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simplify code and pv print
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@Stermere
Stermere committed Aug 28, 2023
1 parent 73448cf commit 5404c66
Showing 1 changed file with 22 additions and 18 deletions.
40 changes: 22 additions & 18 deletions src/engine/board_search.c
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Original file line number Diff line number Diff line change
Expand Up @@ -542,6 +542,12 @@ int generate_moves(intLong p1, intLong p2, intLong p1k, intLong p2k, int pos, in
return num_moves;
}

int adjust_mate_score(int eval) {
return (eval > 500) ?
eval - 1 : ((eval < -500) ?
eval + 1 : eval);
}

// a function that decides if a search should be extended or reduced at a certain node
int should_extend_or_reduce(int depth, int depth_abs, int node_num,
struct hash_table_entry* table_entry,
Expand All @@ -561,7 +567,7 @@ int should_extend_or_reduce(int depth, int depth_abs, int node_num,
return depth + 1;
}

if (node_type == UPPER_BOUND && depth_abs > 3 && node_num > 2){
if (node_type == UPPER_BOUND && depth_abs > 3 && node_num > 5){
return depth - 1;
}

Expand Down Expand Up @@ -605,7 +611,7 @@ int negmax(intLong* p1, intLong* p2, intLong* p1k, intLong* p2k, int player,
struct hash_table_entry* table_entry = get_hash_entry(evaler->hash_table, hash, evaler->search_depth, depth);
if (table_entry != NULL && table_entry->depth >= depth && table_entry->player == player) {
if (table_entry->node_type == PV_NODE) {
return (table_entry->eval > 500.0f) ? table_entry->eval - 1 : ((table_entry->eval < -500.0f) ? table_entry->eval + 1 : table_entry->eval);
return adjust_mate_score(table_entry->eval);
}
else if (table_entry->node_type == LOWER_BOUND) {
alpha = max(alpha, table_entry->eval);
Expand All @@ -614,8 +620,8 @@ int negmax(intLong* p1, intLong* p2, intLong* p1k, intLong* p2k, int player,
beta = min(beta, table_entry->eval);
}
if (alpha >= beta) {
return (table_entry->eval > 500.0f) ? table_entry->eval - 1 : ((table_entry->eval < -500.0f) ? table_entry->eval + 1 : table_entry->eval);
}
return adjust_mate_score(table_entry->eval);
}
}

// if the depth is 0 then we are at the end of the standard search so begin the captures search
Expand Down Expand Up @@ -646,7 +652,7 @@ int negmax(intLong* p1, intLong* p2, intLong* p1k, intLong* p2k, int player,

// the the next boards are ready to be searched so begin the search!
short best_move = NO_MOVE;
int eval;
int eval, flip, next_alpha, next_beta;
for (int i = 0; i < num_moves; i++){
// prepare moves
int move_start = moves[i * 2];
Expand All @@ -665,13 +671,13 @@ int negmax(intLong* p1, intLong* p2, intLong* p1k, intLong* p2k, int player,
int depth_next = should_extend_or_reduce(depth, depth_abs, i, table_entry, evaler, (jumped_piece_type != -1)) - 1;

// only flip the eval if the player changed
int flip = (player != player_next) ? -1 : 1;
int next_alpha = (flip == 1) ? alpha : -beta;
int next_beta = (flip == 1) ? beta : -alpha;
flip = (player != player_next) ? -1 : 1;
next_alpha = (flip == 1) ? alpha : -beta;
next_beta = (flip == 1) ? beta : -alpha;
eval = negmax(p1, p2, p1k, p2k, player_next, piece_loc, depth_next,
next_alpha, next_beta, captures_only, evaler, next_hash,
depth_abs + 1, i) * flip;

// undo the update to the board and piece locations
undo_piece_locations_update(move_start, move_end, piece_loc);
undo_board_update(p1, p2, p1k, p2k, move_start, move_end, jumped_piece_type, initial_piece_type);
Expand Down Expand Up @@ -711,10 +717,7 @@ int negmax(intLong* p1, intLong* p2, intLong* p1k, intLong* p2k, int player,
// store the eval in the hash table
add_hash_entry(evaler->hash_table, hash, board_eval, depth, evaler->search_depth, player, best_move, node_type);

// if the eval is a mating eval update it to reflect how far it traveled up the tree
board_eval = (board_eval > 500) ? board_eval - 1 : (board_eval < -500) ? board_eval + 1 : board_eval;

return board_eval;
return adjust_mate_score(board_eval);
}

// a function to round the float to 2 decimal places
Expand All @@ -731,7 +734,7 @@ struct search_info* start_board_search(intLong p1, intLong p2, intLong p1k, intL
HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);


// the tree will be stored in a linked list of best_move structs (populated during search)
// set for the piece locations
struct set* piece_loc = get_piece_locations(p1, p2, p1k, p2k);
int moves[96];

Expand All @@ -756,7 +759,7 @@ struct search_info* start_board_search(intLong p1, intLong p2, intLong p1k, intL
evaler->max_depth = min(max(i + 10, 5), search_depth);

// call the search function and recurse
eval_ = negmax(&p1, &p2, &p1k, &p2k, player, piece_loc, i, -1000, 1000, 0,
eval_ = negmax(&p1, &p2, &p1k, &p2k, player, piece_loc, i, -2000, 2000, 0,
evaler, hash, 0, 0);

// get the end time
Expand Down Expand Up @@ -919,20 +922,21 @@ void human_readble_board(intLong p1, intLong p2, intLong p1k, intLong p2k){
// print the expected line to standard out in a human readable format (for debugging)
void print_line(intLong p1, intLong p2, intLong p1k, intLong p2k, unsigned long long hash, struct board_evaler* evaler){
// use the hash table to make the line of moves
printf("PV ");
int depth = 0;
while (depth < evaler->search_depth) {
struct hash_table_entry* table_entry = get_hash_entry(evaler->hash_table, hash, evaler->search_depth, depth);
if (table_entry == NULL || table_entry->best_move == NO_MOVE || table_entry->node_type != PV_NODE){
break;
}

printf("ply %d move %d %d\n", depth, table_entry->best_move >> 8, table_entry->best_move & 0xFF);
printf("eval %d\n\n", table_entry->eval);
printf("- %d %d ", depth, table_entry->best_move >> 8, table_entry->best_move & 0xFF);

hash = update_hash(p1, p2, p1k, p2k, table_entry->best_move >> 8, table_entry->best_move & 0xFF, hash, evaler);
update_board(&p1, &p2, &p1k, &p2k, table_entry->best_move >> 8, table_entry->best_move & 0xFF);
depth++;
}
printf("\n");
human_readble_board(p1, p2, p1k, p2k);
}

Expand Down Expand Up @@ -970,7 +974,7 @@ int main(){
clock_t start, end;
double cpu_time_used;

for (int i = 1; i < depth; i++){
for (int i = 2; i < depth; i++){
// get the start time
start = clock();

Expand Down

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