xref: /freebsd/sys/amd64/include/ieeefp.h (revision fe26672a8f5e6d9c940c54c1dea7b0647d9468df)
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  * $FreeBSD$
36  */
37 
38 #ifndef _MACHINE_IEEEFP_H_
39 #define _MACHINE_IEEEFP_H_
40 
41 /*
42  * IEEE floating point type, constant and function definitions.
43  */
44 
45 #ifndef _SYS_CDEFS_H_
46 #error this file needs sys/cdefs.h as a prerequisite
47 #endif
48 
49 /*
50  * FP rounding modes
51  */
52 typedef enum {
53 	FP_RN=0,	/* round to nearest */
54 	FP_RM,		/* round down to minus infinity */
55 	FP_RP,		/* round up to plus infinity */
56 	FP_RZ		/* truncate */
57 } fp_rnd_t;
58 
59 /*
60  * FP precision modes
61  */
62 typedef enum {
63 	FP_PS=0,	/* 24 bit (single-precision) */
64 	FP_PRS,		/* reserved */
65 	FP_PD,		/* 53 bit (double-precision) */
66 	FP_PE		/* 64 bit (extended-precision) */
67 } fp_prec_t;
68 
69 #define fp_except_t	int
70 
71 /*
72  * FP exception masks
73  */
74 #define FP_X_INV	0x01	/* invalid operation */
75 #define FP_X_DNML	0x02	/* denormal */
76 #define FP_X_DZ		0x04	/* zero divide */
77 #define FP_X_OFL	0x08	/* overflow */
78 #define FP_X_UFL	0x10	/* underflow */
79 #define FP_X_IMP	0x20	/* (im)precision */
80 #define FP_X_STK	0x40	/* stack fault */
81 
82 /*
83  * FP registers
84  */
85 #define FP_MSKS_REG	0	/* exception masks */
86 #define FP_PRC_REG	0	/* precision */
87 #define FP_RND_REG	0	/* direction */
88 #define FP_STKY_REG	1	/* sticky flags */
89 
90 /*
91  * FP register bit field masks
92  */
93 #define FP_MSKS_FLD	0x3f	/* exception masks field */
94 #define FP_PRC_FLD	0x300	/* precision control field */
95 #define FP_RND_FLD	0xc00	/* round control field */
96 #define FP_STKY_FLD	0x3f	/* sticky flags field */
97 
98 /*
99  * SSE mxcsr register bit field masks
100  */
101 #define	SSE_STKY_FLD	0x3f	/* exception flags */
102 #define	SSE_DAZ_FLD	0x40	/* Denormals are zero */
103 #define	SSE_MSKS_FLD	0x1f80	/* exception masks field */
104 #define	SSE_RND_FLD	0x6000	/* rounding control */
105 #define	SSE_FZ_FLD	0x8000	/* flush to zero on underflow */
106 
107 /*
108  * FP register bit field offsets
109  */
110 #define FP_MSKS_OFF	0	/* exception masks offset */
111 #define FP_PRC_OFF	8	/* precision control offset */
112 #define FP_RND_OFF	10	/* round control offset */
113 #define FP_STKY_OFF	0	/* sticky flags offset */
114 
115 /*
116  * SSE mxcsr register bit field offsets
117  */
118 #define	SSE_STKY_OFF	0	/* exception flags offset */
119 #define	SSE_DAZ_OFF	6	/* DAZ exception mask offset */
120 #define	SSE_MSKS_OFF	7	/* other exception masks offset */
121 #define	SSE_RND_OFF	13	/* rounding control offset */
122 #define	SSE_FZ_OFF	15	/* flush to zero offset */
123 
124 #if defined(__GNUCLIKE_ASM) && defined(__CC_SUPPORTS___INLINE__) \
125     && !defined(__cplusplus)
126 
127 #define	__fldenv(addr)	__asm __volatile("fldenv %0" : : "m" (*(addr)))
128 #define	__fnstenv(addr)	__asm __volatile("fnstenv %0" : "=m" (*(addr)))
129 #define	__fldcw(addr)	__asm __volatile("fldcw %0" : : "m" (*(addr)))
130 #define	__fnstcw(addr)	__asm __volatile("fnstcw %0" : "=m" (*(addr)))
131 #define	__fnstsw(addr)	__asm __volatile("fnstsw %0" : "=m" (*(addr)))
132 #define	__ldmxcsr(addr)	__asm __volatile("ldmxcsr %0" : : "m" (*(addr)))
133 #define	__stmxcsr(addr)	__asm __volatile("stmxcsr %0" : "=m" (*(addr)))
134 
135 /*
136  * General notes about conflicting SSE vs FP status bits.
137  * This code assumes that software will not fiddle with the control
138  * bits of the SSE and x87 in such a way to get them out of sync and
139  * still expect this to work.  Break this at your peril.
140  * Because I based this on the i386 port, the x87 state is used for
141  * the fpget*() functions, and is shadowed into the SSE state for
142  * the fpset*() functions.  For dual source fpget*() functions, I
143  * merge the two together.  I think.
144  */
145 
146 static __inline__ fp_rnd_t
147 __fpgetround(void)
148 {
149 	unsigned short _cw;
150 
151 	__fnstcw(&_cw);
152 	return ((_cw & FP_RND_FLD) >> FP_RND_OFF);
153 }
154 
155 static __inline__ fp_rnd_t
156 __fpsetround(fp_rnd_t _m)
157 {
158 	unsigned short _cw;
159 	unsigned int _mxcsr;
160 	fp_rnd_t _p;
161 
162 	__fnstcw(&_cw);
163 	_p = (_cw & FP_RND_FLD) >> FP_RND_OFF;
164 	_cw &= ~FP_RND_FLD;
165 	_cw |= (_m << FP_RND_OFF) & FP_RND_FLD;
166 	__fldcw(&_cw);
167 	__stmxcsr(&_mxcsr);
168 	_mxcsr &= ~SSE_RND_FLD;
169 	_mxcsr |= (_m << SSE_RND_OFF) & SSE_RND_FLD;
170 	__ldmxcsr(&_mxcsr);
171 	return (_p);
172 }
173 
174 /*
175  * Get or set the rounding precision for x87 arithmetic operations.
176  * There is no equivalent SSE mode or control.
177  */
178 
179 static __inline__ fp_prec_t
180 __fpgetprec(void)
181 {
182 	unsigned short _cw;
183 
184 	__fnstcw(&_cw);
185 	return ((_cw & FP_PRC_FLD) >> FP_PRC_OFF);
186 }
187 
188 static __inline__ fp_prec_t
189 __fpsetprec(fp_rnd_t _m)
190 {
191 	unsigned short _cw;
192 	fp_prec_t _p;
193 
194 	__fnstcw(&_cw);
195 	_p = (_cw & FP_PRC_FLD) >> FP_PRC_OFF;
196 	_cw &= ~FP_PRC_FLD;
197 	_cw |= (_m << FP_PRC_OFF) & FP_PRC_FLD;
198 	__fldcw(&_cw);
199 	return (_p);
200 }
201 
202 /*
203  * Get or set the exception mask.
204  * Note that the x87 mask bits are inverted by the API -- a mask bit of 1
205  * means disable for x87 and SSE, but for fp*mask() it means enable.
206  */
207 
208 static __inline__ fp_except_t
209 __fpgetmask(void)
210 {
211 	unsigned short _cw;
212 
213 	__fnstcw(&_cw);
214 	return ((~_cw) & FP_MSKS_FLD);
215 }
216 
217 static __inline__ fp_except_t
218 __fpsetmask(fp_except_t _m)
219 {
220 	unsigned short _cw;
221 	unsigned int _mxcsr;
222 	fp_except_t _p;
223 
224 	__fnstcw(&_cw);
225 	_p = (~_cw) & FP_MSKS_FLD;
226 	_cw &= ~FP_MSKS_FLD;
227 	_cw |= (~_m) & FP_MSKS_FLD;
228 	__fldcw(&_cw);
229 	__stmxcsr(&_mxcsr);
230 	/* XXX should we clear non-ieee SSE_DAZ_FLD and SSE_FZ_FLD ? */
231 	_mxcsr &= ~SSE_MSKS_FLD;
232 	_mxcsr |= ((~_m) << SSE_MSKS_OFF) & SSE_MSKS_FLD;
233 	__ldmxcsr(&_mxcsr);
234 	return (_p);
235 }
236 
237 static __inline__ fp_except_t
238 __fpgetsticky(void)
239 {
240 	unsigned short _sw;
241 	unsigned int _mxcsr;
242 	fp_except_t _ex;
243 
244 	__fnstsw(&_sw);
245 	_ex = _sw & FP_STKY_FLD;
246 	__stmxcsr(&_mxcsr);
247 	_ex |= _mxcsr & SSE_STKY_FLD;
248 	return (_ex);
249 }
250 
251 #endif /* __GNUCLIKE_ASM && __CC_SUPPORTS___INLINE__ && !__cplusplus */
252 
253 #if !defined(__IEEEFP_NOINLINES__) && !defined(__cplusplus) \
254     && defined(__GNUCLIKE_ASM) && defined(__CC_SUPPORTS___INLINE__)
255 
256 #define	fpgetround()	__fpgetround()
257 #define	fpsetround(_m)	__fpsetround(_m)
258 #define	fpgetprec()	__fpgetprec()
259 #define	fpsetprec(_m)	__fpsetprec(_m)
260 #define	fpgetmask()	__fpgetmask()
261 #define	fpsetmask(_m)	__fpsetmask(_m)
262 #define	fpgetsticky()	__fpgetsticky()
263 
264 /* Suppress prototypes in the MI header. */
265 #define	_IEEEFP_INLINED_	1
266 
267 #else /* !(!__IEEEFP_NOINLINES__ && !__cplusplus && __GNUCLIKE_ASM
268          && __CC_SUPPORTS___INLINE__) */
269 
270 /* Augment the userland declarations. */
271 __BEGIN_DECLS
272 extern fp_prec_t fpgetprec(void);
273 extern fp_prec_t fpsetprec(fp_prec_t);
274 __END_DECLS
275 
276 #endif /* !__IEEEFP_NOINLINES__ && !__cplusplus && __GNUCLIKE_ASM
277           && __CC_SUPPORTS___INLINE__ */
278 
279 #endif /* !_MACHINE_IEEEFP_H_ */
280