1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
#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
|
