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moves.c
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/*
Sjeng - a chess variants playing program
Copyright (C) 2000 Gian-Carlo Pascutto
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 2 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, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
File: moves.c
Purpose: functions used to generate & make moves
*/
#include "sjeng.h"
#include "extvars.h"
#include "protos.h"
unsigned long total_moves;
unsigned long total_movegens;
int numb_moves;
static move_s *genfor;
int fcaptures;
int gfrom;
int kingcap; /* break if we capture the king */
bool check_legal (move_s moves[], int m, int incheck) {
/* determines if a move made was legal. Checks to see if the player who
just moved castled through check, or is in check. If the move made
was illegal, returns FALSE, otherwise, returns TRUE. */
int castled = moves[m].castled;
int from = moves[m].from;
int target = moves[m].target;
int l;
if (Variant == Suicide) return TRUE;
/* check for castling moves: */
if (castled)
{
/* white kingside castling: */
if (castled == wck) {
if (is_attacked (30, 0)) return FALSE;
if (is_attacked (31, 0)) return FALSE;
if (is_attacked (32, 0)) return FALSE;
return TRUE;
}
/* white queenside castling: */
if (castled == wcq) {
if (is_attacked (30, 0)) return FALSE;
if (is_attacked (29, 0)) return FALSE;
if (is_attacked (28, 0)) return FALSE;
return TRUE;
}
/* black kingside castling: */
if (castled == bck) {
if (is_attacked (114, 1)) return FALSE;
if (is_attacked (115, 1)) return FALSE;
if (is_attacked (116, 1)) return FALSE;
return TRUE;
}
/* black queenside castling: */
if (castled == bcq) {
if (is_attacked (114, 1)) return FALSE;
if (is_attacked (113, 1)) return FALSE;
if (is_attacked (112, 1)) return FALSE;
return TRUE;
}
}
/* otherwise, just check on the kings: */
/* black king: */
/* the code in here checks whether a move could
* have put the king in check, if he was not in
* check before, if not, an early exit is taken */
else if (white_to_move&1)
{
if (!incheck)
{
if (moves[m].from == 0) return TRUE;
switch (moves[m].promoted ? bpawn : board[target])
{
case bpawn:
/* pawn moves, it can discover a rank or diagonal check
* a capture can also discover a file check */
if (moves[m].captured != npiece)
{
if (file(from) != file(bking_loc)
&& rank(from) != rank(bking_loc)
&& diagl(from) != diagl(bking_loc)
&& diagr(from) != diagr(bking_loc))
return TRUE;
}
else
{
if (rank(from) != rank(bking_loc)
&& diagl(from) != diagl(bking_loc)
&& diagr(from) != diagr(bking_loc))
return TRUE;
}
break;
case bknight:
/* discovers all */
if (file(from) != file(bking_loc)
&& rank(from) != rank(bking_loc)
&& diagl(from) != diagl(bking_loc)
&& diagr(from) != diagr(bking_loc))
return TRUE;
break;
case bbishop:
/* always discovers file and rank
* always discovers one diagonal */
if (file(from) != file(bking_loc)
&& rank(from) != rank(bking_loc))
{
if (diagl(from) == diagl(target))
{
/* stays on diag, can only uncover check on
* other diag */
if (diagr(from) != diagr(bking_loc))
return TRUE;
}
else
{
if (diagl(from) != diagl(bking_loc))
return TRUE;
}
}
break;
case brook:
/* discovers diagonal always */
/* one file or rank discovered */
if (diagr(from) != diagr(bking_loc)
&& diagl(from) != diagl(bking_loc))
{
/* rank move ? */
if(rank(from) == rank(target))
{
if (file(from) != file(bking_loc))
return TRUE;
}
else
{
/* file move */
if (rank(from) != rank(bking_loc))
return TRUE;
}
}
break;
case bqueen:
/* find out what move it was: ldiag/rdiag/file/rank*/
if (file(from) == file(target))
{
if (diagr(from) != diagr(bking_loc)
&& diagl(from) != diagl(bking_loc)
&& rank(from) != rank(bking_loc))
return TRUE;
}
else if (rank(from) == rank(target))
{
if (diagr(from) != diagr(bking_loc)
&& file(from) != file(bking_loc)
&& diagl(from) != diagl(bking_loc))
return TRUE;
}
else if (diagl(from) == diagl(target))
{
if (diagr(from) != diagr(bking_loc)
&& file(from) != file(bking_loc)
&& rank(from) != rank(bking_loc))
return TRUE;
}
else if (diagr(from) == diagr(target))
{
if (diagl(from) != diagl(bking_loc)
&& file(from) != file(bking_loc)
&& rank(from) != rank(bking_loc))
return TRUE;
}
break;
default:
break;
}
/* we got so far, we know there can only be some
* kind of possible discovering */
/* find out what */
/* we do not need to check for pawn, king or knightattacks,
* as they cannot be discovered*/
if (board[target] != bking)
{
if (file(from) == file(bking_loc))
{
if (bking_loc > from)
{
for (l = bking_loc-12; board[l] == npiece; l-=12);
if (board[l] == wrook || board[l] == wqueen) return FALSE;
}
else
{
for (l = bking_loc+12; board[l] == npiece; l+=12);
if (board[l] == wrook || board[l] == wqueen) return FALSE;
}
}
else if (rank(from) == rank(bking_loc))
{
if (bking_loc > from)
{
for (l = bking_loc-1; board[l] == npiece; l-=1);
if (board[l] == wrook || board[l] == wqueen) return FALSE;
}
else
{
for (l = bking_loc+1; board[l] == npiece; l+=1);
if (board[l] == wrook || board[l] == wqueen) return FALSE;
}
}
else if (diagl(from) == diagl(bking_loc))
{
if (bking_loc > from)
{
for (l = bking_loc-13; board[l] == npiece; l-=13);
if (board[l] == wbishop || board[l] == wqueen) return FALSE;
}
else
{
for (l = bking_loc+13; board[l] == npiece; l+=13);
if (board[l] == wbishop || board[l] == wqueen) return FALSE;
}
}
else if (diagr(from) == diagr(bking_loc))
{
if (bking_loc > from)
{
for (l = bking_loc-11; board[l] == npiece; l-=11);
if (board[l] == wbishop || board[l] == wqueen) return FALSE;
}
else
{
for (l = bking_loc+11; board[l] == npiece; l+=11);
if (board[l] == wbishop || board[l] == wqueen) return FALSE;
}
}
return TRUE;
}
}
if (is_attacked (bking_loc, 1)) return FALSE;
else return TRUE;
}
/* white king: */
else
{
if (!incheck)
{
if (moves[m].from == 0) return TRUE;
switch (moves[m].promoted ? wpawn : board[target])
{
case wpawn:
/* pawn moves, it can discover a rank or diagonal check
* a capture can also discover a file check */
if (moves[m].captured != npiece)
{
if (file(from) != file(wking_loc)
&& rank(from) != rank(wking_loc)
&& diagl(from) != diagl(wking_loc)
&& diagr(from) != diagr(wking_loc))
return TRUE;
}
else
{
if (rank(from) != rank(wking_loc)
&& diagl(from) != diagl(wking_loc)
&& diagr(from) != diagr(wking_loc))
return TRUE;
}
break;
case wknight:
/* discovers all */
if (file(from) != file(wking_loc)
&& rank(from) != rank(wking_loc)
&& diagl(from) != diagl(wking_loc)
&& diagr(from) != diagr(wking_loc))
return TRUE;
break;
case wbishop:
/* always discovers file and rank
* always discovers one diagonal */
if (file(from) != file(wking_loc)
&& rank(from) != rank(wking_loc))
{
if (diagl(from) == diagl(target))
{
/* stays on diag, can only uncover check on
* other diag */
if (diagr(from) != diagr(wking_loc))
return TRUE;
}
else
{
if (diagl(from) != diagl(wking_loc))
return TRUE;
}
}
break;
case wrook:
/* discovers diagonal always */
/* one file or rank discovered */
if (diagr(from) != diagr(wking_loc)
&& diagl(from) != diagl(wking_loc))
{
/* rank move ? */
if(rank(from) == rank(target))
{
if (file(from) != file(wking_loc))
return TRUE;
}
else
{
/* file move */
if (rank(from) != rank(wking_loc))
return TRUE;
}
}
break;
case wqueen:
/* find out what move it was: ldiag/rdiag/file/rank*/
if (file(from) == file(moves[m].target))
{
if (diagr(from) != diagr(wking_loc)
&& diagl(from) != diagl(wking_loc)
&& rank(from) != rank(wking_loc))
return TRUE;
}
else if (rank(from) == rank(target))
{
if (diagr(from) != diagr(wking_loc)
&& file(from) != file(wking_loc)
&& diagl(from) != diagl(wking_loc))
return TRUE;
}
else if (diagl(from) == diagl(target))
{
if (diagr(from) != diagr(wking_loc)
&& file(from) != file(wking_loc)
&& rank(from) != rank(wking_loc))
return TRUE;
}
else if (diagr(from) == diagr(target))
{
if (diagl(from) != diagl(wking_loc)
&& file(from) != file(wking_loc)
&& rank(from) != rank(wking_loc))
return TRUE;
}
break;
default:
break;
}
if (board[target] != wking)
{
if (file(from) == file(wking_loc))
{
if (wking_loc > from)
{
for (l = wking_loc-12; board[l] == npiece; l-=12);
if (board[l] == brook || board[l] == bqueen) return FALSE;
}
else
{
for (l = wking_loc+12; board[l] == npiece; l+=12);
if (board[l] == brook || board[l] == bqueen) return FALSE;
}
}
else if (rank(from) == rank(wking_loc))
{
if (wking_loc > from)
{
for (l = wking_loc-1; board[l] == npiece; l-=1);
if (board[l] == brook || board[l] == bqueen) return FALSE;
}
else
{
for (l = wking_loc+1; board[l] == npiece; l+=1);
if (board[l] == brook || board[l] == bqueen) return FALSE;
}
}
else if (diagl(from) == diagl(wking_loc))
{
if (wking_loc > from)
{
for (l = wking_loc-13; board[l] == npiece; l-=13);
if (board[l] == bbishop || board[l] == bqueen) return FALSE;
}
else
{
for (l = wking_loc+13; board[l] == npiece; l+=13);
if (board[l] == bbishop || board[l] == bqueen) return FALSE;
}
}
else if (diagr(from) == diagr(wking_loc))
{
if (wking_loc > from)
{
for (l = wking_loc-11; board[l] == npiece; l-=11);
if (board[l] == bbishop || board[l] == bqueen) return FALSE;
}
else
{
for (l = wking_loc+11; board[l] == npiece; l+=11);
if (board[l] == bbishop || board[l] == bqueen) return FALSE;
}
}
return TRUE;
}
}
if (is_attacked (wking_loc, 0)) return FALSE;
else return TRUE;
}
/* should never get here .. but just so it will compile :P */
return FALSE;
}
#define push_slide(t) if (board[(t)] != frame) push_slidE((t))
#define push_knight(t) if (board[(t)] != frame) push_knighT((t))
void gen (move_s moves[]) {
/* generate pseudo-legal moves, and place them in the moves array */
int from, a, j, i;
kingcap = FALSE;
numb_moves = 0;
genfor = &moves[0];
if (Variant == Suicide)
{
captures = FALSE;
fcaptures = FALSE;
};
restart:
/* generate white moves, if it is white to move: */
if (white_to_move) {
for (a = 1, j = 1;
(a <= piece_count)
&& (((Variant != Suicide) && !kingcap)
|| ((Variant == Suicide) && (fcaptures == captures)));
j++) {
i = pieces[j];
if (!i)
continue;
else
a++;
from = i;
gfrom = i;
switch (board[from]) {
case (wpawn):
/* pawn moves up one square: */
if (board[from+12] == npiece) {
/* only promotions when captures == TRUE */
if (rank (from) == 7 && ((Variant != Suicide) && (Variant != Losers))) {
push_pawn (from+12, FALSE);
}
else if (!captures) {
push_pawn (from+12, FALSE);
/* pawn moving up two squares on its first move: */
if (rank(from) == 2 && board[from+24] == npiece)
push_pawn_simple (from+24);
}
}
/* pawn capturing diagonally: */
if ((board[from+13]&1) == 0 && board[from+13] != frame)
push_pawn (from+13, FALSE);
/* pawn captruing diagonally: */
if ((board[from+11]&1) == 0 && board[from+11] != frame)
push_pawn (from+11, FALSE);
/* ep move: */
if (ep_square == from+13)
push_pawn (from+13, TRUE);
/* ep move: */
else if (ep_square == from+11)
push_pawn (from+11, TRUE);
break;
case (wknight):
/* use the knight offsets: */
push_knight (from-25);
push_knight (from-23);
push_knight (from-14);
push_knight (from-10);
push_knight (from+10);
push_knight (from+14);
push_knight (from+23);
push_knight (from+25);
break;
case (wbishop):
/* use the bishop offsets: */
push_slide (from-13);
push_slide (from-11);
push_slide (from+11);
push_slide (from+13);
break;
case (wrook):
/* use the rook offsets: */
push_slide (from-12);
push_slide (from-1);
push_slide (from+1);
push_slide (from+12);
break;
case (wqueen):
/* use the queen offsets: */
push_slide (from-13);
push_slide (from-12);
push_slide (from-11);
push_slide (from-1);
push_slide (from+1);
push_slide (from+11);
push_slide (from+12);
push_slide (from+13);
break;
case (wking):
/* use the king offsets for 'normal' moves: */
push_king (from-13);
push_king (from-12);
push_king (from-11);
push_king (from-1);
push_king (from+1);
push_king (from+11);
push_king (from+12);
push_king (from+13);
/* castling moves: */
if (from == 30 && !moved[30] && !captures && (Variant != Suicide || Giveaway == TRUE)) {
/* kingside: */
if (!moved[33] && board[33] == wrook)
if (board[31] == npiece && board[32] == npiece)
push_king_castle (from+2, wck);
/* queenside: */
if (!moved[26] && board[26] == wrook)
if (board[27] == npiece && board[28] == npiece
&& board[29] == npiece)
push_king_castle (from-2, wcq);
}
break;
default:
break;
}
}
}
/* generate black moves, if it is black to move: */
else {
for (a = 1, j = 1;
(a <= piece_count) &&
(((Variant != Suicide) && !kingcap)
|| ((Variant == Suicide) && (fcaptures == captures)))
; j++) {
i = pieces[j];
if (!i)
continue;
else
a++;
from = i;
gfrom = i;
switch (board[from]) {
case (bpawn):
/* pawn moves up one square: */
if (board[from-12] == npiece) {
/* only promotions when captures == TRUE */
if (rank (from) == 2 && ((Variant != Suicide) && (Variant != Losers))) {
push_pawn (from-12, FALSE);
}
else if (!captures) {
push_pawn (from-12, FALSE);
/* pawn moving up two squares on its first move: */
if (rank(from) == 7 && board[from-24] == npiece)
push_pawn_simple (from-24);
}
};
/* pawn capturing diagonally: */
if ((board[from-13]&1) == 1 && board[from-13] != npiece)
push_pawn (from-13, FALSE);
/* pawn capturing diagonally: */
if ((board[from-11]&1) == 1 && board[from-11] != npiece)
push_pawn (from-11, FALSE);
/* ep move: */
if (ep_square == from-13)
push_pawn (from-13, TRUE);
/* ep move: */
else if (ep_square == from-11)
push_pawn (from-11, TRUE);
break;
case (bknight):
/* use the knight offsets: */
push_knight (from-25);
push_knight (from-23);
push_knight (from-14);
push_knight (from-10);
push_knight (from+10);
push_knight (from+14);
push_knight (from+23);
push_knight (from+25);
break;
case (bbishop):
/* use the bishop offsets: */
push_slide (from-13);
push_slide (from-11);
push_slide (from+11);
push_slide (from+13);
break;
case (brook):
/* use the rook offsets: */
push_slide (from-12);
push_slide (from-1);
push_slide (from+1);
push_slide (from+12);
break;
case (bqueen):
/* use the queen offsets: */
push_slide (from-13);
push_slide (from-12);
push_slide (from-11);
push_slide (from-1);
push_slide (from+1);
push_slide (from+11);
push_slide (from+12);
push_slide (from+13);
break;
case (bking):
/* use the king offsets for 'normal' moves: */
push_king (from-13);
push_king (from-12);
push_king (from-11);
push_king (from-1);
push_king (from+1);
push_king (from+11);
push_king (from+12);
push_king (from+13);
/* castling moves: */
if (from == 114 && !moved[114] && !captures && (Variant != Suicide || Giveaway == TRUE)) {
/* kingside: */
if (!moved[117] && board[117] == brook)
if (board[115] == npiece && board[116] == npiece)
push_king_castle (from+2, bck);
/* queenside: */
if (!moved[110] && board[110] == brook)
if (board[111] == npiece && board[112] == npiece
&& board[113] == npiece)
push_king_castle (from-2, bcq);
}
break;
default:
break;
}
}
}
if (((Variant == Crazyhouse) || (Variant == Bughouse)) && !captures && !kingcap)
{
if (white_to_move &&
(holding[WHITE][wpawn] || holding[WHITE][wknight]
|| holding[WHITE][wbishop] || holding[WHITE][wqueen]
|| holding[WHITE][wrook]))
{
for (from = 26; from < 118; from++)
{
gfrom = from;
switch (board[from])
{
case (frame):
from += 3;
continue;
case (npiece):
if(holding[WHITE][wpawn])
{
if ((rank(from) != 8) && (rank(from) != 1))
{
try_drop(wpawn);
}
}
if(holding[WHITE][wknight])
{
try_drop(wknight);
}
if(holding[WHITE][wbishop])
{
try_drop(wbishop);
}
if(holding[WHITE][wrook])
{
try_drop(wrook);
}
if(holding[WHITE][wqueen])
{
try_drop(wqueen);
}
};
}
}
else if (!white_to_move &&
(holding[BLACK][bpawn] || holding[BLACK][bknight]
|| holding[BLACK][bbishop] || holding[BLACK][bqueen]
|| holding[BLACK][brook]))
{
for (from = 26; from < 118; from++)
{
gfrom = from;
switch (board[from])
{
case (frame):
from += 3;
continue;
case (npiece):
if(holding[BLACK][bpawn])
{
if ((rank(from) != 8) && (rank(from) != 1))
{
try_drop(bpawn);
}
}
if(holding[BLACK][bknight])
{
try_drop(bknight);
}
if(holding[BLACK][bbishop])
{
try_drop(bbishop);
}
if(holding[BLACK][brook])
{
try_drop(brook);
}
if(holding[BLACK][bqueen])
{
try_drop(bqueen);
}
};
};
}
}
if ((Variant == Suicide) && fcaptures == TRUE && captures == FALSE)
{
captures = TRUE;
numb_moves = 0;
goto restart;
}
if (Variant == Suicide) kingcap = FALSE;
}
bool in_check (void) {
/* return true if the side to move is in check: */
if (Variant == Suicide) return FALSE;
if (white_to_move == 1) {
if (is_attacked (wking_loc, 0)) {
return TRUE;
}
}
else {
if (is_attacked (bking_loc, 1)) {
return TRUE;
}
}
return FALSE;
}
bool f_in_check(move_s moves[], int m)
{
int target = moves[m].target;
int from = moves[m].from;
int l;
static const int knight_o[8] = {10, -10, 14, -14, 23, -23, 25, -25};
if (Variant == Suicide) return FALSE;
if (white_to_move == 1)
{
/* is white king attacked */
/* we are certain the king is not in check already,
* as we would capture him in our ply */
/* thus, we need to check if our move could possibly
* put the king in check */
/* this can either be a direct check, or a discover */
switch (board[target])
{
case bpawn:
if (board[target-11] == wking || board[target-13] == wking) return TRUE;
break;
case bbishop:
if (diagl(target) == diagl(wking_loc))
{
/* possible left diag check */
if (wking_loc < target)
{
for (l = wking_loc+13; board[l] == npiece; l +=13);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-13; board[l] == npiece; l -=13);
if (l == target) return TRUE;
}
}
else if (diagr(target) == diagr(wking_loc))
{
if (wking_loc < target)
{
for (l = wking_loc+11; board[l] == npiece; l +=11);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-11; board[l] == npiece; l -=11);
if (l == target) return TRUE;
}
}
break;
case brook:
if (file(target) == file(wking_loc))
{
if (wking_loc < target)
{
for (l = wking_loc+12; board[l] == npiece; l +=12);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-12; board[l] == npiece; l -=12);
if (l == target) return TRUE;
}
}
else if (rank(target) == rank(wking_loc))
{
if (wking_loc < target)
{
for (l = wking_loc+1; board[l] == npiece; l++);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-1; board[l] == npiece; l--);
if (l == target) return TRUE;
}
}
break;
case bknight:
for (l = 0; l < 8; l++)
if ((wking_loc + knight_o[l]) == target) return TRUE;
break;
case bqueen:
if (file(target) == file(wking_loc))
{
if (wking_loc < target)
{
for (l = wking_loc+12; board[l] == npiece; l +=12);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-12; board[l] == npiece; l -=12);
if (l == target) return TRUE;
}
}
else if (rank(target) == rank(wking_loc))
{
if (wking_loc < target)
{
for (l = wking_loc+1; board[l] == npiece; l +=1);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-1; board[l] == npiece; l -=1);
if (l == target) return TRUE;
}
}
else if (diagl(target) == diagl(wking_loc))
{
if (wking_loc < target)
{
for (l = wking_loc+13; board[l] == npiece; l +=13);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-13; board[l] == npiece; l -=13);
if (l == target) return TRUE;
}
}
else if (diagr(target) == diagr(wking_loc))
{
if (wking_loc < target)
{
for (l = wking_loc+11; board[l] == npiece; l +=11);
if (l == target) return TRUE;
}
else
{
for (l = wking_loc-11; board[l] == npiece; l -=11);
if (l == target) return TRUE;
}
}
break;
case bking:
/* can only discover checks */
/* castling is tricky */
if (moves[m].castled)
{
if (is_attacked (wking_loc, 0))
return TRUE;
else
return FALSE;
}
break;
}
/* drop move can never discover check */
if (from == 0) return FALSE;
/* this checks for discovered checks */
if (rank(from) == rank(wking_loc))
{
if (wking_loc > from)
{
for (l = wking_loc-1; board[l] == npiece; l--);
if (board[l] == brook || board[l] == bqueen) return TRUE;
}
else
{
for (l = wking_loc+1; board[l] == npiece; l++);
if (board[l] == brook || board[l] == bqueen) return TRUE;
}
}
else if (file(from) == file(wking_loc))
{
if (wking_loc > from)
{
for (l = wking_loc-12; board[l] == npiece; l-=12);
if (board[l] == brook || board[l] == bqueen) return TRUE;
}
else
{
for (l = wking_loc+12; board[l] == npiece; l+=12);
if (board[l] == brook || board[l] == bqueen) return TRUE;
}
}
else if (diagl(from) == diagl(wking_loc))
{
if (wking_loc > from)
{
for (l = wking_loc-13; board[l] == npiece; l-=13);
if (board[l] == bbishop || board[l] == bqueen) return TRUE;