jheaps/JoshHeaps.Net
1
0
Fork 0
Code Issues Pull Requests 1 Actions Packages Projects Releases Wiki Activity

Feed move history and halfmove clock to the engine for repetition detection

Browse Source 
- Track HalfmoveClock in GameState/ChessService (reset on captures and pawn moves)
- Emit the real halfmove clock in ToFen and add GameState.RepetitionHistory()
  (prior positions since the last irreversible move) in ChessEngineHelpers
- Pass that history through IChessEngine.GetBestMoveAsync to the native engine;
  Stockfish ignores it

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
This commit is contained in:
Josh-Heaps
2026-06-08 18:59:10 -06:00
co-authored by Claude Opus 4.8
parent 5345427e0c
commit d87cea572f
7 changed files with 47 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
JoshHeaps.Net/Services/Implementations/CustomChessEngine.cs
+5 -4
View File
@@ -28,9 +28,10 @@ public sealed partial class CustomChessEngine : IChessEngine
_handle = new EngineSafeHandle(handle);
}
public Task<string> GetBestMoveAsync(string fen) => Task.Run(() => GetBestMove(fen));
public Task<string> GetBestMoveAsync(string fen, IReadOnlyList<string> historyFens) =>
Task.Run(() => GetBestMove(fen, string.Join('\n', historyFens)));
private unsafe string GetBestMove(string fen)
private unsafe string GetBestMove(string fen, string history)
{
const int bufferLength = 16; // longest UCI move is 5 chars ("e7e8q") + NUL
byte* buffer = stackalloc byte[bufferLength];
@@ -40,7 +41,7 @@ public sealed partial class CustomChessEngine : IChessEngine
try
{
_handle.DangerousAddRef(ref added);
var code = NativeMethods.engine_best_move(_handle.DangerousGetHandle(), fen, buffer, bufferLength);
var code = NativeMethods.engine_best_move(_handle.DangerousGetHandle(), fen, history, buffer, bufferLength);
if (code != 0)
throw new InvalidOperationException($"Native chess engine failed to produce a move for FEN '{fen}' (engine_best_move returned {code}).");
@@ -109,7 +110,7 @@ public sealed partial class CustomChessEngine : IChessEngine
[LibraryImport(LibName, StringMarshalling = StringMarshalling.Utf8)]
[UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
internal static unsafe partial int engine_best_move(IntPtr engine, string fen, byte* outBuffer, int outLength);
internal static unsafe partial int engine_best_move(IntPtr engine, string fen, string history, byte* outBuffer, int outLength);
[LibraryImport(LibName)]
[UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]