__setfpucw(3) — Linux manual page

__setfpucw(3)            Library Functions Manual           __setfpucw(3)

NAME         top

       __setfpucw - set FPU control word on i386 architecture (obsolete)

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <i386/fpu_control.h>

       [[deprecated]] void __setfpucw(unsigned short control_word);

DESCRIPTION         top

       __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.

STANDARDS         top

       GNU.

HISTORY         top

       Removed in glibc 2.1.

NOTES         top

       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         top

       __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         top

       feclearexcept(3)

       <fpu_control.h>

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                  __setfpucw(3)

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