Change 11681 by jhi@alpha on 2001/08/15 13:12:50
Also UNICOS is in the general case unable to silently
handle fp overflows.
Affected files ...
... //depot/perl/numeric.c#11 edit
Differences ...
==== //depot/perl/numeric.c#11 (text) ====
Index: perl/numeric.c
--- perl/numeric.c.~1~ Wed Aug 15 07:30:05 2001
+++ perl/numeric.c Wed Aug 15 07:30:05 2001
@@ -572,6 +572,7 @@
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
@@ -591,6 +592,20 @@
return NV_MAX;
# endif
#endif
+
+ /* In UNICOS and in certain Cray models (such as T90) there is no
+ * IEEE fp, and no way at all from C to catch fp overflows gracefully.
+ * There is something you can do if you are willing to use some
+ * inline assembler: the instruction is called DFI-- but that will
+ * disable *all* floating point interrupts, a little bit too large
+ * a hammer. Therefore we need to catch potential overflows before
+ * it's too late. */
+#if defined(_UNICOS) && defined(NV_MAX_10_EXP)
+ if (!negative &&
+ (log10(value) + exponent) >= NV_MAX_10_EXP)
+ return NV_MAX;
+#endif
+
for (bit = 1; exponent; bit <<= 1) {
if (exponent & bit) {
exponent ^= bit;
End of Patch.
