sysdeps/powerpc/fpu/feupdateenv.c

   1 /* Install given floating-point environment and raise exceptions.
   2    Copyright (C) 1997-2013 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <fenv_libc.h>
  21 #include <fpu_control.h>
  22 #include <bp-sym.h>
  23
  24 #define _FPU_MASK_ALL (_FPU_MASK_ZM | _FPU_MASK_OM | _FPU_MASK_UM | _FPU_MASK_XM | _FPU_MASK_IM)
  25
  26 int
  27 __feupdateenv (const fenv_t *envp)
  28 {
  29   fenv_union_t old, new;
  30
  31   /* Save the currently set exceptions.  */
  32   new.fenv = *envp;
  33   old.fenv = fegetenv_register ();
  34
  35   /* Restore rounding mode and exception enable from *envp and merge
  36      exceptions.  Leave fraction rounded/inexact and FP result/CC bits
  37      unchanged.  */
  38   new.l[1] = (old.l[1] & 0x1FFFFF00) | (new.l[1] & 0x1FF80FFF);
  39
  40   /* If the old env has no enabled exceptions and the new env has any enabled
  41      exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits.  This will put
  42      the hardware into "precise mode" and may cause the FPU to run slower on
  43      some hardware.  */
  44   if ((old.l[1] & _FPU_MASK_ALL) == 0 && (new.l[1] & _FPU_MASK_ALL) != 0)
  45     (void)__fe_nomask_env ();
  46
  47   /* If the old env had any enabled exceptions and the new env has no enabled
  48      exceptions, then mask SIGFPE in the MSR FE0/FE1 bits.  This may allow the
  49      FPU to run faster because it always takes the default action and can not
  50      generate SIGFPE. */
  51   if ((old.l[1] & _FPU_MASK_ALL) != 0 && (new.l[1] & _FPU_MASK_ALL) == 0)
  52     (void)__fe_mask_env ();
  53
  54   /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
  55   fesetenv_register (new.fenv);
  56
  57   /* Success.  */
  58   return 0;
  59 }
  60
  61 #include <shlib-compat.h>
  62 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
  63 strong_alias (__feupdateenv, __old_feupdateenv)
  64 compat_symbol (libm, BP_SYM (__old_feupdateenv), BP_SYM (feupdateenv), GLIBC_2_1);
  65 #endif
  66
  67 libm_hidden_ver (__feupdateenv, feupdateenv)
  68 versioned_symbol (libm, BP_SYM (__feupdateenv), BP_SYM (feupdateenv), GLIBC_2_2);