__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 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, fesetround, and the floating-point environment, like fegetenv, feholdexcept, fesetenv, feupdateenv and FPU exception handling, like feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag, fetestexcept.

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.

EXAMPLE

__setfpucw(0x1372)

Set FPU control word on the i386 architecture to

     - extended precision

     - rounding to nearest

     - exceptions on overflow, zero divide and NaN

COLOPHON

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Time: 19:49:25 GMT, April 27, 2011