void __setfpucw(unsigned short control_word);
__setfpucw() transfers control_word to the registers of the FPU (float-
ing-point unit) on the i386 architecture. This was used to control
floating-point precision, rounding and floating-point exceptions.
This function was a nonstandard GNU extension.
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 round-
ing modes, like fegetround, fesetround, and the floating-point environ-
ment, like fegetenv, feholdexcept, fesetenv, feupdateenv and FPU excep-
tion handling, like feclearexcept, fegetexceptflag, feraiseexcept, fes-
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.
Set FPU control word on the i386 architecture to
- extended precision
- rounding to nearest
- exceptions on overflow, zero divide and NaN
This page is part of release 3.35 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://man7.org/linux/man-pages/.
Linux 1997-03-08 __SETFPUCW(3)
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