include/asm-generic/bitops/fls.h

   1 #ifndef _ASM_GENERIC_BITOPS_FLS_H_
   2 #define _ASM_GENERIC_BITOPS_FLS_H_
   3
   4 /**
   5  * fls - find last (most-significant) bit set
   6  * @x: the word to search
   7  *
   8  * This is defined the same way as ffs.
   9  * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
  10  */
  11
  12 static __always_inline int fls(int x)
  13 {
  14         int r = 32;
  15
  16         if (!x)
  17                 return 0;
  18         if (!(x & 0xffff0000u)) {
  19                 x <<= 16;
  20                 r -= 16;
  21         }
  22         if (!(x & 0xff000000u)) {
  23                 x <<= 8;
  24                 r -= 8;
  25         }
  26         if (!(x & 0xf0000000u)) {
  27                 x <<= 4;
  28                 r -= 4;
  29         }
  30         if (!(x & 0xc0000000u)) {
  31                 x <<= 2;
  32                 r -= 2;
  33         }
  34         if (!(x & 0x80000000u)) {
  35                 x <<= 1;
  36                 r -= 1;
  37         }
  38         return r;
  39 }
  40
  41 #endif /* _ASM_GENERIC_BITOPS_FLS_H_ */