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<== Date ==> | <== Thread ==> |
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Subject: | Re: Arithmetic - test with qoriq |
From: | "Johnson, Andrew N. via Core-talk" <core-talk at aps.anl.gov> |
To: | Michael Davidsaver <mdavidsaver at gmail.com> |
Cc: | EPICS core-talk <core-talk at aps.anl.gov> |
Date: | Fri, 15 Jan 2021 23:57:46 +0000 |
On Jan 15, 2021, at 1:00 PM, Michael Davidsaver <mdavidsaver at gmail.com> wrote:
This might have something to do with the PowerPC e500 family, which uses a different set of FP instructions to the older PPC603/604/MPC750 CPU cores (maybe SPE2?). I remember reading that to properly support the full IEEE floating-point standard the OS
has to emulate certain operations. My guess is that RTEMS contains the correct code for doing that (which is why the calc engine is mostly getting the right answers), but the compiler isn’t being given the right flags to tell it to behave similarly.
Agreed, those makeINF() and makeNAN() functions are really only provided there as a last-resort, in most cases the OS-specific epicsMath.h should be making sure that INFINITY and NAN are properly defined from the platform-specific headers.
- Andrew
--
Complexity comes for free, simplicity you have to work for.
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