Fix logic bug introduced on 2007-05-06.

[gnulib.git] / lib / ldexpl.c

diff --git a/lib/ldexpl.c b/lib/ldexpl.c
index 6ad886a..5eb9ff3 100644 (file)
--- a/lib/ldexpl.c
+++ b/lib/ldexpl.c
@@ -25,28 +25,44 @@
 #include <math.h>
 
 #include <float.h>
+#include "fpucw.h"
+#include "isnanl.h"
 
 long double
 ldexpl(long double x, int exp)
 {
   long double factor;
   int bit;
+  DECL_LONG_DOUBLE_ROUNDING
 
-  /* Check for zero, nan and infinity. */
-  if (x != x || x + x == x )
-    return x;
+  BEGIN_LONG_DOUBLE_ROUNDING ();
 
-  if (exp < 0)
+  /* Check for zero, nan and infinity. */
+  if (!(isnanl (x) || x + x == x))
     {
-      exp = -exp;
-      factor = 0.5L;
+      if (exp < 0)
+       {
+         exp = -exp;
+         factor = 0.5L;
+       }
+      else
+       factor = 2.0L;
+
+      if (exp > 0)
+       for (bit = 1;;)
+         {
+           /* Invariant: Here bit = 2^i, factor = 2^-2^i or = 2^2^i,
+              and bit <= exp.  */
+           if (exp & bit)
+             x *= factor;
+           bit <<= 1;
+           if (bit > exp)
+             break;
+           factor = factor * factor;
+         }
     }
-  else
-    factor = 2.0L;
 
-  for (bit = 1; bit <= exp; bit <<= 1, factor *= factor)
-    if (exp & bit)
-      x *= factor;
+  END_LONG_DOUBLE_ROUNDING ();
 
   return x;
 }