105 lines
2.9 KiB
C
105 lines
2.9 KiB
C
/* hash.h - hash management.
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*
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* Copyright (C) 2024 Bruno Raoult ("br")
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* Licensed under the GNU General Public License v3.0 or later.
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* Some rights reserved. See COPYING.
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*
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* You should have received a copy of the GNU General Public License along with this
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* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
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*
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* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
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*
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*/
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#ifndef HASH_H
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#define HASH_H
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#include <assert.h>
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#include "chessdefs.h"
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#define NBUCKETS 4 /* buckets per hash table entry */
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#define HASH_SIZE_DEFAULT 32 /* default: 32Mb */
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#define HASH_SIZE_MIN 4
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#define HASH_SIZE_MAX 32768 /* 32Gb */
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#define key_t u64 /* cannot use typedef for key_t */
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/**
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* hentry_t: hashtable bucket.
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*
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* Size should be exactly 16 bytes. If impossible to fit necessary data in
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* 16 bytes in future, it should be updated to be exactly 32 bytes.
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*/
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typedef struct {
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key_t key; /* zobrist */
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union {
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u64 data;
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struct {
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u16 depth; /* ply in search */
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s16 eval;
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u16 move;
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u8 flags; /* maybe for locking, etc... */
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u8 filler;
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};
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};
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} hentry_t;
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typedef struct {
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hentry_t buckets[NBUCKETS];
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} bucket_t;
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typedef struct {
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bucket_t *keys; /* &hashtable entries */
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/* memory size in bytes/mb */
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size_t bytes;
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u32 mb;
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/* size in buckets/keys */
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size_t nbuckets;
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size_t nkeys; /* nbuckets * NBUCKETS */
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/* internal representation */
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u32 nbits; /* #buckets in bits, power of 2 */
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u32 mask; /* nbuckets - 1, key mask */
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/* stats - unsure about usage */
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size_t used_buckets;
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size_t used_keys;
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u64 collisions;
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} hasht_t;
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/* hack:
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* ep zobrist key index is 0-7 for each en-passant file, 8 for SQUARE_NONE.
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* To transform :
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* - ep == 64 (SQUARE_NONE) to id = 8
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* - ep == 0~63 to idx = sq_file(ep), i.e. (ep & 7)
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* we use the formula:
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* idx = ( ( ep & SQUARE_NONE ) >> 3 ) | sq_file(ep);
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*/
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#define EP_ZOBRIST_IDX(ep) ( ( (ep) >> 3 ) | sq_file(ep) )
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extern key_t zobrist_pieces[16][64];
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extern key_t zobrist_castling[4 * 4 + 1];
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extern key_t zobrist_turn; /* for black, XOR each ply */
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extern key_t zobrist_ep[9]; /* 0-7: ep file, 8: SQUARE_NONE */
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extern hasht_t hash_tt; /* main transposition table */
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void zobrist_init(void);
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key_t zobrist_calc(pos_t *pos);
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#ifdef ZOBRIST_VERIFY
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bool zobrist_verify(pos_t *pos);
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#else
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#define zobrist_verify(p) true
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#endif
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int hash_create(int Mb);
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void hash_clear(void);
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void hash_delete(void);
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#endif /* HASH_H */
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