2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
114 lines
3.2 KiB
Groff
114 lines
3.2 KiB
Groff
.\" $NetBSD: fegetenv.3,v 1.2 2010/08/04 18:58:18 wiz Exp $
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.\" Copyright (c) 2004 David Schultz <das@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd May 8, 2004
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.Dt FEGETENV 3
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.Os
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.Sh NAME
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.Nm fegetenv ,
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.Nm feholdexcept ,
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.Nm fesetenv ,
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.Nm feupdateenv
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.Nd floating-point environment save and restore
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.Sh LIBRARY
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.Lb libm
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.Sh SYNOPSIS
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.In fenv.h
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.Fd "#pragma STDC FENV_ACCESS ON"
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.Ft int
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.Fn fegetenv "fenv_t *envp"
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.Ft int
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.Fn feholdexcept "fenv_t *envp"
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.Ft int
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.Fn fesetenv "const fenv_t *envp"
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.Ft int
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.Fn feupdateenv "const fenv_t *envp"
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.Sh DESCRIPTION
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The floating-point environment includes exception flags and masks, the
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current rounding mode, and other architecture-specific settings.
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However, it does not include the floating-point register file.
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.Pp
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The
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.Fn fegetenv
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function stores the current floating-point environment in the object
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pointed to by
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.Fa envp ,
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whereas
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.Fn feholdexcept
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saves the current environment, then clears all exception flags
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and masks all floating-point exceptions.
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.Pp
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The
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.Fn fesetenv
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function restores a previously saved environment.
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The
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.Fn feupdateenv
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function restores a saved environment as well, but it also
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raises any exceptions that were set in the environment it
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replaces.
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.Pp
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The
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.Fn feholdexcept
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function is often used with
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.Fn feupdateenv
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or
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.Fn fesetenv
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to suppress spurious exceptions that occur as a result of
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intermediate computations.
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An example in
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.Xr fenv 3
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demonstrates how to do this.
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.Sh RETURN VALUES
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The
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.Fn fegetenv ,
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.Fn feholdexcept ,
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.Fn fesetenv ,
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and
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.Fn feupdateenv
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functions return 0 if they succeed, and non-zero otherwise.
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.Sh SEE ALSO
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.Xr feclearexcept 3 ,
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.Xr fenv 3 ,
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.Xr feraiseexcept 3 ,
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.Xr fesetenv 3 ,
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.Xr fetestexcept 3 ,
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.Xr fpgetmask 3 ,
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.\"Xr fpgetprec 3 ,
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.Xr fpsetmask 3
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.\"Xr fpsetprec 3
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.Sh STANDARDS
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The
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.Fn fegetenv ,
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.Fn feholdexcept ,
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.Fn fesetenv ,
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and
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.Fn feupdateenv
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functions conform to
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.St -isoC-99 .
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.Sh HISTORY
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These routines first appeared in
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.Fx 5.3
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and
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.Nx 6.0 .
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