mirror of https://github.com/mkerrisk/man-pages
61 lines
1.5 KiB
Groff
61 lines
1.5 KiB
Groff
.\" Written Sat Mar 8 10:35:08 MEZ 1997 by
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.\" J. "MUFTI" Scheurich (mufti@csv.ica.uni-stuttgart.de)
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.\" This page is licensed under the GNU General Public License
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.\"
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.TH __SETFPUCW 3 1997-03-08 "Linux" "Linux Programmer's Manual"
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.SH NAME
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__setfpucw \- set FPU control word on i386 architecture (obsolete)
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.SH SYNOPSIS
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.B #include <i386/fpu_control.h>
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.sp
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.BI "void __setfpucw(unsigned short " control_word );
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.SH DESCRIPTION
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.BR __setfpucw ()
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transfers
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.I control_word
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to the registers of the FPU (floating-point unit) on the i386 architecture.
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This was used to control floating-point precision,
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rounding and floating-point exceptions.
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.SH CONFORMING TO
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This function was a nonstandard GNU extension.
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.SH NOTES
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As of glibc 2.1 this function does not exist anymore.
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There are new functions from C99, with prototypes in
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.IR <fenv.h> ,
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to control FPU rounding modes, like
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.IR fegetround ,
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.IR fesetround ,
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and the floating-point environment, like
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.IR fegetenv ,
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.IR feholdexcept ,
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.IR fesetenv ,
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.I feupdateenv
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and FPU exception handling, like
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.IR feclearexcept ,
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.IR fegetexceptflag ,
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.IR feraiseexcept ,
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.IR fesetexceptflag ,
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.IR fetestexcept .
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.PP
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If direct access to the FPU control word is still needed, the
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.B _FPU_GETCW
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and
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.B _FPU_SETCW
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macros from
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.I <fpu_control.h>
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can be used.
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.SH EXAMPLE
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.B __setfpucw(0x1372)
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Set FPU control word on the i386 architecture to
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.br
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\- extended precision
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.br
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\- rounding to nearest
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.br
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\- exceptions on overflow, zero divide and NaN
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.SH "SEE ALSO"
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.BR feclearexcept (3)
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.br
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.I <fpu_control.h>
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