break; case 0x4C: mnemonic = "LD C, H"; break; case 0x4D: mnemonic = "LD C, L"; break; case 0x4E: mnemonic = "LD C, (HL)"; break; case 0x4F: mnemonic = "LD C, A"; break; // --- LD D, r --- case 0x50: mnemonic = "LD D, B"; break; case 0x51: mnemonic = "LD D, C"; break; case 0x52: mnemonic = "LD D, D"; break; case 0x53: mnemonic = "LD D, E"; break; case 0x54: mnemonic = "LD D, H"; break; case 0x55: mnemonic = "LD D, L"; break; case 0x56: mnemonic = "LD D, (HL)"; break; case 0x57: mnemonic = "LD D, A"; break; // --- LD E, r --- case 0x58: mnemonic = "LD E, B"; break; case 0x59: mnemonic = "LD E, C"; break; case 0x5A: mnemonic = "LD E, D"; break; case 0x5B: mnemonic = "LD E, E"; break; case 0x5C: mnemonic = "LD E, H"; break; case 0x5D: mnemonic = "LD E, L"; break; case 0x5E: mnemonic = "LD E, (HL)"; break; case 0x5F: mnemonic = "LD E, A"; break; // --- LD H, r --- case 0x60: mnemonic = "LD H, B"; break; case 0x61: mnemonic = "LD H, C"; break; case 0x62: mnemonic = "LD H, D"; break; case 0x63: mnemonic = "LD H, E"; break; case 0x64: mnemonic = "LD H, H"; break; case 0x65: mnemonic = "LD H, L"; break; case 0x66: mnemonic = "LD H, (HL)"; break; case 0x67: mnemonic = "LD H, A"; break; // --- LD L, r --- case 0x68: mnemonic = "LD L, B"; break; case 0x69: mnemonic = "LD L, C"; break; case 0x6A: mnemonic = "LD L, D"; break; case 0x6B: mnemonic = "LD L, E"; break; case 0x6C: mnemonic = "LD L, H"; break; case 0x6D: mnemonic = "LD L, L"; break; case 0x6E: mnemonic = "LD L, (HL)"; break; case 0x6F: mnemonic = "LD L, A"; break; // --- LD (HL), r --- (Note: 0x76 is HALT, so it is skipped) case 0x70: mnemonic = "LD (HL), B"; break; case 0x71: mnemonic = "LD (HL), C"; break; case 0x72: mnemonic = "LD (HL), D"; break; case 0x73: mnemonic = "LD (HL), E"; break; case 0x74: mnemonic = "LD (HL), H"; break; case 0x75: mnemonic = "LD (HL), L"; break; case 0x77: mnemonic = "LD (HL), A"; break; // --- LD A, r --- case 0x78: mnemonic = "LD A, B"; break; case 0x79: mnemonic = "LD A, C"; break; case 0x7A: mnemonic = "LD A, D"; break; case 0x7B: mnemonic = "LD A, E"; break; case 0x7C: mnemonic = "LD A, H"; break; case 0x7D: mnemonic = "LD A, L"; break; case 0x7E: mnemonic = "LD A, (HL)"; break; case 0x7F: mnemonic = "LD A, A"; break; // --- ADD A, r --- case 0x80: mnemonic = "ADD A, B"; break; case 0x81: mnemonic = "ADD A, C"; break; case 0x82: mnemonic = "ADD A, D"; break; case 0x83: mnemonic = "ADD A, E"; break; case 0x84: mnemonic = "ADD A, H"; break; case 0x85: mnemonic = "ADD A, L"; break; case 0x86: mnemonic = "ADD A, (HL)"; break; case 0x87: mnemonic = "ADD A, A"; break; case 0x88: case 0x89: case 0x8A: case 0x8B: case 0x8C: case 0x8D: case 0x8E: case 0x8F: string[] registers = { "B", "C", "D", "E", "H", "L", "(HL)", "A" }; mnemonic = $"ADC A, {registers[opcode - 0x88]}"; instructionLength = 1; break; // --- SUB r --- case 0x90: mnemonic = "SUB B"; break; case 0x91: mnemonic = "SUB C"; break; case 0x92: mnemonic = "SUB D"; break; case 0x93: mnemonic = "SUB E"; break; case 0x94: mnemonic = "SUB H"; break; case 0x95: mnemonic = "SUB L"; break; case 0x96: mnemonic = "SUB (HL)"; break; case 0x97: mnemonic = "SUB A"; break; // --- SBC A, r --- case 0x98: mnemonic = "SBC A, B"; break; case 0x99: mnemonic = "SBC A, C"; break; case 0x9A: mnemonic = "SBC A, D"; break; case 0x9B: mnemonic = "SBC A, E"; break; case 0x9C: mnemonic = "SBC A, H"; break; case 0x9D: mnemonic = "SBC A, L"; break; case 0x9E: mnemonic = "SBC A, (HL)"; break; case 0x9F: mnemonic = "SBC A, A"; break; // --- AND r --- case 0xA0: mnemonic = "AND B"; break; case 0xA1: mnemonic = "AND C"; break; case 0xA2: mnemonic = "AND D"; break; case 0xA3: mnemonic = "AND E"; break; case 0xA4: mnemonic = "AND H"; break; case 0xA5: mnemonic = "AND L"; break; case 0xA6: mnemonic = "AND (HL)"; break; case 0xA7: mnemonic = "AND A"; break; // --- XOR r --- case 0xA8: mnemonic = "XOR B"; break; case 0xA9: mnemonic = "XOR C"; break; case 0xAA: mnemonic = "XOR D"; break; case 0xAB: mnemonic = "XOR E"; break; case 0xAC: mnemonic = "XOR H"; break; case 0xAD: mnemonic = "XOR L"; break; case 0xAE: mnemonic = "XOR (HL)"; break; case 0xAF: mnemonic = "XOR A"; break; // --- OR r --- case 0xB0: mnemonic = "OR B"; break; case 0xB1: mnemonic = "OR C"; break; case 0xB2: mnemonic = "OR D"; break; case 0xB3: mnemonic = "OR E"; break; case 0xB4: mnemonic = "OR H"; break; case 0xB5: mnemonic = "OR L"; break; case 0xB6: mnemonic = "OR (HL)"; break; case 0xB7: mnemonic = "OR A"; break; // --- CP r --- case 0xB8: mnemonic = "CP B"; break; case 0xB9: mnemonic = "CP C"; break; case 0xBA: mnemonic = "CP D"; break; case 0xBB: mnemonic = "CP E"; break; case 0xBC: mnemonic = "CP H"; break; case 0xBD: mnemonic = "CP L"; break; case 0xBE: mnemonic = "CP (HL)"; break; case 0xBF: mnemonic = "CP A"; break; case 0xC1: mnemonic = "POP BC"; break; case 0xC2: case 0xCA: case 0xD2: case 0xDA: case 0xE2: case 0xEA: case 0xF2: case 0xFA: { // Read the 16-bit target address ushort jumpAddr = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); string condition = ""; switch (opcode) { case 0xC2: condition = "NZ"; break; case 0xCA: condition = "Z"; break; case 0xD2: condition = "NC"; break; case 0xDA: condition = "C"; break; case 0xE2: condition = "PO"; break; case 0xEA: condition = "PE"; break; case 0xF2: condition = "P"; break; case 0xFA: condition = "M"; break; } mnemonic = $"JP {condition}, 0x{jumpAddr:X4}"; instructionLength = 3; break; } // --- Conditional Returns --- case 0xC0: mnemonic = "RET NZ"; break; case 0xE0: mnemonic = "RET PO"; break; case 0xE8: mnemonic = "RET PE"; break; case 0xF0: mnemonic = "RET P"; break; case 0xF8: mnemonic = "RET M"; break; case 0xC3: // JP nn byte jpLow = _memoryBus.Read((ushort)(currentPc + 1)); byte jpHigh = _memoryBus.Read((ushort)(currentPc + 2)); mnemonic = $"JP 0x{jpHigh:X2}{jpLow:X2}"; instructionLength = 3; break; case 0xC4: case 0xCC: case 0xD4: case 0xDC: case 0xE4: case 0xEC: case 0xF4: case 0xFC: { // Read the 16-bit target address ushort callAddr = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); string condition = ""; switch (opcode) { case 0xC4: condition = "NZ"; break; case 0xCC: condition = "Z"; break; case 0xD4: condition = "NC"; break; case 0xDC: condition = "C"; break; case 0xE4: condition = "PO"; break; case 0xEC: condition = "PE"; break; case 0xF4: condition = "P"; break; case 0xFC: condition = "M"; break; } mnemonic = $"CALL {condition}, 0x{callAddr:X4}"; instructionLength = 3; break; } case 0xc5: mnemonic = "PUSH BC"; break; case 0xC6: { byte addImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"ADD A, 0x{addImm:X2}"; instructionLength = 2; break; } // --- RST Instructions --- case 0xC7: mnemonic = "RST 00h"; break; case 0xCF: mnemonic = "RST 08h"; break; case 0xD7: mnemonic = "RST 10h"; break; case 0xDF: mnemonic = "RST 18h"; break; case 0xE7: mnemonic = "RST 20h"; break; case 0xEF: mnemonic = "RST 28h"; break; case 0xF7: mnemonic = "RST 30h"; break; case 0xFF: mnemonic = "RST 38h"; break; case 0xC8: mnemonic = "RET Z"; break; case 0xC9: mnemonic = "RET"; break; case 0xCB: cbOp = _memoryBus.Read((ushort)(currentPc + 1)); opGroup = cbOp >> 6; // 00 = Shift, 01 = BIT, 10 = RES, 11 = SET targetBit = (cbOp >> 3) & 0x07; // Extracts a number 0-7 regIdx = cbOp & 0x07; // Extracts register index 0-7 // Map the 0-7 index directly to the Z80 register names targetReg = regNames[regIdx]; if (opGroup == 0) // Shift/Rotate Group (0x00 to 0x3F) { string[] shiftNames = { "RLC", "RRC", "RL", "RR", "SLA", "SRA", "SLL", "SRL" }; string shiftOp = shiftNames[(cbOp >> 3) & 0x07]; mnemonic = $"{shiftOp} {targetReg}"; } else if (opGroup == 1) // BIT Group (0x40 to 0x7F) { mnemonic = $"BIT {targetBit}, {targetReg}"; } else if (opGroup == 2) // RES Group (0x80 to 0xBF) { mnemonic = $"RES {targetBit}, {targetReg}"; } else if (opGroup == 3) // SET Group (0xC0 to 0xFF) { mnemonic = $"SET {targetBit}, {targetReg}"; } else { mnemonic = $"CB UNKNOWN (CB {cbOp:X2})"; } instructionLength = 2; break; case 0xCD: ushort callDest = (ushort)(_memoryBus.Read((ushort)(currentPc + 1)) | (_memoryBus.Read((ushort)(currentPc + 2)) << 8)); mnemonic = $"CALL 0x{callDest:X4}"; instructionLength = 3; break; case 0xCE: // ADC A, n byte n = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"ADC A, 0x{n:X2}"; instructionLength = 2; break; case 0xD0: mnemonic = "RET NC"; break; case 0xD1: mnemonic = "POP DE"; break; case 0xD3: byte outPort = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"OUT (0x{outPort:X2}), A"; instructionLength = 2; break; case 0xD9: mnemonic = "EXX"; break; case 0xd5: mnemonic = "PUSH DE"; break; case 0xD6: byte subImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"SUB 0x{subImm:X2}"; instructionLength = 2; break; case 0xD8: mnemonic = "RET C"; break; case 0xDB: // IN A, (n) n = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"IN A, (0x{n:X2})"; instructionLength = 2; break; case 0xDD: { byte ddOpcode = _memoryBus.Read((ushort)(currentPc + 1)); if (ddOpcode == 0x09) { mnemonic = "ADD IX, BC"; instructionLength = 2; } else if (ddOpcode == 0x19) { mnemonic = "ADD IX, DE"; instructionLength = 2; } else if (ddOpcode == 0x29) { mnemonic = "ADD IX, IX"; instructionLength = 2; } else if (ddOpcode == 0x39) { mnemonic = "ADD IX, SP"; instructionLength = 2; } else if (ddOpcode == 0x21) // LD IX, nn { ushort ixVal = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD IX, 0x{ixVal:X4}"; instructionLength = 4; } else if (ddOpcode == 0x22) // LD (nn), IX { ushort nn = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD (0x{nn:X4}), IX"; instructionLength = 4; } else if (ddOpcode == 0x23) // INC IX { mnemonic = "INC IX"; instructionLength = 2; } else if (ddOpcode == 0x24) // INC IXH { mnemonic = "INC IXH"; instructionLength = 2; } else if (ddOpcode == 0x25) // DEC IXH { mnemonic = "DEC IXH"; instructionLength = 2; } else if (ddOpcode == 0x26) // LD IXH, n { byte nValue = _memoryBus.Read((ushort)(currentPc + 2)); mnemonic = $"LD IXH, 0x{nValue:X2}"; instructionLength = 3; } else if (ddOpcode == 0x2A) // LD IX, (nn) { ushort nn = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD IX, (0x{nn:X4})"; instructionLength = 4; } else if (ddOpcode == 0x2B) // DEC IX { mnemonic = "DEC IX"; instructionLength = 2; } else if (ddOpcode == 0x2D) // DEC IXL { mnemonic = "DEC IXL"; instructionLength = 2; } else if (ddOpcode == 0x2E) // LD IXL, n { byte nValue = _memoryBus.Read((ushort)(currentPc + 2)); mnemonic = $"LD IXL, 0x{nValue:X2}"; instructionLength = 3; } else if (ddOpcode == 0x34) // INC (IX+d) { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"INC (IX{sign}{offset})"; instructionLength = 3; } else if (ddOpcode == 0x35) // DEC (IX+d) { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"DEC (IX{sign}{offset})"; instructionLength = 3; } else if (ddOpcode == 0x36) // LD (IX+d), n { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); n = _memoryBus.Read((ushort)(currentPc + 3)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{d}), 0x{n:X2}"; instructionLength = 4; } else if (ddOpcode == 0x46) // LD B, (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD B, (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0x4E) // LD C, (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD C, (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0x56) // LD D, (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD D, (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0x5E) // LD E, (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD E, (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0x66) // LD H, (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD H, (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0x67) // LD IXH, A { mnemonic = "LD IXH, A"; instructionLength = 2; } else if (ddOpcode == 0x68) // LD IXL, B { mnemonic = "LD IXL, B"; instructionLength = 2; } else if (ddOpcode == 0x69) // LD IXL, C { mnemonic = "LD IXL, C"; instructionLength = 2; } else if (ddOpcode == 0x6A) // LD IXL, D { mnemonic = "LD IXL, D"; instructionLength = 2; } else if (ddOpcode == 0x6E) // LD L, (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD L, (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0x6F) // LD IXL, A { mnemonic = $"LD IXL, A)"; instructionLength = 2; } else if (ddOpcode == 0x71) // LD (IX+d), B { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{offset}), B"; instructionLength = 3; } else if (ddOpcode == 0x71) // LD (IX+d), C { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{offset}), C"; instructionLength = 3; } else if (ddOpcode == 0x72) // LD (IX+d), D { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{offset}), D"; instructionLength = 3; } else if (ddOpcode == 0x73) // LD (IX+d), E { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{offset}), E"; instructionLength = 3; } else if (ddOpcode == 0x74) // LD (IX+d), H { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{d}), H"; instructionLength = 3; } else if (ddOpcode == 0x75) // LD (IX+d), L { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{d}), L"; instructionLength = 3; } else if (ddOpcode == 0x77) // LD (IX+d), A { // Read the 3rd byte (the displacement) sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); // Format nicely with a + or - sign string sign = offset >= 0 ? "+" : ""; mnemonic = $"LD (IX{sign}{offset}), A"; instructionLength = 3; } else if (ddOpcode == 0x7C) // LD A, IXH { mnemonic = "LD A, IXH"; instructionLength = 2; } else if (ddOpcode == 0x7E) // LD A, (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD A, (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0x86) { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"ADD A, (IX{sign}{offset})"; instructionLength = 3; } else if (ddOpcode == 0x96) { sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = offset >= 0 ? "+" : ""; mnemonic = $"SUB (IX{sign}{offset})"; instructionLength = 3; } else if (ddOpcode == 0xCB) { // DD CB instructions are 4 bytes long! sbyte offset = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); cbOp = _memoryBus.Read((ushort)(currentPc + 3)); int operation = cbOp >> 6; int bitIndex = (cbOp >> 3) & 0x07; string sign = offset >= 0 ? "+" : ""; if (operation == 1) mnemonic = $"BIT {bitIndex}, (IX{sign}{offset})"; else mnemonic = $"DD CB (IX{sign}{offset}) {cbOp:X2}"; // Fallback instructionLength = 4; } else if (ddOpcode == 0xBE) // CP (IX+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"CP (IX{sign}{d})"; instructionLength = 3; } else if (ddOpcode == 0xE1) // POP IX { mnemonic = "POP IX"; instructionLength = 2; } else if (ddOpcode == 0xE5) // PUSH IX { mnemonic = "PUSH IX"; instructionLength = 2; } else if (ddOpcode == 0xE9) // JP (IX) { mnemonic = "JP (IX)"; instructionLength = 2; } else { mnemonic = $"DD PREFIX UNKNOWN (0x{ddOpcode:X2})"; instructionLength = 2; // Fallback to prevent UI freezing } break; } case 0xDE: byte sbcValue = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"SBC A, 0x{sbcValue:X2}"; instructionLength = 2; break; case 0xE1: mnemonic = "POP HL"; break; case 0xE3: mnemonic = "EX (SP), HL"; break; case 0xE5: mnemonic = "PUSH HL"; break; case 0xE6: byte andImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"AND 0x{andImm:X2}"; instructionLength = 2; break; case 0xE9: mnemonic = "JP (HL)"; break; case 0xEB: mnemonic = "EX DE, HL"; break; case 0xED: byte extendedOp = _memoryBus.Read((ushort)(currentPc + 1)); switch (extendedOp) { case 0x42: mnemonic = "SBC HL, BC"; instructionLength = 2; break; case 0x43: ushort bcAddr = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD (0x{bcAddr:X4}), BC"; instructionLength = 4; break; case 0x44: // NEG mnemonic = "NEG"; instructionLength = 2; break; case 0x47: mnemonic = "LD I, A"; instructionLength = 2; // 0xED + 0x47 break; // Inside your ED prefix switch statement in the debugger: case 0x4A: mnemonic = "ADC HL, BC"; instructionLength = 2; break; case 0x4B: ushort addr4B = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD BC, (0x{addr4B:X4})"; instructionLength = 4; break; case 0x4D: mnemonic = "RETI"; instructionLength = 2; break; case 0x52: mnemonic = "SBC HL, DE"; instructionLength = 2; // ED 52 break; case 0x53: ushort deAddr = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD (0x{deAddr:X4}), DE"; instructionLength = 4; break; case 0x56: mnemonic = "IM 1"; instructionLength = 2; break; case 0x58: mnemonic = "IN E, (C)"; instructionLength = 2; break; case 0x5A: mnemonic = "ADC HL, DE"; instructionLength = 2; break; case 0x5B: ushort addr5B = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD DE, (0x{addr5B:X4})"; instructionLength = 4; break; case 0x5E: mnemonic = "IM 2"; instructionLength = 2; break; case 0x5F: mnemonic = "LD A, R"; instructionLength = 2; break; case 0x6A: mnemonic = "ADC HL, HL"; instructionLength = 2; break; case 0x62: mnemonic = "SBC HL, HL"; instructionLength = 2; break; case 0x73: ushort addr73 = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD (0x{addr73:X4}), SP"; instructionLength = 4; break; case 0x72: // SBC HL, SP mnemonic = "SBC HL, SP"; instructionLength = 2; break; case 0x78: mnemonic = "IN A, (C)"; instructionLength = 2; break; case 0x7A: mnemonic = "ADC HL, SP"; instructionLength = 2; break; case 0x7B: // LD SP, (nn) ushort nn = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD SP, (0x{nn:X4})"; instructionLength = 4; break; case 0xA0: mnemonic = "LDI"; instructionLength = 2; break; case 0xB0: mnemonic = "LDIR"; instructionLength = 2; break; case 0xB1: mnemonic = "CPIR"; instructionLength = 2; break; case 0xB8: mnemonic = "LDDR"; instructionLength = 2; break; default: mnemonic = $"EXT UNKNOWN (ED {extendedOp:X2})"; instructionLength = 2; // Most ED instructions are 2 bytes, but some have operands! break; } break; case 0xEE: byte xorVal = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"XOR 0x{xorVal:X2}"; instructionLength = 2; break; case 0xF1: mnemonic = "POP AF"; break; case 0xF3: mnemonic = "DI"; break; case 0xf5: mnemonic = "PUSH AF"; break; case 0xF6: byte orImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"OR 0x{orImm:X2}"; instructionLength = 2; break; case 0xF9: mnemonic = "LD SP, HL"; break; case 0xFB: mnemonic = "EI"; break; case 0xFD: { byte fdOpcode = _memoryBus.Read((ushort)(currentPc + 1)); if (fdOpcode == 0x09) // ADD IY, BC { mnemonic = $"ADD IY, BC"; instructionLength = 2; } else if (fdOpcode == 0x19) // ADD IY, DE { mnemonic = $"ADD IY, DE"; instructionLength = 2; } else if (fdOpcode == 0x21) // LD IY, nn { ushort iyVal = (ushort)(_memoryBus.Read((ushort)(currentPc + 2)) | (_memoryBus.Read((ushort)(currentPc + 3)) << 8)); mnemonic = $"LD IY, 0x{iyVal:X4}"; instructionLength = 4; } else if (fdOpcode == 0x29) //Add IY, IY { mnemonic = $"ADD IY, IY"; instructionLength = 2; } else if (fdOpcode == 0x34) // INC IY { //sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); //string sign = d >= 0 ? "+" : ""; mnemonic = $"INC IY"; instructionLength = 2; } else if (fdOpcode == 0x34) // INC (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"INC (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0x35) // DEC (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; // Gives us a clean + or - mnemonic = $"DEC (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0x36) // LD (IY+d), n { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); n = _memoryBus.Read((ushort)(currentPc + 3)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IY{sign}{d}), 0x{n:X2}"; instructionLength = 4; } else if (fdOpcode == 0x46) // LD B, (IY+d) { sbyte dB = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string signB = dB >= 0 ? "+" : ""; mnemonic = $"LD B, (IY{signB}{dB})"; instructionLength = 3; } else if (fdOpcode == 0x4E) // LD C, (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD C, (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0x56) // LD D, (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD D, (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0x5E) // LD E, (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD E, (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0x66) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD H, (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0x6E) { sbyte offsetL = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string signL = offsetL >= 0 ? "+" : ""; mnemonic = $"LD L, (IY{signL}{offsetL})"; instructionLength = 3; } else if (fdOpcode == 0x72) // LD (IY+d), D { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IY{sign}{d}), D"; instructionLength = 3; } else if (fdOpcode == 0x73) // LD (IY+d), E { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IY{sign}{d}), E"; instructionLength = 3; } else if (fdOpcode == 0x74) // LD (IY+d), H { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IY{sign}{d}), H"; instructionLength = 3; } else if (fdOpcode == 0x77) // LD (IY+d), A { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IY{sign}{d}), A"; instructionLength = 3; } else if (fdOpcode == 0x7E) // LD A, (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD A, (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0x84) // ADD A, IYH { mnemonic = $"ADD A, IYH"; instructionLength = 2; } else if (fdOpcode == 0x85) // ADD A, IYL { mnemonic = $"ADD A, IYL"; instructionLength = 2; } else if (fdOpcode == 0x86) // ADD A, (IY+d) { sbyte dAdd = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string signAdd = dAdd >= 0 ? "+" : ""; mnemonic = $"ADD A, (IY{signAdd}{dAdd})"; instructionLength = 3; } else if (fdOpcode == 0x96) // SUB (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"SUB (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0xA6) //AND (IY+d) { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"AND (IY{sign}{d})"; instructionLength = 3; } else if (fdOpcode == 0xCB) // FD CB prefix { cbOp = _memoryBus.Read((ushort)(currentPc + 1)); opGroup = cbOp >> 6; targetBit = (cbOp >> 3) & 0x07; regIdx = cbOp & 0x07; targetReg = regNames[regIdx]; if (opGroup == 1) mnemonic = $"BIT {targetBit}, {targetReg}"; else if (opGroup == 2) mnemonic = $"RES {targetBit}, {targetReg}"; else if (opGroup == 3) mnemonic = $"SET {targetBit}, {targetReg}"; else mnemonic = $"CB SHIFT/ROTATE (0x{cbOp:X2})"; instructionLength = 2; } else if (fdOpcode == 0x71) // LD (IY+d), C { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IY{sign}{d}), C"; instructionLength = 3; } else if (fdOpcode == 0x75) // LD (IY+d), L { sbyte d = (sbyte)_memoryBus.Read((ushort)(currentPc + 2)); string sign = d >= 0 ? "+" : ""; mnemonic = $"LD (IY{sign}{d}), L"; instructionLength = 3; } else if (fdOpcode == 0xE1) { mnemonic = "POP IY"; instructionLength = 2; } else if (fdOpcode == 0xE5) { mnemonic = "PUSH IY"; instructionLength = 2; } else { mnemonic = $"FD PREFIX UNKNOWN (0x{fdOpcode:X2})"; instructionLength = 2; // Fallback so we don't freeze the UI } break; } case 0xFE: byte cpImm = _memoryBus.Read((ushort)(currentPc + 1)); mnemonic = $"CP 0x{cpImm:X2}"; instructionLength = 2; break; default: mnemonic = $"UNKNOWN (0x{opcode:X2})"; break; } lstDisassembly.Items.Add($"{currentPc:X4}: {mnemonic}"); // Advance the fake PC just for drawing the next line in the UI currentPc += (ushort)instructionLength; } } } }