Now that I'm digging into this a bit I'm thinking my issue has to do with
the fix you put in place from back in Aug 2007 (commit
405849610fd96b4f34cd1875c4c033228fea6c0f):
[MATH-EMU]: Fix underflow exception reporting.
2) we ended up rounding back up to normal (this is the case where
we set the exponent to 1 and set the fraction to zero), this
should set inexact too
...
Another example, "0x0.0000000000001p-1022 / 16.0", should signal both
inexact and underflow. The cpu implementations and ieee1754
literature is very clear about this. This is case #2 above.
I'm not clear from your commit comment on what actual number
0x0.0....01p-1022 is?
It looks like the case I have we are exact before rounding, but think it
looks like the rounding case since it appears as if "overflow is set".
000.FFFFFFFFFFFFF / 3FE.FFFFFFFFFFFFE = 001.0000000000000
I think the following adds the check for my case and still works for the
issue your commit was trying to resolve. Take a look any and all comments
are welcome since this code is pretty complicated:
- k
diff --git a/include/math-emu/op-common.h b/include/math-emu/op-common.h
index cc1ec39..bc50aa0 100644
--- a/include/math-emu/op-common.h
+++ b/include/math-emu/op-common.h
@@ -139,18 +139,27 @@ do { \
if (X##_e <= _FP_WFRACBITS_##fs) \
{ \
_FP_FRAC_SRS_##wc(X, X##_e, _FP_WFRACBITS_##fs); \
- _FP_ROUND(wc, X); \
if (_FP_FRAC_HIGH_##fs(X) \
& (_FP_OVERFLOW_##fs >> 1)) \
{ \
X##_e = 1; \
_FP_FRAC_SET_##wc(X, _FP_ZEROFRAC_##wc); \
- FP_SET_EXCEPTION(FP_EX_INEXACT); \
} \
else \
{ \
- X##_e = 0; \
- _FP_FRAC_SRL_##wc(X, _FP_WORKBITS); \
+ _FP_ROUND(wc, X); \
+ if (_FP_FRAC_HIGH_##fs(X) \
+ & (_FP_OVERFLOW_##fs >> 1)) \
+ { \
+ X##_e = 1; \
+ _FP_FRAC_SET_##wc(X, _FP_ZEROFRAC_##wc); \
+ FP_SET_EXCEPTION(FP_EX_INEXACT); \
+ } \
+ else \
+ { \
+ X##_e = 0; \
+ _FP_FRAC_SRL_##wc(X, _FP_WORKBITS); \
+ } \
} \
if ((FP_CUR_EXCEPTIONS & FP_EX_INEXACT) || \
(FP_TRAPPING_EXCEPTIONS & FP_EX_UNDERFLOW)) \
--
