mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-21 04:31:04 +08:00
49 lines
1.5 KiB
C
49 lines
1.5 KiB
C
/* Set current rounding direction.
|
|
Copyright (C) 2001-2017 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
|
|
<http://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)
|