| #include <isl_config.h> |
| |
| #if !HAVE_DECL_FFS && !HAVE_DECL___BUILTIN_FFS && HAVE_DECL__BITSCANFORWARD |
| #include <intrin.h> |
| |
| /* Implementation of ffs in terms of _BitScanForward. |
| * |
| * ffs returns the position of the least significant bit set in i, |
| * with the least significant bit is position 1, or 0 if not bits are set. |
| * |
| * _BitScanForward returns 1 if mask is non-zero and sets index |
| * to the position of the least significant bit set in i, |
| * with the least significant bit is position 0. |
| */ |
| int isl_ffs(int i) |
| { |
| unsigned char non_zero; |
| unsigned long index, mask = i; |
| |
| non_zero = _BitScanForward(&index, mask); |
| |
| return non_zero ? 1 + index : 0; |
| } |
| #endif |
