/*
Glaurung, a UCI chess playing engine.
Copyright (C) 2004-2008 Tord Romstad
Glaurung is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Glaurung is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
////
//// Includes
////
#include
#include "movegen.h"
////
//// Local definitions
////
namespace {
int generate_white_pawn_captures(const Position&, MoveStack*);
int generate_black_pawn_captures(const Position&, MoveStack*);
int generate_white_pawn_noncaptures(const Position&, MoveStack*);
int generate_black_pawn_noncaptures(const Position&, MoveStack*);
int generate_piece_moves(PieceType, const Position&, MoveStack*, Color side, Bitboard t);
int generate_king_moves(const Position&, MoveStack*, Square from, Bitboard t);
int generate_castle_moves(const Position&, MoveStack*, Color us);
}
////
//// Functions
////
/// generate_captures generates() all pseudo-legal captures and queen
/// promotions. The return value is the number of moves generated.
int generate_captures(const Position& pos, MoveStack* mlist) {
assert(pos.is_ok());
assert(!pos.is_check());
Color us = pos.side_to_move();
Bitboard target = pos.pieces_of_color(opposite_color(us));
int n;
if (us == WHITE)
n = generate_white_pawn_captures(pos, mlist);
else
n = generate_black_pawn_captures(pos, mlist);
for (PieceType pce = KNIGHT; pce < KING; pce++)
n += generate_piece_moves(pce, pos, mlist+n, us, target);
n += generate_king_moves(pos, mlist+n, pos.king_square(us), target);
return n;
}
/// generate_noncaptures() generates all pseudo-legal non-captures and
/// underpromotions. The return value is the number of moves generated.
int generate_noncaptures(const Position& pos, MoveStack *mlist) {
assert(pos.is_ok());
assert(!pos.is_check());
Color us = pos.side_to_move();
Bitboard target = pos.empty_squares();
int n;
if (us == WHITE)
n = generate_white_pawn_noncaptures(pos, mlist);
else
n = generate_black_pawn_noncaptures(pos, mlist);
for (PieceType pce = KNIGHT; pce < KING; pce++)
n += generate_piece_moves(pce, pos, mlist+n, us, target);
n += generate_king_moves(pos, mlist+n, pos.king_square(us), target);
n += generate_castle_moves(pos, mlist+n, us);
return n;
}
/// generate_checks() generates all pseudo-legal non-capturing, non-promoting
/// checks, except castling moves (will add this later). It returns the
/// number of generated moves.
int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
assert(pos.is_ok());
assert(!pos.is_check());
Color us, them;
Square ksq, from, to;
Bitboard empty, checkSqs, b1, b2, b3;
int n = 0;
us = pos.side_to_move();
them = opposite_color(us);
ksq = pos.king_square(them);
assert(pos.piece_on(ksq) == king_of_color(them));
dc = pos.discovered_check_candidates(us);
empty = pos.empty_squares();
// Pawn moves. This is somewhat messy, and we use separate code for white
// and black, because we can't shift by negative numbers in C/C++. :-(
if (us == WHITE)
{
// Pawn moves which give discovered check. This is possible only if the
// pawn is not on the same file as the enemy king, because we don't
// generate captures.
// Find all friendly pawns not on the enemy king's file:
b1 = pos.pawns(us) & ~file_bb(ksq);
// Discovered checks, single pawn pushes:
b2 = b3 = ((b1 & dc) << 8) & ~Rank8BB & empty;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_N, to);
}
// Discovered checks, double pawn pushes:
b3 = ((b2 & Rank3BB) << 8) & empty;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
}
// Direct checks. These are possible only for pawns on neighboring files
// of the enemy king:
b1 &= (~dc & neighboring_files_bb(ksq));
// Direct checks, single pawn pushes:
b2 = (b1 << 8) & empty;
b3 = b2 & pos.black_pawn_attacks(ksq);
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_N, to);
}
// Direct checks, double pawn pushes:
b3 = ((b2 & Rank3BB) << 8) & empty & pos.black_pawn_attacks(ksq);
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
}
}
else { // (us == BLACK)
// Pawn moves which give discovered check. This is possible only if the
// pawn is not on the same file as the enemy king, because we don't
// generate captures.
// Find all friendly pawns not on the enemy king's file:
b1 = pos.pawns(us) & ~file_bb(ksq);
// Discovered checks, single pawn pushes:
b2 = b3 = ((b1 & dc) >> 8) & ~Rank1BB & empty;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_S, to);
}
// Discovered checks, double pawn pushes:
b3 = ((b2 & Rank6BB) >> 8) & empty;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
}
// Direct checks. These are possible only for pawns on neighboring files
// of the enemy king:
b1 &= (~dc & neighboring_files_bb(ksq));
// Direct checks, single pawn pushes:
b2 = (b1 >> 8) & empty;
b3 = b2 & pos.white_pawn_attacks(ksq);
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_S, to);
}
// Direct checks, double pawn pushes:
b3 = ((b2 & Rank6BB) >> 8) & empty & pos.black_pawn_attacks(ksq);
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
}
}
// Knight moves
b1 = pos.knights(us);
if(b1) {
// Discovered knight checks:
b2 = b1 & dc;
while(b2) {
from = pop_1st_bit(&b2);
b3 = pos.knight_attacks(from) & empty;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(from, to);
}
}
// Direct knight checks:
b2 = b1 & ~dc;
checkSqs = pos.knight_attacks(ksq) & empty;
while(b2) {
from = pop_1st_bit(&b2);
b3 = pos.knight_attacks(from) & checkSqs;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(from, to);
}
}
}
// Bishop moves
b1 = pos.bishops(us);
if(b1) {
// Discovered bishop checks:
b2 = b1 & dc;
while(b2) {
from = pop_1st_bit(&b2);
b3 = pos.bishop_attacks(from) & empty;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(from, to);
}
}
// Direct bishop checks:
b2 = b1 & ~dc;
checkSqs = pos.bishop_attacks(ksq) & empty;
while(b2) {
from = pop_1st_bit(&b2);
b3 = pos.bishop_attacks(from) & checkSqs;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(from, to);
}
}
}
// Rook moves
b1 = pos.rooks(us);
if(b1) {
// Discovered rook checks:
b2 = b1 & dc;
while(b2) {
from = pop_1st_bit(&b2);
b3 = pos.rook_attacks(from) & empty;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(from, to);
}
}
// Direct rook checks:
b2 = b1 & ~dc;
checkSqs = pos.rook_attacks(ksq) & empty;
while(b2) {
from = pop_1st_bit(&b2);
b3 = pos.rook_attacks(from) & checkSqs;
while(b3) {
to = pop_1st_bit(&b3);
mlist[n++].move = make_move(from, to);
}
}
}
// Queen moves
b1 = pos.queens(us);
if(b1) {
// Discovered queen checks are impossible!
// Direct queen checks:
checkSqs = pos.queen_attacks(ksq) & empty;
while(b1) {
from = pop_1st_bit(&b1);
b2 = pos.queen_attacks(from) & checkSqs;
while(b2) {
to = pop_1st_bit(&b2);
mlist[n++].move = make_move(from, to);
}
}
}
// King moves
from = pos.king_square(us);
if(bit_is_set(dc, from)) {
b1 = pos.king_attacks(from) & empty & ~QueenPseudoAttacks[ksq];
while(b1) {
to = pop_1st_bit(&b1);
mlist[n++].move = make_move(from, to);
}
}
// TODO: Castling moves!
return n;
}
/// generate_evasions() generates all check evasions when the side to move is
/// in check. Unlike the other move generation functions, this one generates
/// only legal moves. It returns the number of generated moves. This
/// function is very ugly, and needs cleaning up some time later. FIXME
int generate_evasions(const Position &pos, MoveStack *mlist) {
assert(pos.is_ok());
assert(pos.is_check());
Color us, them;
Bitboard checkers = pos.checkers();
Bitboard pinned, b1, b2;
Square ksq, from, to;
int n = 0;
us = pos.side_to_move();
them = opposite_color(us);
ksq = pos.king_square(us);
assert(pos.piece_on(ksq) == king_of_color(us));
// Generate evasions for king:
b1 = pos.king_attacks(ksq) & ~pos.pieces_of_color(us);
b2 = pos.occupied_squares();
clear_bit(&b2, ksq);
while(b1) {
to = pop_1st_bit(&b1);
// Make sure to is not attacked by the other side. This is a bit ugly,
// because we can't use Position::square_is_attacked. Instead we use
// the low-level bishop_attacks_bb and rook_attacks_bb with the bitboard
// b2 (the occupied squares with the king removed) in order to test whether
// the king will remain in check on the destination square.
if(((pos.pawn_attacks(us, to) & pos.pawns(them)) == EmptyBoardBB) &&
((pos.knight_attacks(to) & pos.knights(them)) == EmptyBoardBB) &&
((pos.king_attacks(to) & pos.kings(them)) == EmptyBoardBB) &&
((bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them))
== EmptyBoardBB) &&
((rook_attacks_bb(to, b2) & pos.rooks_and_queens(them)) == EmptyBoardBB))
mlist[n++].move = make_move(ksq, to);
}
// Generate evasions for other pieces only if not double check. We use a
// simple bit twiddling hack here rather than calling count_1s in order to
// save some time (we know that pos.checkers() has at most two nonzero bits).
if(!(checkers & (checkers - 1))) {
Square checksq = first_1(checkers);
assert(pos.color_of_piece_on(checksq) == them);
// Find pinned pieces:
pinned = pos.pinned_pieces(us);
// Generate captures of the checking piece:
// Pawn captures:
b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
if(relative_rank(us, checksq) == RANK_8) {
mlist[n++].move = make_promotion_move(from, checksq, QUEEN);
mlist[n++].move = make_promotion_move(from, checksq, ROOK);
mlist[n++].move = make_promotion_move(from, checksq, BISHOP);
mlist[n++].move = make_promotion_move(from, checksq, KNIGHT);
}
else
mlist[n++].move = make_move(from, checksq);
}
// Knight captures:
b1 = pos.knight_attacks(checksq) & pos.knights(us) & ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
mlist[n++].move = make_move(from, checksq);
}
// Bishop and queen captures:
b1 = pos.bishop_attacks(checksq) & pos.bishops_and_queens(us)
& ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
mlist[n++].move = make_move(from, checksq);
}
// Rook and queen captures:
b1 = pos.rook_attacks(checksq) & pos.rooks_and_queens(us)
& ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
mlist[n++].move = make_move(from, checksq);
}
// Blocking check evasions are possible only if the checking piece is
// a slider:
if(checkers & pos.sliders()) {
Bitboard blockSquares = squares_between(checksq, ksq);
assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
// Pawn moves. Because a blocking evasion can never be a capture, we
// only generate pawn pushes. As so often, the code for pawns is a bit
// ugly, and uses separate clauses for white and black pawns. :-(
if(us == WHITE) {
// Find non-pinned pawns:
b1 = pos.pawns(WHITE) & ~pinned;
// Single pawn pushes. We don't have to AND with empty squares here,
// because the blocking squares will always be empty.
b2 = (b1 << 8) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
assert(pos.piece_on(to) == EMPTY);
if(square_rank(to) == RANK_8) {
mlist[n++].move = make_promotion_move(to - DELTA_N, to, QUEEN);
mlist[n++].move = make_promotion_move(to - DELTA_N, to, ROOK);
mlist[n++].move = make_promotion_move(to - DELTA_N, to, BISHOP);
mlist[n++].move = make_promotion_move(to - DELTA_N, to, KNIGHT);
}
else
mlist[n++].move = make_move(to - DELTA_N, to);
}
// Double pawn pushes.
b2 = (((b1 << 8) & pos.empty_squares() & Rank3BB) << 8) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
assert(pos.piece_on(to) == EMPTY);
assert(square_rank(to) == RANK_4);
mlist[n++].move = make_move(to - DELTA_N - DELTA_N, to);
}
}
else { // (us == BLACK)
// Find non-pinned pawns:
b1 = pos.pawns(BLACK) & ~pinned;
// Single pawn pushes. We don't have to AND with empty squares here,
// because the blocking squares will always be empty.
b2 = (b1 >> 8) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
assert(pos.piece_on(to) == EMPTY);
if(square_rank(to) == RANK_1) {
mlist[n++].move = make_promotion_move(to - DELTA_S, to, QUEEN);
mlist[n++].move = make_promotion_move(to - DELTA_S, to, ROOK);
mlist[n++].move = make_promotion_move(to - DELTA_S, to, BISHOP);
mlist[n++].move = make_promotion_move(to - DELTA_S, to, KNIGHT);
}
else
mlist[n++].move = make_move(to - DELTA_S, to);
}
// Double pawn pushes.
b2 = (((b1 >> 8) & pos.empty_squares() & Rank6BB) >> 8) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
assert(pos.piece_on(to) == EMPTY);
assert(square_rank(to) == RANK_5);
mlist[n++].move = make_move(to - DELTA_S - DELTA_S, to);
}
}
// Knight moves
b1 = pos.knights(us) & ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
b2 = pos.knight_attacks(from) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
mlist[n++].move = make_move(from, to);
}
}
// Bishop moves
b1 = pos.bishops(us) & ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
b2 = pos.bishop_attacks(from) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
mlist[n++].move = make_move(from, to);
}
}
// Rook moves
b1 = pos.rooks(us) & ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
b2 = pos.rook_attacks(from) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
mlist[n++].move = make_move(from, to);
}
}
// Queen moves
b1 = pos.queens(us) & ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
b2 = pos.queen_attacks(from) & blockSquares;
while(b2) {
to = pop_1st_bit(&b2);
mlist[n++].move = make_move(from, to);
}
}
}
// Finally, the ugly special case of en passant captures. An en passant
// capture can only be a check evasion if the check is not a discovered
// check. If pos.ep_square() is set, the last move made must have been
// a double pawn push. If, furthermore, the checking piece is a pawn,
// an en passant check evasion may be possible.
if(pos.ep_square() != SQ_NONE && (checkers & pos.pawns(them))) {
to = pos.ep_square();
b1 = pos.pawn_attacks(them, to) & pos.pawns(us);
assert(b1 != EmptyBoardBB);
b1 &= ~pinned;
while(b1) {
from = pop_1st_bit(&b1);
// Before generating the move, we have to make sure it is legal.
// This is somewhat tricky, because the two disappearing pawns may
// cause new "discovered checks". We test this by removing the
// two relevant bits from the occupied squares bitboard, and using
// the low-level bitboard functions for bishop and rook attacks.
b2 = pos.occupied_squares();
clear_bit(&b2, from);
clear_bit(&b2, checksq);
if(((bishop_attacks_bb(ksq, b2) & pos.bishops_and_queens(them))
== EmptyBoardBB) &&
((rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them))
== EmptyBoardBB))
mlist[n++].move = make_ep_move(from, to);
}
}
}
return n;
}
/// generate_legal_moves() computes a complete list of legal moves in the
/// current position. This function is not very fast, and should be used
/// only in situations where performance is unimportant. It wouldn't be
/// very hard to write an efficient legal move generator, but for the moment
/// we don't need it.
int generate_legal_moves(const Position& pos, MoveStack* mlist) {
assert(pos.is_ok());
if (pos.is_check())
return generate_evasions(pos, mlist);
// Generate pseudo-legal moves:
int n = generate_captures(pos, mlist);
n += generate_noncaptures(pos, mlist + n);
Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
// Remove illegal moves from the list:
for (int i = 0; i < n; i++)
if (!pos.move_is_legal(mlist[i].move, pinned))
mlist[i--].move = mlist[--n].move;
return n;
}
/// generate_move_if_legal() takes a position and a (not necessarily
/// pseudo-legal) move and a pinned pieces bitboard as input, and tests
/// whether the move is legal. If the move is legal, the move itself is
/// returned. If not, the function returns MOVE_NONE. This function must
/// only be used when the side to move is not in check.
Move generate_move_if_legal(const Position &pos, Move m, Bitboard pinned) {
assert(pos.is_ok());
assert(!pos.is_check());
assert(move_is_ok(m));
Color us = pos.side_to_move();
Color them = opposite_color(us);
Square from = move_from(m);
Piece pc = pos.piece_on(from);
// If the from square is not occupied by a piece belonging to the side to
// move, the move is obviously not legal.
if (color_of_piece(pc) != us)
return MOVE_NONE;
Square to = move_to(m);
// En passant moves
if (move_is_ep(m))
{
// The piece must be a pawn and destination square must be the
// en passant square.
if ( type_of_piece(pc) != PAWN
|| to != pos.ep_square())
return MOVE_NONE;
assert(pos.square_is_empty(to));
assert(pos.piece_on(to - pawn_push(us)) == pawn_of_color(them));
// The move is pseudo-legal. If it is legal, return it.
return (pos.move_is_legal(m) ? m : MOVE_NONE);
}
// Castling moves
if (move_is_short_castle(m))
{
// The piece must be a king and side to move must still have
// the right to castle kingside.
if ( type_of_piece(pc) != KING
||!pos.can_castle_kingside(us))
return MOVE_NONE;
assert(from == pos.king_square(us));
assert(to == pos.initial_kr_square(us));
assert(pos.piece_on(to) == rook_of_color(us));
Square g1 = relative_square(us, SQ_G1);
Square f1 = relative_square(us, SQ_F1);
Square s;
bool illegal = false;
// Check if any of the squares between king and rook
// is occupied or under attack.
for (s = Min(from, g1); s <= Max(from, g1); s++)
if ( (s != from && s != to && !pos.square_is_empty(s))
|| pos.square_is_attacked(s, them))
illegal = true;
// Check if any of the squares between king and rook
// is occupied.
for (s = Min(to, f1); s <= Max(to, f1); s++)
if (s != from && s != to && !pos.square_is_empty(s))
illegal = true;
return (!illegal ? m : MOVE_NONE);
}
if (move_is_long_castle(m))
{
// The piece must be a king and side to move must still have
// the right to castle kingside.
if ( type_of_piece(pc) != KING
||!pos.can_castle_queenside(us))
return MOVE_NONE;
assert(from == pos.king_square(us));
assert(to == pos.initial_qr_square(us));
assert(pos.piece_on(to) == rook_of_color(us));
Square c1 = relative_square(us, SQ_C1);
Square d1 = relative_square(us, SQ_D1);
Square s;
bool illegal = false;
for (s = Min(from, c1); s <= Max(from, c1); s++)
if( (s != from && s != to && !pos.square_is_empty(s))
|| pos.square_is_attacked(s, them))
illegal = true;
for (s = Min(to, d1); s <= Max(to, d1); s++)
if(s != from && s != to && !pos.square_is_empty(s))
illegal = true;
if ( square_file(to) == FILE_B
&& ( pos.piece_on(to + DELTA_W) == rook_of_color(them)
|| pos.piece_on(to + DELTA_W) == queen_of_color(them)))
illegal = true;
return (!illegal ? m : MOVE_NONE);
}
// Normal moves
// The destination square cannot be occupied by a friendly piece
if (pos.color_of_piece_on(to) == us)
return MOVE_NONE;
// Proceed according to the type of the moving piece.
if (type_of_piece(pc) == PAWN)
{
// If the destination square is on the 8/1th rank, the move must
// be a promotion.
if ( ( (square_rank(to) == RANK_8 && us == WHITE)
||(square_rank(to) == RANK_1 && us != WHITE))
&& !move_promotion(m))
return MOVE_NONE;
// Proceed according to the square delta between the source and
// destionation squares.
switch (to - from)
{
case DELTA_NW:
case DELTA_NE:
case DELTA_SW:
case DELTA_SE:
// Capture. The destination square must be occupied by an enemy
// piece (en passant captures was handled earlier).
if (pos.color_of_piece_on(to) != them)
return MOVE_NONE;
break;
case DELTA_N:
case DELTA_S:
// Pawn push. The destination square must be empty.
if (!pos.square_is_empty(to))
return MOVE_NONE;
break;
case DELTA_NN:
// Double white pawn push. The destination square must be on the fourth
// rank, and both the destination square and the square between the
// source and destination squares must be empty.
if ( square_rank(to) != RANK_4
|| !pos.square_is_empty(to)
|| !pos.square_is_empty(from + DELTA_N))
return MOVE_NONE;
break;
case DELTA_SS:
// Double black pawn push. The destination square must be on the fifth
// rank, and both the destination square and the square between the
// source and destination squares must be empty.
if ( square_rank(to) != RANK_5
|| !pos.square_is_empty(to)
|| !pos.square_is_empty(from + DELTA_S))
return MOVE_NONE;
break;
default:
return MOVE_NONE;
}
// The move is pseudo-legal. Return it if it is legal.
return (pos.move_is_legal(m) ? m : MOVE_NONE);
}
// Luckly we can handle all the other pieces in one go
return ( pos.piece_attacks_square(from, to)
&& pos.move_is_legal(m)
&& !move_promotion(m) ? m : MOVE_NONE);
}
namespace {
int generate_white_pawn_captures(const Position &pos, MoveStack *mlist) {
Bitboard pawns = pos.pawns(WHITE);
Bitboard enemyPieces = pos.pieces_of_color(BLACK);
Bitboard b1, b2;
Square sq;
int n = 0;
// Captures in the a1-h8 direction:
b1 = (pawns << 9) & ~FileABB & enemyPieces;
// Promotions:
b2 = b1 & Rank8BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, QUEEN);
}
// Non-promotions:
b2 = b1 & ~Rank8BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_NE, sq);
}
// Captures in the h1-a8 direction:
b1 = (pawns << 7) & ~FileHBB & enemyPieces;
// Promotions:
b2 = b1 & Rank8BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, QUEEN);
}
// Non-promotions:
b2 = b1 & ~Rank8BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_NW, sq);
}
// Non-capturing promotions:
b1 = (pawns << 8) & pos.empty_squares() & Rank8BB;
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, QUEEN);
}
// En passant captures:
if(pos.ep_square() != SQ_NONE) {
assert(square_rank(pos.ep_square()) == RANK_6);
b1 = pawns & pos.black_pawn_attacks(pos.ep_square());
assert(b1 != EmptyBoardBB);
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_ep_move(sq, pos.ep_square());
}
}
return n;
}
int generate_black_pawn_captures(const Position &pos, MoveStack *mlist) {
Bitboard pawns = pos.pawns(BLACK);
Bitboard enemyPieces = pos.pieces_of_color(WHITE);
Bitboard b1, b2;
Square sq;
int n = 0;
// Captures in the a8-h1 direction:
b1 = (pawns >> 7) & ~FileABB & enemyPieces;
// Promotions:
b2 = b1 & Rank1BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, QUEEN);
}
// Non-promotions:
b2 = b1 & ~Rank1BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_SE, sq);
}
// Captures in the h8-a1 direction:
b1 = (pawns >> 9) & ~FileHBB & enemyPieces;
// Promotions:
b2 = b1 & Rank1BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, QUEEN);
}
// Non-promotions:
b2 = b1 & ~Rank1BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_SW, sq);
}
// Non-capturing promotions:
b1 = (pawns >> 8) & pos.empty_squares() & Rank1BB;
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, QUEEN);
}
// En passant captures:
if(pos.ep_square() != SQ_NONE) {
assert(square_rank(pos.ep_square()) == RANK_3);
b1 = pawns & pos.white_pawn_attacks(pos.ep_square());
assert(b1 != EmptyBoardBB);
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_ep_move(sq, pos.ep_square());
}
}
return n;
}
int generate_white_pawn_noncaptures(const Position &pos, MoveStack *mlist) {
Bitboard pawns = pos.pawns(WHITE);
Bitboard enemyPieces = pos.pieces_of_color(BLACK);
Bitboard emptySquares = pos.empty_squares();
Bitboard b1, b2;
Square sq;
int n = 0;
// Underpromotion captures in the a1-h8 direction:
b1 = (pawns << 9) & ~FileABB & enemyPieces & Rank8BB;
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - DELTA_NE, sq, KNIGHT);
}
// Underpromotion captures in the h1-a8 direction:
b1 = (pawns << 7) & ~FileHBB & enemyPieces & Rank8BB;
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - DELTA_NW, sq, KNIGHT);
}
// Single pawn pushes:
b1 = (pawns << 8) & emptySquares;
b2 = b1 & Rank8BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - DELTA_N, sq, KNIGHT);
}
b2 = b1 & ~Rank8BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_N, sq);
}
// Double pawn pushes:
b2 = ((b1 & Rank3BB) << 8) & emptySquares;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_N - DELTA_N, sq);
}
return n;
}
int generate_black_pawn_noncaptures(const Position &pos, MoveStack *mlist) {
Bitboard pawns = pos.pawns(BLACK);
Bitboard enemyPieces = pos.pieces_of_color(WHITE);
Bitboard emptySquares = pos.empty_squares();
Bitboard b1, b2;
Square sq;
int n = 0;
// Underpromotion captures in the a8-h1 direction:
b1 = (pawns >> 7) & ~FileABB & enemyPieces & Rank1BB;
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - DELTA_SE, sq, KNIGHT);
}
// Underpromotion captures in the h8-a1 direction:
b1 = (pawns >> 9) & ~FileHBB & enemyPieces & Rank1BB;
while(b1) {
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - DELTA_SW, sq, KNIGHT);
}
// Single pawn pushes:
b1 = (pawns >> 8) & emptySquares;
b2 = b1 & Rank1BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - DELTA_S, sq, KNIGHT);
}
b2 = b1 & ~Rank1BB;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_S, sq);
}
// Double pawn pushes:
b2 = ((b1 & Rank6BB) >> 8) & emptySquares;
while(b2) {
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - DELTA_S - DELTA_S, sq);
}
return n;
}
int generate_piece_moves(PieceType piece, const Position &pos, MoveStack *mlist,
Color side, Bitboard target) {
Square from, to;
Bitboard b;
Piece_attacks_fn mem_fn = piece_attacks_fn[piece];
int n = 0;
for (int i = 0; i < pos.piece_count(side, piece); i++)
{
from = pos.piece_list(side, piece, i);
b = (pos.*mem_fn)(from) & target;
while (b)
{
to = pop_1st_bit(&b);
mlist[n++].move = make_move(from, to);
}
}
return n;
}
int generate_king_moves(const Position &pos, MoveStack *mlist,
Square from, Bitboard target) {
Square to;
Bitboard b;
int n = 0;
b = pos.king_attacks(from) & target;
while(b) {
to = pop_1st_bit(&b);
mlist[n++].move = make_move(from, to);
}
return n;
}
int generate_castle_moves(const Position &pos, MoveStack *mlist, Color us) {
int n = 0;
if(pos.can_castle(us)) {
Color them = opposite_color(us);
Square ksq = pos.king_square(us);
assert(pos.piece_on(ksq) == king_of_color(us));
if(pos.can_castle_kingside(us)) {
Square rsq = pos.initial_kr_square(us);
Square g1 = relative_square(us, SQ_G1);
Square f1 = relative_square(us, SQ_F1);
Square s;
bool illegal = false;
assert(pos.piece_on(rsq) == rook_of_color(us));
for(s = Min(ksq, g1); s <= Max(ksq, g1); s++)
if((s != ksq && s != rsq && pos.square_is_occupied(s))
|| pos.square_is_attacked(s, them))
illegal = true;
for(s = Min(rsq, f1); s <= Max(rsq, f1); s++)
if(s != ksq && s != rsq && pos.square_is_occupied(s))
illegal = true;
if(!illegal)
mlist[n++].move = make_castle_move(ksq, rsq);
}
if(pos.can_castle_queenside(us)) {
Square rsq = pos.initial_qr_square(us);
Square c1 = relative_square(us, SQ_C1);
Square d1 = relative_square(us, SQ_D1);
Square s;
bool illegal = false;
assert(pos.piece_on(rsq) == rook_of_color(us));
for(s = Min(ksq, c1); s <= Max(ksq, c1); s++)
if((s != ksq && s != rsq && pos.square_is_occupied(s))
|| pos.square_is_attacked(s, them))
illegal = true;
for(s = Min(rsq, d1); s <= Max(rsq, d1); s++)
if(s != ksq && s != rsq && pos.square_is_occupied(s))
illegal = true;
if(square_file(rsq) == FILE_B &&
(pos.piece_on(relative_square(us, SQ_A1)) == rook_of_color(them) ||
pos.piece_on(relative_square(us, SQ_A1)) == queen_of_color(them)))
illegal = true;
if(!illegal)
mlist[n++].move = make_castle_move(ksq, rsq);
}
}
return n;
}
}