diff options
| -rw-r--r-- | include/asm-arm/bitops.h | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/include/asm-arm/bitops.h b/include/asm-arm/bitops.h index d02de721ecc..eaecd553e85 100644 --- a/include/asm-arm/bitops.h +++ b/include/asm-arm/bitops.h @@ -344,13 +344,42 @@ static inline unsigned long __ffs(unsigned long word) #else +static inline int constant_fls(int x) +{ + int r = 32; + + if (!x) + return 0; + if (!(x & 0xffff0000u)) { + x <<= 16; + r -= 16; + } + if (!(x & 0xff000000u)) { + x <<= 8; + r -= 8; + } + if (!(x & 0xf0000000u)) { + x <<= 4; + r -= 4; + } + if (!(x & 0xc0000000u)) { + x <<= 2; + r -= 2; + } + if (!(x & 0x80000000u)) { + x <<= 1; + r -= 1; + } + return r; +} + /* * On ARMv5 and above those functions can be implemented around * the clz instruction for much better code efficiency. */ #define fls(x) \ - ( __builtin_constant_p(x) ? generic_fls(x) : \ + ( __builtin_constant_p(x) ? constant_fls(x) : \ ({ int __r; asm("clz\t%0, %1" : "=r"(__r) : "r"(x) : "cc"); 32-__r; }) ) #define fls64(x) generic_fls64(x) #define ffs(x) ({ unsigned long __t = (x); fls(__t & -__t); }) |