__SETFPUCW

Section: Linux Programmer's Manual (3)
Updated: 1997-03-08
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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 i386 architecture. This was used to control floating point precision, rounding and floating point exceptions.

EXAMPLE

__setfpucw(0x1372)

Set fpu control word on i386 architecture to

     - extended precision

     - rounding to nearest

     - exceptions on overflow, zero divide and NaN

AVAILABILITY

As of glibc 2.1 this function does not exist anymore. There are new functions from ISO C99, with prototypes in /usr/include/fenv.h, to control fpu rounding modes, like fegetround, fesetround, and the floating point environment, like fegetenv, feholdexcept, fesetenv, feupdateenv and fpu exception handling, like feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag, fetestexcept. These functions don't have manpages, but are documented in the info docs.

If direct acces to the FPU control word is still needed, the _FPU_GETCW and _FPU_SETCW macros from /usr/include/fpu_control.h can be used.

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