// Use type-punning
union b_union {
- Bitboard b;
+ Bitboard dummy;
struct {
#if defined (BIGENDIAN)
uint32_t h;
uint32_t l;
uint32_t h;
#endif
- } dw;
+ } b;
};
-Square pop_1st_bit(Bitboard* bb) {
-
- b_union u;
- Square ret;
+Square pop_1st_bit(Bitboard* b) {
- u.b = *bb;
+ const b_union u = *((b_union*)b);
- if (u.dw.l)
+ if (u.b.l)
{
- ret = Square(BSFTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783A9B23) >> 26]);
- u.dw.l &= (u.dw.l - 1);
- *bb = u.b;
- return ret;
+ ((b_union*)b)->b.l = u.b.l & (u.b.l - 1);
+ return Square(BSFTable[((u.b.l ^ (u.b.l - 1)) * 0x783A9B23) >> 26]);
}
- ret = Square(BSFTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783A9B23) >> 26]);
- u.dw.h &= (u.dw.h - 1);
- *bb = u.b;
- return ret;
+
+ ((b_union*)b)->b.h = u.b.h & (u.b.h - 1);
+ return Square(BSFTable[((~(u.b.h ^ (u.b.h - 1))) * 0x783A9B23) >> 26]);
}
-#endif // !defined(USE_BSFQ)
+Square last_1(Bitboard b) {
+
+ int result = 0;
+ if (b > 0xFFFFFFFF)
+ {
+ b >>= 32;
+ result = 32;
+ }
+
+ if (b > 0xFFFF)
+ {
+ b >>= 16;
+ result += 16;
+ }
+
+ if (b > 0xFF)
+ {
+ b >>= 8;
+ result += 8;
+ }
+
+ return Square(result + BitCount8Bit[b]);
+}
+
+#endif // !defined(USE_BSFQ)
/// bitboards_init() initializes various bitboard arrays. It is called during
/// program initialization.