1 #ifndef _ASM_GENERIC_BITOPS___FFS_H_ 2 #define _ASM_GENERIC_BITOPS___FFS_H_ 3 4 #include <asm/types.h> 5 6 /** 7 * __ffs - find first bit in word. 8 * @word: The word to search 9 * 10 * Undefined if no bit exists, so code should check against 0 first. 11 */ __ffs(unsigned long word)12static __always_inline unsigned long __ffs(unsigned long word) 13 { 14 int num = 0; 15 16 #if BITS_PER_LONG == 64 17 if ((word & 0xffffffff) == 0) { 18 num += 32; 19 word >>= 32; 20 } 21 #endif 22 if ((word & 0xffff) == 0) { 23 num += 16; 24 word >>= 16; 25 } 26 if ((word & 0xff) == 0) { 27 num += 8; 28 word >>= 8; 29 } 30 if ((word & 0xf) == 0) { 31 num += 4; 32 word >>= 4; 33 } 34 if ((word & 0x3) == 0) { 35 num += 2; 36 word >>= 2; 37 } 38 if ((word & 0x1) == 0) 39 num += 1; 40 return num; 41 } 42 43 #endif /* _ASM_GENERIC_BITOPS___FFS_H_ */ 44