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/* Set current rounding direction.
Copyright (C) 2001-2020 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>
int
__fesetround (int round)
{
unsigned short int cw;
int mxcsr;
if ((round & ~0xc00) != 0)
/* ROUND is no valid rounding mode. */
return 1;
/* First set the x87 FPU. */
asm ("fnstcw %0" : "=m" (*&cw));
cw &= ~0xc00;
cw |= round;
asm ("fldcw %0" : : "m" (*&cw));
/* And now the MSCSR register for SSE, the precision is at different bit
positions in the different units, we need to shift it 3 bits. */
asm ("stmxcsr %0" : "=m" (*&mxcsr));
mxcsr &= ~ 0x6000;
mxcsr |= round << 3;
asm ("ldmxcsr %0" : : "m" (*&mxcsr));
return 0;
}
libm_hidden_def (__fesetround)
weak_alias (__fesetround, fesetround)
libm_hidden_weak (fesetround)
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