void chess_generate_init(void)
{
static int initialized = 0;
ChessSquare sq;
int dirs, d;
int slide, jump;
int file, rank;
int to_file, to_rank;
if (initialized)
return;
initialized = 1;
for (sq = CHESS_SQUARE_A1; sq <= CHESS_SQUARE_H8; sq++)
{
dirs = 0;
file = chess_square_file(sq);
rank = chess_square_rank(sq);
for (d = 0; d < 8; d++)
{
slide = slides_array[d];
to_file = file + chess_square_file(slide + 36) - 4;
to_rank = rank + chess_square_rank(slide + 36) - 4;
if (to_file >= CHESS_FILE_A && to_file <= CHESS_FILE_H
&& to_rank >= CHESS_RANK_1 && to_rank <= CHESS_RANK_8)
dirs |= dirs_array[d];
}
slide_dirs[sq] = dirs;
}
for (sq = CHESS_SQUARE_A1; sq <= CHESS_SQUARE_H8; sq++)
{
dirs = 0;
file = chess_square_file(sq);
rank = chess_square_rank(sq);
for (d = 0; d < 8; d++)
{
jump = jumps_array[d];
to_file = file + chess_square_file(jump + 36) - 4;
to_rank = rank + chess_square_rank(jump + 36) - 4;
if (to_file >= CHESS_FILE_A && to_file <= CHESS_FILE_H
&& to_rank >= CHESS_RANK_1 && to_rank <= CHESS_RANK_8)
dirs |= dirs_array[d];
}
jump_dirs[sq] = dirs;
}
}
void chess_position_undo_move(ChessPosition* position, ChessUnmove unmove)
{
ChessSquare from = chess_unmove_from(unmove);
ChessSquare to = chess_unmove_to(unmove);
ChessUnmoveCaptured captured = chess_unmove_captured(unmove);
ChessUnmoveEp ep = chess_unmove_ep(unmove);
ChessPiece piece;
ChessColor other = position->to_move;
ChessColor color = chess_color_other(other);
ChessFile file;
if (from == 0 && to == 0)
{
/* Null move */
piece = CHESS_PIECE_NONE;
}
else
{
if (chess_unmove_promotion(unmove))
piece = chess_piece_of_color(CHESS_PIECE_WHITE_PAWN, color);
else
piece = position->piece[to];
assert(color == chess_piece_color(piece));
/* Unmove the piece */
position->piece[from] = piece;
position->piece[to] = captured_piece(captured, other);
/* Handle castling */
if (piece == CHESS_PIECE_WHITE_KING && from == CHESS_SQUARE_E1)
{
if (to == CHESS_SQUARE_G1)
{
position->piece[CHESS_SQUARE_F1] = CHESS_PIECE_NONE;
position->piece[CHESS_SQUARE_H1] = CHESS_PIECE_WHITE_ROOK;
}
else if (to == CHESS_SQUARE_C1)
{
position->piece[CHESS_SQUARE_D1] = CHESS_PIECE_NONE;
position->piece[CHESS_SQUARE_A1] = CHESS_PIECE_WHITE_ROOK;
}
}
else if (piece == CHESS_PIECE_BLACK_KING && from == CHESS_SQUARE_E8)
{
if (to == CHESS_SQUARE_G8)
{
position->piece[CHESS_SQUARE_F8] = CHESS_PIECE_NONE;
position->piece[CHESS_SQUARE_H8] = CHESS_PIECE_BLACK_ROOK;
}
else if (to == CHESS_SQUARE_C8)
{
position->piece[CHESS_SQUARE_D8] = CHESS_PIECE_NONE;
position->piece[CHESS_SQUARE_A8] = CHESS_PIECE_BLACK_ROOK;
}
}
position->castle = chess_unmove_castle(unmove);
}
/* Handle ep */
if (ep == CHESS_UNMOVE_EP_NONE)
{
position->ep = CHESS_FILE_INVALID;
}
else if (ep == CHESS_UNMOVE_EP_CAPTURE)
{
assert(piece == CHESS_PIECE_WHITE_PAWN || piece == CHESS_PIECE_BLACK_PAWN);
/* Restore the captured pawn */
file = chess_square_file(to);
if (color == CHESS_COLOR_WHITE)
position->piece[chess_square_from_fr(file, CHESS_RANK_5)] = CHESS_PIECE_BLACK_PAWN;
else
position->piece[chess_square_from_fr(file, CHESS_RANK_4)] = CHESS_PIECE_WHITE_PAWN;
position->ep = file;
}
else
{
position->ep = ep - CHESS_UNMOVE_EP_AVAILABLE;
}
/* Update king positions */
if (piece == CHESS_PIECE_WHITE_KING)
position->wking = from;
else if (piece == CHESS_PIECE_BLACK_KING)
position->bking = from;
/* Update move counters */
position->fifty = chess_unmove_fifty(unmove);
position->to_move = color;
if (position->to_move == CHESS_COLOR_BLACK)
position->move_num--;
}
ChessUnmove chess_position_make_move(ChessPosition* position, ChessMove move)
{
ChessSquare from = chess_move_from(move);
ChessSquare to = chess_move_to(move);
ChessMovePromote promote = chess_move_promotes(move);
ChessPiece piece;
ChessColor color = position->to_move;
ChessUnmoveEp ep;
ChessUnmoveCaptured captured;
ChessCastleState castle = position->castle;
int fifty = position->fifty;
/* Move the piece */
if (move == CHESS_MOVE_NULL)
{
piece = CHESS_PIECE_NONE;
captured = CHESS_UNMOVE_CAPTURED_NONE;
}
else
{
piece = position->piece[from];
captured = capture_piece(position->piece[to]);
position->piece[from] = CHESS_PIECE_NONE;
if (promote == CHESS_MOVE_PROMOTE_NONE)
{
position->piece[to] = piece;
if (piece == CHESS_PIECE_WHITE_KING)
position->wking = to;
else if (piece == CHESS_PIECE_BLACK_KING)
position->bking = to;
}
else
{
position->piece[to] = promoted_piece(promote, color);
}
/* Handle castling */
if (piece == CHESS_PIECE_WHITE_KING && from == CHESS_SQUARE_E1)
{
if (to == CHESS_SQUARE_G1)
{
position->piece[CHESS_SQUARE_F1] = CHESS_PIECE_WHITE_ROOK;
position->piece[CHESS_SQUARE_H1] = CHESS_PIECE_NONE;
}
else if (to == CHESS_SQUARE_C1)
{
position->piece[CHESS_SQUARE_D1] = CHESS_PIECE_WHITE_ROOK;
position->piece[CHESS_SQUARE_A1] = CHESS_PIECE_NONE;
}
}
else if (piece == CHESS_PIECE_BLACK_KING && from == CHESS_SQUARE_E8)
{
if (to == CHESS_SQUARE_G8)
{
position->piece[CHESS_SQUARE_F8] = CHESS_PIECE_BLACK_ROOK;
position->piece[CHESS_SQUARE_H8] = CHESS_PIECE_NONE;
}
else if (to == CHESS_SQUARE_C8)
{
position->piece[CHESS_SQUARE_D8] = CHESS_PIECE_BLACK_ROOK;
position->piece[CHESS_SQUARE_A8] = CHESS_PIECE_NONE;
}
}
/* Check if castling availability was lost */
if (position->castle & (CHESS_CASTLE_STATE_WKQ))
{
if (from == CHESS_SQUARE_A1 || to == CHESS_SQUARE_A1)
position->castle &= ~CHESS_CASTLE_STATE_WQ;
if (from == CHESS_SQUARE_H1 || to == CHESS_SQUARE_H1)
position->castle &= ~CHESS_CASTLE_STATE_WK;
if (from == CHESS_SQUARE_E1 || to == CHESS_SQUARE_E1)
position->castle &= ~(CHESS_CASTLE_STATE_WKQ);
}
if (position->castle & (CHESS_CASTLE_STATE_BKQ))
{
if (from == CHESS_SQUARE_A8 || to == CHESS_SQUARE_A8)
position->castle &= ~CHESS_CASTLE_STATE_BQ;
if (from == CHESS_SQUARE_H8 || to == CHESS_SQUARE_H8)
position->castle &= ~CHESS_CASTLE_STATE_BK;
if (from == CHESS_SQUARE_E8 || to == CHESS_SQUARE_E8)
position->castle &= ~(CHESS_CASTLE_STATE_BKQ);
}
}
/* Handle ep */
if (position->ep == CHESS_FILE_INVALID)
{
ep = CHESS_UNMOVE_EP_NONE;
}
else
{
if (piece == CHESS_PIECE_WHITE_PAWN && to == chess_square_from_fr(position->ep, CHESS_RANK_6))
{
position->piece[chess_square_from_fr(position->ep, CHESS_RANK_5)] = CHESS_PIECE_NONE;
ep = CHESS_UNMOVE_EP_CAPTURE;
}
else if (piece == CHESS_PIECE_BLACK_PAWN && to == chess_square_from_fr(position->ep, CHESS_RANK_3))
{
position->piece[chess_square_from_fr(position->ep, CHESS_RANK_4)] = CHESS_PIECE_NONE;
ep = CHESS_UNMOVE_EP_CAPTURE;
}
else
{
ep = CHESS_UNMOVE_EP_AVAILABLE + position->ep;
}
}
/* Update ep on a double pawn move */
if (piece == CHESS_PIECE_WHITE_PAWN && to - from == 16)
position->ep = chess_square_file(to);
else if (piece == CHESS_PIECE_BLACK_PAWN && from - to == 16)
position->ep = chess_square_file(to);
else
position->ep = CHESS_FILE_INVALID;
/* Update fifty counter only if a reversible move was played */
if (piece == CHESS_PIECE_WHITE_PAWN || piece == CHESS_PIECE_BLACK_PAWN
|| captured != CHESS_UNMOVE_CAPTURED_NONE || castle != position->castle)
position->fifty = 0;
else
position->fifty++;
/* Update move counter */
position->to_move = chess_color_other(position->to_move);
if (position->to_move == CHESS_COLOR_WHITE)
position->move_num++;
return chess_unmove_make(from, to, captured,
promote != CHESS_MOVE_PROMOTE_NONE, ep, castle, fifty);
}
