24-add-uci-layer (#39)

Reviewed-on: #39
Co-authored-by: Josh <josh@joshuaschuett.com>
Co-committed-by: Josh <josh@joshuaschuett.com>

uci/uci_engine.py

@@ -0,0 +1,207 @@
+#!/usr/bin/env python3
+import sys, shlex
+import ctypes as C
+from binding.python_c_ffi import ChessFFI, Board, Move, WHITE, Q, R, B, N, q, r, b, n
+
+
+START_FEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
+PROMO_MAP = {"q": (Q, q), "r": (R, r), "b": (B, b), "n": (N, n)}
+ONE_MINUTE = 60000
+THREE_MINUTES = ONE_MINUTE * 3
+FIVE_MINUTES = ONE_MINUTE * 5
+TEN_MINUTES = ONE_MINUTE * 10
+THIRTY_MINUTES = ONE_MINUTE * 30
+
+
+def flushln(s: str):
+    sys.stdout.write(s + "\n")
+    sys.stdout.flush()
+
+
+def sq_to_uci(sq: int) -> str:
+    return chr(ord("a") + (sq % 8)) + chr(ord("1") + (sq // 8))
+
+
+def move_to_uci(m: Move) -> str:
+    s = sq_to_uci(getattr(m, "from")) + sq_to_uci(m.to)
+    if m.promo:
+        for c, (wpid, bpid) in PROMO_MAP.items():
+            if m.promo in (wpid, bpid):
+                s += c
+                break
+    return s
+
+
+def uci_to_move(uci: str, ffi, board) -> Move | None:
+    ffile, frank = ord(uci[0])-97, ord(uci[1])-49
+    tfile, trank = ord(uci[2])-97, ord(uci[3])-49
+    from_sq, to_sq = frank*8+ffile, trank*8+tfile
+    promo = uci[4].lower() if len(uci) > 4 else None
+
+    buf = (Move * 256)()
+    n = ffi.get_legal_moves(board, buf)
+
+    want_promo = None
+    if promo:
+        wpid, bpid = PROMO_MAP[promo]
+        want_promo = wpid if board.side_to_move == WHITE else bpid
+
+    for i in range(n):
+        m = buf[i]
+        if getattr(m, "from") == from_sq and m.to == to_sq:
+            if want_promo is None or m.promo == want_promo:
+                return m
+    return None
+
+
+class UCIEngine:
+    def __init__(self):
+        self.ffi = ChessFFI()
+        self.ffi.init_attack_cache()
+        self._seed_engine()
+        self.board = Board()
+        self.ffi.load_fen(self.board, START_FEN)
+
+        self.options = {
+            "Depth": 5,
+            "WindowCp": 50,
+            "MoveOverhead": 100,
+        }
+
+        self.default_depth = 6
+        self.short_depth = 5
+        self.long_depth = 7
+
+        self.wtime = None
+        self.btime = None
+
+
+    def _seed_engine(self):
+        import ctypes as C, time
+
+        seed = time.time_ns()
+        s32 = int(seed) & 0xFFFFFFFF
+
+        libc = C.CDLL("libc.so.6")
+        libc.srand.argtypes = (C.c_uint,)
+        libc.srand.restype  = None
+        libc.srand(C.c_uint(s32))
+        return s32
+
+
+    def cmd_uci(self):
+        flushln("id name joshsbot")
+        flushln("id author Josh")
+        # UCI options. Do we even need these? We just use this interface
+        # for the lichess-bot. It's not like we plan on using them?
+        flushln("option name Depth type spin default 3 min 1 max 64")
+        flushln("option name WindowCp type spin default 50 min 0 max 1000")
+        flushln("option name Move Overhead type spin default 100 min 0 max 5000")
+        flushln("uciok")
+
+
+    def cmd_isready(self):
+        flushln("readyok")
+
+
+    def cmd_ucinewgame(self):
+        self.ffi.load_fen(self.board, START_FEN)
+
+
+    def cmd_position(self, args):
+        # Reset to startpos or fen
+        if args[0] == "startpos":
+            self.ffi.load_fen(self.board, START_FEN)
+            args = args[1:]
+        elif args[0] == "fen":
+            i = args.index("moves") if "moves" in args else len(args)
+            fen = " ".join(args[1:i]).decode("ascii")
+            self.ffi.load_fen(self.board, fen)
+            args = args[i:]
+
+        # Apply all moves
+        if args and args[0] == "moves":
+            for mstr in args[1:]:
+                m = uci_to_move(mstr, self.ffi, self.board)
+                if m:
+                    next_board = Board()
+                    if self.ffi.apply_move_on_copy(self.board, next_board, m):
+                        self.board = next_board
+
+
+    def cmd_go(self, args):
+        wtime, btime = None, None
+
+        # parse clocks (milliseconds from lichess)
+        if "wtime" in args:
+            wtime = int(args[args.index("wtime") + 1])
+        if "btime" in args:
+            btime = int(args[args.index("btime") + 1])
+
+        self.wtime, self.btime = wtime, btime
+
+        mytime = self.get_my_time()
+
+        best = Move()
+        if mytime >= TEN_MINUTES:
+            ok = self.ffi._c_ai_find_best_move_with_window(self.board, self.long_depth, 3, best)
+        elif mytime < TEN_MINUTES and mytime >= ONE_MINUTE:
+            ok = self.ffi._c_ai_find_best_move_with_window(self.board, self.default_depth, 3, best)
+        else:
+            ok = self.ffi._c_ai_find_best_move_with_window(self.board, self.short_depth, 3, best)
+
+        if ok:
+            flushln(f"bestmove {move_to_uci(best)}")
+        else:
+            flushln("bestmove 0000")
+
+
+    def get_my_time(self):
+        """Return remaining time (ms) for the side to move."""
+        if self.board.side_to_move == WHITE:
+            return self.wtime
+        else:
+            return self.btime
+
+
+    def cmd_setoption(self, tokens):
+        try:
+            i_name = tokens.index("name")
+            i_val = tokens.index("value")
+            name = " ".join(tokens[i_name+1:i_val])
+            value = " ".join(tokens[i_val+1:]) if i_val + 1 < len(tokens) else ""
+        except ValueError:
+            return
+
+        if name in self.options:
+            try:
+                self.options[name] = int(value)
+            except ValueError:
+                pass
+
+
+    def loop(self):
+        for line in sys.stdin:
+            parts = shlex.split(line.strip())
+            if not parts:
+                continue
+            cmd, args = parts[0], parts[1:]
+
+            if cmd == "uci": 
+                self.cmd_uci()
+            elif cmd == "isready": 
+                self.cmd_isready()
+            elif cmd == "ucinewgame": 
+                self.cmd_ucinewgame()
+            elif cmd == "setoption":
+                self.cmd_setoption(args)
+            elif cmd == "position": 
+                self.cmd_position(args)
+            elif cmd == "go": 
+                self.cmd_go(args)
+            elif cmd == "quit": 
+                break
+
+
+if __name__ == "__main__":
+    UCIEngine().loop()