| The Android Open Source Project | a27d2ba | 2008-10-21 07:00:00 -0700 | [diff] [blame] | 1 | .\" Copyright (c) 2004 David Schultz <das@FreeBSD.org> |
| 2 | .\" All rights reserved. |
| 3 | .\" |
| 4 | .\" Redistribution and use in source and binary forms, with or without |
| 5 | .\" modification, are permitted provided that the following conditions |
| 6 | .\" are met: |
| 7 | .\" 1. Redistributions of source code must retain the above copyright |
| 8 | .\" notice, this list of conditions and the following disclaimer. |
| 9 | .\" 2. Redistributions in binary form must reproduce the above copyright |
| 10 | .\" notice, this list of conditions and the following disclaimer in the |
| 11 | .\" documentation and/or other materials provided with the distribution. |
| 12 | .\" |
| 13 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| 14 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 15 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 16 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 17 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 18 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 19 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 20 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 21 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 22 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 23 | .\" SUCH DAMAGE. |
| 24 | .\" |
| 25 | .\" $FreeBSD: src/lib/msun/man/feenableexcept.3,v 1.1 2005/03/16 19:04:28 das Exp $ |
| 26 | .\" |
| 27 | .Dd March 16, 2005 |
| 28 | .Dt FEENABLEEXCEPT 3 |
| 29 | .Os |
| 30 | .Sh NAME |
| 31 | .Nm feenableexcept , |
| 32 | .Nm fedisableexcept , |
| 33 | .Nm fegetexcept |
| 34 | .Nd floating-point exception masking |
| 35 | .Sh LIBRARY |
| 36 | .Lb libm |
| 37 | .Sh SYNOPSIS |
| 38 | .In fenv.h |
| 39 | .Fd "#pragma STDC FENV_ACCESS ON" |
| 40 | .Ft int |
| 41 | .Fn feenableexcept "int excepts" |
| 42 | .Ft int |
| 43 | .Fn fedisableexcept "int excepts" |
| 44 | .Ft int |
| 45 | .Fn fegetexcept "void" |
| 46 | .Sh DESCRIPTION |
| 47 | The |
| 48 | .Fn feenableexcept |
| 49 | and |
| 50 | .Fn fedisableexcept |
| 51 | functions |
| 52 | unmask and mask (respectively) exceptions specified in |
| 53 | .Fa excepts . |
| 54 | The |
| 55 | .Fn fegetexcept |
| 56 | function |
| 57 | returns the current exception mask. |
| 58 | All exceptions are masked by default. |
| 59 | .Pp |
| 60 | Floating-point operations that produce unmasked exceptions will trap, and a |
| 61 | .Dv SIGFPE |
| 62 | will be delivered to the process. |
| 63 | By installing a signal handler for |
| 64 | .Dv SIGFPE , |
| 65 | applications can take appropriate action immediately without |
| 66 | testing the exception flags after every operation. |
| 67 | Note that the trap may not be immediate, but it should occur |
| 68 | before the next floating-point instruction is executed. |
| 69 | .Pp |
| 70 | For all of these functions, the possible types of exceptions |
| 71 | include those described in |
| 72 | .Xr fenv 3 . |
| 73 | Some architectures may define other types of floating-point exceptions. |
| 74 | .Sh RETURN VALUES |
| 75 | The |
| 76 | .Fn feenableexcept , |
| 77 | .Fn fedisableexcept , |
| 78 | and |
| 79 | .Fn fegetexcept |
| 80 | functions return a bitmap of the exceptions that were unmasked |
| 81 | prior to the call. |
| 82 | .Sh SEE ALSO |
| 83 | .Xr sigaction 2 , |
| 84 | .Xr feclearexcept 3 , |
| 85 | .Xr feholdexcept 3 , |
| 86 | .Xr fenv 3 , |
| 87 | .Xr feupdateenv 3 |
| 88 | .Sh BUGS |
| 89 | Functions in the standard library may trigger exceptions multiple |
| 90 | times as a result of intermediate computations; |
| 91 | however, they generally do not trigger spurious exceptions. |
| 92 | .Pp |
| 93 | No interface is provided to permit exceptions to be handled in |
| 94 | nontrivial ways. |
| 95 | There is no uniform way for an exception handler to access |
| 96 | information about the exception-causing instruction, or |
| 97 | to determine whether that instruction should be reexecuted |
| 98 | after returning from the handler. |