1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */ 2*4882a593Smuzhiyun #ifndef _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ 3*4882a593Smuzhiyun #define _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ 4*4882a593Smuzhiyun 5*4882a593Smuzhiyun #include <asm/types.h> 6*4882a593Smuzhiyun #include <asm/bitsperlong.h> 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun /** 9*4882a593Smuzhiyun * __ffs - find first bit in word. 10*4882a593Smuzhiyun * @word: The word to search 11*4882a593Smuzhiyun * 12*4882a593Smuzhiyun * Undefined if no bit exists, so code should check against 0 first. 13*4882a593Smuzhiyun */ __ffs(unsigned long word)14*4882a593Smuzhiyunstatic __always_inline unsigned long __ffs(unsigned long word) 15*4882a593Smuzhiyun { 16*4882a593Smuzhiyun int num = 0; 17*4882a593Smuzhiyun 18*4882a593Smuzhiyun #if __BITS_PER_LONG == 64 19*4882a593Smuzhiyun if ((word & 0xffffffff) == 0) { 20*4882a593Smuzhiyun num += 32; 21*4882a593Smuzhiyun word >>= 32; 22*4882a593Smuzhiyun } 23*4882a593Smuzhiyun #endif 24*4882a593Smuzhiyun if ((word & 0xffff) == 0) { 25*4882a593Smuzhiyun num += 16; 26*4882a593Smuzhiyun word >>= 16; 27*4882a593Smuzhiyun } 28*4882a593Smuzhiyun if ((word & 0xff) == 0) { 29*4882a593Smuzhiyun num += 8; 30*4882a593Smuzhiyun word >>= 8; 31*4882a593Smuzhiyun } 32*4882a593Smuzhiyun if ((word & 0xf) == 0) { 33*4882a593Smuzhiyun num += 4; 34*4882a593Smuzhiyun word >>= 4; 35*4882a593Smuzhiyun } 36*4882a593Smuzhiyun if ((word & 0x3) == 0) { 37*4882a593Smuzhiyun num += 2; 38*4882a593Smuzhiyun word >>= 2; 39*4882a593Smuzhiyun } 40*4882a593Smuzhiyun if ((word & 0x1) == 0) 41*4882a593Smuzhiyun num += 1; 42*4882a593Smuzhiyun return num; 43*4882a593Smuzhiyun } 44*4882a593Smuzhiyun 45*4882a593Smuzhiyun #endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS___FFS_H_ */ 46