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Introduce do_move_bb() to update bitboards after a move

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Avoid a clear_bit() + set_bit() sequence but update bitboards
with only one xor instructions.

This is faster and simplifies the code.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2009-05-21 10:55:23 +02:00
parent 595c7d75a2
commit 3e40bd0648
2 changed files with 22 additions and 15 deletions
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11
src/bitboard.h
View file

@ -205,6 +205,17 @@ inline void clear_bit(Bitboard *b, Square s) {
}
/// Functions used to update a bitboard after a move. This is faster
/// then calling a sequence of clear_bit() + set_bit()
inline Bitboard make_move_bb(Square from, Square to) {
return SetMaskBB[from] | SetMaskBB[to];
}
inline void do_move_bb(Bitboard *b, Bitboard move_bb) {
*b ^= move_bb;
}
/// rank_bb() and file_bb() gives a bitboard containing all squares on a given
/// file or rank. It is also possible to pass a square as input to these
/// functions.

26
src/position.cpp
View file

@ -741,12 +741,11 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
do_capture_move(st->capture, them, to);
// Move the piece
clear_bit(&(byColorBB[us]), from);
clear_bit(&(byTypeBB[piece]), from);
clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
set_bit(&(byColorBB[us]), to);
set_bit(&(byTypeBB[piece]), to);
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
Bitboard move_bb = make_move_bb(from, to);
do_move_bb(&(byColorBB[us]), move_bb);
do_move_bb(&(byTypeBB[piece]), move_bb);
do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
board[to] = board[from];
board[from] = EMPTY;
@ -838,6 +837,7 @@ void Position::do_capture_move(PieceType capture, Color them, Square to) {
// Remove captured piece
clear_bit(&(byColorBB[them]), to);
clear_bit(&(byTypeBB[capture]), to);
clear_bit(&(byTypeBB[0]), to);
// Update hash key
st->key ^= zobrist[them][capture][to];
@ -1170,17 +1170,13 @@ void Position::undo_move(Move m) {
assert(color_of_piece_on(to) == us);
// Put the piece back at the source square
Bitboard move_bb = make_move_bb(to, from);
piece = type_of_piece_on(to);
set_bit(&(byColorBB[us]), from);
set_bit(&(byTypeBB[piece]), from);
set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
do_move_bb(&(byColorBB[us]), move_bb);
do_move_bb(&(byTypeBB[piece]), move_bb);
do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares
board[from] = piece_of_color_and_type(us, piece);
// Clear the destination square
clear_bit(&(byColorBB[us]), to);
clear_bit(&(byTypeBB[piece]), to);
clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
// If the moving piece was a king, update the king square
if (piece == KING)
kingSquare[us] = from;
@ -1193,7 +1189,7 @@ void Position::undo_move(Move m) {
{
assert(st->capture != KING);
// Replace the captured piece
// Restore the captured piece
set_bit(&(byColorBB[them]), to);
set_bit(&(byTypeBB[st->capture]), to);
set_bit(&(byTypeBB[0]), to);