floatingpoint.h revision 2941 
1/*-
2 * Copyright (c) 1993 Andrew Moore, Talke Studio
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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 *	from: @(#) floatingpoint.h	1.0 (Berkeley) 9/23/93
34 *	$Id: floatingpoint.h,v 1.5 1994/08/04 19:16:36 wollman Exp $
35 */
36
37#ifndef _FLOATINGPOINT_H_
38#define _FLOATINGPOINT_H_
39
40/*
41 * IEEE floating point structure and function definitions
42 */
43
44/*-
45 * XXX the following undocumented pollution is exported:
46 *	fpsetsticky().
47 *	FP*FLD, FP*OFF and FP*REG from <machine/ieeefp.h>
48 */
49
50#include <sys/cdefs.h>
51#include <machine/ieeefp.h>
52
53#ifdef __GNUC__
54
55#define __fldenv(addr)	__asm __volatile("fldenv %0" : : "m" (*(addr)))
56#define __fnstenv(addr)	__asm __volatile("fnstenv %0" : "=m" (*(addr)))
57#define __fnstcw(addr)	__asm __volatile("fnstcw %0" : "=m" (*(addr)))
58#define __fnstsw(addr)	__asm __volatile("fnstsw %0" : "=m" (*(addr)))
59
60/*
61 * return the contents of a FP register
62 */
63static __inline__ int
64__fpgetreg(int _reg)
65{
66	unsigned short _mem;
67
68	/*-
69	 * This is more efficient than it looks.  The switch gets optimized
70	 * away if _reg is constant.
71	 *
72	 * The default case only supports _reg == 0.  We could handle more
73	 * registers (e.g., tags) using fnstenv, but the interface doesn't
74	 * support more.
75	 */
76	switch(_reg) {
77	default:
78		__fnstcw(&_mem);
79		break;
80	case FP_STKY_REG:
81		__fnstsw(&_mem);
82		break;
83	}
84	return _mem;
85}
86
87/*
88 * set a FP mode; return previous mode
89 */
90static __inline__ int
91__fpsetreg(int _m, int _reg, int _fld, int _off)
92{
93	unsigned _env[7];
94	unsigned _p;
95
96	/*
97	 * _reg == 0 could be handled better using fnstcw/fldcw.
98	 */
99	__fnstenv(_env);
100	_p =  (_env[_reg] & _fld) >> _off;
101	_env[_reg] = (_env[_reg] & ~_fld) | (_m << _off & _fld);
102	__fldenv(_env);
103	return _p;
104}
105
106#endif /* __GNUC__ */
107
108/*
109 * SysV/386 FP control interface
110 */
111#define fpgetround()	((__fpgetreg(FP_RND_REG) & FP_RND_FLD) >> FP_RND_OFF)
112#define fpsetround(m)	__fpsetreg((m), FP_RND_REG, FP_RND_FLD, FP_RND_OFF)
113#define fpgetprec()	((__fpgetreg(FP_PRC_REG) & FP_PRC_FLD) >> FP_PRC_OFF)
114#define fpsetprec(m)	__fpsetreg((m), FP_PRC_REG, FP_PRC_FLD, FP_PRC_OFF)
115#define fpgetmask()	((~__fpgetreg(FP_MSKS_REG) & FP_MSKS_FLD) >> FP_MSKS_OFF)
116#define fpsetmask(m)	__fpsetreg(~(m), FP_MSKS_REG, FP_MSKS_FLD, FP_MSKS_OFF)
117#define fpgetsticky()	((__fpgetreg(FP_STKY_REG) & FP_STKY_FLD) >> FP_STKY_OFF)
118#define fpresetsticky(m)	__fpsetreg(0, FP_STKY_REG, (m), FP_STKY_OFF)
119#define fpsetsticky(m)	fpresetsticky(m)
120
121#endif /* !_FLOATINGPOINT_H_ */
122