49 lines · c
1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _ASM_GENERIC_BITOPS___FFS_H_3#define _ASM_GENERIC_BITOPS___FFS_H_4 5#include <asm/types.h>6 7/**8 * generic___ffs - find first bit in word.9 * @word: The word to search10 *11 * Undefined if no bit exists, so code should check against 0 first.12 */13static __always_inline unsigned int generic___ffs(unsigned long word)14{15 unsigned int num = 0;16 17#if BITS_PER_LONG == 6418 if ((word & 0xffffffff) == 0) {19 num += 32;20 word >>= 32;21 }22#endif23 if ((word & 0xffff) == 0) {24 num += 16;25 word >>= 16;26 }27 if ((word & 0xff) == 0) {28 num += 8;29 word >>= 8;30 }31 if ((word & 0xf) == 0) {32 num += 4;33 word >>= 4;34 }35 if ((word & 0x3) == 0) {36 num += 2;37 word >>= 2;38 }39 if ((word & 0x1) == 0)40 num += 1;41 return num;42}43 44#ifndef __HAVE_ARCH___FFS45#define __ffs(word) generic___ffs(word)46#endif47 48#endif /* _ASM_GENERIC_BITOPS___FFS_H_ */49