NAME
feupdateenv() — update floating-point environment
SYNOPSIS
#include <fenv.h>
HP Integrity Server Only
int feupdateenv(const fenv_t *envp);
PA-RISC Only
void feupdateenv(const fenv_t *envp);
DESCRIPTION
The
feupdateenv()
function saves the currently raised floating-point exceptions in its automatic storage,
installs the floating-point environment represented by the object
pointed to by
envp,
and then raises the saved floating-point exceptions. Use
feholdexcept()
with
feupdateenv()
to hide spurious floating-point exceptions.
The argument
envp
must point to an object set by a call to
fegetenv()
or
feholdexcept(),
or equal the macro
FE_DFL_ENV.
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 actions were
successfully carried out.
ERRORS
No errors are defined.
EXAMPLES
Store the current floating-point environment in
holdenv,
hide spurious underflow exceptions, and continue on any floating-point
exceptions that occur until the call to
feupdateenv()
is encountered.
#include <fenv.h>
/*...*/
fenv_t holdenv;
feholdexcept(&holdenv);
/* perform operations */
if (/* test for spurious underflow */)
feclearexcept(FE_UNDERFLOW);
feupdateenv(&holdenv); /* raise accumulated exceptions */
STANDARDS CONFORMANCE
feupdateenv()
: ISO/IEC C99 (including Annex F, "IEC 60559 floating-point arithmetic")
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