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glibc  2.9
fesetenv.c
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00001 /* Install given floating-point environment.
00002    Copyright (C) 1997,99,2000,01,02,07 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 #include <bp-sym.h>
00022 
00023 int
00024 __fesetenv (const fenv_t *envp)
00025 {
00026   fenv_union_t old, new;
00027 
00028   /* get the currently set exceptions.  */
00029   new.fenv = *envp;
00030   old.fenv = fegetenv_register ();
00031   
00032   /* If the old env has no eabled exceptions and the new env has any enabled
00033      exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits.  This will put
00034      the hardware into "precise mode" and may cause the FPU to run slower on
00035      some hardware.  */
00036   if ((old.l[1] & 0x000000F8) == 0 && (new.l[1] & 0x000000F8) != 0)
00037     (void)__fe_nomask_env ();
00038   
00039   /* If the old env had any eabled exceptions and the new env has no enabled
00040      exceptions, then mask SIGFPE in the MSR FE0/FE1 bits.  This may allow the
00041      FPU to run faster because it always takes the default action and can not 
00042      generate SIGFPE. */
00043   if ((old.l[1] & 0x000000F8) != 0 && (new.l[1] & 0x000000F8) == 0)
00044     (void)__fe_mask_env ();
00045     
00046   fesetenv_register (*envp);
00047 
00048   /* Success.  */
00049   return 0;
00050 }
00051 
00052 #include <shlib-compat.h>
00053 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
00054 strong_alias (__fesetenv, __old_fesetenv)
00055 compat_symbol (libm, BP_SYM (__old_fesetenv), BP_SYM (fesetenv), GLIBC_2_1);
00056 #endif
00057 
00058 libm_hidden_ver (__fesetenv, fesetenv)
00059 versioned_symbol (libm, BP_SYM (__fesetenv), BP_SYM (fesetenv), GLIBC_2_2);