1 files changed, 26 insertions, 1 deletions
diff --git a/ufloor_log2.c b/ufloor_log2.c
index 7d8e05494..4b9c4a8a5 100644
--- a/ufloor_log2.c
+++ b/ufloor_log2.c
@@ -24,12 +24,37 @@ MA 02111-1307, USA. */
 #include "mpfr.h"
 #include "mpfr-impl.h"
 
-/* returns floor(log(d)/log(2)) */
+/* returns floor(log(abs(d))/log(2)) */
 long
 __gmpfr_floor_log2 (double d)
 {
+#if _GMP_IEEE_FLOATS
   union ieee_double_extract x;
 
   x.d = d;
   return (long) x.s.exp - 1023;
+#else  
+  long exp;
+  double m;
+
+  /* Get Abs */
+  if (d < 0.0)
+    d = -d;
+
+  if (d == 0.0)
+    return -1023;
+  else if (d >= 1.0)
+    {
+      exp = -1;
+      for( m= 1.0 ; m <= d ; m *=2.0 )
+	exp++;
+    }
+  else
+    {
+      exp = 0;
+      for( m= 1.0 ; m > d ; m *= (1.0/2.0) )
+        exp--;      
+    }
+  return exp;
+#endif
 }