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      1  1.1  mrg #include <isl_config.h>
      2  1.1  mrg 
      3  1.1  mrg #if !HAVE_DECL_FFS && !HAVE_DECL___BUILTIN_FFS && HAVE_DECL__BITSCANFORWARD
      4  1.1  mrg #include <intrin.h>
      5  1.1  mrg 
      6  1.1  mrg /* Implementation of ffs in terms of _BitScanForward.
      7  1.1  mrg  *
      8  1.1  mrg  * ffs returns the position of the least significant bit set in i,
      9  1.1  mrg  * with the least significant bit is position 1, or 0 if not bits are set.
     10  1.1  mrg  *
     11  1.1  mrg  * _BitScanForward returns 1 if mask is non-zero and sets index
     12  1.1  mrg  * to the position of the least significant bit set in i,
     13  1.1  mrg  * with the least significant bit is position 0.
     14  1.1  mrg  */
     15  1.1  mrg int isl_ffs(int i)
     16  1.1  mrg {
     17  1.1  mrg 	unsigned char non_zero;
     18  1.1  mrg 	unsigned long index, mask = i;
     19  1.1  mrg 
     20  1.1  mrg 	non_zero = _BitScanForward(&index, mask);
     21  1.1  mrg 
     22  1.1  mrg 	return non_zero ? 1 + index : 0;
     23  1.1  mrg }
     24  1.1  mrg #endif
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