aboutsummaryrefslogtreecommitdiffstats
path: root/lib/hweight.c
diff options
context:
space:
mode:
authorPeter Zijlstra <a.p.zijlstra@chello.nl>2010-02-01 14:03:07 (GMT)
committerH. Peter Anvin <hpa@zytor.com>2010-04-06 22:52:11 (GMT)
commit1527bc8b928dd1399c3d3467dd47d9ede210978a (patch)
treefb391da915bdae9f933b8170ff61aa43c85ef9ae /lib/hweight.c
parent0fdf86754f70e813845af4abaa805165ce57a0bb (diff)
bitops: Optimize hweight() by making use of compile-time evaluation
Rename the extisting runtime hweight() implementations to __arch_hweight(), rename the compile-time versions to __const_hweight() and then have hweight() pick between them. Suggested-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100318111929.GB11152@aftab> Acked-by: H. Peter Anvin <hpa@zytor.com> LKML-Reference: <1265028224.24455.154.camel@laptop> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'lib/hweight.c')
-rw-r--r--lib/hweight.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/lib/hweight.c b/lib/hweight.c
index 63ee4eb..a6927e7 100644
--- a/lib/hweight.c
+++ b/lib/hweight.c
@@ -9,7 +9,7 @@
* The Hamming Weight of a number is the total number of bits set in it.
*/
-unsigned int hweight32(unsigned int w)
+unsigned int __arch_hweight32(unsigned int w)
{
#ifdef ARCH_HAS_FAST_MULTIPLIER
w -= (w >> 1) & 0x55555555;
@@ -24,29 +24,30 @@ unsigned int hweight32(unsigned int w)
return (res + (res >> 16)) & 0x000000FF;
#endif
}
-EXPORT_SYMBOL(hweight32);
+EXPORT_SYMBOL(__arch_hweight32);
-unsigned int hweight16(unsigned int w)
+unsigned int __arch_hweight16(unsigned int w)
{
unsigned int res = w - ((w >> 1) & 0x5555);
res = (res & 0x3333) + ((res >> 2) & 0x3333);
res = (res + (res >> 4)) & 0x0F0F;
return (res + (res >> 8)) & 0x00FF;
}
-EXPORT_SYMBOL(hweight16);
+EXPORT_SYMBOL(__arch_hweight16);
-unsigned int hweight8(unsigned int w)
+unsigned int __arch_hweight8(unsigned int w)
{
unsigned int res = w - ((w >> 1) & 0x55);
res = (res & 0x33) + ((res >> 2) & 0x33);
return (res + (res >> 4)) & 0x0F;
}
-EXPORT_SYMBOL(hweight8);
+EXPORT_SYMBOL(__arch_hweight8);
-unsigned long hweight64(__u64 w)
+unsigned long __arch_hweight64(__u64 w)
{
#if BITS_PER_LONG == 32
- return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
+ return __arch_hweight32((unsigned int)(w >> 32)) +
+ __arch_hweight32((unsigned int)w);
#elif BITS_PER_LONG == 64
#ifdef ARCH_HAS_FAST_MULTIPLIER
w -= (w >> 1) & 0x5555555555555555ul;
@@ -63,4 +64,4 @@ unsigned long hweight64(__u64 w)
#endif
#endif
}
-EXPORT_SYMBOL(hweight64);
+EXPORT_SYMBOL(__arch_hweight64);

Privacy Policy