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glibc  2.9
fclrexcpt.c
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00001 /* Clear given exceptions in current floating-point environment.
00002    Copyright (C) 2001 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 feclearexcept (int excepts)
00024 {
00025   fenv_t temp;
00026   unsigned int mxcsr;
00027 
00028   /* Mask out unsupported bits/exceptions.  */
00029   excepts &= FE_ALL_EXCEPT;
00030 
00031   /* Bah, we have to clear selected exceptions.  Since there is no
00032      `fldsw' instruction we have to do it the hard way.  */
00033   __asm__ ("fnstenv %0" : "=m" (*&temp));
00034 
00035   /* Clear the relevant bits.  */
00036   temp.__status_word &= excepts ^ FE_ALL_EXCEPT;
00037 
00038   /* Put the new data in effect.  */
00039   __asm__ ("fldenv %0" : : "m" (*&temp));
00040 
00041   /* And the same procedure for SSE.  */
00042   __asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
00043 
00044   /* Clear the relevant bits.  */
00045   mxcsr &= ~excepts;
00046 
00047   /* And put them into effect.  */
00048   __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
00049 
00050   /* Success.  */
00051   return 0;
00052 }