bool pseudo_is_legal(int move, board_t * board) {
int me, opp;
int from, to;
int piece;
bool legal;
int king;
undo_t undo[1];
ASSERT(move_is_ok(move));
ASSERT(board!=NULL);
// 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));
// slow test for en-passant captures
if (MOVE_IS_EN_PASSANT(move)) {
move_do(board,move,undo);
legal = !IS_IN_CHECK(board,me);
move_undo(board,move,undo);
return legal;
}
// king moves (including castle)
if (PIECE_IS_KING(piece)) {
legal = !is_attacked(board,to,opp);
if (DEBUG) {
ASSERT(board->square[from]==piece);
board->square[from] = Empty;
ASSERT(legal==!is_attacked(board,to,opp));
board->square[from] = piece;
}
return legal;
}
// pins
if (is_pinned(board,from,me)) {
king = KING_POS(board,me);
return DELTA_INC_LINE(king-to) == DELTA_INC_LINE(king-from); // does not discover the line
}
return true;
}
static void alists_hidden(alists_t * alists, const board_t * board, int from, int to) {
int inc;
int sq, piece;
ASSERT(alists!=NULL);
ASSERT(board!=NULL);
ASSERT(SQUARE_IS_OK(from));
ASSERT(SQUARE_IS_OK(to));
inc = DELTA_INC_LINE(to-from);
if (inc != IncNone) { // line
sq = from;
do sq -= inc; while ((piece=board->square[sq]) == Empty);
if (SLIDER_ATTACK(piece,inc)) {
ASSERT(piece_is_ok(piece));
ASSERT(PIECE_IS_SLIDER(piece));
alist_add(alists->alist[PIECE_COLOUR(piece)],sq,board);
}
}
}
bool is_pinned(const board_t * board, int square, int colour) {
int from, to;
int inc;
int sq, piece;
ASSERT(board!=NULL);
ASSERT(SQUARE_IS_OK(square));
ASSERT(COLOUR_IS_OK(colour));
from = square;
to = KING_POS(board,colour);
inc = DELTA_INC_LINE(to-from);
if (inc == IncNone) return false; // not a line
sq = from;
do sq += inc; while (board->square[sq] == Empty);
if (sq != to) return false; // blocker
sq = from;
do sq -= inc; while ((piece=board->square[sq]) == Empty);
return COLOUR_IS(piece,COLOUR_OPP(colour)) && SLIDER_ATTACK(piece,inc);
}
bool move_is_check(int move, board_t * board) {
undo_t undo[1];
bool check;
int me, opp, king;
int from, to, piece;
ASSERT(move_is_ok(move));
ASSERT(board!=NULL);
// slow test for complex moves
if (MOVE_IS_SPECIAL(move)) {
move_do(board,move,undo);
check = IS_IN_CHECK(board,board->turn);
move_undo(board,move,undo);
return check;
}
// init
me = board->turn;
opp = COLOUR_OPP(me);
king = KING_POS(board,opp);
from = MOVE_FROM(move);
to = MOVE_TO(move);
piece = board->square[from];
ASSERT(COLOUR_IS(piece,me));
// direct check
if (PIECE_ATTACK(board,piece,to,king)) return true;
// indirect check
if (is_pinned(board,from,opp)
&& DELTA_INC_LINE(king-to) != DELTA_INC_LINE(king-from)) {
return true;
}
return false;
}
static void find_pins(int list[], const board_t * board) {
int me, opp;
int king;
const sq_t * ptr;
int from;
int piece;
int delta;
int inc;
int sq;
int capture;
int pin;
ASSERT(list!=NULL);
ASSERT(board!=NULL);
// init
me = board->turn;
opp = COLOUR_OPP(me);
king = KING_POS(board,opp);
for (ptr = &board->piece[me][1]; (from=*ptr) != SquareNone; ptr++) { // HACK: no king
piece = board->square[from];
delta = king - from;
ASSERT(delta_is_ok(delta));
if (PSEUDO_ATTACK(piece,delta)) {
ASSERT(PIECE_IS_SLIDER(piece));
inc = DELTA_INC_LINE(delta);
ASSERT(inc!=IncNone);
ASSERT(SLIDER_ATTACK(piece,inc));
sq = from;
do sq += inc;
while ((capture=board->square[sq]) == Empty);
ASSERT(sq!=king);
if (COLOUR_IS(capture,me)) {
pin = sq;
do sq += inc;
while (board->square[sq] == Empty);
if (sq == king) *list++ = pin;
}
}
}
*list = SquareNone;
}
static void add_quiet_checks(list_t * list, const board_t * board) {
int me, opp;
int king;
const sq_t * ptr, * ptr_2;
int from, to, sq;
int piece;
const inc_t * inc_ptr;
int inc;
int pawn;
int rank;
int pin[8+1];
ASSERT(list!=NULL);
ASSERT(board!=NULL);
// init
me = board->turn;
opp = COLOUR_OPP(me);
king = KING_POS(board,opp);
find_pins(pin,board);
// indirect checks
for (ptr = pin; (from=*ptr) != SquareNone; ptr++) {
piece = board->square[from];
ASSERT(is_pinned(board,from,opp));
if (PIECE_IS_PAWN(piece)) {
inc = PAWN_MOVE_INC(me);
rank = PAWN_RANK(from,me);
if (rank != Rank7) { // promotes are generated with captures
to = from + inc;
if (board->square[to] == Empty) {
if (DELTA_INC_LINE(to-king) != DELTA_INC_LINE(from-king)) {
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE(from,to));
if (rank == Rank2) {
to = from + (2*inc);
if (board->square[to] == Empty) {
ASSERT(DELTA_INC_LINE(to-king)!=DELTA_INC_LINE(from-king));
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
}
}
} else if (PIECE_IS_SLIDER(piece)) {
for (inc_ptr = PIECE_INC(piece); (inc=*inc_ptr) != IncNone; inc_ptr++) {
for (to = from+inc; board->square[to] == Empty; to += inc) {
ASSERT(DELTA_INC_LINE(to-king)!=DELTA_INC_LINE(from-king));
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
} else {
for (inc_ptr = PIECE_INC(piece); (inc=*inc_ptr) != IncNone; inc_ptr++) {
to = from + inc;
if (board->square[to] == Empty) {
if (DELTA_INC_LINE(to-king) != DELTA_INC_LINE(from-king)) {
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
}
}
// piece direct checks
for (ptr = &board->piece[me][1]; (from=*ptr) != SquareNone; ptr++) { // HACK: no king
for (ptr_2 = pin; (sq=*ptr_2) != SquareNone; ptr_2++) {
if (sq == from) goto next_piece;
}
ASSERT(!is_pinned(board,from,opp));
piece = board->square[from];
inc_ptr = PIECE_INC(piece);
if (PIECE_IS_SLIDER(piece)) {
for (; (inc=*inc_ptr) != IncNone; inc_ptr++) {
for (to = from+inc; board->square[to] == Empty; to += inc) {
if (PIECE_ATTACK(board,piece,to,king)) {
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
} else {
for (; (inc=*inc_ptr) != IncNone; inc_ptr++) {
to = from + inc;
if (board->square[to] == Empty) {
if (PSEUDO_ATTACK(piece,king-to)) {
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
}
next_piece:
;
}
// pawn direct checks
inc = PAWN_MOVE_INC(me);
pawn = PAWN_MAKE(me);
to = king - (inc-1);
ASSERT(PSEUDO_ATTACK(pawn,king-to));
from = to - inc;
if (board->square[from] == pawn) {
if (board->square[to] == Empty) {
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE(from,to));
}
} else {
from = to - (2*inc);
if (board->square[from] == pawn) {
if (PAWN_RANK(from,me) == Rank2
&& board->square[to] == Empty
&& board->square[from+inc] == Empty) {
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
to = king - (inc+1);
ASSERT(PSEUDO_ATTACK(pawn,king-to));
from = to - inc;
if (board->square[from] == pawn) {
if (board->square[to] == Empty) {
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE(from,to));
}
} else {
from = to - (2*inc);
if (board->square[from] == pawn) {
if (PAWN_RANK(from,me) == Rank2
&& board->square[to] == Empty
&& board->square[from+inc] == Empty) {
ASSERT(!SQUARE_IS_PROMOTE(to));
LIST_ADD(list,MOVE_MAKE(from,to));
}
}
}
}
void attack_set(attack_t * attack, const board_t * board) {
int me, opp;
const sq_t * ptr;
int from, to;
int inc;
int pawn;
int delta, piece;
int sq;
ASSERT(attack!=NULL);
ASSERT(board!=NULL);
// init
attack->dn = 0;
me = board->turn;
opp = COLOUR_OPP(me);
to = KING_POS(board,me);
// pawn attacks
inc = PAWN_MOVE_INC(opp);
pawn = PAWN_MAKE(opp);
from = to - (inc-1);
if (board->square[from] == pawn) {
attack->ds[attack->dn] = from;
attack->di[attack->dn] = IncNone;
attack->dn++;
}
from = to - (inc+1);
if (board->square[from] == pawn) {
attack->ds[attack->dn] = from;
attack->di[attack->dn] = IncNone;
attack->dn++;
}
// piece attacks
for (ptr = &board->piece[opp][1]; (from=*ptr) != SquareNone; ptr++) { // HACK: no king
piece = board->square[from];
delta = to - from;
ASSERT(delta_is_ok(delta));
if (PSEUDO_ATTACK(piece,delta)) {
inc = IncNone;
if (PIECE_IS_SLIDER(piece)) {
// check for blockers
inc = DELTA_INC_LINE(delta);
ASSERT(inc!=IncNone);
sq = from;
do sq += inc; while (board->square[sq] == Empty);
if (sq != to) continue; // blocker => next attacker
}
attack->ds[attack->dn] = from;
attack->di[attack->dn] = -inc; // HACK
attack->dn++;
}
}
attack->ds[attack->dn] = SquareNone;
attack->di[attack->dn] = IncNone;
// debug
ASSERT(attack_is_ok(attack));
}