PC386 BSP vs. paranoia
joel.sherrill at OARcorp.com
Tue Apr 24 22:42:43 UTC 2001
Eric Norum wrote:
> I'm new to the RTEMS/PC world and I'm having troubles. The latest
> problem is that paranoia does not seem to run properly on my 486-DX2/66
> target (pc386 BSP). I get a couple of `FAILURE' messages (they scroll
> by awfully quickly) and then it locks up after printing:
> Testing X^((X + 1) / (X - 1)) vs. exp(2) = 7.38905609893065041e+00 as X
> -> 1.
>From running this under Linux...
Testing X^((X + 1) / (X - 1)) vs. exp(2) = 7.38905609893065218e+00 as X
ERROR: Severity: DEFECT: Calculated 7.38905609548934539e+00 for
(1 + (-1.11022302462515654e-16) ^ (-1.80143985094819840e+16);
differs from correct value by -3.44130679508225512e-09 .
This much error may spoil financial
calculations involving tiny interest rates.
Testing powers Z^Q at four nearly extreme values.
... no discrepancies found.
> Is there some code to set up the floating point mode that's missing from
> the BSP?
This is probably just the way the i387 is. You can compile
paranoia natively like this:
gcc -o paranoia -DCYGNUS paranoia.c -lm
and compare the output yourself. As I recall, the i387 plays it
fast and loose. :)
> Eric Norum eric.norum at usask.ca
> Department of Electrical Engineering Phone: (306) 966-5394
> University of Saskatchewan FAX: (306) 966-5407
> Saskatoon, Canada.
Joel Sherrill, Ph.D. Director of Research & Development
joel at OARcorp.com On-Line Applications Research
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