fetestexcept()
QNX SDP8.0C Library ReferenceAPIDeveloper
Determine which of the specified floating-point status flags are set
Synopsis:
#include <fenv.h>
int fetestexcept( const int excepts );
Arguments:
- excepts
- A bitwise OR of the flags that you want to check; zero or more of the following:
- FE_ALL_EXCEPT — all the bits
- FE_DENORMAL — the result of a floating-point expression is a denormalized number
- FE_DIVBYZERO — pole error
- FE_INEXACT — the result can't be exactly represented as a floating-point number
- FE_INVALID — domain error
- FE_OVERFLOW — result is too large to be representable
- FE_UNDERFLOW — result is subnormal with a loss of precision
Library:
- libm
- The general-purpose math library.
- libm-sve
- A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.
Your system requirements will determine how you should work with these libraries:
- If you want only selected processes to run with the SVE version, you can include both libraries in your OS image and use the -l m or -l m-sve option to qcc to link explicitly against the appropriate one.
- If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.
Note:
Compile your program with the -fno-builtin option to prevent the compiler from using a
built-in version of the function.
Description:
The fetestexcept() function determines which of the specified floating-point exceptions are currently set.
Returns:
A bitwise OR of the flags that are in excepts and that correspond to floating-point exceptions that are currently set.
Examples:
#include <stdio.h>
#include <math.h>
#include <fenv.h>
#include <stdlib.h>
int main( void )
{
int except_flags;
/* acos(2) should raise a "domain error" exception. */
feclearexcept(FE_ALL_EXCEPT);
printf( "acos(2) is %f\n", acos(2) );
except_flags = fetestexcept(FE_ALL_EXCEPT);
if(except_flags & FE_INVALID)
puts("FE_INVALID (domain error) reported");
return EXIT_SUCCESS;
}
Classification:
Safety: | |
---|---|
Cancellation point | No |
Signal handler | Yes |
Thread | Yes |
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