Avoid a 64 bit load using a pointer. It saves a couple of push/pop
instructions so advantage is only theorical, but anyway we use
pop_1st_bit() as a reference implementation for 32 bit systems so
we keep it more for documentation purposes then for other reasons.
Idea of pointer is of Eric Mullins.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Square pop_1st_bit(Bitboard* bb) {
- b_union u;
+ b_union* u;
Square ret;
- u.b = *bb;
+ u = (b_union*)bb;
- if (u.dw.l)
+ if (u->dw.l)
{
- ret = Square(BitTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783a9b23) >> 26]);
- u.dw.l &= (u.dw.l - 1);
- *bb = u.b;
+ ret = Square(BitTable[((u->dw.l ^ (u->dw.l - 1)) * 0x783a9b23) >> 26]);
+ u->dw.l &= (u->dw.l - 1);
return ret;
}
- ret = Square(BitTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783a9b23) >> 26]);
- u.dw.h &= (u.dw.h - 1);
- *bb = u.b;
+ ret = Square(BitTable[((~(u->dw.h ^ (u->dw.h - 1))) * 0x783a9b23) >> 26]);
+ u->dw.h &= (u->dw.h - 1);
return ret;
}