1 /* $OpenBSD: fpsetround.c,v 1.1 2018/02/28 11:16:54 kettenis Exp $ */
2 /*
3 * Copyright (c) 2018 Mark Kettenis <kettenis@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <ieeefp.h>
19 #ifdef SOFTFLOAT_FOR_GCC
20 #include "softfloat-for-gcc.h"
21 #endif
22 #include "milieu.h"
23 #include <softfloat.h>
24 #include <stdint.h>
25
26 __weak_alias(_fpsetround,fpsetround);
27
28 fp_rnd
fpsetround(fp_rnd rnd_dir)29 fpsetround(fp_rnd rnd_dir)
30 {
31 uint32_t old, new;
32
33 __asm volatile("vmrs %0, fpscr" : "=r" (old));
34 new = old & ~(3 << 22);
35 new |= (rnd_dir & 3) << 22;
36 __asm volatile("vmsr fpscr, %0" :: "r" (new));
37
38 float_rounding_mode = rnd_dir;
39
40 return ((old >> 22) & 3);
41 }
42