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