bruno/brchess
1
0
Fork 0
Code Issues 10 Projects Releases Wiki Activity

adjust nodecounts, fix PVS

Browse Source
This commit is contained in:
Bruno Raoult
2023-07-12 21:31:27 +02:00
parent 3de87daa5a
commit d852e0bc1d
1 changed files with 41 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files

60
src/search.c
View File

@@ -37,6 +37,7 @@ eval_t negamax(pos_t *pos, int depth, int color)
pos_t *newpos;
eval_t best = EVAL_MIN, score;
pos->node_count++;
if (depth == 0) {
moves_gen_all_nomoves(pos);
score = eval(pos) * color;
@@ -70,53 +71,74 @@ eval_t negamax(pos_t *pos, int depth, int color)
* Calculate the PVS value of @pos.
* See https://en.wikipedia.org/wiki/Principal_variation_search
*
* Moves list should be first generated and evaluated/sorted.
*
* @return: The @pos PVS evaluation.
*/
eval_t pvs(pos_t *pos, int depth, int alpha, int beta, int color)
{
move_t *move;
pos_t *newpos;
eval_t score;
int n = 0;
eval_t score = EVAL_INVALID;
bool firstchild = true;
pos->node_count++;
if (depth == 0) {
//return quiesce(p, alpha, beta); /* leaf node */
moves_gen_all_nomoves(pos);
moves_gen_all(pos);
score = eval(pos) * color;
log_f(2, "Terminal: depth=%d ", depth);
log_f(2, "score=%d alpha=%d beta=%d\n", score, alpha, beta);
return score;
}
moves_gen_eval_sort(pos);
moves_gen_all(pos);
//moves_print(pos, M_PR_EVAL);
/* do the full search for first child */
//move = list_first_entry_or_null(&pos->moves[pos->turn], move_t, list);
list_for_each_entry(move, &pos->moves[pos->turn], list) {
log(1, "%.*s", 5 - depth, " ");
newpos = move->pos;
log_f(1, "depth=%d eval=%d move=", depth, move->eval);
move_print(0, move, M_PR_EVAL);
log(1, "\n");
if (!n++) { /* first child */
newpos = move_do(pos, move);
log(2, "%.*s", 5 - depth, " ");
if (firstchild) { /* first child */
score = -pvs(newpos, depth - 1, -beta, -alpha, -color);
log_f(2, "First child depth=%d move=", depth);
//move_print(0, move, 0);
log(2, "score=%d alpha=%d beta=%d\n", score, alpha, beta);
pos->bestmove = move;
} else {
/* search with a null window */
score = -pvs(newpos, depth - 1, -alpha - 1, -alpha, -color);
if (score > alpha && score < beta) {
log_f(2, "Other child depth=%d move=", depth);
//move_print(0, move, 0);
log_f(2, "score=%d alpha=%d beta=%d ", score, alpha, beta);
/* for fail-soft: if (score > alpha && score < beta) */
if (score > alpha) {
/* if failed high, do a full re-search */
score = -pvs(newpos, depth - 1, -beta, -score, -color);
log_f(2, "doing full search.");
score = -pvs(newpos, depth - 1, -beta, -alpha, -color);
}
log(2, "\n");
}
pos->node_count += newpos->node_count;
move_undo(newpos, move);
if (score >= beta) { /* fail-hard hard beta cut-off */
log(2, "%.*s", 5 - depth, " ");
log_f(2, "depth=%d score=%d alpha=%d beta=%d beta cut-off.\n",
depth, score, alpha, beta);
return beta;
}
if (score > alpha) {
log(2, "%.*s", 5 - depth, " ");
log_f(2, "depth=%d setting new alpha from %d to %d\n",
depth, alpha, score);
alpha = score;
pos->bestmove = move;
}
move_undo(newpos, move);
move->pos = NULL;
pos->node_count += newpos->node_count;
move->negamax = score;
// alpha = max(alpha, score);
if (alpha > beta) { /* beta cut-off */
break;
}
firstchild = false;
}
return alpha;