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glibc  2.9
feupdateenv.c
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00001 /* Install given floating-point environment and raise exceptions.
00002    Copyright (C) 1997,99,2000,01,07 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_libc.h>
00022 #include <bp-sym.h>
00023 
00024 int
00025 __feupdateenv (const fenv_t *envp)
00026 {
00027   fenv_union_t old, new;
00028 
00029   /* Save the currently set exceptions.  */
00030   new.fenv = *envp;
00031   old.fenv = fegetenv_register ();
00032 
00033   /* Restore rounding mode and exception enable from *envp and merge
00034      exceptions.  Leave fraction rounded/inexact and FP result/CC bits
00035      unchanged.  */
00036   new.l[1] = (old.l[1] & 0x1FFFFF00) | (new.l[1] & 0x1FF80FFF);
00037   
00038   /* If the old env has no eabled exceptions and the new env has any enabled
00039      exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits.  This will put
00040      the hardware into "precise mode" and may cause the FPU to run slower on
00041      some hardware.  */
00042   if ((old.l[1] & 0x000000F8) == 0 && (new.l[1] & 0x000000F8) != 0)
00043     (void)__fe_nomask_env ();
00044   
00045   /* If the old env had any eabled exceptions and the new env has no enabled
00046      exceptions, then mask SIGFPE in the MSR FE0/FE1 bits.  This may allow the
00047      FPU to run faster because it always takes the default action and can not 
00048      generate SIGFPE. */
00049   if ((old.l[1] & 0x000000F8) != 0 && (new.l[1] & 0x000000F8) == 0)
00050     (void)__fe_mask_env ();
00051 
00052   /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
00053   fesetenv_register (new.fenv);
00054 
00055   /* Success.  */
00056   return 0;
00057 }
00058 
00059 #include <shlib-compat.h>
00060 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
00061 strong_alias (__feupdateenv, __old_feupdateenv)
00062 compat_symbol (libm, BP_SYM (__old_feupdateenv), BP_SYM (feupdateenv), GLIBC_2_1);
00063 #endif
00064 
00065 versioned_symbol (libm, BP_SYM (__feupdateenv), BP_SYM (feupdateenv), GLIBC_2_2);