LXR linux/include/asm-generic/bitops/fls64.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_GENERIC_BITOPS_FLS64_H_
   3#define _ASM_GENERIC_BITOPS_FLS64_H_
   4
   5#include <asm/types.h>
   6
   7/**
   8 * fls64 - find last set bit in a 64-bit word
   9 * @x: the word to search
  10 *
  11 * This is defined in a similar way as the libc and compiler builtin
  12 * ffsll, but returns the position of the most significant set bit.
  13 *
  14 * fls64(value) returns 0 if value is 0 or the position of the last
  15 * set bit if value is nonzero. The last (most significant) bit is
  16 * at position 64.
  17 */
  18#if BITS_PER_LONG == 32
  19static __always_inline int fls64(__u64 x)
  20{
  21        __u32 h = x >> 32;
  22        if (h)
  23                return fls(h) + 32;
  24        return fls(x);
  25}
  26#elif BITS_PER_LONG == 64
  27static __always_inline int fls64(__u64 x)
  28{
  29        if (x == 0)
  30                return 0;
  31        return __fls(x) + 1;
  32}
  33#else
  34#error BITS_PER_LONG not 32 or 64
  35#endif
  36
  37#endif /* _ASM_GENERIC_BITOPS_FLS64_H_ */
  38