__SETFPUCW
Section: Linux Programmer's Manual (3)
Updated: 2020-06-09
Page Index
NAME
__setfpucw - set FPU control word on i386 architecture (obsolete)
SYNOPSIS
#include <i386/fpu_control.h>
void __setfpucw(unsigned short control_word);
DESCRIPTION
__setfpucw()
transfers
control_word
to the registers of the FPU (floating-point unit) on the i386 architecture.
This was used to control floating-point precision,
rounding and floating-point exceptions.
CONFORMING TO
This function was a nonstandard GNU extension.
NOTES
As of glibc 2.1 this function does not exist anymore.
There are new functions from C99, with prototypes in
<fenv.h>,
to control FPU rounding modes, like
fegetround(3),
fesetround(3),
and the floating-point environment, like
fegetenv(3),
feholdexcept(3),
fesetenv(3),
feupdateenv(3),
and FPU exception handling, like
feclearexcept(3),
fegetexceptflag(3),
feraiseexcept(3),
fesetexceptflag(3),
and
fetestexcept(3).
If direct access to the FPU control word is still needed, the
_FPU_GETCW
and
_FPU_SETCW
macros from
<fpu_control.h>
can be used.
EXAMPLES
__setfpucw(0x1372)
Set FPU control word on the i386 architecture to
- extended precision
- rounding to nearest
- exceptions on overflow, zero divide and NaN
SEE ALSO
feclearexcept(3)
<fpu_control.h>
COLOPHON
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