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/* Set the FPU control word for x86.
Copyright (C) 2003-2023 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 <math.h>
#include <fpu_control.h>
#include <fenv.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <dl-procinfo.h>
void
__setfpucw (fpu_control_t set)
{
fpu_control_t cw;
/* Fetch the current control word. */
__asm__ ("fnstcw %0" : "=m" (*&cw));
/* Preserve the reserved bits, and set the rest as the user
specified (or the default, if the user gave zero). */
cw &= _FPU_RESERVED;
cw |= set & ~_FPU_RESERVED;
__asm__ ("fldcw %0" : : "m" (*&cw));
/* If the CPU supports SSE, we set the MXCSR as well. */
if (CPU_FEATURE_USABLE (SSE))
{
unsigned int xnew_exc;
/* Get the current MXCSR. */
__asm__ ("stmxcsr %0" : "=m" (*&xnew_exc));
xnew_exc &= ~((0xc00 << 3) | (FE_ALL_EXCEPT << 7));
xnew_exc |= ((set & 0xc00) << 3) | ((set & FE_ALL_EXCEPT) << 7);
__asm__ ("ldmxcsr %0" : : "m" (*&xnew_exc));
}
}
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