1 /* $NetBSD: fpsetround.c,v 1.2 2008/04/28 20:22:57 martin Exp $ */
2
3 /*
4 * Copyright (c) 1999 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Dan Winship.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: fpsetround.c,v 1.2 2008/04/28 20:22:57 martin Exp $");
35 #endif /* LIBC_SCCS and not lint */
36
37 #include "namespace.h"
38
39 #include <sys/types.h>
40 #include <ieeefp.h>
41 #include <powerpc/fpu.h>
42
43 #ifdef __weak_alias
__weak_alias(fpsetround,_fpsetround)44 __weak_alias(fpsetround,_fpsetround)
45 #endif
46
47 #define ROUNDBITS FPSCR_RN
48
49 fp_rnd
50 fpsetround(fp_rnd rnd_dir)
51 {
52 uint64_t fpscr;
53 fp_rnd old;
54
55 __asm volatile("mffs %0" : "=f"(fpscr));
56 old = (uint32_t)fpscr & ROUNDBITS;
57 fpscr &= ~ROUNDBITS;
58 fpscr |= rnd_dir & ROUNDBITS;
59 __asm volatile("mtfsf 0xff,%0" :: "f"(fpscr));
60 return (old);
61 }
62