Merge branch 'main' into opti-2-compacting-move

level of the search (x4~ improvement)

cpp/src/board.cpp

@@ -182,7 +182,9 @@ Board Board::make_move(Move move) const {
     ret.squares[move.target_square] = this->squares[move.source_square];
 
     // -- Handle en passant target being eaten
-    if (move.en_passant)
+    if (en_passant_target != -1
+        && (squares[move.source_square] & 0b111) == Piece::Pawn
+        && squares[move.target_square] == Piece::None)
         ret.squares[move.target_square + (white_to_play ? -8 : 8)] =
             Piece::None;
 
@@ -203,23 +205,26 @@ Board Board::make_move(Move move) const {
 
     // -- Handle castling (just move the rook over)
     Coords c = Coords::from_index(move.source_square);
-    if (move.castle_side & KingSide) {
-        Coords rook_source{7, c.y};
-        int8_t old_rook = ret.squares[rook_source.to_index()];
-        ret.squares[rook_source.to_index()] = Piece::None;
-        Coords rook_dest{5, c.y};
-        ret.squares[rook_dest.to_index()] = old_rook;
-    } else if (move.castle_side & QueenSide) {
-        Coords rook_source{0, c.y};
-        int8_t old_rook = ret.squares[rook_source.to_index()];
-        ret.squares[rook_source.to_index()] = Piece::None;
-        Coords rook_dest{3, c.y};
-        ret.squares[rook_dest.to_index()] = old_rook;
+    if ((squares[move.source_square] & 0b111) == Piece::King) {
+        if (move.target_square - move.source_square == 2) { // king side castle
+            Coords rook_source{7, c.y};
+            int8_t old_rook = ret.squares[rook_source.to_index()];
+            ret.squares[rook_source.to_index()] = Piece::None;
+            Coords rook_dest{5, c.y};
+            ret.squares[rook_dest.to_index()] = old_rook;
+        } else if (move.target_square - move.source_square == -2) { // queen
+            Coords rook_source{0, c.y};
+            int8_t old_rook = ret.squares[rook_source.to_index()];
+            ret.squares[rook_source.to_index()] = Piece::None;
+            Coords rook_dest{3, c.y};
+            ret.squares[rook_dest.to_index()] = old_rook;
+        }
     }
 
     // -- Check for castling rights
     ret.w_castle_rights = w_castle_rights;
     ret.b_castle_rights = b_castle_rights;
+    bool is_capturing = squares[move.target_square] != Piece::None;
     if (white_to_play) {
         if ((squares[move.source_square] & 0b111) == King)
             ret.w_castle_rights = NeitherSide;
@@ -232,7 +237,7 @@ Board Board::make_move(Move move) const {
         }
 
         Coords target = Coords::from_index(move.target_square);
-        if (move.is_capturing && target.y == 7
+        if (is_capturing && target.y == 7
             && (squares[move.target_square] & 0b111) == Rook) {
             if (target.x == 0 && (ret.b_castle_rights & QueenSide))
                 ret.b_castle_rights &= ~(QueenSide);
@@ -251,7 +256,7 @@ Board Board::make_move(Move move) const {
         }
 
         Coords target = Coords::from_index(move.target_square);
-        if (move.is_capturing && target.y == 0
+        if (is_capturing && target.y == 0
             && (squares[move.target_square] & 0b111) == Rook) {
             if (target.x == 0 && (ret.w_castle_rights & QueenSide))
                 ret.w_castle_rights &= ~(QueenSide);

cpp/src/main.cpp

@@ -5,7 +5,7 @@
 
 int main(int argc, char* argv[]) {
     std::string pos =
-        "r2q1rk1/pP1p2pp/Q4n2/bbp1p3/Np6/1B3NBn/pPPP1PPP/R3K2R b KQ - 0 5";
+        "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
     // Board b = Board::setup_fen_position(pos);
     perft();
     return 0;

cpp/src/move.hpp

@@ -11,9 +11,6 @@ struct Move {
     int8_t source_square;
     int8_t target_square;
 
-    bool is_capturing = false;
-    CastleSide castle_side = CastleSide::NeitherSide;
-    bool en_passant = false;
     int8_t promoting_to = Piece::None;
 
     std::string to_string() const {

cpp/src/pieces/king.cpp

@@ -60,7 +60,6 @@ std::vector<Move> king_moves(const Board& b, const Coords xy) {
         ret.push_back(Move{
             xy.to_index(),
             Coords{6, xy.y}.to_index(),
-            .castle_side = CastleSide::KingSide
         });
     }
 
@@ -68,7 +67,6 @@ std::vector<Move> king_moves(const Board& b, const Coords xy) {
         ret.push_back(Move{
             xy.to_index(),
             Coords{2, xy.y}.to_index(),
-            .castle_side = CastleSide::QueenSide
         });
     }
 

cpp/src/pieces/pawn.cpp

@@ -21,7 +21,6 @@ std::vector<Move> pawn_moves(const Board& b, const Coords xy) {
                         ret.push_back(Move{
                             xy.to_index(),
                             left.to_index(),
-                            .is_capturing = true,
                             .promoting_to = (int8_t) (my_colour | piece)
                         });
                 else
@@ -43,7 +42,6 @@ std::vector<Move> pawn_moves(const Board& b, const Coords xy) {
                         ret.push_back(Move{
                             xy.to_index(),
                             right.to_index(),
-                            .is_capturing = true,
                             .promoting_to = (int8_t) (my_colour | piece)
                         });
                 else
@@ -55,14 +53,8 @@ std::vector<Move> pawn_moves(const Board& b, const Coords xy) {
     if (b.en_passant_target != -1) {
         Coords c = Coords::from_index(b.en_passant_target);
         int dy = my_colour == Colour::White ? 1 : -1;
-        if (c.y == xy.y + dy && (c.x == xy.x - 1 || c.x == xy.x + 1)) {
-            ret.push_back(Move{
-                xy.to_index(),
-                c.to_index(),
-                .is_capturing = true,
-                .en_passant = true
-            });
-        }
+        if (c.y == xy.y + dy && (c.x == xy.x - 1 || c.x == xy.x + 1))
+            ret.push_back(Move{xy.to_index(), c.to_index()});
     }
 
     // -- Normal move + promotion

cpp/src/pieces/piece.cpp

@@ -53,18 +53,11 @@ legal_moves(int8_t p, const Board& b, const Coords xy, bool looking_for_check) {
 
 std::optional<Move>
 move_for_position(const Board& board, const Coords source, const Coords dest) {
-    if (!dest.is_within_bounds())
+    if (!dest.is_within_bounds()
+        || board.colour_at(source) == board.colour_at(dest))
         return {};
 
-    int8_t piece = board.squares[dest.to_index()];
-    if (piece == Piece::None)
-        return Move{source.to_index(), dest.to_index()};
-
-    int8_t source_colour = board.colour_at(source);
-    int8_t dest_colour = board.colour_at(dest);
-    if (source_colour != dest_colour)
-        return Move{source.to_index(), dest.to_index(), true};
-    return {};
+    return Move{source.to_index(), dest.to_index()};
 }
 
 std::vector<Move>
@@ -74,11 +67,11 @@ look_direction(const Board& board, const Coords xy, int mult_dx, int mult_dy) {
         int dx = mult_dx * d;
         int dy = mult_dy * d;
 
-        std::optional<Move> move =
-            move_for_position(board, xy, Coords{xy.x + dx, xy.y + dy});
+        Coords target{xy.x + dx, xy.y + dy};
+        std::optional<Move> move = move_for_position(board, xy, target);
         if (move.has_value()) {
             ret.push_back(move.value());
-            if (move.value().is_capturing)
+            if (board.squares[target.to_index()] != Piece::None)
                 break;
         } else {
             break;

cpp/src/stickfosh.cpp

@@ -2,6 +2,7 @@
 
 #include "board.hpp"
 #include "move.hpp"
+#include "threadpool.hpp"
 
 #include <chrono>
 #include <map>
@@ -102,7 +103,9 @@ static std::map<std::string, std::map<int, int>> pos2expected{
 
 static std::stringstream res;
 
-int move_generation_test(Board& b, int depth, int max_depth) {
+int move_generation_test(
+    const Board& b, int depth, int max_depth, ThreadPool& pool
+) {
     if (depth == max_depth) {
         res.str("");
         res.clear();
@@ -118,15 +121,34 @@ int move_generation_test(Board& b, int depth, int max_depth) {
         return moves.size();
 
     int num_pos = 0;
-    for (const Move& move : moves) {
-        Board tmp_board = b.make_move(move);
-        // std::cout << ">" << move << std::endl;
-        int n = move_generation_test(tmp_board, depth - 1, max_depth);
-        // std::cout << "<" << move << std::endl;
-        if (depth == max_depth)
-            res << move << ": " << n << std::endl;
-        num_pos += n;
+
+    if (depth == max_depth) {
+        // Parallel execution at the top level
+        std::vector<std::future<int>> futures;
+        for (const Move& move : moves) {
+            Board tmp_board = b.make_move(move);
+            futures.push_back(pool.enqueue(
+                move_generation_test,
+                tmp_board,
+                depth - 1,
+                max_depth,
+                std::ref(pool)
+            ));
+        }
+
+        for (auto& future : futures)
+            num_pos += future.get(); // Retrieve the result of each task
+    } else {
+        // Regular sequential execution
+        for (const Move& move : moves) {
+            Board tmp_board = b.make_move(move);
+            int n = move_generation_test(tmp_board, depth - 1, max_depth, pool);
+            if (depth == max_depth)
+                res << move << ": " << n << std::endl;
+            num_pos += n;
+        }
     }
+
     return num_pos;
 }
 
@@ -139,11 +161,12 @@ void perft(std::string pos) {
     std::cout << pos << std::endl;
     std::map<int, int> expected = pos2expected[pos];
     Board b = Board::setup_fen_position(pos);
+    ThreadPool pool(std::thread::hardware_concurrency());
 
     for (const auto& [depth, expected_n_moves] : expected) {
         std::cout << "Depth: " << depth << " " << std::flush;
         auto start = std::chrono::steady_clock::now();
-        int moves = move_generation_test(b, depth, depth);
+        int moves = move_generation_test(b, depth, depth, pool);
         auto end = std::chrono::steady_clock::now();
         auto elapsed =
             std::chrono::duration_cast<std::chrono::milliseconds>(end - start)

cpp/src/threadpool.hpp

@@ -0,0 +1,73 @@
+#pragma once
+
+#include <condition_variable>
+#include <functional>
+#include <future>
+#include <iostream>
+#include <queue>
+#include <thread>
+#include <vector>
+
+class ThreadPool {
+  public:
+    ThreadPool(size_t numThreads) {
+        for (size_t i = 0; i < numThreads; ++i) {
+            workers.emplace_back([this] {
+                while (true) {
+                    std::function<void()> task;
+                    {
+                        std::unique_lock<std::mutex> lock(queueMutex);
+                        condition.wait(lock, [this] {
+                            return stop || !tasks.empty();
+                        });
+                        if (stop && tasks.empty())
+                            return;
+                        task = std::move(tasks.front());
+                        tasks.pop();
+                    }
+                    task();
+                }
+            });
+        }
+    }
+
+    template <class F, class... Args>
+    auto enqueue(F&& f, Args&&... args)
+        -> std::future<typename std::invoke_result<F, Args...>::type> {
+        using return_type = typename std::invoke_result<F, Args...>::type;
+
+        auto task = std::make_shared<std::packaged_task<return_type()>>(
+            std::bind(std::forward<F>(f), std::forward<Args>(args)...)
+        );
+
+        std::future<return_type> res = task->get_future();
+        {
+            std::unique_lock<std::mutex> lock(queueMutex);
+            tasks.emplace([task]() { (*task)(); });
+        }
+        condition.notify_one();
+        return res;
+    }
+
+    void waitAll() {
+        std::unique_lock<std::mutex> lock(queueMutex);
+        condition.wait(lock, [this] { return tasks.empty(); });
+    }
+
+    ~ThreadPool() {
+        {
+            std::unique_lock<std::mutex> lock(queueMutex);
+            stop = true;
+        }
+        condition.notify_all();
+        for (std::thread& worker : workers)
+            worker.join();
+    }
+
+  private:
+    std::vector<std::thread> workers;
+    std::queue<std::function<void()>> tasks;
+    std::mutex queueMutex;
+    std::condition_variable condition;
+    bool stop = false;
+};