Save the floating-point environment, clear all flags, and ignore future errors
Synopsis:
#include <fenv.h>
int feholdexcept( fenv_t *envp );
Arguments:
- envp
- A pointer to a fenv_t object where the function can store the environment.
Library:
- libm
- The general-purpose math library.
- libm-sve
- (QNX Neutrino 7.1 or later)
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 feholdexcept() function
saves the floating-point environment in the object that envp points to,
clears all the floating-point status flags, and installs a nonstop mode.
In nonstop mode, floating-point exceptions don't interrupt execution.
CAUTION:
This operation doesn't work on AArch64 targets.
There's a known hardware limitation that causes any saving of floating-point environments to be ignored.
To restore the floating-point environment, use
fesetenv()
or
feupdateenv().
Classification:
C99,
POSIX 1003.1
| Safety: |
|
|---|
| Cancellation point |
No |
| Interrupt handler |
Yes |
| Signal handler |
Yes |
| Thread |
Yes |