Finding library call information (GNAT-Linux)

From: Carl Franklin (CarlR-junk_at_houston.rr.com)
Date: 08/30/04 

Date: Mon, 30 Aug 2004 20:21:57 GMT

We are chasing some problems... that are rather interesting...

The environment - is a Simulation...

  containing a Robot arm, etc...

  We are on a multi-processor system (2 Pentium IIIs)

  Now, when a particular version of the arm was delivered - constraint
errors - typically having to do with double precision floating point
started occuring... (very intermittently)... and when they occur... they
occur in *flurries*...

  The personnel *instrumented* the code - and the results are very squirelly...

  Constaint Errors being returned for zero (a valid value) - other
times... constraint errors on a number (0 <- zero and by this I mean
0.0)... multiplied by another number - returning some really interesting
values...

  The suspicion is that a driver might be stomping on a register -
however, that doesn't seem all that reasonable...

  Then, we created a little Double Precision test - and ran this as a
seperate process - runs for forever... or seemingly so... with no
problems...

  Then, we ran this little DP process while the Real-Time simulation was
active... and low & behold... intermittent errors (constraint problems)...

  Trying to delve deeper - I was given the assembly source for the program
- and am trying to instrument at a *somewhat lower* level (smile)... than
we can do from ADA code...

  Getting the assembly listing - there are several *calls*... that appear
to be ada/system libraries. The *system* is not Linux system - as the
text strings are not found going through Linux source repository *free
text* searches (or identifier searches)... So, perhaps they are *Ada
System* interfaces...

  I am wondering where to find information about the calls and the results
I should expect... (what the heck they are doing)...

specifically the following calls are of interests...
     system__arith_64__multiply_with_ovflo_check
     _gnat_stack_check
     system__secondary_stack__ss_allocate

and several others...

  I'm wondering - where I can find the *source* or documentation on this
*called* routines... So, I'll be able to completely understand the flow
within the assembly code...

Thank You for Any assistance!,
Carl R. Franklin 

-- 
                                        Just me,
                                        Carl R. Franklin
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There is never a need to outrun anything you can outwit - Garfield (the cat)
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