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More OpCodes - working towards ZEXALL perfection

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This commit is contained in:
Marc Parsons
2026-04-22 22:38:53 +01:00
parent b50f7a79da
commit 02680cb92d
6 changed files with 364 additions and 38 deletions
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62
Core/Cpu/Z80.cs
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@@ -6,6 +6,7 @@ namespace Core.Cpu
{
public partial class Z80
{
public bool IsZexDocMode { get; set; } = false;
//T-State counter
public long TotalTStates { get; set; }
@@ -47,6 +48,7 @@ namespace Core.Cpu
public Func<ushort, long, int>? WaitStateCallback { get; set; }
//Misc Variables
public bool EnableFastLoad { get; set; } = true;
byte newFlags = 0;
int result = 0;
@@ -194,10 +196,44 @@ namespace Core.Cpu
public int Step()
{
if (PC == 0x0556 && _tapManager.HasBlocks)
if (IsZexDocMode && PC == 0x0005)
{
// CP/M System Call Hook
if (BC.Low == 2) // C = 2: Print a single character stored in register E
{
System.Diagnostics.Debug.Write((char)DE.Low);
}
else if (BC.Low == 9) // C = 9: Print a string starting at memory address DE, terminated by '$'
{
ushort addr = DE.Word;
while (true)
{
char c = (char)ReadMemory(addr++);
if (c == '$') break;
System.Diagnostics.Debug.Write(c);
}
}
// Emulate a 'RET' instruction to return from the CALL 0x0005
byte retLow = ReadMemory(SP);
SP++;
byte retHigh = ReadMemory(SP);
SP++;
PC = (ushort)((retHigh << 8) | retLow);
return 10; // Skip normal execution for this cycle
}
if (PC == 0x0556)
{
if (EnableFastLoad)
{
HandleInstantTapeLoad();
return 100; // Return a dummy number of T-States for the hijacking
return 100;
}
else
{
_tapManager.Play();
}
}
// Fetch the next opcode and increment the Program Counter
@@ -2819,7 +2855,7 @@ namespace Core.Cpu
AF.Low = newFlags;
return 19; // 19 T-States
return 19;
case 0xCB: // The FD CB nested prefix
{
sbyte displacement = (sbyte)FetchByte();
@@ -2866,6 +2902,26 @@ namespace Core.Cpu
throw new Exception("Invalid bitwise operation.");
}
}
case 0xE1: // POP IY
// 1. Read the Low byte from the current Stack Pointer, then increment SP
IY.Low = ReadMemory(SP);
SP++;
// 2. Read the High byte from the new Stack Pointer, then increment SP
IY.High = ReadMemory(SP);
SP++;
return 14; // 14 T-States
case 0xE5: // PUSH IY
// 1. Decrement SP and write the High byte
SP--;
WriteMemory(SP, IY.High);
// 2. Decrement SP again and write the Low byte
SP--;
WriteMemory(SP, IY.Low);
return 15; // 15 T-States
default:
throw new NotImplementedException($"FD prefix opcode {opcode:X2} at PC 0x{(PC - 2):X4} not implemented!");
}

10
Core/Io/IO_Bus.cs
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@@ -9,6 +9,12 @@ namespace Core.Io
public byte BorderColorIndex { get; private set; } = 7;
public bool BeeperState { get; private set; } = false;
public byte[] KeyboardRows = new byte[8] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
TapManager _tapManager = new TapManager();
public IO_Bus(TapManager tapManager)
{
_tapManager = tapManager;
}
public byte ReadPort(ushort portAddress)
{
@@ -28,7 +34,11 @@ namespace Core.Io
if ((highByte & 0x20) == 0) result &= KeyboardRows[5]; // 0xDF: P, O, I, U, Y
if ((highByte & 0x40) == 0) result &= KeyboardRows[6]; // 0xBF: ENTER, L, K, J, H
if ((highByte & 0x80) == 0) result &= KeyboardRows[7]; // 0x7F: SPACE, SYM, M, N, B
if (_tapManager.EarBit) result |= 0x40; // Set Bit 6 high
else result &= 0xBF; // Set Bit 6 low
//return result;
// The top 3 bits (5, 6, 7) are unused by the keyboard and usually return 1 on a real Spectrum
return (byte)(result | 0xE0);
}

177
Core/Io/TapManager.cs
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@@ -6,7 +6,19 @@ namespace Core.Io
public class TapManager
{
private Queue<byte[]> _blocks = new Queue<byte[]>();
private byte[] _currentBlock;
// State Machine Tracking
private enum TapeState { Idle, Pilot, Sync1, Sync2, Data, Pause }
private TapeState _state = TapeState.Idle;
public bool EarBit { get; private set; } = false; // The physical audio signal sent to the CPU
private int _pulseTimer = 0;
private int _pilotPulsesRemaining = 0;
private int _byteIndex = 0;
private int _bitIndex = 0;
private int _pulseCountForCurrentBit = 0;
public void LoadTapData(byte[] fileData)
{
@@ -15,20 +27,136 @@ namespace Core.Io
while (position < fileData.Length)
{
// 1. Read the 16-bit block length (Little Endian)
int blockLength = fileData[position] | (fileData[position + 1] << 8);
position += 2;
// 2. Extract the block payload
byte[] blockData = new byte[blockLength];
Array.Copy(fileData, position, blockData, 0, blockLength);
position += blockLength;
// 3. Queue it up
_blocks.Enqueue(blockData);
}
}
public void Play()
{
if (_blocks.Count > 0 && _state == TapeState.Idle)
{
LoadNextBlock();
}
}
private void LoadNextBlock()
{
if (_blocks.Count == 0)
{
_state = TapeState.Idle;
return;
}
_currentBlock = _blocks.Dequeue();
_byteIndex = 0;
_bitIndex = 7; // MSB first
_pulseCountForCurrentBit = 0;
// Header blocks (flag 0x00) have longer pilot tones than Data blocks
bool isHeader = _currentBlock.Length > 0 && _currentBlock[0] == 0;
_pilotPulsesRemaining = isHeader ? 8063 : 3223;
_state = TapeState.Pilot;
_pulseTimer = 2168; // Length of a pilot pulse
EarBit = false;
}
// --- THE ENGINE SYNC ---
// Call this every time the CPU steps, passing in how many T-States elapsed
public void Update(int tStatesElapsed)
{
if (_state == TapeState.Idle) return;
_pulseTimer -= tStatesElapsed;
if (_pulseTimer <= 0)
{
EarBit = !EarBit; // Flip the audio square wave
AdvanceState();
}
}
private void AdvanceState()
{
switch (_state)
{
case TapeState.Pilot:
_pilotPulsesRemaining--;
if (_pilotPulsesRemaining > 0)
{
_pulseTimer += 2168;
}
else
{
_state = TapeState.Sync1;
_pulseTimer += 667;
}
break;
case TapeState.Sync1:
_state = TapeState.Sync2;
_pulseTimer += 735;
break;
case TapeState.Sync2:
_state = TapeState.Data;
CalculateNextDataPulse();
break;
case TapeState.Data:
_pulseCountForCurrentBit++;
if (_pulseCountForCurrentBit < 2)
{
// A bit requires 2 pulses (one high, one low)
CalculateNextDataPulse();
}
else
{
// Move to next bit
_pulseCountForCurrentBit = 0;
_bitIndex--;
if (_bitIndex < 0)
{
// Move to next byte
_bitIndex = 7;
_byteIndex++;
if (_byteIndex >= _currentBlock.Length)
{
// Block finished! 1 second pause before the next block
_state = TapeState.Pause;
_pulseTimer += 3500000;
return;
}
}
CalculateNextDataPulse();
}
break;
case TapeState.Pause:
LoadNextBlock();
break;
}
}
private void CalculateNextDataPulse()
{
// Extract the current bit from the current byte
bool isBitOne = (_currentBlock[_byteIndex] & (1 << _bitIndex)) != 0;
// Bit 0 = 855 T-States, Bit 1 = 1710 T-States
_pulseTimer += isBitOne ? 1710 : 855;
}
// --- FAST LOAD METHODS (For ROM Hijack) ---
public byte[] GetNextBlock()
{
return _blocks.Count > 0 ? _blocks.Dequeue() : null;
@@ -37,3 +165,46 @@ namespace Core.Io
public bool HasBlocks => _blocks.Count > 0;
}
}
//using System;
//using System.Collections.Generic;
//namespace Core.Io
//{
// public class TapManager
// {
// private Queue<byte[]> _blocks = new Queue<byte[]>();
// public void LoadTapData(byte[] fileData)
// {
// _blocks.Clear();
// int position = 0;
// while (position < fileData.Length)
// {
// // 1. Read the 16-bit block length (Little Endian)
// int blockLength = fileData[position] | (fileData[position + 1] << 8);
// position += 2;
// // 2. Extract the block payload
// byte[] blockData = new byte[blockLength];
// Array.Copy(fileData, position, blockData, 0, blockLength);
// position += blockLength;
// // 3. Queue it up
// _blocks.Enqueue(blockData);
// }
// }
// public byte[] GetNextBlock()
// {
// return _blocks.Count > 0 ? _blocks.Dequeue() : null;
// }
// public bool HasBlocks => _blocks.Count > 0;
// }
//}

10
Desktop/DebuggerForm.cs
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@@ -1285,6 +1285,16 @@ namespace Desktop
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})";

31
Desktop/Form1.Designer.cs generated
View File

@@ -42,6 +42,9 @@
resetToolStripMenuItem = new ToolStripMenuItem();
stepToolStripMenuItem = new ToolStripMenuItem();
resetToolStripMenuItem1 = new ToolStripMenuItem();
optionsToolStripMenuItem = new ToolStripMenuItem();
fastLoadingToolStripMenuItem = new ToolStripMenuItem();
runZEXDOCToolStripMenuItem = new ToolStripMenuItem();
((System.ComponentModel.ISupportInitialize)picScreen).BeginInit();
menuStrip1.SuspendLayout();
SuspendLayout();
@@ -59,7 +62,7 @@
// menuStrip1
//
menuStrip1.ImageScalingSize = new Size(24, 24);
menuStrip1.Items.AddRange(new ToolStripItem[] { fileToolStripMenuItem, viewToolStripMenuItem, machineToolStripMenuItem });
menuStrip1.Items.AddRange(new ToolStripItem[] { fileToolStripMenuItem, viewToolStripMenuItem, machineToolStripMenuItem, optionsToolStripMenuItem });
menuStrip1.Location = new Point(0, 0);
menuStrip1.Name = "menuStrip1";
menuStrip1.Padding = new Padding(5, 2, 0, 2);
@@ -151,6 +154,29 @@
resetToolStripMenuItem1.Text = "Reset";
resetToolStripMenuItem1.Click += btnReset_Click;
//
// optionsToolStripMenuItem
//
optionsToolStripMenuItem.DropDownItems.AddRange(new ToolStripItem[] { fastLoadingToolStripMenuItem, runZEXDOCToolStripMenuItem });
optionsToolStripMenuItem.Name = "optionsToolStripMenuItem";
optionsToolStripMenuItem.Size = new Size(75, 24);
optionsToolStripMenuItem.Text = "Options";
//
// fastLoadingToolStripMenuItem
//
fastLoadingToolStripMenuItem.Checked = true;
fastLoadingToolStripMenuItem.CheckState = CheckState.Checked;
fastLoadingToolStripMenuItem.Name = "fastLoadingToolStripMenuItem";
fastLoadingToolStripMenuItem.Size = new Size(224, 26);
fastLoadingToolStripMenuItem.Text = "Fast TAP Loading";
fastLoadingToolStripMenuItem.Click += fastLoadingToolStripMenuItem_Click;
//
// runZEXDOCToolStripMenuItem
//
runZEXDOCToolStripMenuItem.Name = "runZEXDOCToolStripMenuItem";
runZEXDOCToolStripMenuItem.Size = new Size(224, 26);
runZEXDOCToolStripMenuItem.Text = "Run ZEXDOC";
runZEXDOCToolStripMenuItem.Click += btnRunZexDoc_Click;
//
// Form1
//
AutoScaleDimensions = new SizeF(8F, 20F);
@@ -185,5 +211,8 @@
private ToolStripMenuItem resetToolStripMenuItem;
private ToolStripMenuItem stepToolStripMenuItem;
private ToolStripMenuItem resetToolStripMenuItem1;
private ToolStripMenuItem optionsToolStripMenuItem;
private ToolStripMenuItem fastLoadingToolStripMenuItem;
private ToolStripMenuItem runZEXDOCToolStripMenuItem;
}
}

60
Desktop/Form1.cs
View File

@@ -26,6 +26,7 @@ namespace Desktop
public double FramesPerSecond = 0;
public double TotalFrameTime = 0;
public double FrameTime = 0;
public bool exceptionRaised = false;
public Form1()
@@ -40,10 +41,10 @@ namespace Desktop
{
_baseTitle = this.Text;
_memoryBus = new MemoryBus();
_simpleIoBus = new IO_Bus();
_tapManager = new TapManager();
_simpleIoBus = new IO_Bus(_tapManager);
_ula = new ULA(_memoryBus, _simpleIoBus);
_beeper = new BeeperDevice();
_tapManager = new TapManager();
_memoryBus.CrapRAMData();
byte[] romData = RomLoader.Load("48.rom");
_memoryBus.LoadRom(romData);
@@ -92,13 +93,19 @@ namespace Desktop
continue;
}
long tStatesBefore = _cpu.TotalTStates;
// --- Execute Instruction ---
_cpu.Step();
int elapsedTStates = (int)(_cpu.TotalTStates - tStatesBefore);
_tapManager.Update(elapsedTStates);
//Process audio at the correct time
while (_cpu.TotalTStates >= (long)(audioSampleCount * 79.365))
{
_beeper.AddSample(_simpleIoBus.BeeperState);
bool finalAudioOutput = _simpleIoBus.BeeperState ^ _tapManager.EarBit;
_beeper.AddSample(finalAudioOutput);
audioSampleCount++;
}
@@ -119,7 +126,7 @@ namespace Desktop
this.Invoke((MethodInvoker)delegate
{
UpdateScreenBitmap();
this.Text = $"{_baseTitle} - FPS: {FramesPerSecond:F1}";
this.Text = $"{_baseTitle} - FPS: {FramesPerSecond:F1} - Fast Loading: {_cpu.EnableFastLoad.ToString()}";
});
TotalFrameCount++;
@@ -129,7 +136,7 @@ namespace Desktop
if (elapsedMs < targetTimeMs)
{
Thread.Sleep((int)(targetTimeMs - elapsedMs));
//Thread.Sleep((int)(targetTimeMs - elapsedMs));
}
TotalFrameTime += fpsStopwatch.Elapsed.TotalMilliseconds;
if (TotalFrameCount % 50 == 0)
@@ -150,6 +157,7 @@ namespace Desktop
this.Invoke((MethodInvoker)delegate
{
MessageBox.Show(ex.Message, "CPU Crash", MessageBoxButtons.OK, MessageBoxIcon.Error);
});
}
});
@@ -188,6 +196,15 @@ namespace Desktop
}
_isPaused = false;
}
private void fastLoadingToolStripMenuItem_Click(object sender, EventArgs e)
{
// Toggle the checkmark UI
fastLoadingToolStripMenuItem.Checked = !fastLoadingToolStripMenuItem.Checked;
// Tell the CPU to enable or disable the ROM hijack
_cpu.EnableFastLoad = fastLoadingToolStripMenuItem.Checked;
}
private void openSNAToolStripMenuItem_Click(object sender, EventArgs e)
{
_isPaused = true;
@@ -203,6 +220,39 @@ namespace Desktop
_isPaused = false;
}
private void btnRunZexDoc_Click(object sender, EventArgs e)
{
_isPaused = true;
using (OpenFileDialog ofd = new OpenFileDialog())
{
ofd.Filter = "CP/M Binaries (*.com, *.bin)|*.com;*.bin";
if (ofd.ShowDialog() == DialogResult.OK)
{
byte[] zexdocBytes = System.IO.File.ReadAllBytes(ofd.FileName);
// 1. Wipe the RAM completely clean
_memoryBus.CleanRAMData();
// 2. Load ZEXDOC exactly at CP/M start address 0x0100
for (int i = 0; i < zexdocBytes.Length; i++)
{
_memoryBus.Write((ushort)(0x0100 + i), zexdocBytes[i]);
}
// 3. Configure the CPU for CP/M
_cpu.IsZexDocMode = true;
_cpu.PC = 0x0100; // Execution starts here
_cpu.SP = 0xFFFF; // Put the stack at the very top of memory
// 4. Fake a RET address at 0x0000 so the test terminates gracefully when finished
_memoryBus.Write(0x0000, 0xD3); // OUT (n), A (A fake halt sequence)
// Unpause and watch the Visual Studio Output window!
_isPaused = false;
}
}
}
private void btnRun_Click(object sender, EventArgs e) => _isPaused = false;
private void btnPause_Click(object sender, EventArgs e) => _isPaused = true;