1 /*
2 * Copyright (C) 2007-2020 Free Software Foundation, Inc.
3 *
4 * This file is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License as published by the
6 * Free Software Foundation; either version 3, or (at your option) any
7 * later version.
8 *
9 * This file is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * Under Section 7 of GPL version 3, you are granted additional
15 * permissions described in the GCC Runtime Library Exception, version
16 * 3.1, as published by the Free Software Foundation.
17 *
18 * You should have received a copy of the GNU General Public License and
19 * a copy of the GCC Runtime Library Exception along with this program;
20 * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
21 * <http://www.gnu.org/licenses/>.
22 */
23
24 #ifndef _SOFT_FLOAT
25 #if __PREC == 32
26 #define X87CW (0 << 8) /* Single precision (24 bits) */
27 #elif __PREC == 64
28 #define X87CW (2 << 8) /* Double precision (53 bits) */
29 #elif __PREC == 80
30 #define X87CW (3 << 8) /* Extended precision (64 bits) */
31 #else
32 #error "Wrong precision requested."
33 #endif
34
35 #define X87CW_PCMASK (3 << 8)
36
37 static void __attribute__((constructor))
set_precision(void)38 set_precision (void)
39 {
40 unsigned short int cwd;
41
42 asm volatile ("fnstcw\t%0" : "=m" (cwd));
43
44 cwd &= ~X87CW_PCMASK;
45 cwd |= X87CW;
46
47 asm volatile ("fldcw\t%0" : : "m" (cwd));
48 }
49 #endif
50