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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) 2001, 2005, 2007 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <fenv.h>
00021 
00022 int
00023 feholdexcept (fenv_t *envp)
00024 {
00025   unsigned int mxcsr;
00026   fenv_t temp;
00027 
00028   /* Store the environment.  */
00029   __asm__ ("fnstenv %0\n"
00030           "stmxcsr %1" : "=m" (temp), "=m" (temp.__mxcsr));
00031   *envp = temp;
00032 
00033   /* Now set all exceptions to non-stop, first the x87 FPU.  */
00034   temp.__control_word |= 0x3f;
00035 
00036   /* And clear all exceptions.  */
00037   temp.__status_word &= ~0x3f;
00038 
00039   __asm__ ("fldenv %0" : : "m" (temp));
00040 
00041   /* Set the SSE MXCSR register.  */
00042   mxcsr = (envp->__mxcsr | 0x1f80) & ~0x3f;
00043   __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
00044 
00045   return 0;
00046 }
00047 libm_hidden_def (feholdexcept)