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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) 1997,99,2000, 2001, 2003, 2004 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <fenv.h>
00022 #include <unistd.h>
00023 #include <ldsodefs.h>
00024 #include <dl-procinfo.h>
00025 
00026 int
00027 __feclearexcept (int excepts)
00028 {
00029   fenv_t temp;
00030 
00031   /* Mask out unsupported bits/exceptions.  */
00032   excepts &= FE_ALL_EXCEPT;
00033 
00034   /* Bah, we have to clear selected exceptions.  Since there is no
00035      `fldsw' instruction we have to do it the hard way.  */
00036   __asm__ ("fnstenv %0" : "=m" (*&temp));
00037 
00038   /* Clear the relevant bits.  */
00039   temp.__status_word &= excepts ^ FE_ALL_EXCEPT;
00040 
00041   /* Put the new data in effect.  */
00042   __asm__ ("fldenv %0" : : "m" (*&temp));
00043 
00044   /* If the CPU supports SSE, we clear the MXCSR as well.  */
00045   if ((GLRO(dl_hwcap) & HWCAP_I386_XMM) != 0)
00046     {
00047       unsigned int xnew_exc;
00048 
00049       /* Get the current MXCSR.  */
00050       __asm__ ("stmxcsr %0" : "=m" (*&xnew_exc));
00051 
00052       /* Clear the relevant bits.  */
00053       xnew_exc &= ~excepts;
00054 
00055       /* Put the new data in effect.  */
00056       __asm__ ("ldmxcsr %0" : : "m" (*&xnew_exc));
00057     }
00058 
00059   /* Success.  */
00060   return 0;
00061 }
00062 
00063 #include <shlib-compat.h>
00064 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
00065 strong_alias (__feclearexcept, __old_feclearexcept)
00066 compat_symbol (libm, __old_feclearexcept, feclearexcept, GLIBC_2_1);
00067 #endif
00068 
00069 versioned_symbol (libm, __feclearexcept, feclearexcept, GLIBC_2_2);