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position.m
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position.m
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/*
Stockfish, a OS X GUI for the UCI chess engine with the same name.
Copyright (C) 2004-2011 Marco Costalba, Joona Kiiski, Tord Romstad
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "position.h"
const int Directions[16][16] = {
{0},
{15, 17, 0}, // WP
{33, 31, 18, 14, -14, -18, -31, -33, 0}, // WN
{17, 15, -15, -17, 0}, // WB
{16, 1, -1, -16, 0}, // WR
{17, 16, 15, 1, -1, -15, -16, -17, 0}, // WQ
{17, 16, 15, 1, -1, -15, -16, -17, 0}, // WK
{0},
{0},
{-15, -17, 0}, // BP
{-33, -31, -18, -14, 14, 18, 31, 33, 0}, // BN
{-17, -15, 15, 17, 0}, // BB
{-16, -1, 1, 16, 0}, // BR
{-17, -16, -15, -1, 1, 15, 16, 17, 0}, // BQ
{-17, -16, -15, -1, 1, 15, 16, 17, 0}, // BK
{0}
};
const uint32_t FileMask[8] = {1, 2, 4, 8, 16, 32, 64, 128};
const int SlidingArray[16] = {0,0,0,1,2,3,0,0,0,0,0,1,2,3,0};
const int PawnPush[2] = {16, -16};
const int PieceMask[OUTSIDE+1] = {
0,WP_MASK,N_MASK,B_MASK,R_MASK,Q_MASK,K_MASK,0,
0,BP_MASK,N_MASK,B_MASK,R_MASK,Q_MASK,K_MASK,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
};
uint8_t PawnRank[2][128];
attack_data_t AttackData_[256];
attack_data_t *AttackData = AttackData_ + 128;
hashkey_t Zobrist[BK][64], ZobColour, ZobEP[64], ZobCastle[16];
extern uint32_t genrand_int32(void);
extern uint64_t genrand_int64(void);
extern void init_mersenne(void);
void init_zobrist(void) {
int i, j;
for(i=0; i<BK; i++)
for(j=0; j<64; j++)
Zobrist[i][j] = genrand_int64();
ZobEP[0] = 0;
for(i=1; i<64; i++) ZobEP[i] = genrand_int64();
for(i=0; i<16; i++) ZobCastle[i] = genrand_int64();
ZobColour = genrand_int64();
}
hashkey_t compute_hash_key(const position_t *pos) {
hashkey_t result = 0ULL;
int side, sq;
for(side = WHITE; side <= BLACK; side++)
for(sq=KingSquare(pos, side); sq!=PieceListEnd; sq=NextPiece(pos, sq))
if(sq <= H8) result ^= ZOBRIST(pos->board[sq], sq);
result ^= ZOB_EP(pos->ep_square);
result ^= ZOB_CASTLE(pos->castle_flags);
if(pos->side == BLACK) result ^= ZobColour;
return result;
}
static void init_tables(void) {
int i;
for(i = 0; i < 128; i++)
PawnRank[WHITE][i] = PawnRank[BLACK][i^0x70] = SquareRank(i);
}
static void init_attack_data(void) {
int sq, piece, tosq;
const int *ptr;
for(sq = 0; sq < 256; sq++)
AttackData_[sq].may_attack = AttackData_[sq].step = 0;
for(sq = A1; sq <= H8; sq++)
for(piece = WP; piece <= BK; piece++)
for(ptr = Directions[piece]; *ptr; ptr++)
for(tosq = sq+(*ptr); !(tosq & 0x88); tosq += (*ptr)) {
AttackData[sq-tosq].step = *ptr;
AttackData[sq-tosq].may_attack |= PieceMask[piece];
if(!PieceIsSlider(piece)) break;
}
}
void init(void) {
init_tables();
init_mersenne();
init_zobrist();
init_attack_data();
}
void init_position(position_t *pos) {
int i;
for(i=0; i<256; i++) pos->board_[i] = ((i-64)&0x88)? OUTSIDE : EMPTY;
pos->board = pos->board_ + 64;
}
void init_piece_lists(position_t *pos) {
int sq, piece;
for(piece = KING; piece >= KNIGHT; piece--) {
PieceListStart(pos, piece) = piece-1+128;
PieceListStart(pos, piece+8) = piece+7+128;
PrevPiece(pos, piece-1+128) = piece+128;
PrevPiece(pos, piece+7+128) = piece+8+128;
}
PieceListStart(pos, WP) = PieceListStart(pos, BP) = PieceListEnd;
for(sq = A1; sq <= H8; sq++)
if(pos->board[sq] != OUTSIDE && pos->board[sq] != EMPTY)
InsertPiece(pos, pos->board[sq], sq);
}
void copy_position(position_t *dst, const position_t *src) {
memcpy(dst, src, sizeof(position_t));
dst->board = dst->board_ + 64;
}
bool is_attacked(const position_t *pos, int square, int side) {
int sq, tosq, piece, step;
attack_data_t *a = AttackData-square;
for(sq = KingSquare(pos, side); sq != PieceListEnd;
sq = NextPiece(pos, sq)) {
if(sq <= H8) {
piece = pos->board[sq];
if(PieceMask[piece] & a[sq].may_attack) {
if(!PieceIsSlider(piece)) return true;
step = a[sq].step;
for(tosq=sq+step; pos->board[tosq]==EMPTY&&tosq!=square; tosq+=step);
if(tosq == square) return true;
}
}
}
return false;
}
bool position_is_check(const position_t *pos) {
int us, them;
move_t move;
us = pos->side; them = us^1;
move = pos->last_move;
if(move == NullMove) return false;
else if(move == NoMove || MvCastle(move) || MvEP(move))
return is_attacked(pos, KingSquare(pos, us), them);
else {
int ksq = KingSquare(pos, us);
int from = MvFrom(move), to = MvPiece(move);
int piece = pos->board[to];
attack_data_t *a = AttackData - ksq;
if(a[to].may_attack & PieceMask[piece]) {
if(!PieceIsSlider(piece)) return true;
int step = a[to].step, sq;
for(sq = to + step; pos->board[sq] == EMPTY; sq += step);
if(sq == ksq) return true;
}
if(a[from].may_attack & Q_MASK) {
int step = a[from].step, sq;
for(sq = from + step; pos->board[sq] == EMPTY; sq += step);
if(sq == ksq) {
for(sq = from - step; pos->board[sq] == EMPTY; sq -= step);
if(ColourOfPiece(pos->board[sq]) == them &&
(a[sq].may_attack & PieceMask[pos->board[sq]]))
return true;
}
}
}
return false;
}
int find_checkers(const position_t *pos, int chsqs[]) {
int us = pos->side, them = us^1;
int ksq = KingSquare(pos, us), from, to, step, piece, result = 0;
move_t move = pos->last_move;
attack_data_t *a = AttackData - ksq;
if(move == NullMove) return 0;
chsqs[0] = chsqs[1] = 0;
if(move == NoMove || MvCastle(move) || MvEP(move) || MvPromotion(move)) {
for(from = KingSquare(pos, pos->side^1); from != PieceListEnd && result<2;
from = NextPiece(pos, from)) {
if(from > H8) continue;
piece = pos->board[from];
if(PieceMask[piece] & a[from].may_attack) {
if(PieceIsSlider(piece)) {
step = a[from].step;
for(to = from + step; pos->board[to] == EMPTY; to += step);
if(to == ksq) chsqs[result++] = from;
}
else chsqs[result++] = from;
}
}
}
else {
from = MvFrom(move); to = MvTo(move);
piece = pos->board[to];
if(PieceMask[piece] & a[to].may_attack) {
if(PieceIsSlider(piece)) {
int sq;
step = a[to].step;
for(sq = to + step; pos->board[sq]==EMPTY; sq += step);
if(sq == ksq) chsqs[result++] = to;
}
else chsqs[result++] = to;
}
if(a[from].may_attack & Q_MASK) { // Discovered check possible.
int sq;
step = a[from].step;
for(sq = from + step; pos->board[sq] == EMPTY; sq += step);
if(sq == ksq) {
for(sq = from - step; pos->board[sq] == EMPTY; sq -= step);
if(ColourOfPiece(pos->board[sq]) == them &&
(a[sq].may_attack & PieceMask[pos->board[sq]]))
chsqs[result++] = sq;
}
}
}
return result;
}
int is_pinned(const position_t *pos, int square) {
int side, ksq, p1, p2, step, sq;
attack_data_t *a;
side = ColourOfPiece(pos->board[square]);
ksq = KingSquare(pos, side);
a = AttackData - ksq + square;
if(!(a->may_attack & Q_MASK)) return 0;
if(a->may_attack & R_MASK) p1 = RookOfColour(side^1);
else p1 = BishopOfColour(side^1);
p2 = QueenOfColour(side^1);
step = a->step;
for(sq = square + step; pos->board[sq] == EMPTY; sq += step);
if(sq == ksq) {
for(sq = square - step; pos->board[sq] == EMPTY; sq -= step);
if(pos->board[sq] == p1 || pos->board[sq] == p2) return step;
}
return 0;
}
int count_pieces(const position_t *pos, int colour, int type) {
int piece, square, count = 0;
piece = PieceOfColourAndType(colour, type);
for(square = PieceListStart(pos, piece); square <= H8;
square = NextPiece(pos, square))
count++;
return count;
}
void init_piece_counts(position_t *pos) {
int colour, type;
for(colour = WHITE; colour <= BLACK; colour++)
for(type = PAWN; type <= QUEEN; type++)
pos->piece_count[colour][type] = count_pieces(pos, colour, type);
}
char *square2str(int sq, char *str) {
sprintf(str, "%c%d", (char)SquareFile(sq)+'a', SquareRank(sq) + 1);
return str;
}
void print_square(int sq) {
printf("%c%d", (char)SquareFile(sq)+'a', SquareRank(sq) + 1);
}
char *move2str(move_t move, char *str) {
char letters[BK+2] = " pnbrqk pnbrqk";
if(move == NullMove) sprintf(str, "0000");
else if(move == NoMove) sprintf(str, "(none)");
else if(MvPromotion(move))
sprintf(str, "%c%d%c%d%c",
(char)SquareFile(MvFrom(move))+'a', SquareRank(MvFrom(move)) + 1,
(char)SquareFile(MvTo(move))+'a', SquareRank(MvTo(move)) + 1,
letters[MvPromotion(move)]);
else
sprintf(str, "%c%d%c%d",
(char)SquareFile(MvFrom(move))+'a', SquareRank(MvFrom(move)) + 1,
(char)SquareFile(MvTo(move))+'a', SquareRank(MvTo(move)) + 1);
return str;
}
void print_move(move_t move) {
char str[8];
move2str(move, str);
printf("%s ", str);
}
char *time_string(int msecs, char *str) {
int hours, minutes, seconds, milliseconds, centiseconds;
hours = msecs / (1000 * 60 * 60);
minutes = (msecs - hours * 1000 * 60 * 60) / (60 * 1000);
seconds = (msecs - hours * 1000 * 60 * 60 - minutes * 60 * 1000) / 1000;
milliseconds = (msecs - hours*1000*60*60 - minutes*1000*60 - seconds*1000);
centiseconds = milliseconds / 10;
if(hours) {
if(minutes >= 10) {
if(seconds >= 10)
sprintf(str, "%d:%d:%d", hours, minutes, seconds);
else
sprintf(str, "%d:%d:0%d", hours, minutes, seconds);
}
else {
if(seconds >= 10)
sprintf(str, "%d:0%d:%d", hours, minutes, seconds);
else
sprintf(str, "%d:0%d:0%d", hours, minutes, seconds);
}
}
else if(minutes || true) {
if(seconds >= 10)
sprintf(str, "%d:%d", minutes, seconds);
else
sprintf(str, "%d:0%d", minutes, seconds);
}
else {
if(centiseconds >= 10)
sprintf(str, "%d.%d", seconds, centiseconds);
else
sprintf(str, "%d.0%d", seconds, centiseconds);
}
return str;
}
int parse_square(const char str[]) {
if(str[0] >= 'a' && str[0] <= 'h' && str[1] >= '1' && str[1] <= '8')
return str[0]-'a'+(str[1]-'1')*16;
else return -1;
}
void position_from_fen(position_t *pos, const char *fen) {
int sq;
init_position(pos);
for(sq = A8; sq >= A1; fen++) {
if(*fen == '\0') {printf("Error!\n"); return; }
if(isdigit(*fen)) {sq += (*fen) - '1' + 1; continue;}
switch(*fen) {
case 'K': pos->board[sq] = WK; break;
case 'k': pos->board[sq] = BK; break;
case 'Q': pos->board[sq] = WQ; break;
case 'q': pos->board[sq] = BQ; break;
case 'R': pos->board[sq] = WR; break;
case 'r': pos->board[sq] = BR; break;
case 'B': pos->board[sq] = WB; break;
case 'b': pos->board[sq] = BB; break;
case 'N': pos->board[sq] = WN; break;
case 'n': pos->board[sq] = BN; break;
case 'P': pos->board[sq] = WP; break;
case 'p': pos->board[sq] = BP; break;
case '/': sq -= SquareFile(sq) + 16; break;
case ' ': sq = A1 - 1; break;
default: printf("Error!\n"); return;
}
if(strchr(" /", *fen) == NULL) sq++;
}
switch(tolower(*fen)) {
case 'w': pos->side = WHITE; pos->xside = BLACK; break;
case 'b': pos->side = BLACK; pos->xside = WHITE; break;
default: printf("Error!\n"); return;
}
do {fen++;} while(isspace(*fen));
init_piece_lists(pos);
pos->castle_flags = WhiteOOMask | WhiteOOOMask | BlackOOMask | BlackOOOMask;
while(*fen != '\0' && !isspace(*fen)) {
if(*fen == 'K') {
pos->castle_flags ^= WhiteOOMask;
pos->initial_ksq = E1; pos->initial_krsq = H1;
}
else if(*fen == 'Q') {
pos->castle_flags ^= WhiteOOOMask;
pos->initial_ksq = E1; pos->initial_qrsq = A1;
}
else if(*fen == 'k') {
pos->castle_flags ^= BlackOOMask;
pos->initial_ksq = E1; pos->initial_krsq = H1;
}
else if(*fen == 'q') {
pos->castle_flags ^= BlackOOOMask;
pos->initial_ksq = E1; pos->initial_qrsq = A1;
}
else if(*fen >= 'A' && *fen <= 'H') {
pos->initial_ksq = KingSquare(pos, WHITE);
sq = (int) (*fen) - (int) 'A';
if(sq > KingSquare(pos, WHITE)) {
pos->castle_flags ^= WhiteOOMask; pos->initial_krsq = sq;
}
else {
pos->castle_flags ^= WhiteOOOMask; pos->initial_qrsq = sq;
}
}
else if(*fen >= 'a' && *fen <= 'h') {
pos->initial_ksq = KingSquare(pos, WHITE);
sq = (int) (*fen) - (int) 'a';
if(sq > SquareFile(KingSquare(pos, BLACK))) {
pos->castle_flags ^= BlackOOMask; pos->initial_krsq = sq;
}
else {
pos->castle_flags ^= BlackOOOMask; pos->initial_qrsq = sq;
}
}
fen++;
}
while(isspace(*fen)) fen++;
if(*fen=='\0') {
pos->rule50 = 0; pos->ep_square = 0;
}
else {
if(*fen=='-') pos->ep_square = 0;
else {
pos->ep_square = parse_square(fen);
if(pos->ep_square < 0) pos->ep_square = 0;
do{fen++;} while(!isspace(*fen));
}
do{fen++;} while(isspace(*fen));
if(isdigit(*fen)) sscanf(fen, "%d", &pos->rule50);
else pos->rule50 = 0;
}
pos->last_move = NoMove;
pos->check = find_checkers(pos, pos->check_sqs);
init_piece_counts(pos);
pos->key = compute_hash_key(pos);
pos->gply = 0;
}
char *position_to_fen(const position_t *pos, char *fen) {
int rank, file, square, skip, index = 0;
char piece_letters[BK+2] = " PNBRQK pnbrqk";
char str[256];
for(rank = RANK_8; rank >= RANK_1; rank--) {
skip = 0;
for(file = FILE_A; file <= FILE_H; file++) {
square = file + rank*16;
if(pos->board[square] != EMPTY) {
if(skip > 0) str[index++] = (char)skip + '0';
str[index++] = piece_letters[pos->board[square]];
skip = 0;
}
else skip++;
}
if(skip > 0) str[index++] = (char)skip + '0';
str[index++] = (rank > RANK_1)? '/' : ' ';
}
str[index++] = (pos->side == WHITE)? 'w' : 'b';
str[index++] = ' ';
if(!CanCastleQueenside(pos, WHITE) && !CanCastleKingside(pos, WHITE) &&
!CanCastleQueenside(pos, BLACK) && !CanCastleKingside(pos, BLACK))
str[index++] = '-';
else {
if(CanCastleKingside(pos, WHITE))
str[index++] = 'K';
if(CanCastleQueenside(pos, WHITE))
str[index++] = 'Q';
if(CanCastleQueenside(pos, BLACK))
str[index++] = 'k';
if(CanCastleQueenside(pos, BLACK))
str[index++] = 'q';
}
str[index++] = ' ';
if(pos->ep_square) {
str[index++] = (char)(SquareFile(pos->ep_square)) + 'a';
str[index++] = (char)(SquareRank(pos->ep_square)) + '1';
}
else str[index++] = '-';
str[index++] = 0;
sprintf(fen, "%s %d %d", str, pos->rule50, (pos->gply / 2 + 1));
return fen;
}
int get_time(void) {
struct timeval t;
gettimeofday(&t, NULL);
return t.tv_sec*1000 + t.tv_usec/1000;
}
void fprint_position(FILE *f, const position_t *pos) {
int file, rank, square, piece;
char piece_strings[BK+1][8] =
{"| ", "| P ", "| N ", "| B ", "| R ", "| Q ", "| K ", "| ? ",
"| ? ", "|=P=", "|=N=", "|=B=", "|=R=", "|=Q=", "|=K="
};
char fen[256];
for(rank = RANK_8; rank >= RANK_1; rank--) {
fprintf(f, "+---+---+---+---+---+---+---+---+\n");
for(file = FILE_A; file <= FILE_H; file++) {
square = file + rank*16;
piece = pos->board[square];
if(piece == EMPTY) fprintf(f, (rank + file) % 2? "| " : "| . ");
else fprintf(f, piece_strings[piece]);
}
fprintf(f, "|\n");
}
fprintf(f, "+---+---+---+---+---+---+---+---+\n");
fprintf(f, "%s\n", position_to_fen(pos, fen));
fprintf(f, "0x%llxULL\n", pos->key);
}
void print_position(const position_t *pos) {
fprint_position(stdout, pos);
}
bool irreversible(move_t m) {
return MvCapture(m) || MvPiece(m)==PAWN;
}
void make_move(position_t *pos, move_t m, undo_info_t *u) {
int from, to, piece, capture, promotion, prom_or_piece, ep;
int side = pos->side, xside = side^1;
u->ep_square = pos->ep_square;
u->castle_flags = pos->castle_flags;
u->rule50 = pos->rule50;
u->key = pos->previous_keys[pos->gply] = pos->key;
u->last_move = pos->last_move;
u->check = pos->check;
u->check_sqs[0] = pos->check_sqs[0];
u->check_sqs[1] = pos->check_sqs[1];
if(irreversible(m)) pos->rule50 = 0; else pos->rule50++;
from=MvFrom(m); to=MvTo(m); capture=MvCapture(m); promotion=MvPromotion(m);
ep = (m & EPFlag);
piece = pos->board[from];
if(capture) capture |= (xside<<3);
if(promotion) promotion |= (side<<3);
prom_or_piece = promotion? promotion : piece;
pos->key ^= ZOBRIST(piece, from);
pos->key ^= ZOBRIST(prom_or_piece, to);
pos->key ^= ZobColour; pos->key ^= ZOB_EP(pos->ep_square);
if(capture) {
int capsq = ep? to-PawnPush[side] : to;
RemovePiece(pos, capsq);
pos->board[capsq] = EMPTY;
pos->key ^= ZOBRIST(capture, capsq);
pos->piece_count[xside][TypeOfPiece(capture)]--;
}
if(promotion) {
RemovePiece(pos, from); InsertPiece(pos, promotion, to);
pos->piece_count[side][PAWN]--;
pos->piece_count[side][TypeOfPiece(promotion)]++;
}
else MovePiece(pos, from, to);
pos->board[to] = prom_or_piece; pos->board[from] = EMPTY;
if(PieceIsPawn(piece) && to-from == 2*PawnPush[side] &&
(pos->board[to+1] == PawnOfColour(xside) ||
pos->board[to-1] == PawnOfColour(xside))) {
pos->ep_square = (to+from)/2;
pos->key ^= ZOB_EP(pos->ep_square);
}
else pos->ep_square = 0;
if(MvShortCastle(m)) {
int initialKRSQ = pos->initial_krsq+side*A8;
int rook = RookOfColour(side);
int g1 = G1 + side*A8, f1 = F1 + side*A8;
pos->board[initialKRSQ] = EMPTY; pos->board[f1] = rook;
pos->board[g1] = KingOfColour(side);
pos->key ^= ZOBRIST(rook, initialKRSQ); pos->key ^= ZOBRIST(rook, f1);
init_piece_lists(pos);
}
else if(MvLongCastle(m)) {
int initialQRSQ = pos->initial_qrsq+side*A8;
int rook = RookOfColour(side);
int c1 = C1 + side*A8, d1 = D1 + side*A8;
pos->board[initialQRSQ] = EMPTY; pos->board[d1] = rook;
pos->board[c1] = KingOfColour(side);
pos->key ^= ZOBRIST(rook, initialQRSQ); pos->key ^= ZOBRIST(rook, d1);
init_piece_lists(pos);
}
pos->key^=ZOB_CASTLE(pos->castle_flags);
if(from==pos->initial_ksq || from==pos->initial_krsq || to==pos->initial_krsq)
ProhibitOO(pos, WHITE);
if(from==pos->initial_ksq || from==pos->initial_qrsq || to==pos->initial_qrsq)
ProhibitOOO(pos, WHITE);
if(from==pos->initial_ksq+A8 || from==pos->initial_krsq+A8 ||
to==pos->initial_krsq+A8)
ProhibitOO(pos, BLACK);
if(from==pos->initial_ksq+A8 || from==pos->initial_qrsq+A8 ||
to==pos->initial_qrsq+A8)
ProhibitOOO(pos, BLACK);
pos->key^=ZOB_CASTLE(pos->castle_flags);
pos->last_move = m;
pos->gply++; pos->side ^= 1; pos->xside ^= 1;
pos->check = find_checkers(pos, pos->check_sqs);
}
void unmake_move(position_t *pos, move_t m, undo_info_t *u) {
int from, to, piece, capture, promotion, prom_or_piece, ep;
int side, xside;
pos->gply--; pos->xside ^= 1; pos->side ^= 1;
side = pos->side; xside = side^1;
pos->ep_square = u->ep_square;
pos->castle_flags = u->castle_flags;
pos->rule50 = u->rule50;
pos->key = u->key;
pos->last_move = u->last_move;
pos->check = u->check;
pos->check_sqs[0] = u->check_sqs[0];
pos->check_sqs[1] = u->check_sqs[1];
from = MvFrom(m); to = MvTo(m);
capture = MvCapture(m); promotion = MvPromotion(m);
piece = MvPiece(m); ep = (m&EPFlag);
piece |= (side<<3);
if(capture) capture |= (xside<<3);
if(promotion) promotion |= (side<<3);
prom_or_piece = promotion? promotion : piece;
if(promotion) {
RemovePiece(pos, to); InsertPiece(pos, piece, from);
pos->piece_count[side][PAWN]++;
pos->piece_count[side][TypeOfPiece(promotion)]--;
}
else MovePiece(pos, to, from);
pos->board[from] = piece; pos->board[to] = EMPTY;
if(capture) {
int capsq = ep? to-PawnPush[side] : to;
pos->board[capsq] = capture;
InsertPiece(pos, capture, capsq);
pos->piece_count[xside][TypeOfPiece(capture)]++;
}
if(MvShortCastle(m)) {
int initialKRSQ = pos->initial_krsq+side*A8;
int initialKSQ = pos->initial_ksq+side*A8;
int rook = RookOfColour(side), king = KingOfColour(side);
int g1 = G1 + side*A8, f1 = F1 + side*A8;
pos->board[f1] = pos->board[g1] = EMPTY;
pos->board[initialKRSQ] = rook; pos->board[initialKSQ] = king;
init_piece_lists(pos);
}
if(MvLongCastle(m)) {
int initialQRSQ = pos->initial_qrsq+side*A8;
int initialKSQ = pos->initial_ksq+side*A8;
int rook = RookOfColour(side), king = KingOfColour(side);
int c1 = C1 + side*A8, d1 = D1 + side*A8;
pos->board[d1] = pos->board[c1] = EMPTY;
pos->board[initialQRSQ] = rook; pos->board[initialKSQ] = king;
init_piece_lists(pos);
}
}
void make_nullmove(position_t *pos, undo_info_t *u) {
u->ep_square = pos->ep_square;
u->castle_flags = pos->castle_flags;
u->rule50 = pos->rule50;
u->key = pos->previous_keys[pos->gply] = pos->key;
u->last_move = pos->last_move;
pos->key ^= ZobColour; pos->key ^= ZOB_EP(pos->ep_square);
pos->rule50++;
pos->ep_square = 0;
pos->last_move = NullMove;
pos->gply++; pos->side ^= 1; pos->xside ^= 1;
}
void unmake_nullmove(position_t *pos, undo_info_t *u) {
pos->gply--; pos->xside ^= 1; pos->side ^= 1;
pos->ep_square = u->ep_square;
pos->castle_flags = u->castle_flags;
pos->rule50 = u->rule50;
pos->key = u->key;
pos->last_move = u->last_move;
}
bool ep_is_legal(position_t *pos, move_t m) {
bool legal;
undo_info_t u[1];
make_move(pos, m, u);
legal = !is_attacked(pos, KingSquare(pos, (pos->side)^1), pos->side);
unmake_move(pos, m, u);
return legal;
}
bool move_is_legal(position_t *pos, move_t m) {
int side = pos->side, xside = side^1;
int ksq = KingSquare(pos, side);
int from = MvFrom(m);
attack_data_t *a = AttackData-ksq;
if(pos->check) return true;
if(MvPiece(m) == KING) return !is_attacked(pos, MvTo(m), xside);
if(a[from].may_attack & Q_MASK) {
int step = a[from].step, sq;
if(step == a[MvTo(m)].step) return true;
if(MvEP(m)) return ep_is_legal(pos, m);
for(sq = from + step; pos->board[sq] == EMPTY; sq += step);
if(sq == ksq) {
for(sq = from-step; pos->board[sq]==EMPTY; sq -= step);
if(ColourOfPiece(pos->board[sq]) == xside &&
PieceIsSlider(pos->board[sq]) &&
(a[sq].may_attack & PieceMask[pos->board[sq]]))
return false;
}
}
return true;
}
move_stack_t *generate_check_evasions(position_t *pos, move_stack_t *ms) {
int ksq, from, to, piece, type, tmp, step, rank, prom, pin, checks;
int side = pos->side, xside = side^1;
const int *ptr;
checks = pos->check;
ksq = KingSquare(pos, side);
// King moves:
tmp = (ksq<<7)|(KING<<17);
pos->board[ksq] = EMPTY;
for(ptr = Directions[KING]; *ptr; ptr++) {
to = ksq + (*ptr);
if((pos->board[to]==EMPTY || ColourOfPiece(pos->board[to]) == xside) &&
(!is_attacked(pos, to, xside)))
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
pos->board[ksq] = KingOfColour(side);
// Moves by other pieces are only possible if it is not a double check:
if(checks == 1) {
attack_data_t *a = AttackData-ksq;
int chsq = pos->check_sqs[0];
if(PieceIsSlider(pos->board[chsq])) {
int blockstep = a[chsq].step;
for(from = NextPiece(pos, ksq); from != PieceListEnd;
from = NextPiece(pos, from)) {
if(from > H8) continue;
pin = is_pinned(pos, from);
piece = pos->board[from]; type = TypeOfPiece(piece);
tmp = (from<<7)|(type<<17);
if(type == PAWN) {
step = PawnPush[side];
rank = PawnRank[side][from];
if(rank < RANK_7) {
if(!pin || abs(pin)==abs(step)) {
to = from+step;
if(pos->board[to]==EMPTY) {
if(a[to].step==blockstep && (to-ksq)*(to-chsq) < 0)
(ms++)->move = tmp|to;
to += step;
if(rank==RANK_2 && pos->board[to]==EMPTY &&
a[to].step==blockstep
&& (to-ksq)*(to-chsq) < 0)
(ms++)->move = tmp|to;
}
}
for(ptr = Directions[piece]; *ptr; ptr++) {
if(!pin || abs(pin)==abs(*ptr)) {
to = from + (*ptr);
if(ColourOfPiece(pos->board[to]) == xside
&& (to==chsq || (a[to].step==blockstep &&
(to-ksq)*(to-chsq) < 0)))
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
}
else {
to = from+step;
if(!pin || abs(pin)==abs(step))
if(pos->board[to]==EMPTY)
if(a[to].step==blockstep && (to-ksq)*(to-chsq) < 0)
for(prom = QUEEN; prom >= KNIGHT; prom--)
(ms++)->move=tmp|to|(prom<<14);
for(ptr = Directions[piece]; *ptr; ptr++) {
if(!pin || abs(pin)==abs(*ptr)) {
to = from + (*ptr);
if(ColourOfPiece(pos->board[to]) == xside
&& (to==chsq || (a[to].step==blockstep &&
(to-ksq)*(to-chsq) < 0))) {
if(PawnRank[side][to]==RANK_8) {
for(prom = QUEEN; prom >= KNIGHT; prom--)
(ms++)->move=tmp|to|(TypeOfPiece(pos->board[to])<<20)|(prom<<14);
}
else
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
}
}
}
else { // Not a pawn
for(ptr = Directions[piece]; *ptr; ptr++) {
if(pin && abs(pin) != abs(*ptr)) continue;
if(PieceIsSlider(piece)) {
to = from;
do {
to += (*ptr);
if((pos->board[to]==EMPTY ||
ColourOfPiece(pos->board[to]) == xside)
&& (to==chsq ||
(a[to].step==blockstep && (to-ksq)*(to-chsq) < 0)))
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
} while(pos->board[to] == EMPTY);
}
else {
to = from + (*ptr);
if((pos->board[to]==EMPTY||ColourOfPiece(pos->board[to])==xside)
&& (to==chsq ||
(a[to].step==blockstep && (to-ksq)*(to-chsq) < 0)))
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
}
}
}
else { // Checking piece is not a slider. Blocking moves impossible.
for(from = NextPiece(pos, ksq); from != PieceListEnd;
from = NextPiece(pos, from)) {
if(from > H8) continue;
pin = is_pinned(pos, from);
piece = pos->board[from]; type = TypeOfPiece(piece);
tmp = (from<<7)|(type<<17);
if(type == PAWN) {
for(ptr = Directions[piece]; *ptr; ptr++) {
if(!pin || abs(pin)==abs(*ptr)) {
to = from + (*ptr);
if(to==chsq) {
if(PawnRank[side][to]==RANK_8) {
for(prom = QUEEN; prom >= KNIGHT; prom--)
(ms++)->move=tmp|to|(TypeOfPiece(pos->board[to])<<20)|(prom<<14);
}
else (ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
}
}
else {
for(ptr = Directions[piece]; *ptr; ptr++) {
if(pin && abs(pin) != abs(*ptr)) continue;
if(PieceIsSlider(piece)) {
to = from;
do {
to += (*ptr);
if(to==chsq)
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
} while(pos->board[to]==EMPTY);
}
else {
to = from + (*ptr);
if(to==chsq)
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
}
}
}
// Finally, we have the ugly special case of en passant captures:
if(pos->ep_square)
for(ptr = Directions[PawnOfColour(xside)]; *ptr; ptr++) {
from = pos->ep_square + (*ptr);
if(pos->board[from] == PawnOfColour(side)) {
int legal;
undo_info_t u[1];
ms->move = (pos->ep_square)|(from<<7)|(PAWN<<17)|(PAWN<<20)|EPFlag;
make_move(pos, ms->move, u);
legal = !is_attacked(pos, KingSquare(pos, (pos->side)^1), pos->side);
unmake_move(pos, ms->move, u);
if(legal) ms++;
}
}
}
return ms;
}
move_stack_t *generate_moves(position_t *pos, move_stack_t *ms) {
int from, to, piece, type, tmp, step, rank, prom;
int side = pos->side, xside = side^1;
const int *ptr;
if(pos->check) {
ms = generate_check_evasions(pos, ms);
return ms;
}
for(from = KingSquare(pos, side); from != PieceListEnd;
from = NextPiece(pos, from)) {
if(from > H8) continue;
piece = pos->board[from]; type = TypeOfPiece(piece);
tmp = (from<<7)|(type<<17);
if(type == PAWN) {
step = PawnPush[side];
rank = PawnRank[side][from];
if(rank < RANK_7) {
if(pos->board[from+step] == EMPTY) {
(ms++)->move = tmp|(from+step);
if(rank == RANK_2 && pos->board[from+2*step] == EMPTY)
(ms++)->move = tmp|(from+2*step);
}
for(ptr = Directions[piece]; *ptr; ptr++) {
to = from + (*ptr);
if(ColourOfPiece(pos->board[to]) == xside)
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
else {
if(pos->board[from+step] == EMPTY)
for(prom = QUEEN; prom >= KNIGHT; prom--)
(ms++)->move = tmp|(from+step)|(prom<<14);
for(ptr = Directions[piece]; *ptr; ptr++) {
to = from + (*ptr);
if(ColourOfPiece(pos->board[to]) == xside) {
if(PawnRank[side][to] == RANK_8) {
for(prom = QUEEN; prom >= KNIGHT; prom--)
(ms++)->move =
tmp|to|(TypeOfPiece(pos->board[to])<<20)|(prom<<14);
}
else (ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
}
}
else {
for(ptr = Directions[piece]; *ptr; ptr++) {
if(PieceIsSlider(piece)) {
to = from;
do {
to += (*ptr);
if(pos->board[to]==EMPTY || ColourOfPiece(pos->board[to])==xside)
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
} while(pos->board[to]==EMPTY);
}
else {
to = from + (*ptr);
if(pos->board[to]==EMPTY || ColourOfPiece(pos->board[to])==xside)
(ms++)->move = tmp|to|(TypeOfPiece(pos->board[to])<<20);
}
}
}
}
// Finally, we have the ugly special cases of en passant captures and
// castling moves:
if(pos->ep_square)
for(ptr = Directions[PawnOfColour(xside)]; *ptr; ptr++) {
from = pos->ep_square + (*ptr);
if(pos->board[from] == PawnOfColour(side))
(ms++)->move =
(pos->ep_square)|(from<<7)|(PAWN<<17)|(PAWN<<20)|EPFlag;
}
if(!pos->check) {
if(CanCastleKingside(pos, side)) {
int initialKSQ = pos->initial_ksq+side*A8;
int initialKRSQ = pos->initial_krsq+side*A8;
int g1 = G1 + side*A8, f1 = F1 + side*A8;
int illegal = 0, sq;
for(sq = Min(initialKSQ, g1); sq <= Max(initialKSQ, g1); sq++)
if((sq != initialKSQ && sq != initialKRSQ && pos->board[sq] != EMPTY)
|| is_attacked(pos, sq, xside))
illegal = 1;
for(sq = Min(initialKRSQ, f1); sq <= Max(initialKRSQ, f1); sq++)