1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_GENERIC_BITOPS_FLS64_H_ 3 #define _ASM_GENERIC_BITOPS_FLS64_H_ 4 5 #include <asm/types.h> 6 7 /** 8 * fls64 - find last set bit in a 64-bit word 9 * @x: the word to search 10 * 11 * This is defined in a similar way as the libc and compiler builtin 12 * ffsll, but returns the position of the most significant set bit. 13 * 14 * fls64(value) returns 0 if value is 0 or the position of the last 15 * set bit if value is nonzero. The last (most significant) bit is 16 * at position 64. 17 */ 18 #if BITS_PER_LONG == 32 19 static __always_inline int fls64(__u64 x) 20 { 21 __u32 h = x >> 32; 22 if (h) 23 return fls(h) + 32; 24 return fls(x); 25 } 26 #elif BITS_PER_LONG == 64 27 static __always_inline int fls64(__u64 x) 28 { 29 if (x == 0) 30 return 0; 31 return __fls(x) + 1; 32 } 33 #else 34 #error BITS_PER_LONG not 32 or 64 35 #endif 36 37 #endif /* _ASM_GENERIC_BITOPS_FLS64_H_ */ 38