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/*
This file is part of ctak.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with ctak. If not, see <https://www.gnu.org/licenses/>.
*/
#include "tt.h"
#include <string.h>
// ===================================================================
// Variables
// ===================================================================
static tt_entry_t table[TT_SIZE + 1];
static uint16_t tt_gen = 0;
// ===================================================================
// Exported functions
// ===================================================================
int tt_init(void) {
tt_gen++;
if (tt_gen == 0)
memset(table, 0, sizeof(table));
return EXIT_SUCCESS;
}
tt_entry_t *tt_seek(const uint64_t key) {
tt_entry_t *e = &table[key & TT_SIZE];
if (e->gen == tt_gen && e->key == key)
return e;
return NULL;
}
tt_entry_t *tt_store(const uint64_t key, const enum TT_FLAG flag,
const uint8_t depth, const float value,
const action_t action) {
tt_entry_t *e = &table[key & TT_SIZE];
if (e->gen == tt_gen && e->key == key) {
// The slot holds this very position: update it (gen and key are already
// correct).
e->flag = flag;
e->value = value;
e->depth = depth;
e->action = action;
return e;
}
// Empty slot, stale generation, or a different position: keep a deeper search
// of a foreign position over this shallower one.
if (e->gen == tt_gen && e->depth > depth)
return NULL;
e->key = key;
e->value = value;
e->action = action;
e->gen = tt_gen;
e->flag = flag;
e->depth = depth;
return e;
}
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