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| author | Steven Whitehouse <swhiteho@redhat.com> | 2006-09-28 08:29:59 -0400 |
|---|---|---|
| committer | Steven Whitehouse <swhiteho@redhat.com> | 2006-09-28 08:29:59 -0400 |
| commit | 185a257f2f73bcd89050ad02da5bedbc28fc43fa (patch) | |
| tree | 5e32586114534ed3f2165614cba3d578f5d87307 /lib/hweight.c | |
| parent | 3f1a9aaeffd8d1cbc5ab9776c45cbd66af1c9699 (diff) | |
| parent | a77c64c1a641950626181b4857abb701d8f38ccc (diff) | |
| download | op-kernel-dev-185a257f2f73bcd89050ad02da5bedbc28fc43fa.zip op-kernel-dev-185a257f2f73bcd89050ad02da5bedbc28fc43fa.tar.gz | |
Merge branch 'master' into gfs2
Diffstat (limited to 'lib/hweight.c')
| -rw-r--r-- | lib/hweight.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/lib/hweight.c b/lib/hweight.c index 4382576..360556a 100644 --- a/lib/hweight.c +++ b/lib/hweight.c @@ -1,5 +1,6 @@ #include <linux/module.h> #include <asm/types.h> +#include <asm/bitops.h> /** * hweightN - returns the hamming weight of a N-bit word @@ -40,14 +41,19 @@ unsigned long hweight64(__u64 w) #if BITS_PER_LONG == 32 return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); #elif BITS_PER_LONG == 64 +#ifdef ARCH_HAS_FAST_MULTIPLIER + w -= (w >> 1) & 0x5555555555555555ul; + w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul); + w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful; + return (w * 0x0101010101010101ul) >> 56; +#else __u64 res = w - ((w >> 1) & 0x5555555555555555ul); res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; res = res + (res >> 8); res = res + (res >> 16); return (res + (res >> 32)) & 0x00000000000000FFul; -#else -#error BITS_PER_LONG not defined +#endif #endif } EXPORT_SYMBOL(hweight64); |
