include/asm-generic/bitops/fls64.h

   1 #ifndef _ASM_GENERIC_BITOPS_FLS64_H_
   2 #define _ASM_GENERIC_BITOPS_FLS64_H_
   3
   4 #include <asm/types.h>
   5
   6 /**
   7  * fls64 - find last set bit in a 64-bit word
   8  * @x: the word to search
   9  *
  10  * This is defined in a similar way as the libc and compiler builtin
  11  * ffsll, but returns the position of the most significant set bit.
  12  *
  13  * fls64(value) returns 0 if value is 0 or the position of the last
  14  * set bit if value is nonzero. The last (most significant) bit is
  15  * at position 64.
  16  */
  17 #if BITS_PER_LONG == 32
  18 static __always_inline int fls64(__u64 x)
  19 {
  20         __u32 h = x >> 32;
  21         if (h)
  22                 return fls(h) + 32;
  23         return fls(x);
  24 }
  25 #elif BITS_PER_LONG == 64
  26 static __always_inline int fls64(__u64 x)
  27 {
  28         if (x == 0)
  29                 return 0;
  30         return __fls(x) + 1;
  31 }
  32 #else
  33 #error BITS_PER_LONG not 32 or 64
  34 #endif
  35
  36 #endif /* _ASM_GENERIC_BITOPS_FLS64_H_ */