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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, 2005 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_libc.h>
00021 
00022 int
00023 feholdexcept (fenv_t *envp)
00024 {
00025   fenv_union_t old, new;
00026 
00027   /* Save the currently set exceptions.  */
00028   old.fenv = *envp = fegetenv_register ();
00029 
00030   /* Clear everything except for the rounding modes and non-IEEE arithmetic
00031      flag.  */
00032   new.l[1] = old.l[1] & 7;
00033   new.l[0] = old.l[0];
00034   
00035   /* If the old env had any eabled exceptions, then mask SIGFPE in the
00036      MSR FE0/FE1 bits.  This may allow the FPU to run faster because it
00037      always takes the default action and can not generate SIGFPE. */
00038   if ((old.l[1] & 0x000000F8) != 0)
00039     (void)__fe_mask_env ();
00040 
00041   /* Put the new state in effect.  */
00042   fesetenv_register (new.fenv);
00043 
00044   return 0;
00045 }
00046 libm_hidden_def (feholdexcept)