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movegen.c
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/*
This File is part of Boo's Chess Engine
Copyright 2001 by Christopher Bowron
*/
#include <stdlib.h>
#include "bce.h"
void getmovese(int f, int r, int c);
void getmovesp(int f, int r, int c);
void getmovesn(int f, int r, int c);
void getmovesb(int f, int r, int c);
void getmovesr(int f, int r, int c);
void getmovesq(int f, int r, int c);
void getmovesk(int f, int r, int c);
void getmovesk_nocastles(int f, int r, int c);
void genattackse(int f, int r, int c);
void genattacksp(int f, int r, int c);
void genattacksn(int f, int r, int c);
void genattacksb(int f, int r, int c);
void genattacksr(int f, int r, int c);
void genattacksq(int f, int r, int c);
void genattacksk(int f, int r, int c);
void gensliderattacks(int f, int r, int df, int dr, int color);
typedef void (*generator)(int, int, int);
move_and_score move_stack[8096],*move_sp;
inline void pushmove(move m)
{
move_sp->m = m;
move_sp ++;
}
inline move popmove()
{
move_sp--;
return move_sp->m;
}
generator attackgens[]=
{
genattackse,
genattacksp,
genattacksn,
genattacksb,
genattacksr,
genattacksq,
genattacksk
};
generator generators[]=
{
getmovese,
getmovesp,
getmovesn,
getmovesb,
getmovesr,
getmovesq,
getmovesk
};
void genmoves()
{
int f,r;
int col = tomove();
for (f=0;f<8;f++)
{
for (r=0;r<8;r++)
{
chesspiece p = getpiece(f,r);
if (p && (chesspiececolor(p) == col))
{
int v = chesspiecevalue(p);
generators[v](f,r,col);
}
}
}
}
void genmoves_nocastles()
{
int f,r;
int col = tomove();
for (f=0;f<8;f++)
{
for (r=0;r<8;r++)
{
chesspiece p = getpiece(f,r);
if (p && (chesspiececolor(p) == col))
{
int v = chesspiecevalue(p);
if (v==king)
{
getmovesk_nocastles(f,r,col);
}
else
{
generators[v](f,r,col);
}
}
}
}
}
void genattacks()
{
int f,r;
int col = tomove();
for (f=0;f<8;f++)
{
for (r=0;r<8;r++)
{
chesspiece p = getpiece(f,r);
if (p && (chesspiececolor(p)==col))
{
int v;
v = chesspiecevalue(p);
attackgens[v](f,r,col);
}
}
}
}
void getmovese(int f, int r, int c)
{
/* do nothing */
}
void getsliders(int f, int r, int df, int dr, int color)
{
square s1 = SQ(f,r);
chesspiece p;
for (;;)
{
f += df;
r += dr;
if (offboardp(f,r)) return;
p = getpiece(f,r);
if (p == empty)
pushmove(MV(s1, SQ(f,r)));
else if (chesspiececolor(p)==color)
return;
else
{
pushmove(MV(s1, SQ(f,r)));
return;
}
}
}
inline void push_pawn_move(square start, square end)
{
if ((R(end) == 7)||(R(end)==0))
{
pushmove(MV_PR(start, end, queen));
pushmove(MV_PR(start, end, knight));
pushmove(MV_PR(start, end, rook));
pushmove(MV_PR(start, end, bishop));
}
else
{
pushmove(MV(start,end));
}
}
void getmovesp(int f, int r, int c)
{
int forward = dir(c);
square loc = SQ(f,r);
r += forward;
// captures
if ((f<7) && (oppenentp (f+1, r, c)))
{
push_pawn_move(loc, SQ(1+f, r));
}
if ((f>0) && (oppenentp (f-1, r, c)))
{
push_pawn_move(loc, SQ(f-1, r));
}
if (emptyp(f,r))
{
int startrank = ((c == WHITE) ? 2 : 5);
push_pawn_move(loc, SQ(f,r));
/* can go two on first move */
if ((r == startrank)&&(emptyp(f,r+forward)))
pushmove(MV(loc, SQ(f,r+forward)));
}
// if last move was double push we can possibly do an en passante
if (doublepushp())
{
square start;
square end;
move m;
m = lastmove();
start = FR(m);
end = TO(m);
r -= forward; /* restore to original r */
if (R(end) == r)
{
if (((f+1) == F(start))||
((f-1) == F(start)))
pushmove(MV(loc, SQ(F(start),forward+r)));
}
}
}
static int df[] = { 1, 1, -1, -1, 2, -2, 2, -2 };
static int dr[] = { 2, -2, 2, -2, 1, 1, -1, -1 };
void getmovesn(int f, int r, int c)
{
int i, nf, nr;
int o;
chesspiece p;
square s1;
s1 = SQ(f,r);
o = opp(c);
for (i=0;i<8;i++)
{
nf = f+df[i];
nr = r+dr[i];
if (offboardp(nf,nr))
continue;
p = getpiece(nf, nr);
if (!p || (c != chesspiececolor(p)))
{
pushmove(MV(s1, SQ(nf, nr)));
}
}
}
void getmovesb(int f, int r, int c)
{
getsliders(f,r,1,1,c);
getsliders(f,r,1,-1,c);
getsliders(f,r,-1,1,c);
getsliders(f,r,-1,-1,c);
}
void getmovesr(int f, int r, int c)
{
getsliders(f,r, 1, 0,c);
getsliders(f,r, 0, 1,c);
getsliders(f,r,-1, 0,c);
getsliders(f,r, 0,-1,c);
}
void getmovesq(int f, int r, int c)
{
getmovesr(f,r,c);
getmovesb(f,r,c);
}
// test whether this castling is allowed
int castling_test(struct castling_struct *info)
{
// bit test for castling right
if ((board->flags & info->bittest) == 0)
{
return 0;
}
square ks = info->king_start;
square rs = info->rook_start;
int i;
int increment = abs(B1-A1);
// test for empty squres in between rook and king
for (i=min(ks,rs)+increment;i<max(rs,ks);i+=increment)
{
if (getpiece__(i)) return 0;
}
// end square for rook must be empty or be the king
chesspiece p = getpiece__(info->rook_end);
if (p && VALUE(p) != king)
return 0;
square ke = info->king_end;
// test for attacks on king from start to end inclusive
// genmoves_nocastles so that we do not recurse forever
switch_sides();
move_and_score *restore_sp = move_sp;
genmoves_nocastles();
while (move_sp>restore_sp)
{
move m = popmove();
int i_min = min(ke,ks);
int i_max = max(ke,ks);
for (i=i_min;i<=i_max;i+=increment)
{
if (TO(m) == i)
{
move_sp = restore_sp;
switch_sides();
return 0;
}
}
}
switch_sides();
return 1;
}
void getmovesk_nocastles(int f, int r, int c)
{
int df, dr, nf, nr;
int o;
chesspiece p;
square s1 = SQ(f,r);
o = opp(c);
for (df=-1;df<2;df++)
for (dr=-1;dr<2;dr++)
{
if (!df && !dr) continue;
nf = f+df;
nr = r+dr;
p = getpiece(nf, nr);
if (!offboardp(nf, nr) && (!p || (c != chesspiececolor(p))))
pushmove(MV(s1, SQ(nf, nr)));
}
}
void getmovesk(int f, int r, int c)
{
getmovesk_nocastles(f,r,c);
if (c==WHITE)
{
if (castling_test(&g_castling_info[WHITE][0]))
{
pushmove(MV_CA(g_castling_info[WHITE][0].king_start,
g_castling_info[WHITE][0].king_end));
}
else if (castling_test(&g_castling_info[WHITE][1]))
{
pushmove(MV_CA(g_castling_info[WHITE][1].king_start,
g_castling_info[WHITE][1].king_end));
}
}
else
{
if (castling_test(&g_castling_info[BLACK][0]))
{
pushmove(MV_CA(g_castling_info[BLACK][0].king_start,
g_castling_info[BLACK][0].king_end));
}
else if (castling_test(&g_castling_info[BLACK][1]))
{
pushmove(MV_CA(g_castling_info[BLACK][1].king_start,
g_castling_info[BLACK][1].king_end));
}
}
}
/* generate pawn captures */
void genattacksp(int f, int r, int c)
{
int forward = dir(c);
square loc = SQ(f,r);
r += forward;
if (f<7)
{
chesspiece p = getpiece(f+1, r);
if (p&&chesspiececolor(p)!=c)
push_pawn_move(loc, SQ(f+1, r));
}
if (f>0)
{
chesspiece p = getpiece(f-1,r);
if (p&&chesspiececolor(p)!=c)
push_pawn_move(loc, SQ(f-1, r));
}
/* get en passante */
if (doublepushp())
{
square start;
square end;
move m;
m = lastmove();
start = FR(m);
end = TO(m);
r -= forward; /* restore to original r */
if (R(end) == r)
{
if (((f+1) == F(start))||
((f-1) == F(start)))
pushmove(MV(loc, SQ(F(start),forward+r)));
}
}
}
void genattacksn(int f, int r, int c)
{
int i, nf, nr;
int o;
square s1 = SQ(f,r);
chesspiece p;
o = opp(c);
for (i=0;i<8;i++)
{
nf = f+df[i];
nr = r+dr[i];
if (offboardp(nf,nr))
continue;
p = getpiece(nf, nr);
if (p && (c != chesspiececolor(p)))
{
pushmove(MV(s1, SQ(nf, nr)));
}
}
}
void genattacksb(int f, int r, int c)
{
gensliderattacks(f,r,1,1,c);
gensliderattacks(f,r,1,-1,c);
gensliderattacks(f,r,-1,1,c);
gensliderattacks(f,r,-1,-1,c);
}
void genattacksr(int f, int r, int c)
{
gensliderattacks(f,r, 1, 0,c);
gensliderattacks(f,r, 0, 1,c);
gensliderattacks(f,r,-1, 0,c);
gensliderattacks(f,r, 0,-1,c);
}
void genattacksq(int f, int r, int c)
{
genattacksb(f,r,c);
genattacksr(f,r,c);
}
void genattacksk(int f, int r, int c)
{
int df, dr, nf, nr;
int o;
chesspiece p;
square s1 = SQ(f,r);
o = opp(c);
for (df=-1;df<2;df++)
for (dr=-1;dr<2;dr++)
{
if (!df && !dr) continue;
nf = f+df;
nr = r+dr;
if (!offboardp(nf, nr)&&
(p = getpiece(nf, nr))&&
(c != chesspiececolor(p)))
pushmove(MV(s1, SQ(nf, nr)));
}
}
void genattackse(int f, int r, int c)
{
/* do nothing */
}
void gensliderattacks(int f, int r, int df, int dr, int color)
{
chesspiece p;
square s1=SQ(f,r);
for (;;)
{
f += df;
r += dr;
if (offboardp (f,r)) return;
p = getpiece(f,r);
if (p)
{
if (chesspiececolor(p) != color)
{
pushmove(MV(s1, SQ(f,r)));
}
return;
}
}
}