__SETFPUCW

Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
Index Return to Main Contents

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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(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.  

EXAMPLE

__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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Index

NAME

SYNOPSIS

DESCRIPTION

CONFORMING TO

NOTES

EXAMPLE

SEE ALSO

COLOPHON