LXR linux/tools/include/asm-generic/bitops/_

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_GENERIC_BITOPS___FLS_H_
   3#define _ASM_GENERIC_BITOPS___FLS_H_
   4
   5#include <asm/types.h>
   6
   7/**
   8 * __fls - find last (most-significant) set bit in a long word
   9 * @word: the word to search
  10 *
  11 * Undefined if no set bit exists, so code should check against 0 first.
  12 */
  13static __always_inline unsigned long __fls(unsigned long word)
  14{
  15        int num = BITS_PER_LONG - 1;
  16
  17#if BITS_PER_LONG == 64
  18        if (!(word & (~0ul << 32))) {
  19                num -= 32;
  20                word <<= 32;
  21        }
  22#endif
  23        if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
  24                num -= 16;
  25                word <<= 16;
  26        }
  27        if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
  28                num -= 8;
  29                word <<= 8;
  30        }
  31        if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
  32                num -= 4;
  33                word <<= 4;
  34        }
  35        if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
  36                num -= 2;
  37                word <<= 2;
  38        }
  39        if (!(word & (~0ul << (BITS_PER_LONG-1))))
  40                num -= 1;
  41        return num;
  42}
  43
  44#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */
  45