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
98 lines
3.3 KiB
Groff
98 lines
3.3 KiB
Groff
.\" $NetBSD: feenableexcept.3,v 1.1 2010/07/31 21:47:53 joerg 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 March 16, 2005
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.Dt FEENABLEEXCEPT 3
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.Os
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.Sh NAME
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.Nm feenableexcept ,
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.Nm fedisableexcept ,
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.Nm fegetexcept
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.Nd floating-point exception masking
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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 feenableexcept "int excepts"
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.Ft int
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.Fn fedisableexcept "int excepts"
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.Ft int
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.Fn fegetexcept "void"
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.Sh DESCRIPTION
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The
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.Fn feenableexcept
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and
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.Fn fedisableexcept
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functions
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unmask and mask (respectively) exceptions specified in
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.Fa excepts .
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The
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.Fn fegetexcept
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function
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returns the current exception mask.
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All exceptions are masked by default.
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.Pp
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Floating-point operations that produce unmasked exceptions will trap, and a
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.Dv SIGFPE
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will be delivered to the process.
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By installing a signal handler for
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.Dv SIGFPE ,
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applications can take appropriate action immediately without
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testing the exception flags after every operation.
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Note that the trap may not be immediate, but it should occur
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before the next floating-point instruction is executed.
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.Pp
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For all of these functions, the possible types of exceptions
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include those described in
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.Xr fenv 3 .
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Some architectures may define other types of floating-point exceptions.
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.Sh RETURN VALUES
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The
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.Fn feenableexcept ,
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.Fn fedisableexcept ,
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and
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.Fn fegetexcept
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functions return a bitmap of the exceptions that were unmasked
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prior to the call.
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.Sh SEE ALSO
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.Xr sigaction 2 ,
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.Xr feclearexcept 3 ,
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.Xr feholdexcept 3 ,
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.Xr fenv 3 ,
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.Xr feupdateenv 3
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.Sh BUGS
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Functions in the standard library may trigger exceptions multiple
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times as a result of intermediate computations;
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however, they generally do not trigger spurious exceptions.
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.Pp
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No interface is provided to permit exceptions to be handled in
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nontrivial ways.
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There is no uniform way for an exception handler to access
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information about the exception-causing instruction, or
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to determine whether that instruction should be reexecuted
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after returning from the handler.
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