void board_from_fen(board_t * board, const char fen[]) {
int pos;
int file, rank, sq;
int c;
int i, len;
int piece;
int pawn;
ASSERT(board!=NULL);
ASSERT(fen!=NULL);
board_clear(board);
pos = 0;
c = fen[pos];
// piece placement
for (rank = Rank8; rank >= Rank1; rank--) {
for (file = FileA; file <= FileH;) {
if (c >= '1' && c <= '8') { // empty square(s)
len = c - '0';
for (i = 0; i < len; i++) {
if (file > FileH) my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
board->square[SQUARE_MAKE(file,rank)] = Empty;
file++;
}
} else { // piece
piece = piece_from_char(c);
if (piece == PieceNone256) my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
board->square[SQUARE_MAKE(file,rank)] = piece;
file++;
}
c = fen[++pos];
}
if (rank > Rank1) {
if (c != '/') my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
c = fen[++pos];
}
}
// active colour
if (c != ' ') my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
c = fen[++pos];
switch (c) {
case 'w':
board->turn = White;
break;
case 'b':
board->turn = Black;
break;
default:
my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
break;
}
c = fen[++pos];
// castling
if (c != ' ') my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
c = fen[++pos];
board->flags = FlagsNone;
if (c == '-') { // no castling rights
c = fen[++pos];
} else {
if (c == 'K') {
if (board->square[E1] == WK && board->square[H1] == WR) board->flags |= FlagsWhiteKingCastle;
c = fen[++pos];
}
if (c == 'Q') {
if (board->square[E1] == WK && board->square[A1] == WR) board->flags |= FlagsWhiteQueenCastle;
c = fen[++pos];
}
if (c == 'k') {
if (board->square[E8] == BK && board->square[H8] == BR) board->flags |= FlagsBlackKingCastle;
c = fen[++pos];
}
if (c == 'q') {
if (board->square[E8] == BK && board->square[A8] == BR) board->flags |= FlagsBlackQueenCastle;
c = fen[++pos];
}
}
// en-passant
if (c != ' ') my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
c = fen[++pos];
if (c == '-') { // no en-passant
sq = SquareNone;
c = fen[++pos];
} else {
if (c < 'a' || c > 'h') my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
file = file_from_char(c);
c = fen[++pos];
if (c != (COLOUR_IS_WHITE(board->turn) ? '6' : '3')) my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
rank = rank_from_char(c);
c = fen[++pos];
sq = SQUARE_MAKE(file,rank);
pawn = SQUARE_EP_DUAL(sq);
if (board->square[sq] != Empty
|| board->square[pawn] != PAWN_MAKE(COLOUR_OPP(board->turn))
|| (board->square[pawn-1] != PAWN_MAKE(board->turn)
&& board->square[pawn+1] != PAWN_MAKE(board->turn))) {
sq = SquareNone;
}
}
board->ep_square = sq;
// halfmove clock
board->ply_nb = 0;
if (c != ' ') {
if (!Strict) goto update;
my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
}
c = fen[++pos];
if (!isdigit(c)) {
if (!Strict) goto update;
my_fatal("board_from_fen(): bad FEN (pos=%d)\n",pos);
}
board->ply_nb = atoi(&fen[pos]);
// board update
update:
board_init_list(board);
}
static bool add_pawn_captures(list_t * list, const board_t * board, int to, bool legal, bool stop) {
int me;
int inc;
int pawn;
int from;
ASSERT(list!=NULL);
ASSERT(board!=NULL);
ASSERT(SQUARE_IS_OK(to));
ASSERT(legal==true||legal==false);
ASSERT(stop==true||stop==false);
ASSERT(COLOUR_IS(board->square[to],COLOUR_OPP(board->turn)));
me = board->turn;
inc = PAWN_MOVE_INC(me);
pawn = PAWN_MAKE(me);
from = to - (inc-1);
if (board->square[from] == pawn) {
if (!legal || !is_pinned(board,from,me)) {
if (stop) return true;
add_pawn_move(list,from,to);
}
}
from = to - (inc+1);
if (board->square[from] == pawn) {
if (!legal || !is_pinned(board,from,me)) {
if (stop) return true;
add_pawn_move(list,from,to);
}
}
if (board->ep_square != SquareNone
&& to == SQUARE_EP_DUAL(board->ep_square)) {
ASSERT(PAWN_RANK(to,me)==Rank5);
ASSERT(PIECE_IS_PAWN(board->square[to]));
to = board->ep_square;
ASSERT(PAWN_RANK(to,me)==Rank6);
ASSERT(board->square[to]==Empty);
from = to - (inc-1);
if (board->square[from] == pawn) {
if (!legal || !is_pinned(board,from,me)) {
if (stop) return true;
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE_FLAGS(from,to,MoveEnPassant));
}
}
from = to - (inc+1);
if (board->square[from] == pawn) {
if (!legal || !is_pinned(board,from,me)) {
if (stop) return true;
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE_FLAGS(from,to,MoveEnPassant));
}
}
}
return false;
}
int see_move(int move, const board_t * board) {
int att, def;
int from, to;
alists_t alists[1];
int value, piece_value;
int piece, capture;
alist_t * alist;
int pos;
ASSERT(move_is_ok(move));
ASSERT(board!=NULL);
// init
from = MOVE_FROM(move);
to = MOVE_TO(move);
// move the piece
piece_value = 0;
piece = board->square[from];
ASSERT(piece_is_ok(piece));
att = PIECE_COLOUR(piece);
def = COLOUR_OPP(att);
// promote
if (MOVE_IS_PROMOTE(move)) {
ASSERT(PIECE_IS_PAWN(piece));
piece = move_promote(move);
ASSERT(piece_is_ok(piece));
ASSERT(COLOUR_IS(piece,att));
}
piece_value += VALUE_PIECE(piece);
// clear attacker lists
ALIST_CLEAR(alists->alist[Black]);
ALIST_CLEAR(alists->alist[White]);
// find hidden attackers
alists_hidden(alists,board,from,to);
// capture the piece
value = 0;
capture = board->square[to];
if (capture != Empty) {
ASSERT(piece_is_ok(capture));
ASSERT(COLOUR_IS(capture,def));
value += VALUE_PIECE(capture);
}
// promote
if (MOVE_IS_PROMOTE(move)) {
value += VALUE_PIECE(piece) - ValuePawn;
}
// en-passant
if (MOVE_IS_EN_PASSANT(move)) {
ASSERT(value==0);
ASSERT(PIECE_IS_PAWN(board->square[SQUARE_EP_DUAL(to)]));
value += ValuePawn;
alists_hidden(alists,board,SQUARE_EP_DUAL(to),to);
}
// build defender list
alist = alists->alist[def];
alist_build(alist,board,to,def);
if (alist->size == 0) return value; // no defender => stop SEE
// build attacker list
alist = alists->alist[att];
alist_build(alist,board,to,att);
// remove the moved piece (if it's an attacker)
for (pos = 0; pos < alist->size && alist->square[pos] != from; pos++)
;
if (pos < alist->size) alist_remove(alist,pos);
// SEE search
value -= see_rec(alists,board,def,to,piece_value);
return value;
}
void move_do(board_t * board, int move, undo_t * undo) {
int me, opp;
int from, to;
int piece, pos, capture;
int old_flags, new_flags;
int delta;
int sq;
int pawn, rook;
ASSERT(board!=NULL);
ASSERT(move_is_ok(move));
ASSERT(undo!=NULL);
ASSERT(board_is_legal(board));
// initialise undo
undo->capture = false;
undo->turn = board->turn;
undo->flags = board->flags;
undo->ep_square = board->ep_square;
undo->ply_nb = board->ply_nb;
undo->cap_sq = board->cap_sq;
undo->opening = board->opening;
undo->endgame = board->endgame;
undo->key = board->key;
undo->pawn_key = board->pawn_key;
undo->material_key = board->material_key;
// init
me = board->turn;
opp = COLOUR_OPP(me);
from = MOVE_FROM(move);
to = MOVE_TO(move);
piece = board->square[from];
ASSERT(COLOUR_IS(piece,me));
// update key stack
ASSERT(board->sp<StackSize);
board->stack[board->sp++] = board->key;
// update turn
board->turn = opp;
board->key ^= RANDOM_64(RandomTurn);
// update castling rights
old_flags = board->flags;
new_flags = old_flags & CastleMask[from] & CastleMask[to];
board->flags = new_flags;
board->key ^= Castle64[new_flags^old_flags]; // HACK
// update en-passant square
if ((sq=board->ep_square) != SquareNone) {
board->key ^= RANDOM_64(RandomEnPassant+SQUARE_FILE(sq)-FileA);
board->ep_square = SquareNone;
}
if (PIECE_IS_PAWN(piece)) {
delta = to - from;
if (delta == +32 || delta == -32) {
pawn = PAWN_MAKE(opp);
if (board->square[to-1] == pawn || board->square[to+1] == pawn) {
board->ep_square = (from + to) / 2;
board->key ^= RANDOM_64(RandomEnPassant+SQUARE_FILE(to)-FileA);
}
}
}
// update move number (captures are handled later)
board->ply_nb++;
if (PIECE_IS_PAWN(piece)) board->ply_nb = 0; // conversion
// update last square
board->cap_sq = SquareNone;
// remove the captured piece
sq = to;
if (MOVE_IS_EN_PASSANT(move)) sq = SQUARE_EP_DUAL(sq);
if ((capture=board->square[sq]) != Empty) {
ASSERT(COLOUR_IS(capture,opp));
ASSERT(!PIECE_IS_KING(capture));
undo->capture = true;
undo->capture_square = sq;
undo->capture_piece = capture;
undo->capture_pos = board->pos[sq];
square_clear(board,sq,capture,true);
board->ply_nb = 0; // conversion
board->cap_sq = to;
}
// move the piece
if (MOVE_IS_PROMOTE(move)) {
// promote
undo->pawn_pos = board->pos[from];
square_clear(board,from,piece,true);
piece = move_promote(move);
// insert the promote piece in MV order
for (pos = board->piece_size[me]; pos > 0 && piece > board->square[board->piece[me][pos-1]]; pos--) // HACK
;
square_set(board,to,piece,pos,true);
board->cap_sq = to;
} else {
// normal move
square_move(board,from,to,piece,true);
}
// move the rook in case of castling
if (MOVE_IS_CASTLE(move)) {
rook = Rook64 | COLOUR_FLAG(me); // HACK
if (to == G1) {
square_move(board,H1,F1,rook,true);
} else if (to == C1) {
square_move(board,A1,D1,rook,true);
} else if (to == G8) {
square_move(board,H8,F8,rook,true);
} else if (to == C8) {
square_move(board,A8,D8,rook,true);
} else {
ASSERT(false);
}
}
// debug
ASSERT(board_is_ok(board));
}
