fenv.c revision 130142 
1/*-
2 * Copyright (c) 2004 David Schultz <das@FreeBSD.ORG>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/lib/msun/amd64/fenv.c 130142 2004-06-06 10:03:25Z das $
27 */
28
29#include <sys/cdefs.h>
30#include <sys/types.h>
31#include <machine/fpu.h>
32#include <fenv.h>
33
34const fenv_t __fe_dfl_env = {
35	{ 0xffff0000 | __INITIAL_FPUCW__,
36	  0xffff0000,
37	  0xffffffff,
38	  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
39	    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff }
40	},
41	__INITIAL_MXCSR__
42};
43
44int
45fesetexceptflag(const fexcept_t *flagp, int excepts)
46{
47	fenv_t env;
48
49	__fnstenv(&env.__x87);
50	env.__x87.__status &= ~excepts;
51	env.__x87.__status |= *flagp & excepts;
52	__fldenv(env.__x87);
53
54	__stmxcsr(&env.__mxcsr);
55	env.__mxcsr &= ~excepts;
56	env.__mxcsr |= *flagp & excepts;
57	__ldmxcsr(env.__mxcsr);
58
59	return (0);
60}
61
62int
63feraiseexcept(int excepts)
64{
65	fexcept_t ex = excepts;
66
67	fesetexceptflag(&ex, excepts);
68	__fwait();
69	return (0);
70}
71
72int
73fegetenv(fenv_t *envp)
74{
75	int control;
76
77	/*
78	 * fnstenv masks all exceptions, so we need to save and
79	 * restore the control word to avoid this side effect.
80	 */
81	__fnstcw(&control);
82	__fnstenv(&envp->__x87);
83	__stmxcsr(&envp->__mxcsr);
84	__fldcw(control);
85	return (0);
86}
87
88int
89feholdexcept(fenv_t *envp)
90{
91	int mxcsr;
92
93	__stmxcsr(&mxcsr);
94	__fnstenv(&envp->__x87);
95	__fnclex();
96	envp->__mxcsr = mxcsr;
97	mxcsr &= FE_ALL_EXCEPT;
98	mxcsr |= FE_ALL_EXCEPT << _SSE_EMASK_SHIFT;
99	__ldmxcsr(mxcsr);
100	return (0);
101}
102
103int
104feupdateenv(const fenv_t *envp)
105{
106	int mxcsr, status;
107
108	__fnstsw(&status);
109	__stmxcsr(&mxcsr);
110	fesetenv(envp);
111	feraiseexcept((mxcsr | status) & FE_ALL_EXCEPT);
112	return (0);
113}
114
115int
116__fesetmask(int mask)
117{
118	int mxcsr, control, omask;
119
120	__fnstcw(&control);
121	__stmxcsr(&mxcsr);
122	omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
123	control = (control | FE_ALL_EXCEPT) & ~mask;
124	__fldcw(control);
125	mxcsr |= FE_ALL_EXCEPT << _SSE_EMASK_SHIFT;
126	mxcsr &= ~(mask << _SSE_EMASK_SHIFT);
127	__ldmxcsr(mxcsr);
128	return (~omask);
129}
130
131__weak_reference(__fesetmask, fesetmask);
132