From: Zeng Zhaoxiu <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 V2: - Fix build errors Changes to V1: - Use hweight32 instead __arch_hweight32 Signed-off-by: Zeng Zhaoxiu <zhaoxiu.z...@gmail.com> --- arch/blackfin/include/asm/bitops.h | 144 ++++++++++++++++++++++++++----------- 1 file changed, 104 insertions(+), 40 deletions(-) diff --git a/arch/blackfin/include/asm/bitops.h b/arch/blackfin/include/asm/bitops.h index b298b65..8380d1b 100644 --- a/arch/blackfin/include/asm/bitops.h +++ b/arch/blackfin/include/asm/bitops.h @@ -9,20 +9,115 @@ #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> - #ifndef _LINUX_BITOPS_H #error only <linux/bitops.h> can be included directly #endif -#include <asm-generic/bitops/sched.h> -#include <asm-generic/bitops/ffs.h> +/* + * hweightN: returns the hamming weight (i.e. the number + * of bits set) of a N-bit word + */ + +static inline unsigned int __arch_hweight32(unsigned int w) +{ + unsigned int res; + + __asm__ ("%0.l = ONES %1;" + "%0 = %0.l (Z);" + : "=d" (res) : "d" (w)); + return res; +} + +static inline unsigned int __arch_hweight64(__u64 w) +{ + return __arch_hweight32((unsigned int)(w >> 32)) + + __arch_hweight32((unsigned int)w); +} + +static inline unsigned int __arch_hweight16(unsigned int w) +{ + return __arch_hweight32(w & 0xffff); +} + +static inline unsigned int __arch_hweight8(unsigned int w) +{ + return __arch_hweight32(w & 0xff); +} + #include <asm-generic/bitops/const_hweight.h> + +/** + * 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 ^ (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; +} + +#include <asm-generic/bitops/fls64.h> +#include <asm-generic/bitops/find.h> + +#include <asm-generic/bitops/sched.h> #include <asm-generic/bitops/lock.h> #include <asm-generic/bitops/ext2-atomic.h> @@ -106,35 +201,4 @@ static inline int test_and_change_bit(int nr, volatile unsigned long *addr) /* Needs to be after test_bit and friends */ #include <asm-generic/bitops/le.h> -/* - * hweightN: returns the hamming weight (i.e. the number - * of bits set) of a N-bit word - */ - -static inline unsigned int __arch_hweight32(unsigned int w) -{ - unsigned int res; - - __asm__ ("%0.l = ONES %1;" - "%0 = %0.l (Z);" - : "=d" (res) : "d" (w)); - return res; -} - -static inline unsigned int __arch_hweight64(__u64 w) -{ - return __arch_hweight32((unsigned int)(w >> 32)) + - __arch_hweight32((unsigned int)w); -} - -static inline unsigned int __arch_hweight16(unsigned int w) -{ - return __arch_hweight32(w & 0xffff); -} - -static inline unsigned int __arch_hweight8(unsigned int w) -{ - return __arch_hweight32(w & 0xff); -} - #endif /* _BLACKFIN_BITOPS_H */ -- 2.5.5
