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/* Set floating-point environment exception handling.
Copyright (C) 1997-2024 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 <ldsodefs.h>
int
__fesetexceptflag (const fexcept_t *flagp, int excepts)
{
/* The flags can be set in the 387 unit or in the SSE unit. When we need to
clear a flag, we need to do so in both units, due to the way fetestexcept
is implemented.
When we need to set a flag, it is sufficient to do it in the SSE unit,
because that is guaranteed to not trap. However, on i386 CPUs that have
only a 387 unit, set the flags in the 387, as long as this cannot trap. */
fenv_t temp;
excepts &= FE_ALL_EXCEPT;
/* Get the current x87 FPU environment. We have to do this since we
cannot separately set the status word.
Note: fnstenv masks all floating-point exceptions until the fldenv
or fldcw below. */
__asm__ ("fnstenv %0" : "=m" (*&temp));
if (CPU_FEATURE_USABLE (SSE))
{
unsigned int mxcsr;
/* Clear relevant flags. */
temp.__status_word &= ~(excepts & ~ *flagp);
/* Store the new status word (along with the rest of the environment). */
__asm__ ("fldenv %0" : : "m" (*&temp));
/* And now similarly for SSE. */
__asm__ ("stmxcsr %0" : "=m" (*&mxcsr));
/* Clear or set relevant flags. */
mxcsr ^= (mxcsr ^ *flagp) & excepts;
/* Put the new data in effect. */
__asm__ ("ldmxcsr %0" : : "m" (*&mxcsr));
}
else
{
/* Clear or set relevant flags. */
temp.__status_word ^= (temp.__status_word ^ *flagp) & excepts;
if ((~temp.__control_word) & temp.__status_word & excepts)
{
/* Setting the exception flags may trigger a trap (at the next
floating-point instruction, but that does not matter).
ISO C 23 § 7.6.4.5 does not allow it. */
__asm__ volatile ("fldcw %0" : : "m" (*&temp.__control_word));
return -1;
}
/* Store the new status word (along with the rest of the environment). */
__asm__ ("fldenv %0" : : "m" (*&temp));
}
/* Success. */
return 0;
}
#include <shlib-compat.h>
#if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_2)
strong_alias (__fesetexceptflag, __old_fesetexceptflag)
compat_symbol (libm, __old_fesetexceptflag, fesetexceptflag, GLIBC_2_1);
#endif
versioned_symbol (libm, __fesetexceptflag, fesetexceptflag, GLIBC_2_2);
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