NAME
fesetexceptflag() — set floating-point exception flags
SYNOPSIS
#include <fenv.h>
HP Integrity Server Only
int fesetexceptflag(const fexcept_t *flagp, int excepts);
PA-RISC Only
void fesetexceptflag(const fexcept_t *flagp, int excepts);
DESCRIPTION
The
fesetexceptflag()
function sets the status for the floating-point exception flags
indicated by the argument
excepts
to the states stored in the object pointed to by
flagp.
The value of
*flagp
must have been set by a previous call to
fegetexceptflag()
whose second argument represented at least
those floating-point exceptions represented by the argument
excepts;
otherwise, the effect on the indicated floating-point exception flags
is undefined. This function does not raise exceptions, but only sets
the state of the flags (hence no traps will be taken). The
excepts
argument can be constructed as a bitwise OR of the floating-point exception macros:
FE_INEXACT,
FE_DIVBYZERO,
FE_UNDERFLOW,
FE_OVERFLOW,
and
FE_INVALID.
FE_ALL_EXCEPT
represents all the floating-point exceptions.
USAGE
To use this function, compile either with the default
-Ae
option or with the
-Aa
and
-D_HPUX_SOURCE
options. Make sure your program includes
<fenv.h>.
For Integrity servers, specify
+Ofenvaccess
on the compiler command line or
place the call to this function under the effect of
an affirmative
FENV_ACCESS
pragma:
#pragma STDC FENV_ACCESS ON
If the
FENV_ACCESS
pragma is placed outside of any top-level
declarations in a file, the pragma will apply to all declarations in
the compilation following the pragma until another
FENV_ACCESS
pragma
is encountered or until the end of the file is reached.
If the
FENV_ACCESS
pragma is placed at the beginning of a block
(compound statement), the pragma will apply until another
FENV_ACCESS
pragma is encountered or until the end of the block is reached.
For PA-RISC, you might need to use the
+Onomoveflops compiler option
in order to prevent optimizations that can undermine the specified behavior
of this function.
Link in the math library by specifying
-lm
on the compiler or linker command line.
For more information, see the
HP-UX floating-point guide for HP Integrity servers
at the following site:
http://www.hp.com/go/fp.
RETURN VALUE
Integrity Server Only
This function always returns 0, indicating that all the specified flags
were successfully set to the appropriate state.
ERRORS
No errors are defined.
EXAMPLES
Use
fegetexceptflag()
to save the current state of two floating-point exception flags.
Later, use
fesetexceptflag()
to restore the saved state.
#include <fenv.h>
/*...*/
fexcept_t saved_flags;
/*...*/
fegetexceptflag(&saved_flags, FE_DIVBYZERO | FE_INEXACT);
/*...*/
fesetexceptflag(&saved_flags, FE_DIVBYZERO | FE_INEXACT);
STANDARDS CONFORMANCE
fesetexceptflag()
: ISO/IEC C99 (including Annex F, "IEC 60559 floating-point arithmetic")
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