1 /* $NetBSD: fpsetsticky.c,v 1.11 2011/07/10 21:18:47 matt 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 1.11 2011/07/10 21:18:47 matt 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
__weak_alias(fpsetsticky,_fpsetsticky)50 __weak_alias(fpsetsticky,_fpsetsticky)
51 #endif
52
53 fp_except
54 fpsetsticky(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