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glibc  2.9
feholdexcpt.c
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00001 /* Store current floating-point environment and clear exceptions.
00002    Copyright (C) 1997, 1999, 2003, 2004, 2005, 2007
00003    Free Software Foundation, Inc.
00004    This file is part of the GNU C Library.
00005    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
00006 
00007    The GNU C Library is free software; you can redistribute it and/or
00008    modify it under the terms of the GNU Lesser General Public
00009    License as published by the Free Software Foundation; either
00010    version 2.1 of the License, or (at your option) any later version.
00011 
00012    The GNU C Library is distributed in the hope that it will be useful,
00013    but WITHOUT ANY WARRANTY; without even the implied warranty of
00014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015    Lesser General Public License for more details.
00016 
00017    You should have received a copy of the GNU Lesser General Public
00018    License along with the GNU C Library; if not, write to the Free
00019    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00020    02111-1307 USA.  */
00021 
00022 #include <fenv.h>
00023 #include <unistd.h>
00024 #include <ldsodefs.h>
00025 #include <dl-procinfo.h>
00026 
00027 int
00028 feholdexcept (fenv_t *envp)
00029 {
00030   fenv_t temp;
00031 
00032   /* Store the environment.  */
00033   __asm__ ("fnstenv %0" : "=m" (temp));
00034   *envp = temp;
00035 
00036   /* Now set all exceptions to non-stop.  */
00037   temp.__control_word |= 0x3f;
00038 
00039   /* And clear all exceptions.  */
00040   temp.__status_word &= ~0x3f;
00041 
00042   __asm__ ("fldenv %0" : : "m" (temp));
00043 
00044   /* If the CPU supports SSE we set the MXCSR as well.  */
00045   if ((GLRO(dl_hwcap) & HWCAP_I386_XMM) != 0)
00046     {
00047       unsigned int xwork;
00048 
00049       /* Get the current control word.  */
00050       __asm__ ("stmxcsr %0" : "=m" (*&xwork));
00051 
00052       /* Set all exceptions to non-stop and clear them.  */
00053       xwork = (xwork | 0x1f80) & ~0x3f;
00054 
00055       __asm__ ("ldmxcsr %0" : : "m" (*&xwork));
00056     }
00057 
00058   return 0;
00059 }
00060 libm_hidden_def (feholdexcept)