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#include "engine/ttable.h"
void ttable_init() {
tbucket_t *table = calloc(TABLE_SIZE * sizeof(*table));
for (int i = 0; i < PIECE_TYPE_COUNT; i++) {
for (int j = 0; j < 64; j++) {
zobrist_keys.piece[i][j] = random_u64();
}
}
for (int i = 0; i < CASTLE_COUNT; i++) {
zobrist_keys.castle[i] = random_u64();
}
for (int i = 0; i < TURN_COUNT; i++) {
zobrist_keys.turn[i] = random_u64();
}
for (int i = 0; i < 64; i++) {
zobrist_keys.en_passant[i] = random_u64();
}
}
u64 zobrist_hash(position_t position) {
u64 output = 0;
for (int i = 0; i < 64; i++) {
int piece_type = find_piece_on_square(&position, i);
output ^= zobrist_keys.piece[piece_type][i];
}
if (position.castling & WHITE_SHORT_CASTLE) {
output ^= zobrist_keys.castle[0];
}
if (position.castling & WHITE_LONG_CASTLE) {
output ^= zobrist_keys.castle[1];
}
if (position.castling & BLACK_SHORT_CASTLE) {
output ^= zobrist_keys.castle[2];
}
if (position.castling & BLACK_LONG_CASTLE) {
output ^= zobrist_keys.castle[3];
}
output ^= zobrist_keys.turn[position.turn];
output ^= zobrist_keys.en_passant[position.passantable_file];
return output;
}
void ttable_store(
ttable_t *ttable,
u64 key,
move_t move,
i16 score,
i16 eval,
u16 depth,
u16 generation,
u8 flag
) {
tbucket_t *bucket = ttable + (key & MASK);
tentry_t *best = bucket.entries;
for (int i = 1; i < TT_BUCKET_SIZE; i++) {
if (bucket.entries[i].depth >= best->depth) continue;
best = bucket.entries + i;
}
tentry_t object;
object.move = move;
object.score = score;
object.eval = eval;
object.depth = depth;
object.flag = flag;
object.generation = generation;
memcpy(best, &object, sizeof(object));
atomic_store_explicit(&best->key, key, memory_order_release);
}
tentry_t *ttable_probe(ttable_t *table, u64 key) {
tbucket_t *bucket = ttable + key & MASK;
for (int i = 0; i < TT_BUCKET_SIZE; i++) {
if (atomic_load_explicit(
&(bucket.entries + i)->key,
memory_order_acquire
) != key) continue;
return bucket.entries + i;
}
return NULL;
}
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