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float assignment results in NaN

eltury
Genius 3330 points
Other Parts Discussed in Thread: MSP430G2955

I'm using CCS 6.1.0.00104 with an MSP430G2955.

I have a global variable float f1 initialized to 0.0.

I have a second local variable float f2 which can be from 0.0 to -10.00 and for this example = -5.03.

The C line

f1 = f2;

 results in f1 = NaN.

Why is this happening?

Thanks for any insight.

  • Genius 3330 points

    Okay, so i changed my program such that I make the above assignment by returning f2 from a function call:

    f1 = somefunc();


    This gives correct result for f1.

    Some compiler quirk?
  • TI__Guru* 84225 points
    I'm sorry, I cannot reproduce the error. Could you post a complete test case, including all of the command line options? How do you know the result is NaN; are you looking at it in the watch window?
  • TI__Guru**** 244930 points

    eltury said:

    The C line

    f1 = f2;

     results in f1 = NaN.

    It is likely whatever went wrong happened before this point, possibly long before this point.  One wild guess ... the stack overflowed.  Exactly how do you observe that, right before this assignment, f2 contains -5.03?

    Thanks and regards,

    -George

  • in reply to George Mock
    Genius 3330 points
    I was in debug mode and had f1 & f2 in a watch window. Breakpoint on line above the assignment then single stepped the assignment line and f1 became NaN. Also noticed that once in a while instead of NaN I got an extrememly small number - -45 for exponent.
  • in reply to eltury
    TI__Guru**** 244930 points

    Just like Archeaologist said, we need a test case we can build and directly see this behavior.  If this is organized as a CCS project, it would be ideal if you submitted it.

    Thanks and regards,

    -George

  • in reply to George Mock
    Genius 3330 points
    I will do that when I get a chance.
    Thanks.