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BadFish/src/movegen.cpp
Marco Costalba 84ce43498a Introduce generate_piece_blocking_evasions()
Start to simplify generate_evasions

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
2008-10-19 08:49:26 +01:00

930 lines
30 KiB
C++

/*
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 <http://www.gnu.org/licenses/>.
*/
////
//// Includes
////
#include <cassert>
#include "movegen.h"
////
//// Local definitions
////
namespace {
inline Bitboard forward_white(Bitboard b) { return b << 8; }
inline Bitboard forward_right_white(Bitboard b) { return b << 9; }
inline Bitboard forward_left_white(Bitboard b) { return b << 7; }
inline Bitboard forward_black(Bitboard b) { return b >> 8; }
inline Bitboard forward_right_black(Bitboard b) { return b >> 7; }
inline Bitboard forward_left_black(Bitboard b) { return b >> 9; }
struct PawnOffsets {
Bitboard Rank3BB, Rank8BB;
SquareDelta DELTA_N, DELTA_NE, DELTA_NW;
Color us, them;
typedef Bitboard (*Shift_fn)(Bitboard b);
Shift_fn forward, forward_left, forward_right;
};
const PawnOffsets WhitePawnOffsets = { Rank3BB, Rank8BB, DELTA_N, DELTA_NE, DELTA_NW, WHITE, BLACK,
&forward_white, forward_left_white, forward_right_white };
const PawnOffsets BlackPawnOffsets = { Rank6BB, Rank1BB, DELTA_S, DELTA_SE, DELTA_SW, BLACK, WHITE,
&forward_black, &forward_left_black, &forward_right_black };
int generate_pawn_captures(const PawnOffsets&, const Position&, MoveStack*);
int generate_pawn_noncaptures(const PawnOffsets&, const Position&, MoveStack*);
int generate_pawn_checks(const PawnOffsets&, const Position&, Bitboard, Square, MoveStack*, int);
int generate_piece_checks(PieceType, const Position&, Bitboard, Bitboard, Square, MoveStack*, int);
int generate_piece_moves(PieceType, const Position&, MoveStack*, Color, Bitboard);
int generate_castle_moves(const Position&, MoveStack*, Color);
int generate_piece_blocking_evasions(PieceType, const Position&, Bitboard, Bitboard, MoveStack*, int);
}
////
//// 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_pawn_captures(WhitePawnOffsets, pos, mlist);
else
n = generate_pawn_captures(BlackPawnOffsets, pos, mlist);
for (PieceType pce = KNIGHT; pce <= KING; pce++)
n += generate_piece_moves(pce, pos, mlist+n, 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_pawn_noncaptures(WhitePawnOffsets, pos, mlist);
else
n = generate_pawn_noncaptures(BlackPawnOffsets, pos, mlist);
for (PieceType pce = KNIGHT; pce <= KING; pce++)
n += generate_piece_moves(pce, pos, mlist+n, 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());
int n;
Color us = pos.side_to_move();
Square ksq = pos.king_square(opposite_color(us));
assert(pos.piece_on(ksq) == king_of_color(opposite_color(us)));
dc = pos.discovered_check_candidates(us);
// Pawn moves
if (us == WHITE)
n = generate_pawn_checks(WhitePawnOffsets, pos, dc, ksq, mlist, 0);
else
n = generate_pawn_checks(BlackPawnOffsets, pos, dc, ksq, mlist, 0);
// Pieces moves
Bitboard b = pos.knights(us);
if (b)
n = generate_piece_checks(KNIGHT, pos, b, dc, ksq, mlist, n);
b = pos.bishops(us);
if (b)
n = generate_piece_checks(BISHOP, pos, b, dc, ksq, mlist, n);
b = pos.rooks(us);
if (b)
n = generate_piece_checks(ROOK, pos, b, dc, ksq, mlist, n);
b = pos.queens(us);
if (b)
n = generate_piece_checks(QUEEN, pos, b, dc, ksq, mlist, n);
// King moves
Square from = pos.king_square(us);
if (bit_is_set(dc, from))
{
b = pos.king_attacks(from) & pos.empty_squares() & ~QueenPseudoAttacks[ksq];
while (b)
{
Square to = pop_1st_bit(&b);
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 = pos.side_to_move();
Color them = opposite_color(us);
Square ksq = pos.king_square(us);
Square from, to;
int n = 0;
assert(pos.piece_on(ksq) == king_of_color(us));
// Generate evasions for king
Bitboard b1 = pos.king_attacks(ksq) & ~pos.pieces_of_color(us);
Bitboard b2 = pos.occupied_squares();
clear_bit(&b2, ksq);
while (b1)
{
Square 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 (!( (bishop_attacks_bb(to, b2) & pos.bishops_and_queens(them))
|| (rook_attacks_bb(to, b2) & pos.rooks_and_queens(them))
|| (pos.knight_attacks(to) & pos.knights(them))
|| (pos.pawn_attacks(us, to) & pos.pawns(them))
|| (pos.king_attacks(to) & pos.kings(them))))
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).
Bitboard checkers = pos.checkers();
if (!(checkers & (checkers - 1))) // Only one bit set?
{
Square checksq = first_1(checkers);
assert(pos.color_of_piece_on(checksq) == them);
// Find pinned pieces
Bitboard not_pinned = ~pos.pinned_pieces(us);
// Generate captures of the checking piece
// Pawn captures
b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_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);
}
// Pieces captures
b1 = (pos.knight_attacks(checksq) & pos.knights(us))
| (pos.bishop_attacks(checksq) & pos.bishops_and_queens(us))
| (pos.rook_attacks(checksq) & pos.rooks_and_queens(us))
& not_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) & not_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) & not_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);
}
}
// Pieces moves
b1 = pos.knights(us) & not_pinned;
if (b1)
n = generate_piece_blocking_evasions(KNIGHT, pos, b1, blockSquares, mlist, n);
b1 = pos.bishops(us) & not_pinned;
if (b1)
n = generate_piece_blocking_evasions(BISHOP, pos, b1, blockSquares, mlist, n);
// Rook moves
b1 = pos.rooks(us) & not_pinned;
if (b1)
n = generate_piece_blocking_evasions(ROOK, pos, b1, blockSquares, mlist, n);
// Queen moves
b1 = pos.queens(us) & not_pinned;
if (b1)
n = generate_piece_blocking_evasions(QUEEN, pos, b1, blockSquares, mlist, n);
}
// 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 &= not_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))
||(rook_attacks_bb(ksq, b2) & pos.rooks_and_queens(them))))
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_pawn_captures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) {
Bitboard pawns = pos.pawns(ofs.us);
Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
Square sq;
int n = 0;
// Captures in the a1-h8 (a8-h1 for black) direction
Bitboard b1 = (ofs.forward_right)(pawns) & ~FileABB & enemyPieces;
// Capturing promotions
Bitboard b2 = b1 & ofs.Rank8BB;
while (b2)
{
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, QUEEN);
}
// Capturing non-promotions
b2 = b1 & ~ofs.Rank8BB;
while (b2)
{
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - ofs.DELTA_NE, sq);
}
// Captures in the h1-a8 (h8-a1 for black) direction
b1 = (ofs.forward_left)(pawns) & ~FileHBB & enemyPieces;
// Capturing promotions
b2 = b1 & ofs.Rank8BB;
while (b2)
{
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, QUEEN);
}
// Capturing non-promotions
b2 = b1 & ~ofs.Rank8BB;
while (b2)
{
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - ofs.DELTA_NW, sq);
}
// Non-capturing promotions
b1 = (ofs.forward)(pawns) & pos.empty_squares() & Rank8BB;
while (b1)
{
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, QUEEN);
}
// En passant captures
if (pos.ep_square() != SQ_NONE)
{
assert(ofs.us != WHITE || square_rank(pos.ep_square()) == RANK_6);
assert(ofs.us != BLACK || square_rank(pos.ep_square()) == RANK_3);
b1 = pawns & pos.pawn_attacks(ofs.them, 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_pawn_noncaptures(const PawnOffsets& ofs, const Position& pos, MoveStack* mlist) {
Bitboard pawns = pos.pawns(ofs.us);
Bitboard enemyPieces = pos.pieces_of_color(ofs.them);
Bitboard emptySquares = pos.empty_squares();
Bitboard b1, b2;
Square sq;
int n = 0;
// Underpromotion captures in the a1-h8 (a8-h1 for black) direction
b1 = ofs.forward_right(pawns) & ~FileABB & enemyPieces & ofs.Rank8BB;
while (b1)
{
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NE, sq, KNIGHT);
}
// Underpromotion captures in the h1-a8 (h8-a1 for black) direction
b1 = ofs.forward_left(pawns) & ~FileHBB & enemyPieces & ofs.Rank8BB;
while (b1)
{
sq = pop_1st_bit(&b1);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_NW, sq, KNIGHT);
}
// Single pawn pushes
b1 = ofs.forward(pawns) & emptySquares;
b2 = b1 & ofs.Rank8BB;
while (b2)
{
sq = pop_1st_bit(&b2);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, ROOK);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, BISHOP);
mlist[n++].move = make_promotion_move(sq - ofs.DELTA_N, sq, KNIGHT);
}
b2 = b1 & ~ofs.Rank8BB;
while (b2)
{
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - ofs.DELTA_N, sq);
}
// Double pawn pushes
b2 = (ofs.forward(b1 & ofs.Rank3BB)) & emptySquares;
while (b2)
{
sq = pop_1st_bit(&b2);
mlist[n++].move = make_move(sq - ofs.DELTA_N - ofs.DELTA_N, sq);
}
return n;
}
int generate_piece_moves(PieceType piece, const Position &pos, MoveStack *mlist,
Color side, Bitboard target) {
const Piece_attacks_fn mem_fn = piece_attacks_fn[piece];
Square from, to;
Bitboard b;
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_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;
}
int generate_piece_checks(PieceType pce, const Position& pos, Bitboard target,
Bitboard dc, Square ksq, MoveStack* mlist, int n) {
const Piece_attacks_fn mem_fn = piece_attacks_fn[pce];
// Discovered checks
Bitboard b = target & dc;
while (b)
{
Square from = pop_1st_bit(&b);
Bitboard bb = (pos.*mem_fn)(from) & pos.empty_squares();
while (bb)
{
Square to = pop_1st_bit(&bb);
mlist[n++].move = make_move(from, to);
}
}
// Direct checks
b = target & ~dc;
Bitboard checkSqs = (pos.*mem_fn)(ksq) & pos.empty_squares();
while (b)
{
Square from = pop_1st_bit(&b);
Bitboard bb = (pos.*mem_fn)(from) & checkSqs;
while (bb)
{
Square to = pop_1st_bit(&bb);
mlist[n++].move = make_move(from, to);
}
}
return n;
}
int generate_pawn_checks(const PawnOffsets& ofs, const Position& pos, Bitboard dc, Square ksq, MoveStack* mlist, int n)
{
// 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.
Bitboard empty = pos.empty_squares();
// Find all friendly pawns not on the enemy king's file
Bitboard b1 = pos.pawns(pos.side_to_move()) & ~file_bb(ksq), b2, b3;
// Discovered checks, single pawn pushes
b2 = b3 = (ofs.forward)(b1 & dc) & ~ofs.Rank8BB & empty;
while (b3)
{
Square to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - ofs.DELTA_N, to);
}
// Discovered checks, double pawn pushes
b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty;
while (b3)
{
Square to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
}
// Direct checks. These are possible only for pawns on neighboring files
// of the enemy king
b1 &= (~dc & neighboring_files_bb(ksq)); // FIXME why ~dc ??
// Direct checks, single pawn pushes
b2 = (ofs.forward)(b1) & empty;
b3 = b2 & pos.pawn_attacks(ofs.them, ksq);
while (b3)
{
Square to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - ofs.DELTA_N, to);
}
// Direct checks, double pawn pushes
b3 = (ofs.forward)(b2 & ofs.Rank3BB) & empty & pos.pawn_attacks(ofs.them, ksq);
while (b3)
{
Square to = pop_1st_bit(&b3);
mlist[n++].move = make_move(to - ofs.DELTA_N - ofs.DELTA_N, to);
}
return n;
}
int generate_piece_blocking_evasions(PieceType pce, const Position& pos, Bitboard b,
Bitboard blockSquares, MoveStack* mlist, int n) {
const Piece_attacks_fn mem_fn = piece_attacks_fn[pce];
while (b)
{
Square from = pop_1st_bit(&b);
Bitboard bb = (pos.*mem_fn)(from) & blockSquares;
while (bb)
{
Square to = pop_1st_bit(&bb);
mlist[n++].move = make_move(from, to);
}
}
return n;
}
}