x86, core: Optimize hweight32()

[net-next-2.6.git] / lib / hweight.c

diff --git a/lib/hweight.c b/lib/hweight.c
index 389424ecb129f13760de1677bd297b392264c953..63ee4eb1228d13ff4b712cb8f1dd8385bf9c1bcb 100644 (file)
--- a/lib/hweight.c
+++ b/lib/hweight.c
@@ -11,11 +11,18 @@
 
 unsigned int hweight32(unsigned int w)
 {
+#ifdef ARCH_HAS_FAST_MULTIPLIER
+       w -= (w >> 1) & 0x55555555;
+       w =  (w & 0x33333333) + ((w >> 2) & 0x33333333);
+       w =  (w + (w >> 4)) & 0x0f0f0f0f;
+       return (w * 0x01010101) >> 24;
+#else
        unsigned int res = w - ((w >> 1) & 0x55555555);
        res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
        res = (res + (res >> 4)) & 0x0F0F0F0F;
        res = res + (res >> 8);
        return (res + (res >> 16)) & 0x000000FF;
+#endif
 }
 EXPORT_SYMBOL(hweight32);