Make engine dep-free/standalone and add Wasm target

wasm-compat.c

@@ -0,0 +1,71 @@
+
+#include "base.h"
+
+#include <stdint.h>
+
+static struct search_option g_tt_buf[TT_ENTRIES];
+
+static struct board g_board;
+
+static inline uint32_t move_serialize(struct move m) 
+{
+	_Static_assert(sizeof m.from * CHAR_BIT == 8,
+			"this must be checked if struct move's `from` changes");
+	_Static_assert(sizeof m.to * CHAR_BIT == 8,
+			"this must be checked if struct move's `to` changes");
+	return ((uint32_t)m.appeal << 24ULL)
+		 | ((uint32_t)m.attr << 16ULL)
+		 | ((uint32_t)m.from << 8ULL)
+		 | ((uint32_t)m.to);
+}
+
+static inline struct move move_deserialize(uint64_t m)
+{
+	return (struct move) {
+		/* appeal and attributes are ignored regardless */
+		/*
+		.appeal = (m >> 24) & 0xFF,
+		.attr   = (m >> 16) & 0xFF,
+		*/
+		.from   = (m >>  8) & 0xFF,
+		.to     = (m >>  0) & 0xFF,
+	};
+}
+
+uint64_t wb_search(int8_t max_depth)
+{
+	struct search_result const sr = search(&g_board, g_board.pos.player, max_depth);
+	return move_serialize(sr.move);
+}
+
+enum move_result wb_move(uint32_t move)
+{
+	struct move m = move_deserialize(move);
+	enum move_result const r = board_move_2(&g_board, m);
+	return r;
+}
+
+void wb_init()
+{
+	g_board = BOARD_INIT;
+	g_board.tt.entries = g_tt_buf;
+}
+
+static int32_t player_piece_serialize(enum player c, enum piece pz)
+{
+	return ((c  & 0xFF) << 8U)
+		 |  (pz & 0xFF);
+}
+
+int32_t wb_board_at(index at)
+{
+	bitboard const m = SQ_MASK_FROM_INDEX(at);
+	for (enum player pl = PLAYER_BEGIN; pl < PLAYER_COUNT; ++pl) {
+		for (enum piece pz = PIECE_BEGIN; pz < PIECE_COUNT; ++pz) {
+			if (g_board.pos.pieces[pl][pz] & m) {
+				return player_piece_serialize(pl, pz);
+			}
+		}
+	}
+	return -1;
+}