sysdeps/powerpc/fpu/feupdateenv.c

   1 /* Install given floating-point environment and raise exceptions.
   2    Copyright (C) 1997,99,2000,01,07 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <fenv_libc.h>
  22 #include <bp-sym.h>
  23
  24 int
  25 __feupdateenv (const fenv_t *envp)
  26 {
  27   fenv_union_t old, new;
  28
  29   /* Save the currently set exceptions.  */
  30   new.fenv = *envp;
  31   old.fenv = fegetenv_register ();
  32
  33   /* Restore rounding mode and exception enable from *envp and merge
  34      exceptions.  Leave fraction rounded/inexact and FP result/CC bits
  35      unchanged.  */
  36   new.l[1] = (old.l[1] & 0x1FFFFF00) | (new.l[1] & 0x1FF80FFF);
  37
  38   /* If the old env has no eabled exceptions and the new env has any enabled
  39      exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits.  This will put
  40      the hardware into "precise mode" and may cause the FPU to run slower on
  41      some hardware.  */
  42   if ((old.l[1] & 0x000000F8) == 0 && (new.l[1] & 0x000000F8) != 0)
  43     (void)__fe_nomask_env ();
  44
  45   /* If the old env had any eabled exceptions and the new env has no enabled
  46      exceptions, then mask SIGFPE in the MSR FE0/FE1 bits.  This may allow the
  47      FPU to run faster because it always takes the default action and can not
  48      generate SIGFPE. */
  49   if ((old.l[1] & 0x000000F8) != 0 && (new.l[1] & 0x000000F8) == 0)
  50     (void)__fe_mask_env ();
  51
  52   /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
  53   fesetenv_register (new.fenv);
  54
  55   /* Success.  */
  56   return 0;
  57 }
  58
  59 #include <shlib-compat.h>
  60 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
  61 strong_alias (__feupdateenv, __old_feupdateenv)
  62 compat_symbol (libm, BP_SYM (__old_feupdateenv), BP_SYM (feupdateenv), GLIBC_2_1);
  63 #endif
  64
  65 versioned_symbol (libm, BP_SYM (__feupdateenv), BP_SYM (feupdateenv), GLIBC_2_2);