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refactor: cleanup movegen code
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@Disservin
Disservin committed Oct 24, 2024
1 parent 0ee8ace commit 6cf732c
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Showing 4 changed files with 67 additions and 60 deletions.
63 changes: 33 additions & 30 deletions include/chess.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ THIS FILE IS AUTO GENERATED DO NOT CHANGE MANUALLY.
Source: https://github.com/Disservin/chess-library
VERSION: 0.6.75
VERSION: 0.6.76
*/

#ifndef CHESS_HPP
Expand Down Expand Up @@ -1458,7 +1458,7 @@ class movegen {

// Generate the checkmask. Returns a bitboard where the attacker path between the king and enemy piece is set.
template <Color::underlying c>
[[nodiscard]] static Bitboard checkMask(const Board &board, Square sq, int &double_check);
[[nodiscard]] static std::pair<Bitboard, int> checkMask(const Board &board, Square sq);

// Generate the pin mask for horizontal and vertical pins. Returns a bitboard where the ray between the king and the
// pinner is set.
Expand Down Expand Up @@ -3319,26 +3319,26 @@ inline auto movegen::init_squares_between() {
}

template <Color::underlying c>
[[nodiscard]] inline Bitboard movegen::checkMask(const Board &board, Square sq, int &double_check) {
double_check = 0;

[[nodiscard]] inline std::pair<Bitboard, int> movegen::checkMask(const Board &board, Square sq) {
const auto opp_knight = board.pieces(PieceType::KNIGHT, ~c);
const auto opp_bishop = board.pieces(PieceType::BISHOP, ~c);
const auto opp_rook = board.pieces(PieceType::ROOK, ~c);
const auto opp_queen = board.pieces(PieceType::QUEEN, ~c);

const auto opp_pawns = board.pieces(PieceType::PAWN, ~c);

int checks = 0;

// check for knight checks
Bitboard knight_attacks = attacks::knight(sq) & opp_knight;
double_check += bool(knight_attacks);
checks += bool(knight_attacks);

Bitboard mask = knight_attacks;

// check for pawn checks
Bitboard pawn_attacks = attacks::pawn(board.sideToMove(), sq) & opp_pawns;
mask |= pawn_attacks;
double_check += bool(pawn_attacks);
checks += bool(pawn_attacks);

// check for bishop checks
Bitboard bishop_attacks = attacks::bishop(sq, board.occ()) & (opp_bishop | opp_queen);
Expand All @@ -3347,27 +3347,28 @@ template <Color::underlying c>
const auto index = bishop_attacks.lsb();

mask |= SQUARES_BETWEEN_BB[sq.index()][index] | Bitboard::fromSquare(index);
double_check++;
checks++;
}

Bitboard rook_attacks = attacks::rook(sq, board.occ()) & (opp_rook | opp_queen);

if (rook_attacks) {
if (rook_attacks.count() > 1) {
double_check = 2;
return mask;
checks = 2;
return {mask, checks};
}

const auto index = rook_attacks.lsb();

mask |= SQUARES_BETWEEN_BB[sq.index()][index] | Bitboard::fromSquare(index);
double_check++;
checks++;
}

if (!mask) {
return constants::DEFAULT_CHECKMASK;
return {constants::DEFAULT_CHECKMASK, checks};
}

return mask;
return {mask, checks};
}

template <Color::underlying c>
Expand Down Expand Up @@ -3553,8 +3554,11 @@ inline void movegen::generatePawnMoves(const Board &board, Movelist &moves, Bitb
moves.add(Move::make<Move::NORMAL>(index + DOWN + DOWN, index));
}

if constexpr (mt == MoveGenType::QUIET) return;

const Square ep = board.enpassantSq();
if (mt != MoveGenType::QUIET && ep != Square::underlying::NO_SQ) {

if (ep != Square::underlying::NO_SQ) {
auto m = generateEPMove(board, checkmask, pin_d, pawns_lr, ep, c);

for (const auto &move : m) {
Expand Down Expand Up @@ -3657,6 +3661,8 @@ template <Color::underlying c, movegen::MoveGenType mt>
[[nodiscard]] inline Bitboard movegen::generateCastleMoves(const Board &board, Square sq, Bitboard seen,
Bitboard pin_hv) {
if constexpr (mt == MoveGenType::CAPTURE) return 0ull;
if (!Square::back_rank(sq, c) || !board.castlingRights().has(c)) return 0ull;

const auto rights = board.castlingRights();

Bitboard moves = 0ull;
Expand Down Expand Up @@ -3709,19 +3715,17 @@ inline void movegen::legalmoves(Movelist &movelist, const Board &board, int piec
*/
auto king_sq = board.kingSq(c);

int double_check = 0;

Bitboard occ_us = board.us(c);
Bitboard occ_opp = board.us(~c);
Bitboard occ_all = occ_us | occ_opp;

Bitboard opp_empty = ~occ_us;

Bitboard check_mask = checkMask<c>(board, king_sq, double_check);
Bitboard pin_hv = pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
Bitboard pin_d = pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);
const auto [checkmask, checks] = checkMask<c>(board, king_sq);
const auto pin_hv = pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
const auto pin_d = pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);

assert(double_check <= 2);
assert(checks <= 2);

// Moves have to be on the checkmask
Bitboard movable_square;
Expand All @@ -3740,24 +3744,24 @@ inline void movegen::legalmoves(Movelist &movelist, const Board &board, int piec
whileBitboardAdd(movelist, Bitboard::fromSquare(king_sq),
[&](Square sq) { return generateKingMoves(sq, seen, movable_square); });

if (check_mask == constants::DEFAULT_CHECKMASK && Square::back_rank(king_sq, c) &&
board.castlingRights().has(c)) {
if (checks == 0) {
Bitboard moves_bb = generateCastleMoves<c, mt>(board, king_sq, seen, pin_hv);

while (moves_bb) {
Square to = moves_bb.pop();
movelist.add(Move::make<Move::CASTLING>(king_sq, to));
}
}
}

movable_square &= check_mask;
movable_square &= checkmask;

// Early return for double check as described earlier
if (double_check == 2) return;
if (checks == 2) return;

// Add the moves to the movelist.
if (pieces & PieceGenType::PAWN) {
generatePawnMoves<c, mt>(board, movelist, pin_d, pin_hv, check_mask, occ_opp);
generatePawnMoves<c, mt>(board, movelist, pin_d, pin_hv, checkmask, occ_opp);
}

if (pieces & PieceGenType::KNIGHT) {
Expand Down Expand Up @@ -3804,16 +3808,15 @@ inline void movegen::legalmoves(Movelist &movelist, const Board &board, int piec

template <Color::underlying c>
inline bool movegen::isEpSquareValid(const Board &board, Square ep) {
const auto stm = board.sideToMove();
int double_check = 0;
const auto stm = board.sideToMove();

Bitboard occ_us = board.us(stm);
Bitboard occ_opp = board.us(~stm);
auto king_sq = board.kingSq(stm);

Bitboard checkmask = movegen::checkMask<c>(board, king_sq, double_check);
Bitboard pin_hv = movegen::pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
Bitboard pin_d = movegen::pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);
const auto [checkmask, checks] = movegen::checkMask<c>(board, king_sq);
const auto pin_hv = movegen::pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
const auto pin_d = movegen::pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);

const auto pawns = board.pieces(PieceType::PAWN, stm);
const auto pawns_lr = pawns & ~pin_hv;
Expand Down
2 changes: 1 addition & 1 deletion src/include.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ THIS FILE IS AUTO GENERATED DO NOT CHANGE MANUALLY.
Source: https://github.com/Disservin/chess-library
VERSION: 0.6.75
VERSION: 0.6.76
*/

#ifndef CHESS_HPP
Expand Down
59 changes: 31 additions & 28 deletions src/movegen.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,26 +30,26 @@ inline auto movegen::init_squares_between() {
}

template <Color::underlying c>
[[nodiscard]] inline Bitboard movegen::checkMask(const Board &board, Square sq, int &double_check) {
double_check = 0;

[[nodiscard]] inline std::pair<Bitboard, int> movegen::checkMask(const Board &board, Square sq) {
const auto opp_knight = board.pieces(PieceType::KNIGHT, ~c);
const auto opp_bishop = board.pieces(PieceType::BISHOP, ~c);
const auto opp_rook = board.pieces(PieceType::ROOK, ~c);
const auto opp_queen = board.pieces(PieceType::QUEEN, ~c);

const auto opp_pawns = board.pieces(PieceType::PAWN, ~c);

int checks = 0;

// check for knight checks
Bitboard knight_attacks = attacks::knight(sq) & opp_knight;
double_check += bool(knight_attacks);
checks += bool(knight_attacks);

Bitboard mask = knight_attacks;

// check for pawn checks
Bitboard pawn_attacks = attacks::pawn(board.sideToMove(), sq) & opp_pawns;
mask |= pawn_attacks;
double_check += bool(pawn_attacks);
checks += bool(pawn_attacks);

// check for bishop checks
Bitboard bishop_attacks = attacks::bishop(sq, board.occ()) & (opp_bishop | opp_queen);
Expand All @@ -58,27 +58,28 @@ template <Color::underlying c>
const auto index = bishop_attacks.lsb();

mask |= SQUARES_BETWEEN_BB[sq.index()][index] | Bitboard::fromSquare(index);
double_check++;
checks++;
}

Bitboard rook_attacks = attacks::rook(sq, board.occ()) & (opp_rook | opp_queen);

if (rook_attacks) {
if (rook_attacks.count() > 1) {
double_check = 2;
return mask;
checks = 2;
return {mask, checks};
}

const auto index = rook_attacks.lsb();

mask |= SQUARES_BETWEEN_BB[sq.index()][index] | Bitboard::fromSquare(index);
double_check++;
checks++;
}

if (!mask) {
return constants::DEFAULT_CHECKMASK;
return {constants::DEFAULT_CHECKMASK, checks};
}

return mask;
return {mask, checks};
}

template <Color::underlying c>
Expand Down Expand Up @@ -264,8 +265,11 @@ inline void movegen::generatePawnMoves(const Board &board, Movelist &moves, Bitb
moves.add(Move::make<Move::NORMAL>(index + DOWN + DOWN, index));
}

if constexpr (mt == MoveGenType::QUIET) return;

const Square ep = board.enpassantSq();
if (mt != MoveGenType::QUIET && ep != Square::underlying::NO_SQ) {

if (ep != Square::underlying::NO_SQ) {
auto m = generateEPMove(board, checkmask, pin_d, pawns_lr, ep, c);

for (const auto &move : m) {
Expand Down Expand Up @@ -368,6 +372,8 @@ template <Color::underlying c, movegen::MoveGenType mt>
[[nodiscard]] inline Bitboard movegen::generateCastleMoves(const Board &board, Square sq, Bitboard seen,
Bitboard pin_hv) {
if constexpr (mt == MoveGenType::CAPTURE) return 0ull;
if (!Square::back_rank(sq, c) || !board.castlingRights().has(c)) return 0ull;

const auto rights = board.castlingRights();

Bitboard moves = 0ull;
Expand Down Expand Up @@ -420,19 +426,17 @@ inline void movegen::legalmoves(Movelist &movelist, const Board &board, int piec
*/
auto king_sq = board.kingSq(c);

int double_check = 0;

Bitboard occ_us = board.us(c);
Bitboard occ_opp = board.us(~c);
Bitboard occ_all = occ_us | occ_opp;

Bitboard opp_empty = ~occ_us;

Bitboard check_mask = checkMask<c>(board, king_sq, double_check);
Bitboard pin_hv = pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
Bitboard pin_d = pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);
const auto [checkmask, checks] = checkMask<c>(board, king_sq);
const auto pin_hv = pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
const auto pin_d = pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);

assert(double_check <= 2);
assert(checks <= 2);

// Moves have to be on the checkmask
Bitboard movable_square;
Expand All @@ -451,24 +455,24 @@ inline void movegen::legalmoves(Movelist &movelist, const Board &board, int piec
whileBitboardAdd(movelist, Bitboard::fromSquare(king_sq),
[&](Square sq) { return generateKingMoves(sq, seen, movable_square); });

if (check_mask == constants::DEFAULT_CHECKMASK && Square::back_rank(king_sq, c) &&
board.castlingRights().has(c)) {
if (checks == 0) {
Bitboard moves_bb = generateCastleMoves<c, mt>(board, king_sq, seen, pin_hv);

while (moves_bb) {
Square to = moves_bb.pop();
movelist.add(Move::make<Move::CASTLING>(king_sq, to));
}
}
}

movable_square &= check_mask;
movable_square &= checkmask;

// Early return for double check as described earlier
if (double_check == 2) return;
if (checks == 2) return;

// Add the moves to the movelist.
if (pieces & PieceGenType::PAWN) {
generatePawnMoves<c, mt>(board, movelist, pin_d, pin_hv, check_mask, occ_opp);
generatePawnMoves<c, mt>(board, movelist, pin_d, pin_hv, checkmask, occ_opp);
}

if (pieces & PieceGenType::KNIGHT) {
Expand Down Expand Up @@ -515,16 +519,15 @@ inline void movegen::legalmoves(Movelist &movelist, const Board &board, int piec

template <Color::underlying c>
inline bool movegen::isEpSquareValid(const Board &board, Square ep) {
const auto stm = board.sideToMove();
int double_check = 0;
const auto stm = board.sideToMove();

Bitboard occ_us = board.us(stm);
Bitboard occ_opp = board.us(~stm);
auto king_sq = board.kingSq(stm);

Bitboard checkmask = movegen::checkMask<c>(board, king_sq, double_check);
Bitboard pin_hv = movegen::pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
Bitboard pin_d = movegen::pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);
const auto [checkmask, checks] = movegen::checkMask<c>(board, king_sq);
const auto pin_hv = movegen::pinMaskRooks<c>(board, king_sq, occ_opp, occ_us);
const auto pin_d = movegen::pinMaskBishops<c>(board, king_sq, occ_opp, occ_us);

const auto pawns = board.pieces(PieceType::PAWN, stm);
const auto pawns_lr = pawns & ~pin_hv;
Expand Down
3 changes: 2 additions & 1 deletion src/movegen_fwd.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

#include <array>
#include <cstdint>
#include <utility>

#include "movelist.hpp"

Expand Down Expand Up @@ -39,7 +40,7 @@ class movegen {

// Generate the checkmask. Returns a bitboard where the attacker path between the king and enemy piece is set.
template <Color::underlying c>
[[nodiscard]] static Bitboard checkMask(const Board &board, Square sq, int &double_check);
[[nodiscard]] static std::pair<Bitboard, int> checkMask(const Board &board, Square sq);

// Generate the pin mask for horizontal and vertical pins. Returns a bitboard where the ray between the king and the
// pinner is set.
Expand Down

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