glibc/sysdeps/x86_64/fpu/fsetexcptflg.c

54 lines
1.8 KiB
C

/* Set floating-point environment exception handling.
Copyright (C) 2001-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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 <math.h>
int
fesetexceptflag (const fexcept_t *flagp, int excepts)
{
fenv_t temp;
unsigned int mxcsr;
/* XXX: Do we really need to set both the exception in both units?
Shouldn't it be enough to set only the SSE unit? */
/* Get the current x87 FPU environment. We have to do this since we
cannot separately set the status word. */
__asm__ ("fnstenv %0" : "=m" (*&temp));
temp.__status_word &= ~(excepts & FE_ALL_EXCEPT);
temp.__status_word |= *flagp & excepts & FE_ALL_EXCEPT;
/* Store the new status word (along with the rest of the environment.
Possibly new exceptions are set but they won't get executed unless
the next floating-point instruction. */
__asm__ ("fldenv %0" : : "m" (*&temp));
/* And now the same for SSE. */
__asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
mxcsr &= ~(excepts & FE_ALL_EXCEPT);
mxcsr |= *flagp & excepts & FE_ALL_EXCEPT;
__asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
/* Success. */
return 0;
}