diff options
Diffstat (limited to 'include/asm-ppc')
| -rw-r--r-- | include/asm-ppc/bitops.h | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/include/asm-ppc/bitops.h b/include/asm-ppc/bitops.h index 4e9c608..daa66cf 100644 --- a/include/asm-ppc/bitops.h +++ b/include/asm-ppc/bitops.h @@ -152,6 +152,7 @@ extern __inline__ int test_bit(int nr, __const__ volatile void *addr) } /* Return the bit position of the most significant 1 bit in a word */ +/* - the result is undefined when x == 0 */ extern __inline__ int __ilog2(unsigned int x) { int lz; @@ -167,6 +168,57 @@ extern __inline__ int ffz(unsigned int x) return __ilog2(x & -x); } +/* + * fls: find last (most-significant) bit set. + * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. + * + * On powerpc, __ilog2(0) returns -1, but this is not safe in general + */ +static __inline__ int fls(unsigned int x) +{ + return __ilog2(x) + 1; +} + +/** + * fls64 - find last set bit in a 64-bit word + * @x: the word to search + * + * This is defined in a similar way as the libc and compiler builtin + * ffsll, but returns the position of the most significant set bit. + * + * fls64(value) returns 0 if value is 0 or the position of the last + * set bit if value is nonzero. The last (most significant) bit is + * at position 64. + */ +#if BITS_PER_LONG == 32 +static inline int fls64(__u64 x) +{ + __u32 h = x >> 32; + if (h) + return fls(h) + 32; + return fls(x); +} +#elif BITS_PER_LONG == 64 +static inline int fls64(__u64 x) +{ + if (x == 0) + return 0; + return __ilog2(x) + 1; +} +#else +#error BITS_PER_LONG not 32 or 64 +#endif + +static inline int __ilog2_u64(u64 n) +{ + return fls64(n) - 1; +} + +static inline int ffs64(u64 x) +{ + return __ilog2_u64(x & -x) + 1ull; +} + #ifdef __KERNEL__ /* |