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fix mailbox related bug causing king to be capturable

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This commit is contained in:
Ole Morud
2025-12-17 18:53:35 +01:00
parent be5ec8d0dc
commit 509f58a379
2 changed files with 100 additions and 89 deletions
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123
base.h
View File

@@ -9,8 +9,9 @@
#include <stdlib.h> #include <stdlib.h>
#include <inttypes.h> #include <inttypes.h>
#define index string_index
#include <string.h> #include <string.h>
#undef index
static struct { static struct {
/* all globals are zero by default in C */ /* all globals are zero by default in C */
@@ -669,6 +670,7 @@ static bitboard bishop_attacks_from_index(enum square_index sq, bitboard occ)
- `mbb_bishop[SQ_INDEX_COUNT]` - `mbb_bishop[SQ_INDEX_COUNT]`
- `bitboard bishop_attacks[SQ_INDEX_COUNT][1<<9ULL] */ - `bitboard bishop_attacks[SQ_INDEX_COUNT][1<<9ULL] */
#include "mbb_bishop.h" #include "mbb_bishop.h"
assert(sq < SQ_INDEX_COUNT);
struct magic const m = mbb_bishop[sq]; struct magic const m = mbb_bishop[sq];
occ &= m.mask; occ &= m.mask;
occ *= m.magic; occ *= m.magic;
@@ -864,29 +866,26 @@ struct move {
index from; index from;
index to; index to;
uint8_t attr; uint8_t attr;
#define APPEAL_MAX 127 #define APPEAL_MAX UINT8_MAX
int8_t appeal; uint8_t appeal;
};
enum {
SO_ATTR_CHECK = 1<<0,
}; };
_Static_assert(sizeof(struct move) == 4,
"this static assert is here to check when sizeof(move) changes");
struct search_option { struct search_option {
/* TODO: optimize field order */ /* TODO: optimize order of fields and size */
double score; double score;
struct move move; struct move move;
uint64_t hash; uint64_t hash;
int8_t depth; uint8_t init : 1;
uint8_t init; enum tt_flag {TT_EXACT, TT_LOWER, TT_UPPER} flag : 3;
enum tt_flag {TT_EXACT, TT_LOWER, TT_UPPER} flag; int8_t depth : 4;
uint16_t attr;
}; };
#define TT_ADDRESS_BITS 24 #define TT_ADDRESS_BITS 24
#define TT_ENTRIES (1ULL<<TT_ADDRESS_BITS) #define TT_ENTRIES (1ULL<<TT_ADDRESS_BITS)
struct tt { struct tt {
struct search_option* entries; /* must be malloc'ed or mmap'ed */ struct search_option* entries; /* must be initialized somewhere */
}; };
@@ -929,12 +928,12 @@ static void move_compute_appeal(struct move* m,
/* MVV-LVA: https://www.chessprogramming.org/MVV-LVA */ /* MVV-LVA: https://www.chessprogramming.org/MVV-LVA */
enum piece const atk = mailbox[m->from]; enum piece const atk = mailbox[m->from];
int8_t n = 1; uint8_t n = 1;
if (SQ_MASK_FROM_INDEX(m->to) & pos->occupied[them]) { if (SQ_MASK_FROM_INDEX(m->to) & pos->occupied[them]) {
n += (int8_t)piece_value[mailbox[m->to]]; n += (uint8_t)piece_value[mailbox[m->to]];
} }
m->appeal = 16*(int8_t)n - (int8_t)piece_value[atk]; m->appeal = 16*n - (uint8_t)piece_value[atk];
} }
#define BOARD_INITIAL (struct board) { \ #define BOARD_INITIAL (struct board) { \
@@ -1007,13 +1006,13 @@ static void move_compute_appeal(struct move* m,
.hist = {0}, \ .hist = {0}, \
} }
static void board_print_fen(struct board const* b, FILE* out) static void board_print_fen(struct pos const* pos, FILE* out)
{ {
int buf[8][8] = {0}; int buf[8][8] = {0};
for (enum player player = PLAYER_BEGIN; player < PLAYER_COUNT; ++player) { for (enum player player = PLAYER_BEGIN; player < PLAYER_COUNT; ++player) {
for (enum piece piece = PIECE_BEGIN; piece < PIECE_COUNT; ++piece) { for (enum piece piece = PIECE_BEGIN; piece < PIECE_COUNT; ++piece) {
bitboard x = b->pos.pieces[player][piece]; bitboard x = pos->pieces[player][piece];
for (index i = 7; i < 8; i--) { for (index i = 7; i < 8; i--) {
for (index j = 0; j < 8; ++j) { for (index j = 0; j < 8; ++j) {
@@ -1045,22 +1044,22 @@ static void board_print_fen(struct board const* b, FILE* out)
fprintf(out, "/"); fprintf(out, "/");
} }
fprintf(out, " %c ", b->pos.player == PLAYER_WHITE ? 'w' : 'b'); fprintf(out, " %c ", pos->player == PLAYER_WHITE ? 'w' : 'b');
bool any_castle = false; bool any_castle = false;
if (!b->pos.castling_illegal[PLAYER_WHITE][CASTLE_KINGSIDE]) { if (!pos->castling_illegal[PLAYER_WHITE][CASTLE_KINGSIDE]) {
fprintf(out, "K"); fprintf(out, "K");
any_castle = true; any_castle = true;
} }
if (!b->pos.castling_illegal[PLAYER_WHITE][CASTLE_QUEENSIDE]) { if (!pos->castling_illegal[PLAYER_WHITE][CASTLE_QUEENSIDE]) {
fprintf(out, "Q"); fprintf(out, "Q");
any_castle = true; any_castle = true;
} }
if (!b->pos.castling_illegal[PLAYER_BLACK][CASTLE_KINGSIDE]) { if (!pos->castling_illegal[PLAYER_BLACK][CASTLE_KINGSIDE]) {
fprintf(out, "k"); fprintf(out, "k");
any_castle = true; any_castle = true;
} }
if (!b->pos.castling_illegal[PLAYER_BLACK][CASTLE_QUEENSIDE]) { if (!pos->castling_illegal[PLAYER_BLACK][CASTLE_QUEENSIDE]) {
fprintf(out, "q"); fprintf(out, "q");
any_castle = true; any_castle = true;
} }
@@ -1068,7 +1067,7 @@ static void board_print_fen(struct board const* b, FILE* out)
fprintf(out, "-"); fprintf(out, "-");
} }
if (b->pos.ep_targets) { if (pos->ep_targets) {
/* should be ep target square in algebraic notation */ /* should be ep target square in algebraic notation */
fprintf(stderr, "not implemented: fen with en passent squares\n"); fprintf(stderr, "not implemented: fen with en passent squares\n");
fprintf(out, "<TODO>"); fprintf(out, "<TODO>");
@@ -1076,8 +1075,8 @@ static void board_print_fen(struct board const* b, FILE* out)
fprintf(out, " -"); fprintf(out, " -");
} }
fprintf(out, " %d", b->pos.halfmoves); fprintf(out, " %d", pos->halfmoves);
fprintf(out, " %d", b->pos.fullmoves); fprintf(out, " %d", pos->fullmoves);
fprintf(out, "\n"); fprintf(out, "\n");
} }
@@ -1301,40 +1300,6 @@ static bitboard attacks_to(struct pos const* pos,
& ~pretend_occupied; & ~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;
}
_Static_assert(sizeof(struct move) == 4,
"this static assert is here to check when sizeof(move) changes");
#define MOVE_CASTLE_KINGSIDE_WHITE (struct move) \ #define MOVE_CASTLE_KINGSIDE_WHITE (struct move) \
{.from = SQ_INDEX_E1, .to = SQ_INDEX_G1, .attr = MATTR_CASTLE_KINGSIDE} {.from = SQ_INDEX_E1, .to = SQ_INDEX_G1, .attr = MATTR_CASTLE_KINGSIDE}
@@ -1475,8 +1440,7 @@ static void all_moves(struct pos const* restrict pos,
assert(myking); assert(myking);
enum square_index const myking_index = bitboard_lsb(myking); enum square_index const myking_index = bitboard_lsb(myking);
bitboard const attackers = attacks_to_king(pos, myking, 0ULL, 0ULL) & ~pos->occupied[us]; bitboard const attackers = attacks_to(pos, myking, 0ULL, 0ULL) & ~pos->occupied[us];
bitboard allowed = ~0ULL; bitboard allowed = ~0ULL;
@@ -1629,6 +1593,8 @@ enum move_result {
MR_CHECKMATE, MR_CHECKMATE,
}; };
static void board_print(const struct pos* pos, struct move* move, FILE* out);
/* does not check validity */ /* does not check validity */
static enum move_result board_move(struct pos* restrict pos, static enum move_result board_move(struct pos* restrict pos,
struct history* restrict hist, struct history* restrict hist,
@@ -1638,6 +1604,20 @@ static enum move_result board_move(struct pos* restrict pos,
enum player const us = pos->player; enum player const us = pos->player;
enum player const them = opposite_player(us); enum player const them = opposite_player(us);
#ifndef NDEBUG
if (SQ_MASK_FROM_INDEX(move.to) & pos->pieces[them][PIECE_KING]) {
fprintf(stderr, "fatal error: king capture\n");
board_print_fen(pos, stderr);
board_print(pos, &move, stderr);
for (enum piece p = PIECE_BEGIN; p < PIECE_COUNT; ++p) {
if (pos->pieces[us][p] & SQ_MASK_FROM_INDEX(move.from)) {
fprintf(stderr, "%s found on %s\n", piece_str[p], square_index_display[move.from]);
}
}
__builtin_trap();
}
#endif
enum piece const from_piece = mailbox[move.from]; enum piece const from_piece = mailbox[move.from];
enum piece const to_piece = mailbox[move.to]; enum piece const to_piece = mailbox[move.to];
@@ -1681,6 +1661,7 @@ static enum move_result board_move(struct pos* restrict pos,
pos->pieces[owner][piece] |= x; \ pos->pieces[owner][piece] |= x; \
pos->occupied[owner] |= x; \ pos->occupied[owner] |= x; \
pos->hash = tt_hash_update(pos->hash, at, owner, piece); \ pos->hash = tt_hash_update(pos->hash, at, owner, piece); \
mailbox[at] = piece; \
pos->halfmoves = 0; \ pos->halfmoves = 0; \
hist->length = 0; \ hist->length = 0; \
} while (0) } while (0)
@@ -1785,7 +1766,7 @@ static enum move_result board_move(struct pos* restrict pos,
return MR_STALEMATE; return MR_STALEMATE;
} }
if (attacks_to_king(pos, pos->pieces[them][PIECE_KING], 0ULL, 0ULL) & ~pos->occupied[them]) { if (attacks_to(pos, pos->pieces[them][PIECE_KING], 0ULL, 0ULL) & ~pos->occupied[them]) {
return MR_CHECK; return MR_CHECK;
} else { } else {
return MR_NORMAL; return MR_NORMAL;
@@ -1909,7 +1890,7 @@ double quiesce(struct pos const* pos,
while (move_count) { while (move_count) {
struct move m = moves_linear_search(moves, &move_count); struct move m = moves_linear_search(moves, &move_count);
if ((m.attr & MATTR_CAPTURE) == 0) { if ((m.attr & MATTR_CAPTURE) == 0ULL) {
continue; continue;
} }
@@ -2010,11 +1991,14 @@ struct search_option alphabeta_search(struct pos const* pos,
all_moves(pos, us, &move_count, moves); all_moves(pos, us, &move_count, moves);
if (move_count == 0) { if (move_count == 0) {
/* TODO: detect stalemate */
/* TODO: reusing mate distances correctly needs ply normalization */ /* TODO: reusing mate distances correctly needs ply normalization */
/* TODO: detect stalemate */
double score = 0;
if (attacks_to(pos, pos->pieces[us][PIECE_KING], 0ULL, 0ULL) != 0ULL) {
score = -(999.0 + (double)depth);
}
return (struct search_option) { return (struct search_option) {
.score = -(999.0 + (double)depth), .score = score,
.move = (struct move){0}, .move = (struct move){0},
.depth = depth, .depth = depth,
.hash = pos->hash, .hash = pos->hash,
@@ -2040,7 +2024,6 @@ struct search_option alphabeta_search(struct pos const* pos,
double best_score = -1e300; double best_score = -1e300;
struct move best_move = moves[0]; struct move best_move = moves[0];
while (move_count) { while (move_count) {
struct move m = moves_linear_search(moves, &move_count); struct move m = moves_linear_search(moves, &move_count);
@@ -2123,7 +2106,7 @@ struct move search(struct board* b, enum player us, int8_t max_depth)
#define SCORE_INF 1e80 #define SCORE_INF 1e80
for (int8_t d = 1; d <= max_depth; ++d) { for (int8_t d = 1; d <= max_depth; ++d) {
double window = 0.5; /* half a pawn */ double window = 0.5;
double alpha = score - window; double alpha = score - window;
double beta = score + window; double beta = score + window;
@@ -2184,7 +2167,7 @@ static void board_print(const struct pos* pos, struct move* move, FILE* out)
for (index j = 0; j < 8; ++j) { for (index j = 0; j < 8; ++j) {
index const n = INDEX_FROM_RF(i,j); index const n = INDEX_FROM_RF(i,j);
if (move && n == move->from) { if (move && n == move->from) {
fprintf(out, "\033[%d;%dm", 30, 44); /* 44: blue*/ fprintf(out, "\033[%d;%dm", 30, 104); /* 44: blue*/
} else if (move && n == move->to) { } else if (move && n == move->to) {
fprintf(out, "\033[%d;%dm", 30, 44); /* 104: bright blue*/ fprintf(out, "\033[%d;%dm", 30, 44); /* 104: bright blue*/
} else { } else {

52
tests.c
View File

@@ -205,15 +205,15 @@ static void print_bishop_test(const char *label,
bitboard all_occ, bitboard all_occ,
bitboard own_occ) bitboard own_occ)
{ {
printf("\n%s\n", label); fprintf(stderr, "\n%s\n", label);
printf("All occ:\n"); fprintf(stderr, "All occ:\n");
bitboard_print(all_occ, stdout); bitboard_print(all_occ, stderr);
printf("Own occ:\n"); fprintf(stderr, "Own occ:\n");
bitboard_print(own_occ, stdout); bitboard_print(own_occ, stderr);
const bitboard attacks = bishop_attacks_from_index(sq, all_occ) & ~own_occ; const bitboard attacks = bishop_attacks_from_index(sq, all_occ) & ~own_occ;
printf("Bishop attacks:\n"); fprintf(stderr, "Bishop attacks:\n");
bitboard_print(attacks, stdout); bitboard_print(attacks, stderr);
} }
static void test_bishops(void) static void test_bishops(void)
@@ -354,6 +354,34 @@ static void test_bishops(void)
assert(attacks == expected); assert(attacks == expected);
} }
/* Test 6: Bishop at H8, no occupancy */
{
const enum square_index sq = SQ_INDEX_H8;
const bitboard enemies = 0ULL;
const bitboard all_occ = 0ULL;
const bitboard own_occ = SQ_MASK_FROM_INDEX(sq);
/*
* From D4:
* NE: E5, then friendly F6 (stop; F6 not included)
* SW: C3, B2 (enemy, included, then stop)
* NW: C5, B6, A7
* SE: E3, F2, G1
* Bishop at F4 is irrelevant; it does not sit on a diagonal from D4.
*/
bitboard expected = 0ULL;
expected = SQ_MASK_G7 | SQ_MASK_F6 | SQ_MASK_E5 | SQ_MASK_D4 |
SQ_MASK_C3 | SQ_MASK_B2 | SQ_MASK_A1;
print_bishop_test("Bishop Test 6: H8, no occupancy", sq, all_occ, own_occ);
const bitboard attacks = bishop_attacks_from_index(sq, all_occ) & ~own_occ;
if (attacks != expected) {
bitboard_print(attacks, stderr);
}
assert(attacks == expected);
}
printf("\nAll bishop_attacks_from_index tests passed.\n"); printf("\nAll bishop_attacks_from_index tests passed.\n");
} }
@@ -365,7 +393,7 @@ int main()
printf("sizeof mailbox: %zu\n", sizeof (struct board){0}.mailbox); printf("sizeof mailbox: %zu\n", sizeof (struct board){0}.mailbox);
printf("sizeof tt: %zu\n", sizeof (struct tt)); printf("sizeof tt: %zu\n", sizeof (struct tt));
#if 0 #if 1
test_rooks(); test_rooks();
test_bishops(); test_bishops();
#endif #endif
@@ -377,8 +405,8 @@ int main()
struct board board = BOARD_INITIAL; struct board board = BOARD_INITIAL;
//board_load_fen_unsafe(&board, "1n1q1rk1/r1p2P2/1p1pp2p/pB2P3/2P5/PPN5/6b1/3QK1NR b - - 0 1"); //board_load_fen_unsafe(&board, "1n1q1rk1/r1p2P2/1p1pp2p/pB2P3/2P5/PPN5/6b1/3QK1NR b - - 0 1");
board_load_fen_unsafe(&board, "5R2/7k/P7/6pp/3B4/1PPK2bP/4r3/8 b - - 3 57"); //board_load_fen_unsafe(&board, "5R2/7k/P7/6pp/3B4/1PPK2bP/4r3/8 b - - 3 57");
board_print_fen(&board, stdout); board_print_fen(&board.pos, stdout);
board_print(&board.pos, NULL, stdout); board_print(&board.pos, NULL, stdout);
struct move moves[MOVE_MAX]; struct move moves[MOVE_MAX];
@@ -396,7 +424,7 @@ int main()
} }
//struct move move = moves[0]; //struct move move = moves[0];
struct move move = search(&board, board.pos.player, 7); struct move move = search(&board, board.pos.player, 8);
printf("move %d: {\n" printf("move %d: {\n"
" .from = %s, (%s)\n" " .from = %s, (%s)\n"
@@ -414,7 +442,7 @@ int main()
enum move_result const r = board_move_2(&board, move); enum move_result const r = board_move_2(&board, move);
#if 1 #if 1
board_print_fen(&board, stdout); board_print_fen(&board.pos, stdout);
print_stats(stdout); print_stats(stdout);
board_print(&board.pos, &move, stdout); board_print(&board.pos, &move, stdout);
#endif #endif