1/*	$NetBSD: fpsetsticky.c,v 1.10 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: fpsetsticky.c,v 1.10 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#define	STICKYBITS	(FPSCR_XX|FPSCR_ZX|FPSCR_UX|FPSCR_OX|FPSCR_VX)
44#define	INVBITS		(FPSCR_VXCVI|FPSCR_VXSQRT|FPSCR_VXSOFT|FPSCR_VXVC|\
45			 FPSCR_VXIMZ|FPSCR_VXZDZ|FPSCR_VXIDI|FPSCR_VXISI|\
46			 FPSCR_VXSNAN)
47#define	STICKYSHFT	25
48
49#ifdef __weak_alias
50__weak_alias(fpsetsticky,_fpsetsticky)
51#endif
52
53fp_except
54fpsetsticky(fp_except mask)
55{
56	union {
57		double u_d;
58		uint64_t u_fpscr;
59	} ud;
60	fp_except old;
61
62	__asm volatile("mffs %0" : "=f"(ud.u_d));
63	old = ((uint32_t)ud.u_fpscr & STICKYBITS) >> STICKYSHFT;
64	/*
65	 * FPSCR_VX (aka FP_X_INV) is not a sticky bit but a summary of the
66	 * all the FPSCR_VX* sticky bits.  So when FP_X_INV is cleared then
67	 * clear all of those bits, likewise when it's set, set them all.
68	 */
69	if ((mask & FP_X_INV) == 0)
70		ud.u_fpscr &= ~INVBITS;
71	else
72		ud.u_fpscr |= INVBITS;
73	ud.u_fpscr &= ~STICKYBITS;
74	ud.u_fpscr |= ((uint32_t)mask << STICKYSHFT) & STICKYBITS;
75	/*
76	 * Make FPSCR_FX reflect the presence of a set sticky bit (or not).
77	 */
78	if (ud.u_fpscr & (STICKYBITS|INVBITS))
79		ud.u_fpscr |= FPSCR_FX;
80	else
81		ud.u_fpscr &= ~FPSCR_FX;
82	/*
83	 * Write back the fpscr.
84	 */
85	__asm volatile("mtfsf 0xff,%0" :: "f"(ud.u_d));
86	return (old);
87}
88