Changeset 153 for sbliveos2/trunk/lib32/misc.c

Timestamp:

Jul 23, 2000, 6:21:57 PM (25 years ago)

Author:

sandervl

Message:

update

File:

• sbliveos2/trunk/lib32/misc.c (modified) (1 diff)

sbliveos2/trunk/lib32/misc.c

@@ -210 +210 @@
 
 
+/* --------------------------------------------------------------------- */
+/*
+ * hweightN: returns the hamming weight (i.e. the number
+ * of bits set) of a N-bit word
+ */
+
+#ifdef hweight32
+#undef hweight32
+#endif
+
+unsigned int hweight32(unsigned int w)
+{
+        unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
+        res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
+        res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
+        res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
+        return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
+}