1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */ 2*4882a593Smuzhiyun #ifndef _ASM_GENERIC_BITOPS_FFS_H_ 3*4882a593Smuzhiyun #define _ASM_GENERIC_BITOPS_FFS_H_ 4*4882a593Smuzhiyun 5*4882a593Smuzhiyun /** 6*4882a593Smuzhiyun * ffs - find first bit set 7*4882a593Smuzhiyun * @x: the word to search 8*4882a593Smuzhiyun * 9*4882a593Smuzhiyun * This is defined the same way as 10*4882a593Smuzhiyun * the libc and compiler builtin ffs routines, therefore 11*4882a593Smuzhiyun * differs in spirit from the above ffz (man ffs). 12*4882a593Smuzhiyun */ ffs(int x)13*4882a593Smuzhiyunstatic inline int ffs(int x) 14*4882a593Smuzhiyun { 15*4882a593Smuzhiyun int r = 1; 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun if (!x) 18*4882a593Smuzhiyun return 0; 19*4882a593Smuzhiyun if (!(x & 0xffff)) { 20*4882a593Smuzhiyun x >>= 16; 21*4882a593Smuzhiyun r += 16; 22*4882a593Smuzhiyun } 23*4882a593Smuzhiyun if (!(x & 0xff)) { 24*4882a593Smuzhiyun x >>= 8; 25*4882a593Smuzhiyun r += 8; 26*4882a593Smuzhiyun } 27*4882a593Smuzhiyun if (!(x & 0xf)) { 28*4882a593Smuzhiyun x >>= 4; 29*4882a593Smuzhiyun r += 4; 30*4882a593Smuzhiyun } 31*4882a593Smuzhiyun if (!(x & 3)) { 32*4882a593Smuzhiyun x >>= 2; 33*4882a593Smuzhiyun r += 2; 34*4882a593Smuzhiyun } 35*4882a593Smuzhiyun if (!(x & 1)) { 36*4882a593Smuzhiyun x >>= 1; 37*4882a593Smuzhiyun r += 1; 38*4882a593Smuzhiyun } 39*4882a593Smuzhiyun return r; 40*4882a593Smuzhiyun } 41*4882a593Smuzhiyun 42*4882a593Smuzhiyun #endif /* _ASM_GENERIC_BITOPS_FFS_H_ */ 43