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 */ 13 static __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