sysdeps/powerpc/fpu/feupdateenv.c

   1 /* Install given floating-point environment and raise exceptions.
   2    Copyright (C) 1997-2018 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
  23 #define _FPU_MASK_ALL (_FPU_MASK_ZM | _FPU_MASK_OM | _FPU_MASK_UM | _FPU_MASK_XM | _FPU_MASK_IM)
  24
  25 int
  26 __feupdateenv (const fenv_t *envp)
  27 {
  28   fenv_union_t old, new;
  29
  30   /* Save the currently set exceptions.  */
  31   new.fenv = *envp;
  32   old.fenv = fegetenv_register ();
  33
  34   /* Restore rounding mode and exception enable from *envp and merge
  35      exceptions.  Leave fraction rounded/inexact and FP result/CC bits
  36      unchanged.  */
  37   new.l = (old.l & 0xffffffff1fffff00LL) | (new.l & 0x1ff80fff);
  38
  39   /* If the old env has no enabled exceptions and the new env has any enabled
  40      exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits.  This will put
  41      the hardware into "precise mode" and may cause the FPU to run slower on
  42      some hardware.  */
  43   if ((old.l & _FPU_MASK_ALL) == 0 && (new.l & _FPU_MASK_ALL) != 0)
  44     (void) __fe_nomask_env_priv ();
  45
  46   /* If the old env had any enabled exceptions and the new env has no enabled
  47      exceptions, then mask SIGFPE in the MSR FE0/FE1 bits.  This may allow the
  48      FPU to run faster because it always takes the default action and can not
  49      generate SIGFPE. */
  50   if ((old.l & _FPU_MASK_ALL) != 0 && (new.l & _FPU_MASK_ALL) == 0)
  51     (void)__fe_mask_env ();
  52
  53   /* Atomically enable and raise (if appropriate) exceptions set in `new'. */
  54   fesetenv_register (new.fenv);
  55
  56   /* Success.  */
  57   return 0;
  58 }
  59
  60 #include <shlib-compat.h>
  61 #if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
  62 strong_alias (__feupdateenv, __old_feupdateenv)
  63 compat_symbol (libm, __old_feupdateenv, feupdateenv, GLIBC_2_1);
  64 #endif
  65
  66 libm_hidden_def (__feupdateenv)
  67 libm_hidden_ver (__feupdateenv, feupdateenv)
  68 versioned_symbol (libm, __feupdateenv, feupdateenv, GLIBC_2_2);