ieeefp.h revision 302408 
1/*-
2 * Copyright (c) 2003 Peter Wemm.
3 * Copyright (c) 1990 Andrew Moore, Talke Studio
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 *    must display the following acknowledgement:
16 *	This product includes software developed by the University of
17 *	California, Berkeley and its contributors.
18 * 4. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * 	from: @(#) ieeefp.h 	1.0 (Berkeley) 9/23/93
35 * $FreeBSD: stable/11/sys/i386/include/ieeefp.h 226607 2011-10-21 06:41:46Z das $
36 */
37
38#ifndef _MACHINE_IEEEFP_H_
39#define _MACHINE_IEEEFP_H_
40
41/*
42 * Deprecated historical FPU control interface
43 *
44 * IEEE floating point type, constant and function definitions.
45 * XXX: FP*FLD and FP*OFF are undocumented pollution.
46 */
47
48#ifndef _SYS_CDEFS_H_
49#error this file needs sys/cdefs.h as a prerequisite
50#endif
51
52/*
53 * Rounding modes.
54 */
55typedef enum {
56	FP_RN=0,	/* round to nearest */
57	FP_RM,		/* round down towards minus infinity */
58	FP_RP,		/* round up towards plus infinity */
59	FP_RZ		/* truncate */
60} fp_rnd_t;
61
62/*
63 * Precision (i.e., rounding precision) modes.
64 */
65typedef enum {
66	FP_PS=0,	/* 24 bit (single-precision) */
67	FP_PRS,		/* reserved */
68	FP_PD,		/* 53 bit (double-precision) */
69	FP_PE		/* 64 bit (extended-precision) */
70} fp_prec_t;
71
72#define fp_except_t	int
73
74/*
75 * Exception bit masks.
76 */
77#define FP_X_INV	0x01	/* invalid operation */
78#define FP_X_DNML	0x02	/* denormal */
79#define FP_X_DZ		0x04	/* zero divide */
80#define FP_X_OFL	0x08	/* overflow */
81#define FP_X_UFL	0x10	/* underflow */
82#define FP_X_IMP	0x20	/* (im)precision */
83#define FP_X_STK	0x40	/* stack fault */
84
85/*
86 * FPU control word bit-field masks.
87 */
88#define FP_MSKS_FLD	0x3f	/* exception masks field */
89#define FP_PRC_FLD	0x300	/* precision control field */
90#define	FP_RND_FLD	0xc00	/* rounding control field */
91
92/*
93 * FPU status word bit-field masks.
94 */
95#define FP_STKY_FLD	0x3f	/* sticky flags field */
96
97/*
98 * FPU control word bit-field offsets (shift counts).
99 */
100#define FP_MSKS_OFF	0	/* exception masks offset */
101#define FP_PRC_OFF	8	/* precision control offset */
102#define	FP_RND_OFF	10	/* rounding control offset */
103
104/*
105 * FPU status word bit-field offsets (shift counts).
106 */
107#define FP_STKY_OFF	0	/* sticky flags offset */
108
109#ifdef __GNUCLIKE_ASM
110
111#define	__fldcw(addr)	__asm __volatile("fldcw %0" : : "m" (*(addr)))
112#define	__fldenv(addr)	__asm __volatile("fldenv %0" : : "m" (*(addr)))
113#define	__fnclex()	__asm __volatile("fnclex")
114#define	__fnstcw(addr)	__asm __volatile("fnstcw %0" : "=m" (*(addr)))
115#define	__fnstenv(addr)	__asm __volatile("fnstenv %0" : "=m" (*(addr)))
116#define	__fnstsw(addr)	__asm __volatile("fnstsw %0" : "=m" (*(addr)))
117
118/*
119 * Load the control word.  Be careful not to trap if there is a currently
120 * unmasked exception (ones that will become freshly unmasked are not a
121 * problem).  This case must be handled by a save/restore of the
122 * environment or even of the full x87 state.  Accessing the environment
123 * is very inefficient, so only do it when necessary.
124 */
125static __inline void
126__fnldcw(unsigned short _cw, unsigned short _newcw)
127{
128	struct {
129		unsigned _cw;
130		unsigned _other[6];
131	} _env;
132	unsigned short _sw;
133
134	if ((_cw & FP_MSKS_FLD) != FP_MSKS_FLD) {
135		__fnstsw(&_sw);
136		if (((_sw & ~_cw) & FP_STKY_FLD) != 0) {
137			__fnstenv(&_env);
138			_env._cw = _newcw;
139			__fldenv(&_env);
140			return;
141		}
142	}
143	__fldcw(&_newcw);
144}
145
146static __inline fp_rnd_t
147fpgetround(void)
148{
149	unsigned short _cw;
150
151	__fnstcw(&_cw);
152	return ((fp_rnd_t)((_cw & FP_RND_FLD) >> FP_RND_OFF));
153}
154
155static __inline fp_rnd_t
156fpsetround(fp_rnd_t _m)
157{
158	fp_rnd_t _p;
159	unsigned short _cw, _newcw;
160
161	__fnstcw(&_cw);
162	_p = (fp_rnd_t)((_cw & FP_RND_FLD) >> FP_RND_OFF);
163	_newcw = _cw & ~FP_RND_FLD;
164	_newcw |= (_m << FP_RND_OFF) & FP_RND_FLD;
165	__fnldcw(_cw, _newcw);
166	return (_p);
167}
168
169static __inline fp_prec_t
170fpgetprec(void)
171{
172	unsigned short _cw;
173
174	__fnstcw(&_cw);
175	return ((fp_prec_t)((_cw & FP_PRC_FLD) >> FP_PRC_OFF));
176}
177
178static __inline fp_prec_t
179fpsetprec(fp_prec_t _m)
180{
181	fp_prec_t _p;
182	unsigned short _cw, _newcw;
183
184	__fnstcw(&_cw);
185	_p = (fp_prec_t)((_cw & FP_PRC_FLD) >> FP_PRC_OFF);
186	_newcw = _cw & ~FP_PRC_FLD;
187	_newcw |= (_m << FP_PRC_OFF) & FP_PRC_FLD;
188	__fnldcw(_cw, _newcw);
189	return (_p);
190}
191
192/*
193 * Get or set the exception mask.
194 * Note that the x87 mask bits are inverted by the API -- a mask bit of 1
195 * means disable for x87 and SSE, but for fp*mask() it means enable.
196 */
197
198static __inline fp_except_t
199fpgetmask(void)
200{
201	unsigned short _cw;
202
203	__fnstcw(&_cw);
204	return ((~_cw & FP_MSKS_FLD) >> FP_MSKS_OFF);
205}
206
207static __inline fp_except_t
208fpsetmask(fp_except_t _m)
209{
210	fp_except_t _p;
211	unsigned short _cw, _newcw;
212
213	__fnstcw(&_cw);
214	_p = (~_cw & FP_MSKS_FLD) >> FP_MSKS_OFF;
215	_newcw = _cw & ~FP_MSKS_FLD;
216	_newcw |= (~_m << FP_MSKS_OFF) & FP_MSKS_FLD;
217	__fnldcw(_cw, _newcw);
218	return (_p);
219}
220
221static __inline fp_except_t
222fpgetsticky(void)
223{
224	unsigned _ex;
225	unsigned short _sw;
226
227	__fnstsw(&_sw);
228	_ex = (_sw & FP_STKY_FLD) >> FP_STKY_OFF;
229	return ((fp_except_t)_ex);
230}
231
232static __inline fp_except_t
233fpresetsticky(fp_except_t _m)
234{
235	struct {
236		unsigned _cw;
237		unsigned _sw;
238		unsigned _other[5];
239	} _env;
240	fp_except_t _p;
241
242	_m &= FP_STKY_FLD >> FP_STKY_OFF;
243	_p = fpgetsticky();
244	if ((_p & ~_m) == _p)
245		return (_p);
246	if ((_p & ~_m) == 0) {
247		__fnclex();
248		return (_p);
249	}
250	__fnstenv(&_env);
251	_env._sw &= ~_m;
252	__fldenv(&_env);
253	return (_p);
254}
255
256#endif /* __GNUCLIKE_ASM */
257
258#endif /* !_MACHINE_IEEEFP_H_ */
259