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Problems with floating point calculations in main loop as well as in ISR

Question asked by Third Eye on Sep 14, 2015
Latest reply on Sep 15, 2015 by luca
Hello everybody,

in my Cosmic C program for a STM8S003 I have a problem: The result of some floating point calculations are sporadically corrupted.
The usage of variables can not be the cause for that because the used ones are are interrupt-save. Also RAM space for variables and stack is not getting narrow. There is much space left.

In my normal main loop program there are some floating point calculations (multiplications, additions, divisions).
In an interrupt service routine there are also floating point multiplications and additions used.
When I disable interrupts while the main loop calculations are done the problem is gone! But I don't really want to do that. I want to understand the cause.

In the disassembly I noticed that in both cases (main and ISR) the folowing assembly "functions" are used:
CALL  c_rtol
CALL  c_ltor
CALL  c_fmul

Could it be possible that these functions are not reentrant and that data is corrupted when the same "function" is called from main and from the ISR?

When this is the case, is this normal or could it be considered as a bug?

Thank you.