#pragma once #include #include #include #include #include #include #include #include #include /* BIT MANIPULATION * ================ */ static inline uint64_t popcount(uint64_t n) { // TODO: check of popcountll support return (uint64_t)__builtin_popcountll(n); } static inline uint64_t ctz(uint64_t n) { assert(n != 0); return (uint64_t)__builtin_ctzll(n); } /**/ static uint64_t rand64() { union { uint64_t v; uint16_t vs[4]; } x = { .vs = { (uint16_t)rand(), (uint16_t)rand(), (uint16_t)rand(), (uint16_t)rand(), } }; return x.v; } /* BITBOARD AND INDEX DATATYPES AND HELPERS * ========================================= */ typedef uint64_t bitboard; #define BITBOARD( \ a8,b8,c8,d8,e8,f8,g8,h8, \ a7,b7,c7,d7,e7,f7,g7,h7, \ a6,b6,c6,d6,e6,f6,g6,h6, \ a5,b5,c5,d5,e5,f5,g5,h5, \ a4,b4,c4,d4,e4,f4,g4,h4, \ a3,b3,c3,d3,e3,f3,g3,h3, \ a2,b2,c2,d2,e2,f2,g2,h2, \ a1,b1,c1,d1,e1,f1,g1,h1) \ (bitboard)\ 0b##\ h8##g8##f8##e8##d8##c8##b8##a8##\ h7##g7##f7##e7##d7##c7##b7##a7##\ h6##g6##f6##e6##d6##c6##b6##a6##\ h5##g5##f5##e5##d5##c5##b5##a5##\ h4##g4##f4##e4##d4##c4##b4##a4##\ h3##g3##f3##e3##d3##c3##b3##a3##\ h2##g2##f2##e2##d2##c2##b2##a2##\ h1##g1##f1##e1##d1##c1##b1##a1##\ ULL #define BITBOARD_FMT PRIu64 #define BITBOARD_FMT_X PRIx64 typedef uint8_t index; #define INDEX(n) n##ULL #define INDEX_FMT PRIu8 #define RANK_SHIFT_UP(b, n) ((b) << ((index)(n)*8U)) #define RANK_SHIFT_DOWN(b, n) ((b) >> ((index)(n)*8U)) #define FILE_SHIFT_LEFT(b, n) ((b) >> ((index)(n)*1U)) #define FILE_SHIFT_RIGHT(b, n) ((b) << ((index)(n)*1U)) #define FILE_MASK(n) FILE_SHIFT_RIGHT((bitboard)0x0101010101010101ULL, n) #define RANK_MASK(n) RANK_SHIFT_UP((bitboard)0x00000000000000FFULL, n) #define INDEX_FROM_RF(rank, file) ((index)(8U*(index)(rank) + (index)(file))) #define SQ_MASK_FROM_INDEX(idx) (((bitboard)1ULL)<<((index)idx)) #define SQ_MASK_FROM_RF(rank, file) (SQ_MASK_FROM_INDEX(INDEX_FROM_RF(rank,file))) enum file_index : index { FILE_INDEX_BEGIN, FILE_INDEX_A = FILE_INDEX_BEGIN, FILE_INDEX_B, FILE_INDEX_C, FILE_INDEX_D, FILE_INDEX_E, FILE_INDEX_F, FILE_INDEX_G, FILE_INDEX_H, FILE_INDEX_COUNT, }; enum rank_index : index { RANK_INDEX_BEGIN, RANK_INDEX_1 = RANK_INDEX_BEGIN, RANK_INDEX_2, RANK_INDEX_3, RANK_INDEX_4, RANK_INDEX_5, RANK_INDEX_6, RANK_INDEX_7, RANK_INDEX_8, RANK_INDEX_COUNT, }; #define STR(x) #x #define SQ_MASK_PREFIX SQ_MASK_ #define SQUARES_LIST_BEGIN \ X(A, 1) #define SQUARES_LIST \ X(A, 1) \ X(A, 2) \ X(A, 3) \ X(A, 4) \ X(A, 5) \ X(A, 6) \ X(A, 7) \ X(A, 8) \ X(B, 1) \ X(B, 2) \ X(B, 3) \ X(B, 4) \ X(B, 5) \ X(B, 6) \ X(B, 7) \ X(B, 8) \ X(C, 1) \ X(C, 2) \ X(C, 3) \ X(C, 4) \ X(C, 5) \ X(C, 6) \ X(C, 7) \ X(C, 8) \ X(D, 1) \ X(D, 2) \ X(D, 3) \ X(D, 4) \ X(D, 5) \ X(D, 6) \ X(D, 7) \ X(D, 8) \ X(E, 1) \ X(E, 2) \ X(E, 3) \ X(E, 4) \ X(E, 5) \ X(E, 6) \ X(E, 7) \ X(E, 8) \ X(F, 1) \ X(F, 2) \ X(F, 3) \ X(F, 4) \ X(F, 5) \ X(F, 6) \ X(F, 7) \ X(F, 8) \ X(G, 1) \ X(G, 2) \ X(G, 3) \ X(G, 4) \ X(G, 5) \ X(G, 6) \ X(G, 7) \ X(G, 8) \ X(H, 1) \ X(H, 2) \ X(H, 3) \ X(H, 4) \ X(H, 5) \ X(H, 6) \ X(H, 7) \ X(H, 8) /* define mask constants: SQ_MASK_A1, SQ_MASK_A2, ..., SQ_MASK_H8 */ enum : bitboard { #define X(file, rank) SQ_MASK_##file##rank = SQ_MASK_FROM_RF(RANK_INDEX_##rank, FILE_INDEX_##file), SQUARES_LIST #undef X }; enum square_index : index { #define X(file, rank) SQ_INDEX_##file##rank = INDEX_FROM_RF(RANK_INDEX_##rank, FILE_INDEX_##file), SQUARES_LIST SQ_INDEX_COUNT, #undef X /* define iterator begin enum */ #define X(file, rank) SQ_INDEX_BEGIN = SQ_INDEX_##file##rank, SQUARES_LIST_BEGIN #undef X }; static char* const square_index_display[SQ_INDEX_COUNT] = { #define X(file, rank) \ [SQ_INDEX_##file##rank] = STR(file##rank), SQUARES_LIST #undef X }; static char* const square_index_str[SQ_INDEX_COUNT] = { #define X(file, rank) \ [SQ_INDEX_##file##rank] = STR(SQ_INDEX_##file##rank), SQUARES_LIST #undef X }; enum : bitboard { FILE_MASK_A = FILE_MASK(FILE_INDEX_A), FILE_MASK_B = FILE_MASK(FILE_INDEX_B), FILE_MASK_C = FILE_MASK(FILE_INDEX_C), FILE_MASK_D = FILE_MASK(FILE_INDEX_D), FILE_MASK_E = FILE_MASK(FILE_INDEX_E), FILE_MASK_F = FILE_MASK(FILE_INDEX_F), FILE_MASK_G = FILE_MASK(FILE_INDEX_G), FILE_MASK_H = FILE_MASK(FILE_INDEX_H), RANK_MASK_1 = RANK_MASK(RANK_INDEX_1), RANK_MASK_2 = RANK_MASK(RANK_INDEX_2), RANK_MASK_3 = RANK_MASK(RANK_INDEX_3), RANK_MASK_4 = RANK_MASK(RANK_INDEX_4), RANK_MASK_5 = RANK_MASK(RANK_INDEX_5), RANK_MASK_6 = RANK_MASK(RANK_INDEX_6), RANK_MASK_7 = RANK_MASK(RANK_INDEX_7), RANK_MASK_8 = RANK_MASK(RANK_INDEX_8), FILE_SHIFT_RIGHT_GUARD_0 = ~0ULL, FILE_SHIFT_RIGHT_GUARD_1 = ~FILE_MASK_H, FILE_SHIFT_RIGHT_GUARD_2 = ~(FILE_MASK_G | FILE_MASK_H), FILE_SHIFT_RIGHT_GUARD_3 = ~(FILE_MASK_F | FILE_MASK_G | FILE_MASK_H), FILE_SHIFT_RIGHT_GUARD_4 = ~(FILE_MASK_E | FILE_MASK_F | FILE_MASK_G | FILE_MASK_H), FILE_SHIFT_RIGHT_GUARD_5 = ~(FILE_MASK_D | FILE_MASK_E | FILE_MASK_F | FILE_MASK_G | FILE_MASK_H), FILE_SHIFT_RIGHT_GUARD_6 = ~(FILE_MASK_C | FILE_MASK_D | FILE_MASK_E | FILE_MASK_F | FILE_MASK_G | FILE_MASK_H), FILE_SHIFT_RIGHT_GUARD_7 = ~(FILE_MASK_B | FILE_MASK_C | FILE_MASK_D | FILE_MASK_E | FILE_MASK_F | FILE_MASK_G | FILE_MASK_H), FILE_SHIFT_LEFT_GUARD_0 = ~0ULL, FILE_SHIFT_LEFT_GUARD_1 = ~FILE_MASK_A, FILE_SHIFT_LEFT_GUARD_2 = ~(FILE_MASK_A | FILE_MASK_B), FILE_SHIFT_LEFT_GUARD_3 = ~(FILE_MASK_A | FILE_MASK_B | FILE_MASK_C), FILE_SHIFT_LEFT_GUARD_4 = ~(FILE_MASK_A | FILE_MASK_B | FILE_MASK_C | FILE_MASK_D), FILE_SHIFT_LEFT_GUARD_5 = ~(FILE_MASK_A | FILE_MASK_B | FILE_MASK_C | FILE_MASK_D | FILE_MASK_E), FILE_SHIFT_LEFT_GUARD_6 = ~(FILE_MASK_A | FILE_MASK_B | FILE_MASK_C | FILE_MASK_D | FILE_MASK_E | FILE_MASK_F), FILE_SHIFT_LEFT_GUARD_7 = ~(FILE_MASK_A | FILE_MASK_B | FILE_MASK_C | FILE_MASK_D | FILE_MASK_E | FILE_MASK_F | FILE_MASK_G), }; #define _FILE_SHIFT_RIGHT_GUARDED(b, n) \ (((bitboard)(b) & FILE_SHIFT_RIGHT_GUARD_##n) << (index)(n)) #define _FILE_SHIFT_LEFT_GUARDED(b, n) \ (((bitboard)(b) & FILE_SHIFT_LEFT_GUARD_##n) >> (index)(n)) /* FILE_SHIFT_RIGHT_n shifts the bitboard right by n ranks without wrapping */ #define FILE_SHIFT_RIGHT_1(b) _FILE_SHIFT_RIGHT_GUARDED(b, 1) #define FILE_SHIFT_RIGHT_2(b) _FILE_SHIFT_RIGHT_GUARDED(b, 2) #define FILE_SHIFT_RIGHT_3(b) _FILE_SHIFT_RIGHT_GUARDED(b, 3) #define FILE_SHIFT_RIGHT_4(b) _FILE_SHIFT_RIGHT_GUARDED(b, 4) #define FILE_SHIFT_RIGHT_5(b) _FILE_SHIFT_RIGHT_GUARDED(b, 5) #define FILE_SHIFT_RIGHT_6(b) _FILE_SHIFT_RIGHT_GUARDED(b, 6) #define FILE_SHIFT_RIGHT_7(b) _FILE_SHIFT_RIGHT_GUARDED(b, 7) #define FILE_SHIFT_RIGHT_8(b) _FILE_SHIFT_RIGHT_GUARDED(b, 8) /* FILE_SHIFT_LEFT_n shifts the bitboard left by n ranks without wrapping */ #define FILE_SHIFT_LEFT_1(b) _FILE_SHIFT_LEFT_GUARDED(b, 1) #define FILE_SHIFT_LEFT_2(b) _FILE_SHIFT_LEFT_GUARDED(b, 2) #define FILE_SHIFT_LEFT_3(b) _FILE_SHIFT_LEFT_GUARDED(b, 3) #define FILE_SHIFT_LEFT_4(b) _FILE_SHIFT_LEFT_GUARDED(b, 4) #define FILE_SHIFT_LEFT_5(b) _FILE_SHIFT_LEFT_GUARDED(b, 5) #define FILE_SHIFT_LEFT_6(b) _FILE_SHIFT_LEFT_GUARDED(b, 6) #define FILE_SHIFT_LEFT_7(b) _FILE_SHIFT_LEFT_GUARDED(b, 7) #define FILE_SHIFT_LEFT_8(b) _FILE_SHIFT_LEFT_GUARDED(b, 8) /* RANK_SHIFT_UP_n shifts the bitboard up by n ranks without wrapping */ #define RANK_SHIFT_UP_1(b) RANK_SHIFT_UP(b, 1) #define RANK_SHIFT_UP_2(b) RANK_SHIFT_UP(b, 2) #define RANK_SHIFT_UP_3(b) RANK_SHIFT_UP(b, 3) #define RANK_SHIFT_UP_4(b) RANK_SHIFT_UP(b, 4) #define RANK_SHIFT_UP_5(b) RANK_SHIFT_UP(b, 5) #define RANK_SHIFT_UP_6(b) RANK_SHIFT_UP(b, 6) #define RANK_SHIFT_UP_7(b) RANK_SHIFT_UP(b, 7) #define RANK_SHIFT_UP_8(b) RANK_SHIFT_UP(b, 8) /* RANK_SHIFT_DOWN_n shifts the bitboard down by n ranks without wrapping */ #define RANK_SHIFT_DOWN_1(b) RANK_SHIFT_DOWN(b, 1) #define RANK_SHIFT_DOWN_2(b) RANK_SHIFT_DOWN(b, 2) #define RANK_SHIFT_DOWN_3(b) RANK_SHIFT_DOWN(b, 3) #define RANK_SHIFT_DOWN_4(b) RANK_SHIFT_DOWN(b, 4) #define RANK_SHIFT_DOWN_5(b) RANK_SHIFT_DOWN(b, 5) #define RANK_SHIFT_DOWN_6(b) RANK_SHIFT_DOWN(b, 6) #define RANK_SHIFT_DOWN_7(b) RANK_SHIFT_DOWN(b, 7) #define RANK_SHIFT_DOWN_8(b) RANK_SHIFT_DOWN(b, 8) /* * Player * =========== * */ enum player : size_t { PLAYER_BEGIN, PLAYER_WHITE = PLAYER_BEGIN, PLAYER_BLACK, PLAYER_COUNT, }; static inline enum player opposite_player(enum player p) { return (p == PLAYER_WHITE ? PLAYER_BLACK : PLAYER_WHITE); } static char const* player_str[PLAYER_COUNT] = { [PLAYER_WHITE] = "PLAYER_WHITE", [PLAYER_BLACK] = "PLAYER_BLACK", }; /* * Piece * =========== * */ /* enum value white char white unicode black char black unicode */ #define PIECES \ X(PIECE_PAWN, 1.0, 'P', 0x2659, 'p', 0x265F) \ X(PIECE_KING, 5.0, 'K', 0x2654, 'k', 0x265A) \ X(PIECE_QUEEN, 9.0, 'Q', 0x2655, 'q', 0x265B) \ X(PIECE_BISHOP, 3.0, 'B', 0x2657, 'b', 0x265D) \ X(PIECE_ROOK, 5.0, 'R', 0x2656, 'r', 0x265C) \ X(PIECE_KNIGHT, 3.0, 'N', 0x2658, 'n', 0x265E) enum piece : uint8_t { #define X(e, v, wc, wu, bc, bu) e, PIECES PIECE_COUNT, PIECE_BEGIN = 0, #undef X }; static double piece_value[PIECE_COUNT] = { #define X(e, v, wc, wu, bc, bu) [e] = v, PIECES #undef X }; static char const* piece_str[PIECE_COUNT] = { #define X(e, v, wc, wu, bc, bu) [e] = STR(e), PIECES #undef X }; struct piece_player {enum piece piece; enum player player;} const piece_and_player_from_char[256] = { #define X(e, v, wc, wu, bc, bu) \ [(uint8_t)bc] = {.piece = e, .player = PLAYER_BLACK}, \ [(uint8_t)wc] = {.piece = e, .player = PLAYER_WHITE}, PIECES #undef X }; static char const piece_char[PLAYER_COUNT][PIECE_COUNT] = { [PLAYER_WHITE] = { #define X(e, v, wc, wu, bc, bu) [e] = wc, PIECES #undef X }, [PLAYER_BLACK] = { #define X(e, v, wc, wu, bc, bu) [e] = bc, PIECES #undef X } }; static int const piece_unicode[PLAYER_COUNT][PIECE_COUNT] = { [PLAYER_WHITE] = { #define X(e, v, wc, wu, bc, bu) [e] = wu, PIECES #undef X }, [PLAYER_BLACK] = { #define X(e, v, wc, wu, bc, bu) [e] = bu, PIECES #undef X } }; /* MISC * ============*/ /* TODO: Put these struct definition in a sensible category */ /* `struct magic` is used by magic bitboard lookups, see * rook_attacks_from_index and bishop_attacks_from_index */ struct magic { bitboard mask; bitboard magic; }; /* BITBOARD PRIMITIVES * ======================== */ static enum square_index bitboard_lsb(bitboard p) { return (enum square_index)__builtin_ffsll((int64_t)p) - 1; } static enum square_index bitboard_pop_lsb(bitboard* p) { index const lsb = bitboard_lsb(*p); *p &= ~(1ULL<<(lsb)); return lsb; } static uint64_t bitboard_popcount(bitboard b) { return (uint64_t)__builtin_popcountll(b); } static inline enum file_index index_to_file(enum square_index p) { return p % 8ULL; } static inline enum rank_index index_to_rank(enum square_index p) { return p / 8ULL; } static bitboard cardinals_from_index(enum square_index p) { /* might benefit from a lookup table */ return (FILE_MASK(index_to_file(p)) | RANK_MASK(index_to_rank(p))) & ~SQ_MASK_FROM_INDEX(p); } static bitboard diagonals_from_index(enum square_index sq) { enum rank_index const rank = index_to_rank(sq); enum file_index const file = index_to_file(sq); bitboard mask = 0ULL; /* Ensure signed-underflow detection rules match your style */ _Static_assert(((enum rank_index)-1) > 0, "rank_index must be unsigned"); _Static_assert(((enum file_index)-1) > 0, "file_index must be unsigned"); enum rank_index r; enum file_index f; for (r = rank+1, f = file+1; r <= RANK_INDEX_8 && f <= FILE_INDEX_H; ++r, ++f) { mask |= SQ_MASK_FROM_RF(r, f); } /* NW (rank+1, file-1) */ for (r = rank+1, f = file-1; r <= RANK_INDEX_8 && f <= FILE_INDEX_H; ++r, --f) { mask |= SQ_MASK_FROM_RF(r, f); } /* SE (rank-1, file+1) */ for (r = rank-1, f = file+1; r <= RANK_INDEX_8 && f <= FILE_INDEX_H; --r, ++f) { mask |= SQ_MASK_FROM_RF(r, f); } /* SW (rank-1, file-1) */ for (r = rank-1, f = file-1; r <= RANK_INDEX_8 && f <= FILE_INDEX_H; --r, --f) { mask |= SQ_MASK_FROM_RF(r, f); } return mask; } /* PIECE ATTACKS * ================== * * All piece attack functions rely on the caller masking their own pieces. * e.g. `knight_attacks(knights) & ~our_occupied` * */ static bitboard knight_attacks(bitboard p) { bitboard const l1 = FILE_SHIFT_RIGHT_1(p /*& ~FILE_MASK_H*/); bitboard const l2 = FILE_SHIFT_RIGHT_2(p /*& ~(FILE_MASK_G | FILE_MASK_H)*/); bitboard const r1 = FILE_SHIFT_LEFT_1 (p /*& ~FILE_MASK_A*/); bitboard const r2 = FILE_SHIFT_LEFT_2 (p /*& ~(FILE_MASK_A | FILE_MASK_B)*/); bitboard const h1 = l1 | r1; bitboard const h2 = l2 | r2; return RANK_SHIFT_UP_2(h1) | RANK_SHIFT_DOWN_2(h1) | RANK_SHIFT_UP_1(h2) | RANK_SHIFT_DOWN_1(h2); } static bitboard rook_attacks_from_index(enum square_index sq, bitboard occ) { #ifdef CODEGEN enum rank_index const rank = index_to_rank(sq); enum file_index const file = index_to_file(sq); bitboard atk = 0ULL; /* following loops assume rank and file types are unsigned, which relies on C23 enums */ _Static_assert(((enum rank_index)-1) > 0, "rank_index must be unsigned"); _Static_assert(((enum file_index)-1) > 0, "file_index must be unsigned"); for (enum rank_index walk_rank = rank+1; walk_rank <= RANK_INDEX_8; ++walk_rank) { bitboard const sq = SQ_MASK_FROM_RF(walk_rank, file); atk |= sq; if (occ & sq) { break; } } for (enum rank_index walk_rank = rank-1; walk_rank <= RANK_INDEX_8; --walk_rank) { bitboard const sq = SQ_MASK_FROM_RF(walk_rank, file); atk |= sq; if (occ & sq) { break; } } for (enum file_index walk_file = file+1; walk_file <= FILE_INDEX_H; ++walk_file) { bitboard const sq = SQ_MASK_FROM_RF(rank, walk_file); atk |= sq; if (occ & sq) { break; } } for (enum file_index walk_file = file-1; walk_file <= FILE_INDEX_H; --walk_file) { bitboard const sq = SQ_MASK_FROM_RF(rank, walk_file); atk |= sq; if (occ & sq) { break; } } return atk; #else #if ! __has_include("mbb_rook.h") #error "compile with -DCODEGEN and run once to generate required header files" #else /* defines - `mbb_rook[SQ_INDEX_COUNT]` - `bitboard rook_attacks[SQ_INDEX_COUNT][1<<12ULL] */ #include "mbb_rook.h" struct magic const m = mbb_rook[sq]; occ &= m.mask; occ *= m.magic; occ >>= (64ULL-12ULL); assert(rook_attacks[sq][occ] != SQ_MASK_FROM_INDEX(sq)); return rook_attacks[sq][occ]; #endif #endif } static bitboard rook_attacks(bitboard p, bitboard occ) { bitboard b = 0ULL; while (p) { index const lsb = bitboard_pop_lsb(&p); b |= rook_attacks_from_index(lsb, occ); } return b; } static bitboard bishop_attacks_from_index(enum square_index sq, bitboard occ) { #ifdef CODEGEN enum rank_index const rank = index_to_rank(sq); enum file_index const file = index_to_file(sq); bitboard atk = 0ULL; /* following loops assume rank and file types are unsigned, which relies on C23 enums */ _Static_assert(((enum rank_index)-1) > 0, "rank_index must be unsigned"); _Static_assert(((enum file_index)-1) > 0, "file_index must be unsigned"); enum rank_index walk_rank; enum file_index walk_file; for (walk_rank = rank+1, walk_file = file+1; walk_rank <= RANK_INDEX_8 && walk_file <= FILE_INDEX_H; ++walk_rank, ++walk_file) { bitboard const sq = SQ_MASK_FROM_RF(walk_rank, walk_file); atk |= sq; if (occ & sq) { break; } } for (walk_rank = rank+1, walk_file = file-1; walk_rank <= RANK_INDEX_8 && walk_file <= FILE_INDEX_H; ++walk_rank, --walk_file) { bitboard const sq = SQ_MASK_FROM_RF(walk_rank, walk_file); atk |= sq; if (occ & sq) { break; } } for (walk_rank = rank-1, walk_file = file+1; walk_rank <= RANK_INDEX_8 && walk_file <= FILE_INDEX_H; --walk_rank, ++walk_file) { bitboard const sq = SQ_MASK_FROM_RF(walk_rank, walk_file); atk |= sq; if (occ & sq) { break; } } for (walk_rank = rank-1, walk_file = file-1; walk_rank <= RANK_INDEX_8 && walk_file <= FILE_INDEX_H; --walk_rank, --walk_file) { bitboard const sq = SQ_MASK_FROM_RF(walk_rank, walk_file); atk |= sq; if (occ & sq) { break; } } return atk; #else #if ! __has_include("mbb_bishop.h") #error "compile with -DCODEGEN and run once to generate required header files" #else /* defines - `mbb_bishop[SQ_INDEX_COUNT]` - `bitboard bishop_attacks[SQ_INDEX_COUNT][1<<9ULL] */ #include "mbb_bishop.h" struct magic const m = mbb_bishop[sq]; occ &= m.mask; occ *= m.magic; occ >>= (64ULL-9ULL); return bishop_attacks[sq][occ]; #endif #endif } static bitboard bishop_attacks(bitboard p, bitboard occ) { bitboard b = 0ULL; while (p) { index const lsb = bitboard_pop_lsb(&p); b |= bishop_attacks_from_index(lsb, occ); } return b; } static bitboard queen_attacks_from_index(enum square_index sq, bitboard occ) { return bishop_attacks_from_index(sq, occ) | rook_attacks_from_index(sq, occ); } static bitboard queen_attacks(bitboard p, bitboard occ) { bitboard b = 0ULL; while (p) { index const lsb = bitboard_pop_lsb(&p); b |= queen_attacks_from_index(lsb, occ); } return b; } static inline bitboard pawn_moves_white(bitboard p, bitboard empty) { /* Assumptions: - empty = ~(black_occupied | white_occupied); */ bitboard const single_push = RANK_SHIFT_UP_1(p) & empty; bitboard const double_push = RANK_SHIFT_UP_1(single_push & RANK_MASK_3) & empty; return (single_push | double_push); } static inline bitboard pawn_attacks_white(bitboard p) { bitboard const up = RANK_SHIFT_UP_1(p); bitboard const captures_right = FILE_SHIFT_RIGHT_1(up); bitboard const captures_left = FILE_SHIFT_LEFT_1(up); return (captures_right | captures_left); } static inline bitboard pawn_moves_black(bitboard p, bitboard empty) { /* Assumptions: - empty = ~(black_occupied | white_occupied); */ bitboard const single_push = RANK_SHIFT_DOWN_1(p) & empty; bitboard const double_push = RANK_SHIFT_DOWN_1(single_push & RANK_MASK_6) & empty; return (single_push | double_push); } static inline bitboard pawn_attacks_black(bitboard p) { bitboard const down = RANK_SHIFT_DOWN_1(p); bitboard const captures_right = FILE_SHIFT_RIGHT_1(down); bitboard const captures_left = FILE_SHIFT_LEFT_1(down); return (captures_right | captures_left); } /* temporary solution, annoying branch */ static inline bitboard pawn_moves_dispatch(bitboard p, bitboard empty, enum player attacker) { if (attacker == PLAYER_WHITE) { return pawn_moves_white(p, empty); } else { return pawn_moves_black(p, empty); } } /* temporary solution, annoying branch */ static inline bitboard pawn_attacks_dispatch(bitboard p, enum player attacker) { if (attacker == PLAYER_WHITE) { return pawn_attacks_white(p); } else { return pawn_attacks_black(p); } } static bitboard king_attacks(bitboard sq) { /* potential untested improvements: * - lookup table * - union of three files, three ranks and ~sq */ bitboard const n = RANK_SHIFT_UP_1(sq); bitboard const s = RANK_SHIFT_DOWN_1(sq); bitboard const w = FILE_SHIFT_LEFT_1(sq); bitboard const e = FILE_SHIFT_RIGHT_1(sq); bitboard const nw = FILE_SHIFT_LEFT_1(n); bitboard const ne = FILE_SHIFT_RIGHT_1(n); bitboard const sw = FILE_SHIFT_LEFT_1(s); bitboard const se = FILE_SHIFT_RIGHT_1(s); return (n | s | w | e | nw | ne | sw | se); } static bitboard piece_attacks(enum piece piece, enum player player, bitboard ep_targets, bitboard p, bitboard occ, bitboard their_occ) { switch (piece) { case PIECE_PAWN: { return pawn_attacks_dispatch(p, player) & (their_occ | ep_targets); } break; case PIECE_KNIGHT: { return knight_attacks(p); } break; case PIECE_BISHOP: { return bishop_attacks(p, occ); } break; case PIECE_ROOK: { return rook_attacks(p, occ); } break; case PIECE_QUEEN: { return queen_attacks(p, occ); } break; case PIECE_KING: { return king_attacks(p); } break; #ifndef NDEBUG default: { assert(!"unreachable"); __builtin_trap(); __builtin_unreachable(); } break; #endif } } static bitboard piece_moves(enum piece piece, enum player player, bitboard ep_targets, bitboard p, bitboard occ, bitboard their_occ) { bitboard x = 0ULL; if (piece == PIECE_PAWN) { x |= pawn_moves_dispatch(p, ~occ, player); } x |= piece_attacks(piece, player, ep_targets, p, occ, their_occ); return x; } /* BOARD * ================= */ enum castle_direction { CASTLE_BEGIN, CASTLE_KINGSIDE = CASTLE_BEGIN, CASTLE_QUEENSIDE, CASTLE_COUNT, }; /* transposition table */ struct move { index from : 8; index to : 8; unsigned int attr : 8; }; struct search_option { double score; struct move move; bool set; }; #define TT_ADDRESS_BITS 12 #define TT_SIZE (1ULL<piece lookups, not central to logic. Does not * store which player owns the square piece, and checking non-occupied * squares is undefined * * TODO: make mailbox smaller, only 3 bits are needed per piece * */ enum piece mailbox[SQ_INDEX_COUNT]; }; #define BOARD_INITIAL (struct board) { \ .pos = { \ .fullmoves = 1, \ .pieces = { \ [PLAYER_WHITE] = { \ [PIECE_PAWN] = RANK_MASK_2, \ [PIECE_ROOK] = SQ_MASK_A1 | SQ_MASK_H1, \ [PIECE_KNIGHT] = SQ_MASK_B1 | SQ_MASK_G1, \ [PIECE_BISHOP] = SQ_MASK_C1 | SQ_MASK_F1, \ [PIECE_QUEEN] = SQ_MASK_D1, \ [PIECE_KING] = SQ_MASK_E1, \ }, \ [PLAYER_BLACK] = { \ [PIECE_PAWN] = RANK_MASK_7, \ [PIECE_ROOK] = SQ_MASK_A8 | SQ_MASK_H8, \ [PIECE_KNIGHT] = SQ_MASK_B8 | SQ_MASK_G8, \ [PIECE_BISHOP] = SQ_MASK_C8 | SQ_MASK_F8, \ [PIECE_QUEEN] = SQ_MASK_D8, \ [PIECE_KING] = SQ_MASK_E8, \ } \ }, \ .occupied = { \ [PLAYER_WHITE] = \ RANK_MASK_2 | SQ_MASK_A1 | SQ_MASK_H1 | \ SQ_MASK_B1 | SQ_MASK_G1 | SQ_MASK_C1 | \ SQ_MASK_F1 | SQ_MASK_D1 | SQ_MASK_E1, \ [PLAYER_BLACK] = \ RANK_MASK_7 | SQ_MASK_A8 | SQ_MASK_H8 | \ SQ_MASK_B8 | SQ_MASK_G8| SQ_MASK_C8 | \ SQ_MASK_F8| SQ_MASK_D8| SQ_MASK_E8, \ }, \ .hash = ~0ULL, \ }, \ .mailbox = { \ [SQ_INDEX_A1] = PIECE_ROOK, \ [SQ_INDEX_B1] = PIECE_KNIGHT, \ [SQ_INDEX_C1] = PIECE_BISHOP, \ [SQ_INDEX_D1] = PIECE_QUEEN, \ [SQ_INDEX_E1] = PIECE_KING, \ [SQ_INDEX_F1] = PIECE_BISHOP, \ [SQ_INDEX_G1] = PIECE_KNIGHT, \ [SQ_INDEX_H1] = PIECE_ROOK, \ [SQ_INDEX_A2] = PIECE_PAWN, \ [SQ_INDEX_B2] = PIECE_PAWN, \ [SQ_INDEX_C2] = PIECE_PAWN, \ [SQ_INDEX_D2] = PIECE_PAWN, \ [SQ_INDEX_E2] = PIECE_PAWN, \ [SQ_INDEX_F2] = PIECE_PAWN, \ [SQ_INDEX_G2] = PIECE_PAWN, \ [SQ_INDEX_H2] = PIECE_PAWN, \ [SQ_INDEX_A7] = PIECE_PAWN, \ [SQ_INDEX_B7] = PIECE_PAWN, \ [SQ_INDEX_C7] = PIECE_PAWN, \ [SQ_INDEX_D7] = PIECE_PAWN, \ [SQ_INDEX_E7] = PIECE_PAWN, \ [SQ_INDEX_F7] = PIECE_PAWN, \ [SQ_INDEX_G7] = PIECE_PAWN, \ [SQ_INDEX_H7] = PIECE_PAWN, \ [SQ_INDEX_A8] = PIECE_ROOK, \ [SQ_INDEX_B8] = PIECE_KNIGHT, \ [SQ_INDEX_C8] = PIECE_BISHOP, \ [SQ_INDEX_D8] = PIECE_QUEEN, \ [SQ_INDEX_E8] = PIECE_KING, \ [SQ_INDEX_F8] = PIECE_BISHOP, \ [SQ_INDEX_G8] = PIECE_KNIGHT, \ [SQ_INDEX_H8] = PIECE_ROOK, \ }, \ .hist = {0}, \ } static void board_print_fen(struct board const* b, FILE* out) { int buf[8][8] = {0}; for (enum player player = PLAYER_BEGIN; player < PLAYER_COUNT; ++player) { for (enum piece piece = PIECE_BEGIN; piece < PIECE_COUNT; ++piece) { bitboard x = b->pos.pieces[player][piece]; for (index i = 7; i < 8; i--) { for (index j = 0; j < 8; ++j) { if (x & (1ULL<<(i*8+j))) { buf[i][j] = piece_char[player][piece]; } } } } } for (enum rank_index i = RANK_INDEX_8; i < RANK_INDEX_COUNT; --i) { int consequtive_empty = 0; for (enum file_index j = FILE_INDEX_A; j < FILE_INDEX_COUNT; ++j) { if (buf[i][j]) { if (consequtive_empty) { fprintf(out, "%d", consequtive_empty); } fprintf(out, "%lc", buf[i][j]); } else { consequtive_empty += 1; } } if (consequtive_empty) { fprintf(out, "%d", consequtive_empty); } if (i > 0) fprintf(out, "/"); } fprintf(out, " %c ", b->pos.player == PLAYER_WHITE ? 'w' : 'b'); bool any_castle = false; if (!b->pos.castling_illegal[PLAYER_WHITE][CASTLE_KINGSIDE]) { fprintf(out, "K"); any_castle = true; } if (!b->pos.castling_illegal[PLAYER_WHITE][CASTLE_QUEENSIDE]) { fprintf(out, "Q"); any_castle = true; } if (!b->pos.castling_illegal[PLAYER_BLACK][CASTLE_KINGSIDE]) { fprintf(out, "k"); any_castle = true; } if (!b->pos.castling_illegal[PLAYER_BLACK][CASTLE_QUEENSIDE]) { fprintf(out, "q"); any_castle = true; } if (!any_castle) { fprintf(out, "-"); } if (b->pos.ep_targets) { /* should be ep target square in algebraic notation */ fprintf(stderr, "not implemented: fen with en passent squares\n"); abort(); } else { fprintf(out, " -"); } fprintf(out, " %d", b->pos.halfmoves); fprintf(out, " %d", b->pos.fullmoves); fprintf(out, "\n"); } static bool board_load_fen_unsafe(struct board* b, char const* fen_str) { /* TODO: this function is not tested for malicious/corrupted inputs */ struct { char const* buf; size_t i; size_t len; } fen = { .buf = fen_str, .i = 0, .len = strlen(fen_str), }; #define BUF_GETCHAR(x) (assert(x.i < x.len), x.buf[x.i++]) memset(&b->pos, 0, sizeof b->pos); b->pos.hash = ~0ULL; for (enum rank_index ri = RANK_INDEX_8; ri < RANK_INDEX_COUNT; --ri) { for (enum file_index fi = FILE_INDEX_BEGIN; fi < FILE_INDEX_COUNT; ++fi) { char const ch = BUF_GETCHAR(fen); if (isdigit(ch)) { fi += ch - '0' - 1; } else { struct piece_player const p = piece_and_player_from_char[(uint8_t)ch]; bitboard const sq_mask = SQ_MASK_FROM_RF(ri, fi); b->pos.pieces[p.player][p.piece] |= sq_mask; b->pos.occupied[p.player] |= sq_mask; b->mailbox[INDEX_FROM_RF(ri, fi)] = p.piece; } } (void)BUF_GETCHAR(fen); /* discard '/' or ' ' */ } { /* active color */ char const ch = BUF_GETCHAR(fen); if (ch == 'w') { b->pos.player = PLAYER_WHITE; } else if (ch == 'b') { b->pos.player = PLAYER_BLACK; } else { abort(); } } { /* castling */ char ch = BUF_GETCHAR(fen); if (ch != ' ') { abort(); } do { ch = BUF_GETCHAR(fen); switch (ch) { case 'K': b->pos.castling_illegal[PLAYER_WHITE][CASTLE_KINGSIDE] = true; break; case 'Q': b->pos.castling_illegal[PLAYER_WHITE][CASTLE_QUEENSIDE] = true; break; case 'k': b->pos.castling_illegal[PLAYER_BLACK][CASTLE_KINGSIDE] = true; break; case 'q': b->pos.castling_illegal[PLAYER_BLACK][CASTLE_QUEENSIDE] = true; break; case ' ': break; case '-': { b->pos.castling_illegal[PLAYER_WHITE][CASTLE_KINGSIDE] = true; b->pos.castling_illegal[PLAYER_WHITE][CASTLE_QUEENSIDE] = true; b->pos.castling_illegal[PLAYER_BLACK][CASTLE_KINGSIDE] = true; b->pos.castling_illegal[PLAYER_BLACK][CASTLE_QUEENSIDE] = true; } break; default: { fprintf(stderr, "unexpected char '%c'\n", ch); abort(); } break; } } while (ch != ' '); } { /* en passent */ char const ch = BUF_GETCHAR(fen); if (ch != '-') { fprintf(stderr, "ep targets in fen not implemented yet\n"); abort(); } } { /* halfmoves */ b->pos.halfmoves = 0; char ch = BUF_GETCHAR(fen); while (ch != ' ') { b->pos.halfmoves *= 10; b->pos.halfmoves += ch-'0'; ch = BUF_GETCHAR(fen); } } { /* fullmoves */ b->pos.fullmoves = 0; char ch = BUF_GETCHAR(fen); while (ch != ' ') { b->pos.fullmoves *= 10; b->pos.fullmoves += ch-'0'; ch = BUF_GETCHAR(fen); } } #undef BUF_GETCHAR return true; } static bitboard all_threats_from_player(struct pos const * pos, enum player player) { bitboard const occ = pos->occupied[PLAYER_WHITE] | pos->occupied[PLAYER_BLACK]; bitboard const* p = pos->pieces[player]; bitboard t = 0ULL; t |= pawn_attacks_dispatch(p[PIECE_PAWN], player); t |= knight_attacks(p[PIECE_KNIGHT]); t |= bishop_attacks(p[PIECE_BISHOP], occ); t |= rook_attacks(p[PIECE_ROOK], occ); t |= queen_attacks(p[PIECE_QUEEN], occ); t |= king_attacks(p[PIECE_KING]); return t; } static bitboard between_mask(enum square_index a, enum square_index b) { #ifdef CODEGEN enum rank_index const ra = index_to_rank(a); enum file_index const fa = index_to_file(a); enum rank_index const rb = index_to_rank(b); enum file_index const fb = index_to_file(b); /* directional differences */ int const dr = (int)rb - (int)ra; int const df = (int)fb - (int)fa; int step_r = 0; int step_f = 0; if (df == 0 && dr != 0) { step_r = (dr > 0) ? 1 : -1; step_f = 0; } else if (dr == 0 && df != 0) { step_r = 0; step_f = (df > 0) ? 1 : -1; } else if (dr != 0 && (dr > 0 ? dr : -dr) == (df > 0 ? df : -df)) { step_r = (dr > 0) ? 1 : -1; step_f = (df > 0) ? 1 : -1; } else { return 0ULL; } bitboard mask = 0ULL; enum rank_index r = (enum rank_index)((int)ra + step_r); enum file_index f = (enum file_index)((int)fa + step_f); while (r != rb || f != fb) { mask |= SQ_MASK_FROM_RF(r, f); r = (enum rank_index)((int)r + step_r); f = (enum file_index)((int)f + step_f); } return mask; #else #if ! __has_include("between_lookup.h") #error "compile codegen.c and run once to generate required header files" #else /* defines static between_lookup[SQUARE_INDEX_COUNT][SQUARE_INDEX_COUNT] */ #include "between_lookup.h" return between_lookup[a][b]; #endif #endif } static bitboard attacks_to(struct pos const* pos, bitboard target_square, bitboard pretend_occupied, bitboard pretend_empty) { bitboard const occ_orig = pos->occupied[PLAYER_WHITE] | pos->occupied[PLAYER_BLACK]; bitboard const occ = (occ_orig & ~pretend_empty) | pretend_occupied; bitboard const* pw = pos->pieces[PLAYER_WHITE]; bitboard const* pb = pos->pieces[PLAYER_BLACK]; bitboard const wps = pw[PIECE_PAWN]; bitboard const bps = pb[PIECE_PAWN]; bitboard const ns = (pw[PIECE_KNIGHT] | pb[PIECE_KNIGHT]) ; bitboard const ks = (pw[PIECE_KING] | pb[PIECE_KING]) ; bitboard const qs = (pw[PIECE_QUEEN] | pb[PIECE_QUEEN]) ; bitboard const qrs = (pw[PIECE_ROOK] | pb[PIECE_ROOK] | qs) ; bitboard const qbs = (pw[PIECE_BISHOP] | pb[PIECE_BISHOP] | qs) ; enum square_index target_index = bitboard_lsb(target_square); return ((bps & pawn_attacks_white(target_square)) | (wps & pawn_attacks_black(target_square)) | (ns & knight_attacks(target_square)) | (qbs & bishop_attacks_from_index(target_index, occ)) | (qrs & rook_attacks_from_index(target_index, occ)) | (ks & king_attacks(target_square))) & ~pretend_occupied; } static bitboard attacks_to_king(struct pos const* pos, bitboard target_square, bitboard pretend_occupied, bitboard pretend_empty) { bitboard const occ_orig = pos->occupied[PLAYER_WHITE] | pos->occupied[PLAYER_BLACK]; bitboard const occ = (occ_orig & ~pretend_empty) | pretend_occupied; bitboard const* pw = pos->pieces[PLAYER_WHITE]; bitboard const* pb = pos->pieces[PLAYER_BLACK]; bitboard const wps = pw[PIECE_PAWN]; bitboard const bps = pb[PIECE_PAWN]; bitboard const ns = (pw[PIECE_KNIGHT] | pb[PIECE_KNIGHT]); bitboard const qs = (pw[PIECE_QUEEN] | pb[PIECE_QUEEN]); bitboard const qrs = (pw[PIECE_ROOK] | pb[PIECE_ROOK] | qs) ; bitboard const qbs = (pw[PIECE_BISHOP] | pb[PIECE_BISHOP] | qs) ; enum square_index target_index = bitboard_lsb(target_square); return ((bps & pawn_attacks_white(target_square)) | (wps & pawn_attacks_black(target_square)) | (ns & knight_attacks(target_square)) | (qbs & bishop_attacks_from_index(target_index, occ)) | (qrs & rook_attacks_from_index(target_index, occ))) & ~pretend_occupied; } enum { MATTR_CAPTURE = 1<<0, MATTR_PROMOTE = 1<<1, /*MATTR_CHECK = 1<<2,*/ MATTR_CASTLE_KINGSIDE = 1<<3, MATTR_CASTLE_QUEENSIDE = 1<<4, }; _Static_assert(sizeof(struct move) == 4, "this static assert is here to check when sizeof(move) changes"); #define MOVE_CASTLE_KINGSIDE_WHITE (struct move) \ {.from = SQ_INDEX_E1, .to = SQ_INDEX_G1, .attr = MATTR_CASTLE_KINGSIDE} #define MOVE_CASTLE_QUEENSIDE_WHITE \ (struct move){.from = SQ_INDEX_E1, .to = SQ_INDEX_C1, .attr = MATTR_CASTLE_QUEENSIDE} #define MOVE_CASTLE_KINGSIDE_BLACK (struct move) \ {.from = SQ_INDEX_E8, .to = SQ_INDEX_G8, .attr = MATTR_CASTLE_KINGSIDE} #define MOVE_CASTLE_QUEENSIDE_BLACK \ (struct move){.from = SQ_INDEX_E8, .to = SQ_INDEX_C8, .attr = MATTR_CASTLE_QUEENSIDE} struct move move_make(struct pos const* pos, enum piece piece, index from, index to, uint16_t add_attr) { enum player const us = pos->player; enum player const them = opposite_player(us); bitboard const their_occ = pos->occupied[them]; bitboard const tomask = SQ_MASK_FROM_INDEX(to); bitboard const finishline = (us == PLAYER_WHITE ? RANK_MASK_8 : RANK_MASK_1); uint16_t attr = 0ULL; #define MASK_IF32(x) ((~(uint32_t)0U) + (uint32_t)!(x)) attr |= MATTR_CAPTURE & MASK_IF32(tomask & their_occ); attr |= MATTR_PROMOTE & MASK_IF32((piece == PIECE_PAWN) && (tomask & finishline)); attr |= add_attr; #undef MASK_IF32 return (struct move){.from = from, .to = to, .attr = attr}; } #define MOVE_MAX 256 static void all_moves_from_piece(struct pos const* restrict pos, enum piece piece, enum player us, enum square_index from, bitboard allowed, size_t* restrict out_count, struct move out[restrict static MOVE_MAX]) { /* TODO: this function is terrible, needs major rework * * instead of dispatching to a generalized `piece_moves`, this can be specialized for each * piece * */ assert(piece != PIECE_KING); enum player const them = opposite_player(us); bitboard const our_occ = pos->occupied[us]; bitboard const their_occ = pos->occupied[them]; bitboard const all_occ = pos->occupied[PLAYER_WHITE] | pos->occupied[PLAYER_BLACK]; bitboard const from_mask = SQ_MASK_FROM_INDEX(from); bitboard move_mask = piece_moves(piece, us, pos->ep_targets, from_mask, all_occ, their_occ) & ~our_occ /*& allowed*/ ; while (move_mask) { enum square_index const to = bitboard_pop_lsb(&move_mask); bitboard const to_mask = SQ_MASK_FROM_INDEX(to); bitboard const king_attackers = attacks_to(pos, pos->pieces[us][PIECE_KING], to_mask, from_mask) & ~(our_occ | to_mask); if (king_attackers == 0ULL) { out[(*out_count)++] = move_make(pos, piece, from, to, 0); } } } static void all_moves_from_king(struct pos const* restrict pos, enum player us, enum square_index from, size_t* restrict out_count, struct move out[restrict static MOVE_MAX]) { enum player const them = opposite_player(us); bitboard const our_occ = pos->occupied[us]; bitboard const all_occ = pos->occupied[PLAYER_WHITE] | pos->occupied[PLAYER_BLACK]; bitboard const from_mask = SQ_MASK_FROM_INDEX(from); bitboard const threats = all_threats_from_player(pos, them); bitboard move_mask = king_attacks(from_mask) & ~(threats | our_occ); /* general moves */ while (move_mask) { enum square_index const to = bitboard_pop_lsb(&move_mask); bitboard const to_mask = SQ_MASK_FROM_INDEX(to); bitboard const king_attackers = attacks_to(pos, to_mask, to_mask, from_mask) & ~(our_occ | to_mask); if (king_attackers == 0ULL) { out[(*out_count)++] = move_make(pos, PIECE_KING, from, to, 0); } } /* castling */ if (from_mask & ~threats) { bool kingside_free, queenside_free; if (us == PLAYER_WHITE) { kingside_free = !((threats | all_occ) & (SQ_MASK_F1 | SQ_MASK_G1)) && (pos->pieces[us][PIECE_ROOK] & SQ_MASK_H1); queenside_free = !((threats | all_occ) & (SQ_MASK_B1 | SQ_MASK_C1 | SQ_MASK_D1)) && (pos->pieces[us][PIECE_ROOK] & SQ_MASK_A1); } else { kingside_free = !((threats | all_occ) & (SQ_MASK_F8 | SQ_MASK_G8)) && (pos->pieces[us][PIECE_ROOK] & SQ_MASK_H8); queenside_free = !((threats | all_occ) & (SQ_MASK_B8 | SQ_MASK_C8 | SQ_MASK_D8)) && (pos->pieces[us][PIECE_ROOK] & SQ_MASK_A8); } if (!pos->castling_illegal[us][CASTLE_KINGSIDE] && kingside_free) { out[(*out_count)++] = us == PLAYER_WHITE ? MOVE_CASTLE_KINGSIDE_WHITE : MOVE_CASTLE_KINGSIDE_BLACK; } if (!pos->castling_illegal[us][CASTLE_QUEENSIDE] && queenside_free) { out[(*out_count)++] = us == PLAYER_WHITE ? MOVE_CASTLE_QUEENSIDE_WHITE : MOVE_CASTLE_QUEENSIDE_BLACK; } } } static void all_moves(struct pos const* restrict pos, enum player us, size_t* restrict out_count, struct move out[restrict static MOVE_MAX]) { *out_count = 0ULL; bitboard const myking = pos->pieces[us][PIECE_KING]; enum square_index const myking_index = bitboard_lsb(myking); bitboard const attackers = attacks_to(pos, myking, 0ULL, 0ULL) & ~pos->occupied[us]; assert(myking); bitboard allowed = ~0ULL; uint64_t const natk = bitboard_popcount(attackers); //if (natk == 1) { // enum square_index const attacker_index = bitboard_lsb(attackers); // allowed = between_mask(myking_index, attacker_index) | attackers; //} else { // bitboard const pinners = pinning_lines(pos, us, myking_index); //} /* king */ { all_moves_from_king(pos, us, myking_index, out_count, out); } //if (natk >= 2) { // fprintf(stderr, "more than 2 king attackers\n"); // return; //} /* pawns */ { bitboard ps = pos->pieces[us][PIECE_PAWN]; while (ps) { enum square_index const from = bitboard_pop_lsb(&ps); all_moves_from_piece(pos, PIECE_PAWN, us, from, allowed, out_count, out); } } /* knights */ { bitboard ns = pos->pieces[us][PIECE_KNIGHT]; while (ns) { index const from = bitboard_pop_lsb(&ns); all_moves_from_piece(pos, PIECE_KNIGHT, us, from, allowed, out_count, out); } } /* bishops */ { bitboard bs = pos->pieces[us][PIECE_BISHOP]; while (bs) { index const from = bitboard_pop_lsb(&bs); all_moves_from_piece(pos, PIECE_BISHOP, us, from, allowed, out_count, out); } } /* rooks */ { bitboard rs = pos->pieces[us][PIECE_ROOK]; while (rs) { index const from = bitboard_pop_lsb(&rs); all_moves_from_piece(pos, PIECE_ROOK, us, from, allowed, out_count, out); } } /* queens */ { bitboard qs = pos->pieces[us][PIECE_QUEEN]; while (qs) { index const from = bitboard_pop_lsb(&qs); all_moves_from_piece(pos, PIECE_QUEEN, us, from, allowed, out_count, out); } } } static void init_zobrist(uint64_t zobrist[SQ_INDEX_COUNT][PLAYER_COUNT][PIECE_COUNT]) { for (enum square_index sq = SQ_INDEX_BEGIN; sq < SQ_INDEX_COUNT; ++sq) { for (enum player pl = PLAYER_BEGIN; pl < PLAYER_COUNT; ++pl) { for (enum piece piece = PIECE_BEGIN; piece < PIECE_COUNT; ++piece) { zobrist[sq][pl][piece] = rand64(); } } } } static inline uint64_t zobrist_at(enum square_index sq, enum player pl, enum piece pc) { #if ! __has_include("zobrist_table.h") /* zobrist hashing: https://en.wikipedia.org/wiki/Zobrist_hashing */ static uint64_t zobrist[SQ_INDEX_COUNT][PLAYER_COUNT][PIECE_COUNT]; static bool init; if (!init) { init_zobrist(zobrist); init = true; } #else #include "zobrist_table.h" #endif /* __has_include("zobrist_table.h") */ return zobrist[sq][pl][pc]; } /* * * * */ static inline uint64_t tt_hash_update(uint64_t hash, enum square_index sq, enum player us, enum piece piece) { assert(zobrist_at(sq, us, piece) != 0ULL); return hash ^ zobrist_at(sq, us, piece); } static inline struct search_option tt_get(struct tt const* tt, uint64_t hash) { /* shitty bloom-filter-eque check */ uint64_t const addr = hash % TT_SIZE; return tt->entries[addr]; } static inline void tt_insert(struct tt* tt, uint64_t hash, struct search_option so) { uint64_t const addr = hash % TT_SIZE; so.set = true; tt->entries[addr] = so; } /* does not check validity */ enum move_result { MR_NORMAL, MR_STALEMATE, MR_CHECKMATE, }; static enum move_result board_move(struct pos* restrict pos, struct history* restrict hist, enum piece mailbox[restrict static SQ_INDEX_COUNT], struct move move) { enum player const us = pos->player; enum player const them = opposite_player(us); bool const w = (us == PLAYER_WHITE); bitboard const from_mask = SQ_MASK_FROM_INDEX(move.from); bitboard const to_mask = SQ_MASK_FROM_INDEX(move.to); bitboard const rook_home_q_us = w ? SQ_MASK_A1 : SQ_MASK_A8; bitboard const rook_home_k_us = w ? SQ_MASK_H1 : SQ_MASK_H8; bitboard const rook_home_q_them = w ? SQ_MASK_A8 : SQ_MASK_A1; bitboard const rook_home_k_them = w ? SQ_MASK_H8 : SQ_MASK_H1; enum piece const from_piece = mailbox[move.from]; bool const is_castle_ks = (from_piece == PIECE_KING && ((move.from == SQ_INDEX_E1 && move.to == SQ_INDEX_G1) || (move.from == SQ_INDEX_E8 && move.to == SQ_INDEX_G8))); bool const is_castle_qs = (from_piece == PIECE_KING && ((move.from == SQ_INDEX_E1 && move.to == SQ_INDEX_C1) || (move.from == SQ_INDEX_E8 && move.to == SQ_INDEX_C8))); bool const is_castle = is_castle_ks || is_castle_qs; bool const is_capture = !!(move.to & pos->occupied[them]); bitboard const ep_targets = pos->ep_targets; pos->ep_targets = 0ULL; /* our castling rights from moving king/rook */ if (from_piece == PIECE_KING) { pos->castling_illegal[us][CASTLE_KINGSIDE] = true; pos->castling_illegal[us][CASTLE_QUEENSIDE] = true; } else if (from_mask == rook_home_q_us) { pos->castling_illegal[us][CASTLE_QUEENSIDE] = true; } else if (from_mask == rook_home_k_us) { pos->castling_illegal[us][CASTLE_KINGSIDE] = true; } /* their castling rights: any move landing on their rook home squares kills it */ if (to_mask == rook_home_q_them) { pos->castling_illegal[them][CASTLE_QUEENSIDE] = true; } else if (to_mask == rook_home_k_them) { pos->castling_illegal[them][CASTLE_KINGSIDE] = true; } pos->pieces[us][from_piece] &= ~from_mask; pos->hash = tt_hash_update(pos->hash, move.from, us, from_piece); /* handle captures without reading mailbox[to] (since empty is undefined) */ bool const is_pawn = (from_piece == PIECE_PAWN); bool const is_ep = is_pawn && ((to_mask & ep_targets) != 0ULL); if (is_capture) { if (is_ep) { /* en passant captured pawn is behind the destination square */ bitboard const ep_capture_mask = w ? RANK_SHIFT_DOWN_1(to_mask) : RANK_SHIFT_UP_1(to_mask); pos->pieces[them][PIECE_PAWN] &= ~ep_capture_mask; pos->hash = tt_hash_update(pos->hash, bitboard_lsb(ep_capture_mask), them, PIECE_PAWN); } else { /* normal capture: clear whatever enemy piece sits on to_mask */ for (enum piece p = PIECE_BEGIN; p < PIECE_COUNT; ++p) { if (p & to_mask) { pos->pieces[them][p] &= ~to_mask; pos->hash = tt_hash_update(pos->hash, move.to, them, p); } } } } if (is_castle) { bitboard const king_home = w ? SQ_MASK_E1 : SQ_MASK_E8; bitboard const king_to = is_castle_ks ? FILE_SHIFT_RIGHT_2(king_home) : FILE_SHIFT_LEFT_2(king_home); bitboard const rook_from = is_castle_ks ? rook_home_k_us : rook_home_q_us; bitboard const rook_to = is_castle_ks ? FILE_SHIFT_LEFT_2(rook_home_k_us) : FILE_SHIFT_RIGHT_3(rook_home_q_us); pos->pieces[us][PIECE_KING] |= king_to; mailbox[move.to] = PIECE_KING; pos->hash = tt_hash_update(pos->hash, bitboard_lsb(king_to), us, PIECE_KING); pos->pieces[us][PIECE_ROOK] &= ~rook_from; pos->hash = tt_hash_update(pos->hash, bitboard_lsb(rook_from), us, PIECE_ROOK); const enum square_index rook_to_index = bitboard_lsb(rook_to); pos->pieces[us][PIECE_ROOK] |= rook_to; mailbox[rook_to_index] = PIECE_ROOK; pos->hash = tt_hash_update(pos->hash, rook_to_index, us, PIECE_ROOK); } else if (is_pawn) { /* promotion must be based on destination square */ bitboard const finishline = w ? RANK_MASK_8 : RANK_MASK_1; if (to_mask & finishline) { pos->pieces[us][PIECE_QUEEN] |= to_mask; mailbox[move.to] = PIECE_QUEEN; pos->hash = tt_hash_update(pos->hash, move.to, us, PIECE_QUEEN); } else { pos->pieces[us][PIECE_PAWN] |= to_mask; mailbox[move.to] = PIECE_PAWN; pos->hash = tt_hash_update(pos->hash, move.to, us, PIECE_PAWN); } /* double push -> set ep target */ bitboard const start = w ? RANK_MASK_2 : RANK_MASK_7; bitboard const doublepush = w ? RANK_MASK_4 : RANK_MASK_5; if ((from_mask & start) && (to_mask & doublepush)) { pos->ep_targets = w ? RANK_SHIFT_UP_1(from_mask) : RANK_SHIFT_DOWN_1(from_mask); } } else { pos->pieces[us][from_piece] |= to_mask; mailbox[move.to] = from_piece; pos->hash = tt_hash_update(pos->hash, move.to, us, from_piece); } /* rebuild occupancy */ pos->occupied[PLAYER_WHITE] = 0ULL; pos->occupied[PLAYER_BLACK] = 0ULL; for (enum piece p = PIECE_BEGIN; p < PIECE_COUNT; ++p) { pos->occupied[PLAYER_WHITE] |= pos->pieces[PLAYER_WHITE][p]; pos->occupied[PLAYER_BLACK] |= pos->pieces[PLAYER_BLACK][p]; } pos->player = them; /* TODO: this stalemates on just one repetition, fine for the engine but not the player */ assert(hist->length < 4096); for (size_t i = 0; i < hist->length; ++i) { _Static_assert(sizeof *pos == sizeof hist->items[i]); if (memcmp(&hist->items[i], pos, sizeof *pos) == 0) { return MR_STALEMATE; } } if (is_capture) { hist->length = 0; pos->halfmoves = 0; } hist->items[hist->length++] = *pos; pos->halfmoves += 1; if (pos->halfmoves > 50) { return MR_STALEMATE; } pos->fullmoves += (pos->player == PLAYER_BLACK); return MR_NORMAL; } static enum move_result board_move_2(struct board* b, struct move move) { return board_move(&b->pos, &b->hist, b->mailbox, move); } /* * Placeholder heuristic * * */ static double board_score_heuristic(struct pos const* pos) { double score = 0.0; enum player const player = pos->player; enum player const opp = opposite_player(player); #define BOARD_CENTER ((FILE_MASK_C | FILE_MASK_D | FILE_MASK_E | FILE_MASK_F) \ & ~(RANK_MASK_1 | RANK_MASK_2 | RANK_MASK_7 | RANK_MASK_8)) static const bitboard positional_bonus[PIECE_COUNT] = { [PIECE_PAWN] = BOARD_CENTER, [PIECE_KNIGHT] = BOARD_CENTER, [PIECE_QUEEN] = RANK_MASK_3 | RANK_MASK_4 | RANK_MASK_5 | RANK_MASK_6, }; static const double positional_bonus_factor[PIECE_COUNT] = { [PIECE_PAWN] = 0.20, [PIECE_KNIGHT] = 0.20, [PIECE_QUEEN] = -0.30, }; bitboard const our_threats = all_threats_from_player(pos, player); bitboard const their_threats = all_threats_from_player(pos, opp); for (enum piece p = PIECE_BEGIN; p < PIECE_COUNT; ++p) { score += 0.05 * (double)bitboard_popcount(our_threats & pos->pieces[opp][p]) * piece_value[p]; score += 1.00 * (double)bitboard_popcount(pos->pieces[player][p]) * piece_value[p]; score += positional_bonus_factor[p] * (double)bitboard_popcount(pos->pieces[player][p] & positional_bonus[p]); score -= 0.05 * (double)bitboard_popcount(their_threats & pos->pieces[player][p]) * piece_value[p]; score -= (double)bitboard_popcount(pos->pieces[opp][p]) * piece_value[p]; score -= positional_bonus_factor[p] * (double)bitboard_popcount(pos->pieces[opp][p] & positional_bonus[p]); } return score; } struct search_option alphabeta_search(const struct pos* pos, struct history* hist, struct tt* tt, enum piece mailbox[restrict static SQ_INDEX_COUNT], enum player us, int depth, double alpha, double beta) { if (depth <= 0) { return (struct search_option){.score = board_score_heuristic(pos)}; } struct move moves[MOVE_MAX]; size_t move_count = 0ULL; all_moves(pos, us, &move_count, moves); if (move_count == 0) { return (struct search_option){.score = -999*depth}; } double value = alpha; for (size_t i = 0; i < move_count; ++i) { struct pos poscpy = *pos; enum piece mailbox_cpy[SQ_INDEX_COUNT]; memcpy(mailbox_cpy, mailbox, sizeof mailbox_cpy); size_t old_hist_length = hist->length; enum move_result const r = board_move(&poscpy, hist, mailbox_cpy, moves[i]); double x; if (r == MR_STALEMATE) { x = 0.0; } else { x = -alphabeta_search(&poscpy, hist, tt, mailbox_cpy, opposite_player(us), depth-1, -beta, -value).score; } hist->length = old_hist_length; if (x > value) { value = x; } if (value >= beta) { return (struct search_option) {.score = value, .move = moves[i]}; } } return (struct search_option){.score = value, .move = moves[0]}; } struct move search(struct board* b, enum player us, int depth) { struct move moves[MOVE_MAX]; size_t move_count = 0ULL; all_moves(&b->pos, us, &move_count, moves); if (move_count == 0) { abort(); } struct search_option best = { .score = -INFINITY, .move = moves[0], }; memset(&b->tt, 0, sizeof b->tt); for (size_t i = 0; i < move_count; ++i) { struct pos poscpy = b->pos; enum piece mailbox_cpy[SQ_INDEX_COUNT]; memcpy(mailbox_cpy, b->mailbox, sizeof mailbox_cpy); size_t old_hist_length = b->hist.length; enum move_result const r = board_move(&poscpy, &b->hist, mailbox_cpy, moves[i]); double x; if (r == MR_STALEMATE) { x = 0.0; } else { x = -alphabeta_search(&poscpy, &b->hist, &b->tt, mailbox_cpy, opposite_player(us), depth-1, -INFINITY, -best.score).score; } b->hist.length = old_hist_length; x += 1.0 * !!(moves[i].attr & MATTR_CASTLE_KINGSIDE); x += 0.5 * !!(moves[i].attr & MATTR_CASTLE_QUEENSIDE); x += -0.5 * !!(b->pos.pieces[us][PIECE_QUEEN] & SQ_MASK_FROM_INDEX(moves[i].from)); if (x > best.score) { best.score = x; best.move = moves[i]; } } printf("move %s->%s has score %lf\n", square_index_str[best.move.from], square_index_str[best.move.to], best.score ); assert(best.move.from != best.move.to); return best.move; } static void board_print(const struct pos* pos, struct move* move, FILE* out) { int buf[8][8] = {0}; for (enum player player = PLAYER_BEGIN; player < PLAYER_COUNT; ++player) { for (enum piece piece = PIECE_BEGIN; piece < PIECE_COUNT; ++piece) { bitboard x = pos->pieces[player][piece]; for (index i = 7; i < 8; i--) { for (index j = 0; j < 8; ++j) { if (x & (1ULL<<(i*8+j))) { buf[i][j] = piece_unicode[player][piece]; } } } } } /* see: https://en.wikipedia.org/wiki/ANSI_escape_code#Colors */ setlocale(LC_ALL, ""); for (index i = 7; i < 8; i--) { fprintf(out, "\033[0m"); /* reset background color */ fprintf(out, "%"INDEX_FMT" ", i+1); for (index j = 0; j < 8; ++j) { index const n = INDEX_FROM_RF(i,j); if (move && n == move->from) { fprintf(out, "\033[%d;%dm", 30, 44); /* 44: blue*/ } else if (move && n == move->to) { fprintf(out, "\033[%d;%dm", 30, 44); /* 104: bright blue*/ } else { /* 45: magenta, 47: white */ fprintf(out, "\033[%d;%dm", 30, (i+j) % 2 ? 45 : 47); } if (buf[i][j]) { fprintf(out, "%lc ", buf[i][j]); } else { fprintf(out, " "); /* idk why this hack is needed but "%lc " is not working when buf[i][j] = ' ' */ } } fprintf(out, "\033[0m"); /* reset background color */ fprintf(out, "\n"); } fprintf(out, " A B C D E F G H \n"); } static void bitboard_print(bitboard b, FILE* out) { setlocale(LC_ALL, ""); fprintf(out, "\n"); for (index i = 7; i < 8; i--) { fprintf(out, "\033[0m"); /* reset background color */ fprintf(out, "%"INDEX_FMT" ", i+1); for (index j = 0; j < 8; ++j) { index const n = INDEX_FROM_RF(i,j); int color; if ((b >> n) & 1) { /* 41: red */ color = 41; } else { /* 45: magenta, 47: white */ color = (i+j)%2 ? 45 : 47; } fprintf(out, "\033[30;%dm", color); fprintf(out, " "); } fprintf(out, "\033[0m"); /* reset background color */ fprintf(out, "\n"); } fprintf(out, " A B C D E F G H \n"); } static void board_print_threats(const struct pos* pos, FILE* out, struct move* move) { enum player const player = pos->player; int buf[8][8] = {0}; bitboard const threats = all_threats_from_player(pos, player); for (enum player player = PLAYER_BEGIN; player < PLAYER_COUNT; ++player) { for (enum piece piece = PIECE_BEGIN; piece < PIECE_COUNT; ++piece) { bitboard x = pos->pieces[player][piece]; for (index i = 7; i < 8; i--) { for (index j = 0; j < 8; ++j) { if (x & (1ULL<<(i*8+j))) { buf[i][j] = piece_unicode[player][piece]; } } } } } /* see: https://en.wikipedia.org/wiki/ANSI_escape_code#Colors */ setlocale(LC_ALL, ""); /* needed for unicode symbols */ for (index i = 7; i < 8; i--) { fprintf(out, "\033[0m"); /* reset background color */ fprintf(out, "%"INDEX_FMT" ", i+1); for (index j = 0; j < 8; ++j) { index const n = INDEX_FROM_RF(i,j); if (move && n == move->from) { fprintf(out, "\033[%d;%dm", 30, 44); /* 44: blue*/ } else if (move && n == move->to) { fprintf(out, "\033[%d;%dm", 30, 44); /* 104: bright blue*/ } else if ((threats >> n) & 1) { fprintf(out, "\033[%d;%dm", 30, 41); /* 41: red */ } else { /* 45: magenta, 47: white */ fprintf(out, "\033[%d;%dm", 30, (i+j) % 2 ? 45 : 47); } if (buf[i][j]) { fprintf(out, "%lc ", buf[i][j]); } else { fprintf(out, " "); /* idk why this hack is needed but "%lc " is not working when buf[i][j] = ' ' */ } } fprintf(out, "\033[0m"); /* reset background color */ fprintf(out, "\n"); } fprintf(out, " A B C D E F G H \n"); }