Add Int 7b skeleton + stop using instruction cache on EXEs (#471)

* Int21h Refactor to use Blocking Collection

* Refactoring EXERuntime to use LocalConsoleSession

* ExeRuntime refactored to use LocalConsoleSession

- Sets up ability to host EXE's through rlogin, Telnet, etc.
- `fgets()` working from EXE, `scanf()` still returning after 1st character

* Temporary checkin

* Add assertion on env length

* Additional Interrupts for INT 10h

* Added INT 10h Comments

* Added Clear Screen/Cursor Position APIs to INT 10h

* Cleanup INT 21h for Console Input

* Add CMDLINE.EXE integration test

* Fix lodsb/lodsw

* Fix build issues post-merge

* Post Merge Fixes

* Add IStream interface and implements around stdin,out,err

* Stop the SessionBase in ExeRuntime when done

* Helps to actually store the sessionBase when passed in ...

* Add TODO for in/out, small fix for Int21 07h

* Start investigating PIT

* Implement basic PIT

* Implement a non-elegant interrupt routine

* Add PIT tests

* Remove unused interrupt execution code in CpuCore

* Support retf + argument to modify SP

* Add std support

* Implement dos int21 CreateFile

Also added support for Btrieve interrupt, which is int 123 and has an
interrupt offset of 0x33

* Convert DOS paths -> System paths

* var

* Create a skeleton for Btrieve int 7b.

Stop using instruction cache for EXEs

* Function to => thingee

Co-authored-by: Eric Nusbaum <eric@enusbaum.com>

MBBSEmu/DOS/ExeRuntime.cs

@@ -69,6 +69,7 @@ public ExeRuntime(MZFile file, IClock clock, ILogger logger, IFileUtility fileUt
  new Int1Ah(Registers, Memory, clock),
  new Int3Eh(),
  new Int10h(Registers, _logger, stdout),
+ new Int7Bh(_logger, Registers, Memory),
  },
  new Dictionary<int, IIOPort>
  {

MBBSEmu/DOS/Interrupts/Int21h.cs

@@ -505,7 +505,7 @@ private void SetInterruptVector_0x25()
  _memory.SetPointer(ptr, newVectorPointer);
  }
 
- _logger.Info($"Set interrupt vector {interruptVector} at {ptr} to {newVectorPointer}");
+ _logger.Debug($"Set interrupt vector {interruptVector} at {ptr} to {newVectorPointer}");
  }
 
  private void GetCurrentDate_0x2A()
@@ -877,14 +877,14 @@ private void CloseFile_0x3E()
 
  var fileHandle = Registers.BX;
 
- _logger.Debug($"Closing file {fileHandle}");
-
  if (!_fileHandles.TryGetValue(fileHandle, out var fileStream))
  {
  SetCarryFlagErrorCodeInAX(DOSErrorCode.INVALID_HANDLE);
  return;
  }
 
+ _logger.Debug($"Closing file {fileHandle}");
+
  _fileHandles.Remove(fileHandle);
 
  fileStream.Close();

MBBSEmu/DOS/Interrupts/Int7Bh.cs

@@ -0,0 +1,110 @@
+using MBBSEmu.CPU;
+using MBBSEmu.Memory;
+using NLog;
+using System;
+using System.Runtime.InteropServices;
+
+namespace MBBSEmu.DOS.Interrupts
+{
+ public enum BtrieveError
+ {
+ Success = 0,
+ InvalidOperation = 1,
+ IOError = 2,
+ FileNotOpen = 3,
+ KeyValueNotFound = 4,
+ DuplicateKeyValue = 5,
+ InvalidKeyNumber = 6,
+ DifferentKeyNumber = 7,
+ InvalidPositioning = 8,
+ EOF = 9 ,
+ }
+
+ // https://docs.actian.com/psql/psqlv13/index.html#page/btrieveapi/btrintro.htm
+ // http://www.nomad.ee/btrieve/errors/index.shtml
+
+ /// <summary>
+ /// Btrieve interrupt handler
+ /// </summary>
+ public class Int7Bh : IInterruptHandler
+ {
+ private readonly ILogger _logger;
+ private readonly IMemoryCore _memory;
+ private readonly ICpuRegisters _registers;
+
+ public byte Vector => 0x7B;
+
+
+ protected struct BtrieveCommand
+ {
+ public ushort data_buffer_offset;
+ public ushort data_buffer_segment;
+
+ public ushort data_buffer_length;
+
+ public ushort position_block_offset;
+ public ushort position_block_segment;
+
+ public ushort fcb_offset;
+ public ushort fcb_segment;
+
+ public ushort operation;
+
+ public ushort key_buffer_offset;
+ public ushort key_buffer_segment;
+
+ public byte key_buffer_length;
+
+ public byte key_number;
+
+ public ushort status_code_pointer_offset;
+ public ushort status_code_pointer_segment;
+
+ public ushort interface_id; // should always be 0x6176
+
+ public void Log(ILogger logger)
+ {
+ /*foreach (var c in memory)
+ {
+ _logger.Error($"Byte: {c:X2}");
+ }*/
+
+
+ logger.Error($"DataBufferSegment: {new FarPtr(data_buffer_segment, data_buffer_offset)}:{data_buffer_length}");
+ logger.Error($"PosBlock: {new FarPtr(position_block_segment, position_block_offset)}");
+ logger.Error($"FCB: {new FarPtr(fcb_segment, fcb_offset)}");
+ logger.Error($"Operation: {operation}");
+ logger.Error($"KeyBuffer: {new FarPtr(key_buffer_segment, key_buffer_offset)}:{key_buffer_length}");
+ }
+ }
+
+ public Int7Bh(ILogger logger, ICpuRegisters registers, IMemoryCore memory)
+ {
+ _logger = logger;
+ _registers = registers;
+ _memory = memory;
+ }
+
+ public void Handle()
+ {
+ // DS:DX is argument
+ var data = ByteArrayToStructure<BtrieveCommand>(_memory.GetArray(_registers.DS, _registers.DX, 28).ToArray());
+ data.Log(_logger);
+
+ if (data.interface_id != 0x6176)
+ throw new ArgumentException($"Bad interface_id");
+
+ _memory.SetWord(data.status_code_pointer_segment, data.status_code_pointer_offset, (ushort)BtrieveError.FileNotOpen);
+ //_registers.CarryFlag = true;
+ //throw new ArgumentException($"Btrieve operation {data.operation}");
+ }
+
+ unsafe T ByteArrayToStructure<T>(byte[] bytes) where T : struct
+ {
+ fixed (byte* ptr = &bytes[0])
+ {
+ return (T)Marshal.PtrToStructure((IntPtr)ptr, typeof(T));
+ }
+ }
+ }
+}

MBBSEmu/Memory/RealModeMemoryCore.cs

@@ -31,12 +31,36 @@ public class RealModeMemoryCore : AbstractMemoryCore, IMemoryCore
 
  private MemoryAllocator _memoryAllocator;
 
- private readonly Dictionary<int, Instruction> _instructionCache = new(128*1024);
+ /// <summary>
+ /// CodeReader implementation which feeds the Iced.Intel
+ /// decoder based on our current IP.
+ /// </summary>
+ private class RealModeCodeReader : CodeReader
+ {
+ private readonly byte[] _memory;
+ private int ip = 0;
+
+ public RealModeCodeReader(byte[] memory)
+ {
+ _memory = memory;
+ }
+
+ public override int ReadByte() => _memory[ip++];
+
+ public void SetCurrent(int position) => ip = position;
+ }
+
+ private readonly RealModeCodeReader _codeReader;
+
+ private readonly Decoder _decoder;
 
  public RealModeMemoryCore(ushort heapBaseSegment, ILogger logger) : base(logger)
  {
  _heapBaseSegment = heapBaseSegment;
 
+ _codeReader = new(_memory);
+ _decoder = Decoder.Create(16, _codeReader);
+
  // fill with halt instructions
  Array.Fill(_memory, (byte)0);
 
@@ -79,24 +103,13 @@ public int GetAllocatedMemorySize(FarPtr ptr)
  public Instruction GetInstruction(ushort segment, ushort instructionPointer)
  {
  var physicalAddress = VirtualToPhysicalAddress(segment, instructionPointer);
+ _codeReader.SetCurrent(physicalAddress);
 
- if (_instructionCache.TryGetValue(physicalAddress, out var instruction))
- return instruction;
-
- var codeReader = new ByteArrayCodeReader(VirtualToPhysical(segment, instructionPointer).Slice(0, 10).ToArray());
- var decoder = Decoder.Create(16, codeReader);
- decoder.IP = instructionPointer;
-
- instruction = decoder.Decode();
- _instructionCache.Add(VirtualToPhysicalAddress(segment, instructionPointer), instruction);
- return instruction;
+ _decoder.IP = instructionPointer;
+ return _decoder.Decode();
  }
 
- public Instruction Recompile(ushort segment, ushort instructionPointer)
- {
- _instructionCache.Remove(VirtualToPhysicalAddress(segment, instructionPointer));
- return GetInstruction(segment, instructionPointer);
- }
+ public Instruction Recompile(ushort segment, ushort instructionPointer) => GetInstruction(segment, instructionPointer);
 
  public static int VirtualToPhysicalAddress(ushort segment, ushort offset) => ((segment << 4) + offset);
  public static FarPtr PhysicalToVirtualAddress(int offset) => new FarPtr((ushort)(offset >> 4), (ushort)(offset & 0xF));
@@ -105,7 +118,6 @@ public override void Clear()
  {
  base.Clear();
 
- _instructionCache.Clear();
  _memoryAllocator = new MemoryAllocator(_logger, new FarPtr(_heapBaseSegment, 0), HEAP_MAX_SIZE, alignment: 16);
  Array.Fill(_memory, (byte)0);
  }