From: Zhaoxiu Zeng <zhaoxiu.z...@gmail.com> blackfin has popcount instruction (ONES), we can do the efficient computing (ffz, __ffs, ffs, __fls, and fls) use this instruction.
Adapted from "https://en.wikipedia.org/wiki/Find_first_set"; and arch/ia64/include/asm/bitops.h. Changes to V1: - Use hweight32 instead __arch_hweight32 Signed-off-by: Zhaoxiu Zeng <zhaoxiu.z...@gmail.com> --- arch/blackfin/include/asm/bitops.h | 73 +++++++++++++++++++++++++++++++++++--- 1 file changed, 68 insertions(+), 5 deletions(-) diff --git a/arch/blackfin/include/asm/bitops.h b/arch/blackfin/include/asm/bitops.h index b298b65..602e7c0 100644 --- a/arch/blackfin/include/asm/bitops.h +++ b/arch/blackfin/include/asm/bitops.h @@ -9,10 +9,6 @@ #include <linux/compiler.h> -#include <asm-generic/bitops/__ffs.h> -#include <asm-generic/bitops/ffz.h> -#include <asm-generic/bitops/fls.h> -#include <asm-generic/bitops/__fls.h> #include <asm-generic/bitops/fls64.h> #include <asm-generic/bitops/find.h> @@ -21,7 +17,6 @@ #endif #include <asm-generic/bitops/sched.h> -#include <asm-generic/bitops/ffs.h> #include <asm-generic/bitops/const_hweight.h> #include <asm-generic/bitops/lock.h> @@ -137,4 +132,72 @@ static inline unsigned int __arch_hweight8(unsigned int w) return __arch_hweight32(w & 0xff); } +/** + * ffz - find the first zero bit in a long word + * @x: The long word to find the bit in + * + * Returns the bit-number (0..31) of the first (least significant) zero bit. + * Undefined if no zero exists, so code should check against ~0UL first... + */ +static inline unsigned long ffz(unsigned long x) +{ + return hweight32(x & (~x - 1)); +} + +/** + * ffs - find first bit set + * @x: the word to search + * + * This is defined the same way as + * the libc and compiler builtin ffs routines, therefore + * differs in spirit from the above ffz (man ffs). + */ +static inline int ffs(int x) +{ + if (!x) + return 0; + return hweight32(x ^ ((unsigned int)x - 1)); +} + +/** + * __ffs - find first bit in word. + * @x: The word to search + * + * Undefined if no bit exists, so code should check against 0 first. + */ +static inline unsigned long __ffs(unsigned long x) +{ + return hweight32(~x & (x - 1)); +} + +/* + * Find the last (most significant) bit set. Returns 0 for x==0 and + * bits are numbered from 1..32 (e.g., fls(9) == 4). + */ +static inline int fls(int x) +{ + if (!x) + return 0; + x |= x >> 1; + x |= x >> 2; + x |= x >> 4; + x |= x >> 8; + x |= x >> 16; + return hweight32(x); +} + +/* + * Find the last (most significant) bit set. Undefined for x==0. + * Bits are numbered from 0..31 (e.g., __fls(9) == 3). + */ +static inline unsigned long __fls(unsigned long x) +{ + x |= x >> 1; + x |= x >> 2; + x |= x >> 4; + x |= x >> 8; + x |= x >> 16; + return hweight32(x) - 1; +} + #endif /* _BLACKFIN_BITOPS_H */ -- 2.5.0
