Change 11679 by jhi@alpha on 2001/08/15 12:48:32
Re-establish the fp overflow detection for VAX VMS; there
is no easy way to have the IEEE fp silent overflow semantics.
(in Alpha VMS we still will use IEEE fp by default-- but it
is still possible to configure Perl to use G_FLOAT)
Affected files ...
... //depot/perl/numeric.c#10 edit
Differences ...
==== //depot/perl/numeric.c#10 (text) ====
Index: perl/numeric.c
--- perl/numeric.c.~1~ Wed Aug 15 07:00:05 2001
+++ perl/numeric.c Wed Aug 15 07:00:05 2001
@@ -572,6 +572,25 @@
negative = 1;
exponent = -exponent;
}
+ /* Avoid %SYSTEM-F-FLTOVF_F sans VAXC$ESTABLISH.
+ * In VAX VMS we by default use the D_FLOAT double format,
+ * and that format does not have *easy* capabilities [1] for
+ * overflowing doubles 'silently' as IEEE fp does. Therefore we
+ * need to detect early whether we would overflow (this is
+ * the behaviour of the native string-to-float conversion routines,
+ * and therefore the behaviour of native applications, too.)
+ *
+ * [1] VAXC$EXTABLISH is the capability but it is basically a signal
+ * handler setup routine, and one cannot return from a fp exception
+ * handler and except much anything useful. */
+#if defined(VMS) && !defined(__IEEE_FP)
+# if defined(__DECC_VER) && __DECC_VER <= 50390006
+ /* __F_FLT_MAX_10_EXP - 5 == 33 */
+ if (!negative &&
+ (log10(value) + exponent) >= (__F_FLT_MAX_10_EXP - 5))
+ return NV_MAX;
+# endif
+#endif
for (bit = 1; exponent; bit <<= 1) {
if (exponent & bit) {
exponent ^= bit;
End of Patch.
