1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ 3 #define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ 4 5 #include <asm/types.h> 6 #include <asm/bitsperlong.h> 7 8 /** 9 * __ffs - find first bit in word. 10 * @word: The word to search 11 * 12 * Undefined if no bit exists, so code should check against 0 first. 13 */ 14 static __always_inline unsigned long __ffs(unsigned long word) 15 { 16 int num = 0; 17 18 #if __BITS_PER_LONG == 64 19 if ((word & 0xffffffff) == 0) { 20 num += 32; 21 word >>= 32; 22 } 23 #endif 24 if ((word & 0xffff) == 0) { 25 num += 16; 26 word >>= 16; 27 } 28 if ((word & 0xff) == 0) { 29 num += 8; 30 word >>= 8; 31 } 32 if ((word & 0xf) == 0) { 33 num += 4; 34 word >>= 4; 35 } 36 if ((word & 0x3) == 0) { 37 num += 2; 38 word >>= 2; 39 } 40 if ((word & 0x1) == 0) 41 num += 1; 42 return num; 43 } 44 45 #endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ */ 46