--- rxvt-unicode/src/rxvtutil.C	2006/01/25 00:42:21	1.3
+++ rxvt-unicode/src/rxvtutil.C	2006/01/29 22:27:04	1.4
@@ -23,6 +23,33 @@
   e = w.u;
 }
 
+#if !HAVE_GCC_BUILTINS
+int ctz (unsigned int x)
+{
+  int r = 0;
+
+  x &= -x; // this isolates the lowest bit
+
+  if (x & 0xaaaaaaaa) r +=  1;
+  if (x & 0xcccccccc) r +=  2;
+  if (x & 0xf0f0f0f0) r +=  4;
+  if (x & 0xff00ff00) r +=  8;
+  if (x & 0xffff0000) r += 16;
+
+  return r;
+}
+
+int popcount (unsigned int x)
+{
+  x -=  (x >> 1) & 0x55555555;
+  x  = ((x >> 2) & 0x33333333) + (x & 0x33333333);
+  x  = ((x >> 4) + x) & 0x0f0f0f0f;
+  x *= 0x01010101;
+
+  return x >> 24;
+}
+#endif
+
 void *
 zero_initialized::operator new (size_t s)
 {