1 /* Set current rounding direction.
2    Copyright (C) 1997-2022 Free Software Foundation, Inc.
3    This file is part of the GNU C Library.
4 
5    The GNU C Library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Lesser General Public
7    License as published by the Free Software Foundation; either
8    version 2.1 of the License, or (at your option) any later version.
9 
10    The GNU C Library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    Lesser General Public License for more details.
14 
15    You should have received a copy of the GNU Lesser General Public
16    License along with the GNU C Library; if not, see
17    <https://www.gnu.org/licenses/>.  */
18 
19 #include <fenv.h>
20 #include <unistd.h>
21 #include <ldsodefs.h>
22 #include <dl-procinfo.h>
23 
24 int
__fesetround(int round)25 __fesetround (int round)
26 {
27   unsigned short int cw;
28 
29   if ((round & ~0xc00) != 0)
30     /* ROUND is no valid rounding mode.  */
31     return 1;
32 
33   __asm__ ("fnstcw %0" : "=m" (*&cw));
34   cw &= ~0xc00;
35   cw |= round;
36   __asm__ ("fldcw %0" : : "m" (*&cw));
37 
38   /* If the CPU supports SSE we set the MXCSR as well.  */
39   if (CPU_FEATURE_USABLE (SSE))
40     {
41       unsigned int xcw;
42 
43       __asm__ ("stmxcsr %0" : "=m" (*&xcw));
44       xcw &= ~0x6000;
45       xcw |= round << 3;
46       __asm__ ("ldmxcsr %0" : : "m" (*&xcw));
47     }
48 
49   return 0;
50 }
51 libm_hidden_def (__fesetround)
52 weak_alias (__fesetround, fesetround)
53 libm_hidden_weak (fesetround)
54