glibc/sysdeps/i386/fpu/feholdexcpt.c

51 lines
1.7 KiB
C

/* Store current floating-point environment and clear exceptions.
Copyright (C) 1997-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <fenv.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <dl-procinfo.h>
int
__feholdexcept (fenv_t *envp)
{
/* Store the environment. Recall that fnstenv has a side effect of
masking all exceptions. Then clear all exceptions. */
__asm__ volatile ("fnstenv %0; fnclex" : "=m" (*envp));
/* If the CPU supports SSE we set the MXCSR as well. */
if (HAS_CPU_FEATURE (SSE))
{
unsigned int xwork;
/* Get the current control word. */
__asm__ ("stmxcsr %0" : "=m" (envp->__eip));
/* Set all exceptions to non-stop and clear them. */
xwork = (envp->__eip | 0x1f80) & ~0x3f;
__asm__ ("ldmxcsr %0" : : "m" (*&xwork));
}
return 0;
}
libm_hidden_def (__feholdexcept)
weak_alias (__feholdexcept, feholdexcept)
libm_hidden_weak (feholdexcept)