static int see_rec(alists_t * alists, const board_t * board, int colour, int to, int piece_value) {
int from, piece;
int value;
ASSERT(alists!=NULL);
ASSERT(board!=NULL);
ASSERT(COLOUR_IS_OK(colour));
ASSERT(SQUARE_IS_OK(to));
ASSERT(piece_value>0);
// find the least valuable attacker
from = alist_pop(alists->alist[colour],board);
if (from == SquareNone) return 0; // no more attackers
// find hidden attackers
alists_hidden(alists,board,from,to);
// calculate the capture value
value = +piece_value; // captured piece
if (value == ValueKing) return value; // do not allow an answer to a king capture
piece = board->square[from];
ASSERT(piece_is_ok(piece));
ASSERT(COLOUR_IS(piece,colour));
piece_value = VALUE_PIECE(piece);
// promote
if (piece_value == ValuePawn && SQUARE_IS_PROMOTE(to)) { // HACK: PIECE_IS_PAWN(piece)
ASSERT(PIECE_IS_PAWN(piece));
piece_value = ValueQueen;
value += ValueQueen - ValuePawn;
}
value -= see_rec(alists,board,COLOUR_OPP(colour),to,piece_value);
if (value < 0) value = 0;
return value;
}
int see_square(const board_t * board, int to, int colour) {
int att, def;
alists_t alists[1];
alist_t * alist;
int piece_value;
int piece;
ASSERT(board!=NULL);
ASSERT(SQUARE_IS_OK(to));
ASSERT(COLOUR_IS_OK(colour));
ASSERT(COLOUR_IS(board->square[to],COLOUR_OPP(colour)));
// build attacker list
att = colour;
alist = alists->alist[att];
ALIST_CLEAR(alist);
alist_build(alist,board,to,att);
if (alist->size == 0) return 0; // no attacker => stop SEE
// build defender list
def = COLOUR_OPP(att);
alist = alists->alist[def];
ALIST_CLEAR(alist);
alist_build(alist,board,to,def);
// captured piece
piece = board->square[to];
ASSERT(piece_is_ok(piece));
ASSERT(COLOUR_IS(piece,def));
piece_value = VALUE_PIECE(piece);
// SEE search
return see_rec(alists,board,att,to,piece_value);
}
U64 hash_turn_key(S8 colour) {
ASSERT(COLOUR_IS_OK(colour));
return (COLOUR_IS_WHITE(colour)) ? RANDOM_64(RandomTurn) : 0;
}
bool board_is_ok(const board_t * board) {
int sq, piece, colour;
int size, pos;
if (board == NULL) return false;
// optional heavy DEBUG mode
if (!UseSlowDebug) return true;
// squares
for (sq = 0; sq < SquareNb; sq++) {
piece = board->square[sq];
pos = board->pos[sq];
if (SQUARE_IS_OK(sq)) {
// inside square
if (piece == Empty) {
if (pos != -1) return false;
} else {
if (!piece_is_ok(piece)) return false;
if (!PIECE_IS_PAWN(piece)) {
colour = PIECE_COLOUR(piece);
if (pos < 0 || pos >= board->piece_size[colour]) return false;
if (board->piece[colour][pos] != sq) return false;
} else { // pawn
if (SQUARE_IS_PROMOTE(sq)) return false;
colour = PIECE_COLOUR(piece);
if (pos < 0 || pos >= board->pawn_size[colour]) return false;
if (board->pawn[colour][pos] != sq) return false;
}
}
} else {
// edge square
if (piece != Edge) return false;
if (pos != -1) return false;
}
}
// piece lists
for (colour = 0; colour < ColourNb; colour++) {
// piece list
size = board->piece_size[colour];
if (size < 1 || size > 16) return false;
for (pos = 0; pos < size; pos++) {
sq = board->piece[colour][pos];
if (!SQUARE_IS_OK(sq)) return false;
if (board->pos[sq] != pos) return false;
piece = board->square[sq];
if (!COLOUR_IS(piece,colour)) return false;
if (pos == 0 && !PIECE_IS_KING(piece)) return false;
if (pos != 0 && PIECE_IS_KING(piece)) return false;
if (pos != 0 && PIECE_ORDER(piece) > PIECE_ORDER(board->square[board->piece[colour][pos-1]])) {
return false;
}
}
sq = board->piece[colour][size];
if (sq != SquareNone) return false;
// pawn list
size = board->pawn_size[colour];
if (size < 0 || size > 8) return false;
for (pos = 0; pos < size; pos++) {
sq = board->pawn[colour][pos];
if (!SQUARE_IS_OK(sq)) return false;
if (SQUARE_IS_PROMOTE(sq)) return false;
if (board->pos[sq] != pos) return false;
piece = board->square[sq];
if (!COLOUR_IS(piece,colour)) return false;
if (!PIECE_IS_PAWN(piece)) return false;
}
sq = board->pawn[colour][size];
if (sq != SquareNone) return false;
// piece total
if (board->piece_size[colour] + board->pawn_size[colour] > 16) return false;
}
// material
if (board->piece_nb != board->piece_size[White] + board->pawn_size[White]
+ board->piece_size[Black] + board->pawn_size[Black]) {
return false;
}
if (board->number[WhitePawn12] != board->pawn_size[White]) return false;
if (board->number[BlackPawn12] != board->pawn_size[Black]) return false;
if (board->number[WhiteKing12] != 1) return false;
if (board->number[BlackKing12] != 1) return false;
// misc
if (!COLOUR_IS_OK(board->turn)) return false;
if (board->ply_nb < 0) return false;
if (board->sp < board->ply_nb) return false;
if (board->cap_sq != SquareNone && !SQUARE_IS_OK(board->cap_sq)) return false;
if (board->opening != board_opening(board)) return false;
if (board->endgame != board_endgame(board)) return false;
if (board->key != hash_key(board)) return false;
if (board->pawn_key != hash_pawn_key(board)) return false;
if (board->material_key != hash_material_key(board)) return false;
return true;
}
static bool kpk_draw(int wp, int wk, int bk, int turn) {
int wp_file, wp_rank;
int wk_file;
int bk_file, bk_rank;
ASSERT(SQUARE_IS_OK(wp));
ASSERT(SQUARE_IS_OK(wk));
ASSERT(SQUARE_IS_OK(bk));
ASSERT(COLOUR_IS_OK(turn));
ASSERT(SQUARE_FILE(wp)<=FileD);
wp_file = SQUARE_FILE(wp);
wp_rank = SQUARE_RANK(wp);
wk_file = SQUARE_FILE(wk);
bk_file = SQUARE_FILE(bk);
bk_rank = SQUARE_RANK(bk);
if (false) {
} else if (bk == wp+16) {
if (wp_rank <= Rank6) {
return true;
} else {
ASSERT(wp_rank==Rank7);
if (COLOUR_IS_WHITE(turn)) {
if (wk == wp-15 || wk == wp-17) return true;
} else {
if (wk != wp-15 && wk != wp-17) return true;
}
}
} else if (bk == wp+32) {
if (wp_rank <= Rank5) {
return true;
} else {
ASSERT(wp_rank==Rank6);
if (COLOUR_IS_WHITE(turn)) {
if (wk != wp-1 && wk != wp+1) return true;
} else {
return true;
}
}
} else if (wk == wp-1 || wk == wp+1) {
if (bk == wk+32 && COLOUR_IS_WHITE(turn)) { // opposition
return true;
}
} else if (wk == wp+15 || wk == wp+16 || wk == wp+17) {
if (wp_rank <= Rank4) {
if (bk == wk+32 && COLOUR_IS_WHITE(turn)) { // opposition
return true;
}
}
}
// rook pawn
if (wp_file == FileA) {
if (DISTANCE(bk,A8) <= 1) return true;
if (wk_file == FileA) {
if (wp_rank == Rank2) wp_rank++; // HACK
if (bk_file == FileC && bk_rank > wp_rank) return true;
}
}
return false;
}
