stellar

UCI Chess engine written in C++20
git clone git://git.dimitrijedobrota.com/stellar.git
Log | Files | Refs | README | LICENSE |
commitf8a5dd96409dbbd8818aef7f6984dda121053c0a
parent120c077931942c5cc5308bf9ccc62cc83cfd6c82
authorDimitrije Dobrota <mail@dimitrijedobrota.com>
dateMon, 25 Sep 2023 19:45:53 +0000

Incremental sorting, fix quiescence timeout

Diffstat:
MCMakeLists.txt|+-
Msrc/engine/engine.cpp|++++++++++++++++++++++++++---------------
Msrc/move/movelist.hpp|+

3 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt

@@ -3,7 +3,7 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

project(
Stellar
VERSION 9.0.2
VERSION 9.0.3
DESCRIPTION "Chess engine written in C++"
HOMEPAGE_URL https://git.dimitrijedobrota.com/stellar.git
LANGUAGES CXX

diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp

@@ -116,7 +116,7 @@ static bool follow_pv;

static U64 nodes;
static uint8_t ply;
U32 inline move_list_score(Move move) {
U32 inline move_score(const Move move) {
static constexpr const uint16_t capture[6][6] = {
// clang-format off
{105, 205, 305, 405, 505, 605},

@@ -138,19 +138,30 @@ U32 inline move_list_score(Move move) {

return history[piece::get_index(type, board.get_side())][to_underlying(move.target())];
}
std::vector<int> move_list_sort(MoveList &list, const Move best) {
static std::vector<int> score(256);
void move_list_sort(MoveList &list, std::vector<int> &score, int crnt) {
for (int i = crnt + 1; i < list.size(); i++) {
if (score[crnt] < score[i]) {
std::swap(list[crnt], list[i]);
std::swap(score[crnt], score[i]);
}
}
}
std::vector<int> move_list_score(MoveList &list, const Move best) {
std::vector<int> score(list.size(), 0);
bool best_found = false;
for (int i = 0; i < list.size(); i++) {
score[i] = move_list_score(list[i]);
score[i] = move_score(list[i]);
if (list[i] == best) {
score[i] = 30000;
best_found = true;
}
}
if (!best_found && ply && follow_pv) {
if (best_found) return score;
if (ply && follow_pv) {
follow_pv = false;
for (int i = 0; i < list.size(); i++) {
if (list[i] == pvtable.best(ply)) {

@@ -161,10 +172,7 @@ std::vector<int> move_list_sort(MoveList &list, const Move best) {

}
}
std::vector<int> index(list.size());
std::iota(begin(index), end(index), 0);
sort(begin(index), end(index), [&](int a, int b) { return score[a] > score[b]; });
return index;
return score;
}
int stats_move_make(Board &copy, const Move move) {

@@ -213,19 +221,20 @@ int16_t quiescence(int16_t alpha, int16_t beta) {

Board copy;
MoveList list(board, true);
for (int idx : move_list_sort(list, Move())) {
const Move move = list[idx];
std::vector<int> listScore = move_list_score(list, Move());
for (int i = 0; i < list.size(); i++) {
move_list_sort(list, listScore, i);
const Move move = list[i];
if (!stats_move_make(copy, move)) continue;
score = -quiescence(-beta, -alpha);
stats_move_unmake(copy, move);
if (settings->stopped) return 0;
if (score > alpha) {
alpha = score;
pvtable.store(move, ply);
if (score >= beta) return beta;
}
if (settings->stopped) return 0;
}
return alpha;

@@ -314,8 +323,10 @@ int16_t negamax(int16_t alpha, int16_t beta, uint8_t depth, bool null) {

uint8_t searched = 0;
MoveList list(board);
for (int idx : move_list_sort(list, bestMove)) {
const Move move = list[idx];
std::vector<int> listScore = move_list_score(list, bestMove);
for (int i = 0; i < list.size(); i++) {
move_list_sort(list, listScore, i);
const Move move = list[i];
if (!stats_move_make(copy, move)) continue;
legal_moves++;

diff --git a/src/move/movelist.hpp b/src/move/movelist.hpp

@@ -32,6 +32,7 @@ class MoveList {

int size() const { return list.size(); }
const Move operator[](size_t idx) const { return list[idx]; }
Move &operator[](size_t idx) { return list[idx]; }
void push(const Move move) { list.push_back(move); }
friend std::ostream &operator<<(std::ostream &os, const MoveList &list);