feat: DOS INT21H 0x4B (WIP)

Signed-off-by: Maximilien Noal <noal.maximilien@gmail.com>

src/Spice86.Core/Emulator/InterruptHandlers/Dos/DosInt21Handler.cs

@@ -88,6 +88,7 @@ private void FillDispatchTable() {
         AddAction(0x2F, GetDiskTransferAddress);
         AddAction(0x30, GetDosVersion);
         AddAction(0x33, GetSetControlBreak);
+        AddAction(0x34, GetInDosFlag);
         AddAction(0x35, GetInterruptVector);
         AddAction(0x36, GetFreeDiskSpace);
         AddAction(0x38, () => SetCountryCode(true));
@@ -675,6 +676,13 @@ public void GetSetControlBreak() {
         }
     }
 
+    /// <summary>
+    /// Returns the current value of the IN DOS flag in the BX register.
+    /// </summary>
+    public void GetInDosFlag() {
+        //State.ES 
+    }
+
     /// <summary>
     /// Returns the current MS-DOS time in CH (hour), CL (minute), DH (second), and DL (millisecond) from the host's DateTime.Now.
     /// </summary>
@@ -730,17 +738,53 @@ private enum TypeOfLoad : byte {
     /// <returns>
     /// CF is cleared on success. <br/>
     /// CF is set on error.
+    /// TODO: This needs the DOS Swappable Area, and a lot of other DOS globals (current drive, current folder, ...)
     /// </returns>
     /// </summary>
     /// <param name="calledFromVm">Whether the code was called by the emulator.</param>
     public void LoadAndOrExecuteProgram(bool calledFromVm) {
         bool success = false;
+        byte typeOfLoadByte = State.AL;
+        if (!Enum.IsDefined(typeof(TypeOfLoad), typeOfLoadByte)) {
+            SetCarryFlag(false, calledFromVm);
+            return;
+        }
         TypeOfLoad typeOfLoad = (TypeOfLoad)State.AL;
         string programName = GetZeroTerminatedStringAtDsDx();
+        string? fullHostPath = _dosFileManager.TryGetFullHostPathFromDos(programName);
+
+        if(string.IsNullOrWhiteSpace(fullHostPath) || !File.Exists(fullHostPath)) {
+            SetCarryFlag(false, calledFromVm);
+            return;
+        }
 
         if (LoggerService.IsEnabled(LogEventLevel.Verbose)) {
             LoggerService.Verbose("LOAD AND/OR EXECUTE PROGRAM {TypeOfLoad}, {ProgramName}", typeOfLoad, programName);
         }
+
+        bool isComFile = string.Equals(Path.GetExtension(programName).ToLowerInvariant(), ".com", StringComparison.OrdinalIgnoreCase);
+
+        switch (typeOfLoad) {
+            case TypeOfLoad.LoadAndExecute:
+                if (isComFile) {
+                    LoadAndExecComFile(fullHostPath, "", 0x1000);
+                } else {
+                    LoadAndExecExeFile(fullHostPath, "", 0x1000);
+                }
+                success = true;
+                break;
+            case TypeOfLoad.LoadOnly:
+                // Not implemented
+                success = false;
+                break;
+            case TypeOfLoad.LoadOverlay:
+                // Not implemented
+                success = false;
+                break;
+            default:
+                SetCarryFlag(false, calledFromVm);
+                return;
+        }
         SetCarryFlag(success, calledFromVm);
     }
 
@@ -1108,7 +1152,7 @@ private void SetStateFromDosFileOperationResult(bool calledFromVm, DosFileOperat
 
     private const ushort ComOffset = 0x100;
 
-    internal void LoadEXEFile(string hostFile, string? arguments, ushort startSegment) {
+    internal void LoadAndExecExeFile(string hostFile, string? arguments, ushort startSegment) {
         byte[] exe = File.ReadAllBytes(hostFile);
         if (LoggerService.IsEnabled(LogEventLevel.Debug)) {
             LoggerService.Debug("Exe size: {ExeSize}", exe.Length);
@@ -1186,7 +1230,7 @@ private void SetEntryPoint(ushort cs, ushort ip) {
         }
     }
 
-    internal void LoadCOMFile(string hostFile, string? arguments, ushort startSegment) {
+    internal void LoadAndExecComFile(string hostFile, string? arguments, ushort startSegment) {
         new PspGenerator(Memory, _dos.EnvironmentVariables, _dosMemoryManager, _dosFileManager).GeneratePsp(startSegment, arguments);
         byte[] com = File.ReadAllBytes(hostFile);
         uint physicalStartAddress = MemoryUtils.ToPhysicalAddress(startSegment, ComOffset);

src/Spice86.Core/Emulator/LoadableFile/Dos/Exe/ExeFile.cs

@@ -5,7 +5,7 @@
 using Spice86.Shared.Emulator.Memory;
 
 /// <summary>
-/// Representation of an EXE file as a MemoryBasedDataStructure
+/// Representation of an EXE file as it is stored on disk, loaded into memory.
 /// </summary>
 public class ExeFile : MemoryBasedDataStructure {
     /// <summary>

src/Spice86.Core/Emulator/OperatingSystem/Dos.cs

@@ -28,6 +28,11 @@ public class Dos {
     private readonly KeyboardStreamedInput _keyboardStreamedInput;
     private readonly ILoggerService _loggerService;
 
+    /// <summary>
+    /// Gets or sets the last DOS error code.
+    /// </summary>
+    public ErrorCode ErrorCode { get; set; }
+
     /// <summary>
     /// Gets the INT 20h DOS services.
     /// </summary>
@@ -48,10 +53,12 @@ public class Dos {
     /// </summary>
     public DosInt28Handler DosInt28Handler { get; }
 
+    public DosTables DosTables { get; }
+
     /// <summary>
     /// Gets the country ID from the CountryInfo table
     /// </summary>
-    public byte CurrentCountryId => CountryInfo.Country;
+    public CountryId CurrentCountryId => DosTables.CountryInfo.CountryId;
 
     /// <summary>
     /// Gets the list of virtual devices.
@@ -78,11 +85,6 @@ public class Dos {
     /// </summary>
     public DosFileManager FileManager { get; }
 
-    /// <summary>
-    /// Gets the global DOS memory structures.
-    /// </summary>
-    public CountryInfo CountryInfo { get; } = new();
-
     /// <summary>
     /// Gets the current DOS master environment variables.
     /// </summary>
@@ -113,7 +115,10 @@ public Dos(IMemory memory, Cpu cpu, KeyboardInt16Handler keyboardInt16Handler,
         _state = cpu.State;
         _vgaFunctionality = vgaFunctionality;
         _keyboardStreamedInput = new KeyboardStreamedInput(keyboardInt16Handler);
+
         AddDefaultDevices();
+        DosTables = new(memory);
+
         FileManager = new DosFileManager(_memory, cDriveFolderPath, executablePath, _loggerService, this.Devices);
         MemoryManager = new DosMemoryManager(_memory, _loggerService);
         DosInt20Handler = new DosInt20Handler(_memory, cpu, _loggerService);

src/Spice86.Core/Emulator/OperatingSystem/Enums/DosConstants.cs

@@ -0,0 +1,25 @@
+namespace Spice86.Core.Emulator.OperatingSystem.Enums;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+internal static class DosConstants {
+    public const ushort DosSdaSegment = 0xb2;
+    public const ushort DosSdaOffset = 0x0;
+    public const ushort DosCurrentDirectoryStructureSegment = 0x108;
+    public const ushort DosInfoBlockSegment = 0x80;
+    public const ushort DosConDrvSegment = 0Xa0;
+    public const ushort DosConStringSegment = 0xa8;
+    public const ushort DosFirstShell = 0x118;
+    public const ushort DosFirstUsableMemorySegment = 0x16f;
+    public const ushort DosPrivateSegmentStart = 0xc800;
+    public const ushort DosPrivateSegmentEnd = 0xd000;
+    public const int SftHeaderSize = 6;
+    public const int SftEntrySize = 59;
+    public const uint SftEndPointer = 0xffffffff;
+    public const ushort SftNextTableOffset = 0x0;
+    public const ushort SftNumberOfFilesOffset = 0x04;
+    public const int FakeSftEntries = 16;
+}

src/Spice86.Core/Emulator/OperatingSystem/Enums/DosReturnMode.cs

@@ -0,0 +1,13 @@
+namespace Spice86.Core.Emulator.OperatingSystem.Enums;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+internal enum DosReturnMode : byte {
+    Exit = 0,
+    CtrlC = 1,
+    Abort = 2,
+    TerminateAndStayResident = 3
+}

src/Spice86.Core/Emulator/OperatingSystem/Enums/ErrorCode.cs

@@ -3,8 +3,7 @@ namespace Spice86.Core.Emulator.OperatingSystem.Enums;
 /// <summary>
 /// Defines error codes for MS-DOS operations.
 /// </summary>
-public enum ErrorCode : byte
-{
+public enum ErrorCode : byte {
     /// <summary>
     /// No error occurred during the operation.
     /// </summary>
@@ -103,5 +102,15 @@ public enum ErrorCode : byte
     /// <summary>
     /// No more files match the criteria
     /// </summary>
-    NoMoreMatchingFiles
+    NoMoreMatchingFiles,
+
+    /// <summary>
+    /// File, or a part of the file, is locked
+    /// </summary>
+    LockViolation = 0x33,
+
+    /// <summary>
+    /// File already exists in the directory
+    /// </summary>
+    FileAlreadyExists = 0x80,
 }

src/Spice86.Core/Emulator/OperatingSystem/Structures/CountryInfo.cs

@@ -1,42 +1,104 @@
 namespace Spice86.Core.Emulator.OperatingSystem.Structures;
 
+using Spice86.Core.Emulator.Memory.ReaderWriter;
 using Spice86.Core.Emulator.OperatingSystem.Enums;
+using Spice86.Core.Emulator.ReverseEngineer.DataStructure;
+
+using System.Diagnostics;
+
 /// <summary>
 /// Represents information about the formatting of dates, times, and numbers for a specific country.
 /// </summary>
-public class CountryInfo {
+[DebuggerDisplay("{CountryId}")]
+public class CountryInfo : MemoryBasedDataStructure {
+
+    public CountryInfo(IByteReaderWriter byteReaderWriter) : base(byteReaderWriter, 0) {
+    }
+
     /// <summary>
     /// Gets or sets the country code for the specific country, where 1 represents the United States, 2 represents Canada, and so on.
     /// </summary>
-    public byte Country { get; set; } = (byte)CountryId.UnitedStates;
+    public byte Country { get => UInt8[0]; set => UInt8[0] = value; }
+
+    public CountryId CountryId => (CountryId)Country;
 
     /// <summary>
     /// Gets or sets the format of the date in the specified country.
     /// </summary>
-    public byte DateFormat { get; set; }
+    public byte DateFormat { get => UInt8[1]; set => UInt8[1] = value; }
+
+    /// <summary>
+    /// Gets or sets the currency string for the specified country.
+    /// </summary>
+    public string CurrencyString { get => GetZeroTerminatedString(2, 5); set => SetZeroTerminatedString(2, value, 5); }
+
+    /// <summary>
+    /// Gets or sets the thousands separator for the specified country.
+    /// </summary>
+    public byte ThousandsSeparator { get => UInt8[8]; set => UInt8[8] = value; }
+
+    /// <summary>
+    /// Gets or sets the decimal separator for the specified country.
+    /// </summary>
+    public byte DecimalSeparator { get => UInt8[9]; set => UInt8[9] = value; }
+
+    /// <summary>
+    /// Gets or sets the date separator for the specified country.
+    /// </summary>
+    public byte DateSeparator { get => UInt8[10]; set => UInt8[10] = value; }
+
+    /// <summary>
+    /// Gets or sets the time separator for the specified country.
+    /// </summary>
+    public byte TimeSeparator { get => UInt8[11]; set => UInt8[11] = value; }
+
+    /// <summary>
+    /// Gets or sets the currency format for the specified country.
+    /// </summary>
+    public byte CurrencyFormat { get => UInt8[12]; set => UInt8[12] = value; }
+
+    /// <summary>
+    /// Gets or sets the number of digits after the decimal for the specified country.
+    /// </summary>
+    public byte DigitsAfterDecimal { get => UInt8[13]; set => UInt8[13] = value; }
+
+    /// <summary>
+    /// Gets or sets the time format for the specified country.
+    /// </summary>
+    public byte TimeFormat { get => UInt8[14]; set => UInt8[14] = value; }
+
+    /// <summary>
+    /// Gets or sets the casemap for the specified country.
+    /// </summary>
+    public byte Casemap { get => UInt8[15]; set => UInt8[15] = value; }
+
+    /// <summary>
+    /// Gets or sets the data separator for the specified country.
+    /// </summary>
+    public byte DataSeparator { get => UInt8[19]; set => UInt8[19] = value; }
 
     /// <summary>
-    /// Gets or sets the character used to separate the components of a date in the specified country.
+    /// Gets or sets the reserved value 1 for the specified country.
     /// </summary>
-    public byte DateSeparator { get; set; }
+    public byte Reserved1 { get => UInt8[20]; set => UInt8[20] = value; }
 
     /// <summary>
-    /// Gets or sets the format of the time in the specified country.
+    /// Gets or sets the reserved value 2 for the specified country.
     /// </summary>
-    public byte TimeFormat { get; set; }
+    public byte Reserved2 { get => UInt8[21]; set => UInt8[21] = value; }
 
     /// <summary>
-    /// Gets or sets the character used to separate the components of a time in the specified country.
+    /// Gets or sets the reserved value 3 for the specified country.
     /// </summary>
-    public byte TimeSeparator { get; set; }
+    public byte Reserved3 { get => UInt8[22]; set => UInt8[22] = value; }
 
     /// <summary>
-    /// Gets or sets the character used to separate thousands in a number in the specified country.
+    /// Gets or sets the reserved value 4 for the specified country.
     /// </summary>
-    public byte ThousandsSeparator { get; set; }
+    public byte Reserved4 { get => UInt8[23]; set => UInt8[23] = value; }
 
     /// <summary>
-    /// Gets or sets the character used to separate the whole number part from the fractional part in a number in the specified country.
+    /// Gets or sets the reserved value 5 for the specified country.
     /// </summary>
-    public byte DecimalSeparator { get; set; }
+    public byte Reserved5 { get => UInt8[24]; set => UInt8[24] = value; }
 }

src/Spice86.Core/Emulator/OperatingSystem/Structures/DosCommandTail.cs

@@ -0,0 +1,16 @@
+namespace Spice86.Core.Emulator.OperatingSystem.Structures;
+
+using Spice86.Core.Emulator.Memory.ReaderWriter;
+using Spice86.Core.Emulator.ReverseEngineer.DataStructure;
+
+public class DosCommandTail : MemoryBasedDataStructure {
+    public DosCommandTail(IByteReaderWriter byteReaderWriter, uint baseAddress) : base(byteReaderWriter, baseAddress) {
+    }
+
+    public string Command {
+        get => GetZeroTerminatedString(BaseAddress, MaxCharacterLength);
+        set => SetZeroTerminatedString(BaseAddress, value, MaxCharacterLength);
+    }
+
+    public const int MaxCharacterLength = 128;
+}

src/Spice86.Core/Emulator/OperatingSystem/Structures/DosEnvironmentBlock.cs

@@ -0,0 +1,13 @@
+namespace Spice86.Core.Emulator.OperatingSystem.Structures;
+
+using Spice86.Core.Emulator.Memory.ReaderWriter;
+using Spice86.Core.Emulator.ReverseEngineer.DataStructure;
+
+public abstract class DosEnvironmentBlock : MemoryBasedDataStructure {
+    protected DosEnvironmentBlock(IByteReaderWriter byteReaderWriter, uint baseAddress) : base(byteReaderWriter, baseAddress) {
+    }
+
+    public abstract string? GetEnvironmentVariable(string variableName);
+
+    public abstract void SetEnvironmentVariable(string variableName, string value);
+}