diff options
Diffstat (limited to 'include/zobrist.c')
| -rw-r--r-- | include/zobrist.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/include/zobrist.c b/include/zobrist.c index d8d1856..2922abf 100644 --- a/include/zobrist.c +++ b/include/zobrist.c @@ -1,5 +1,5 @@ /* - This file is part of ct. + 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 @@ -12,10 +12,11 @@ General Public License for more details. You should have received a copy of the GNU General Public License - along with ct. If not, see <https://www.gnu.org/licenses/>. + along with ctak. If not, see <https://www.gnu.org/licenses/>. */ #include "zobrist.h" +#include "xorshift64.h" // =================================================================== // Variables @@ -35,8 +36,7 @@ int zobrist_init(const uint8_t board_size) { // TODO: trap errno for (int k = 0; k < board_size * board_size * (15 * 2 * 3); k++) { - XORSHIFT64; - zobrist[k] = RANDOM64; + zobrist[k] = rand64(); } return EXIT_SUCCESS; @@ -49,6 +49,11 @@ void zobrist_free(void) { } } + +// a position's value is from the perspective of the player to move, which flips +// with parity, so we must track this +#define PLY_PARITY_MAGIC 0x9E3779B97F4A7C15ULL + uint64_t zobrist_compute(tak_state_p state) { uint64_t hash = 0; for (uint8_t l = 0; l < state->board_size * state->board_size; l++) { @@ -58,5 +63,5 @@ uint64_t zobrist_compute(tak_state_p state) { for (uint8_t h = 0; h < count; h++, c >>= 1) hash ^= zobrist[l * (15 * 2 * 3) + h * 2 * 3 + (c & 1) * 3 + s]; } - return hash; + return hash ^ ((state->ply & 1) ? PLY_PARITY_MAGIC : 0); } |