Dynamic Link Error

Question

I am observing some behavior for which I am finding it tough to reason.

I have a piece of code as follows:

int timer_temp_var;

if ((timer_temp_var/1000.0) > 5.0) 
{
  //Do something
}

This piece leads to link error.

> 
> dld: warning: Undefined symbol _d_fle"
> dld: no output written make[1]: ***
> [app.elf] Error 1

But on replacing the equality check as :

if ((timer_temp_var/1000.0) < 5.0)  // replace '>' with '<'.

I see no issues.

Also instead of doing division by 1000.0 if I do by 1000 as follows:

 if ((timer_temp_var/1000) > 5) 
    {
      //Do something
    }

I see no issues irrespective of the kind of equality check.

The application is compiled to run on a pSOS operating system.

What is the reason for such a behavior?

Answer 1

Seems your compiler replaces ">" operator with call to _d_fle() function, so you need to link some library to your executable.

Surprisingly "<" works although it should be replaced with d_fgt() function that most likely to be located in the same lib.

Changing from 100.0 to 100 makes left operand of ">" integer and it seems integer comparison doesn't require any function calls - probably it gets compiled to CPU instruction rather than function call.

EDIT: Looks like you need SFPE (software floating-point emulation) library. Do you have anything like libsfpe ?

Answer 2

The change from 1000.0 to 1000 suggest problem with floating point operation. Try cast 1000.0 to (int) and see if you have any progress.

Changing the sign < to > sounds not reasonable to lead to any changes...

Answer 3

You are missing a floating-point library. Try including the math library (libm.a) and see if that does the trick.