xref: /freebsd/lib/msun/x86/fenv.h (revision ab0b9f6b3073e6c4d1dfbf07444d7db67a189a96)
1 /*-
2  * Copyright (c) 2004-2005 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  * $FreeBSD$
27  */
28 
29 #ifndef	_FENV_H_
30 #define	_FENV_H_
31 
32 #include <sys/cdefs.h>
33 #include <sys/_types.h>
34 
35 #ifndef	__fenv_static
36 #define	__fenv_static	static
37 #endif
38 
39 typedef	__uint16_t	fexcept_t;
40 
41 /* Exception flags */
42 #define	FE_INVALID	0x01
43 #define	FE_DENORMAL	0x02
44 #define	FE_DIVBYZERO	0x04
45 #define	FE_OVERFLOW	0x08
46 #define	FE_UNDERFLOW	0x10
47 #define	FE_INEXACT	0x20
48 #define	FE_ALL_EXCEPT	(FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
49 			 FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
50 
51 /* Rounding modes */
52 #define	FE_TONEAREST	0x0000
53 #define	FE_DOWNWARD	0x0400
54 #define	FE_UPWARD	0x0800
55 #define	FE_TOWARDZERO	0x0c00
56 #define	_ROUND_MASK	(FE_TONEAREST | FE_DOWNWARD | \
57 			 FE_UPWARD | FE_TOWARDZERO)
58 
59 /*
60  * As compared to the x87 control word, the SSE unit's control word
61  * has the rounding control bits offset by 3 and the exception mask
62  * bits offset by 7.
63  */
64 #define	_SSE_ROUND_SHIFT	3
65 #define	_SSE_EMASK_SHIFT	7
66 
67 #ifdef __i386__
68 /*
69  * To preserve binary compatibility with FreeBSD 5.3, we pack the
70  * mxcsr into some reserved fields, rather than changing sizeof(fenv_t).
71  */
72 typedef struct {
73 	__uint16_t	__control;
74 	__uint16_t      __mxcsr_hi;
75 	__uint16_t	__status;
76 	__uint16_t      __mxcsr_lo;
77 	__uint32_t	__tag;
78 	char		__other[16];
79 } fenv_t;
80 #else /* __amd64__ */
81 typedef struct {
82 	struct {
83 		__uint32_t	__control;
84 		__uint32_t	__status;
85 		__uint32_t	__tag;
86 		char		__other[16];
87 	} __x87;
88 	__uint32_t		__mxcsr;
89 } fenv_t;
90 #endif /* __i386__ */
91 
92 __BEGIN_DECLS
93 
94 /* Default floating-point environment */
95 extern const fenv_t	__fe_dfl_env;
96 #define	FE_DFL_ENV	(&__fe_dfl_env)
97 
98 #define	__fldcw(__cw)		__asm __volatile("fldcw %0" : : "m" (__cw))
99 #define	__fldenv(__env)		__asm __volatile("fldenv %0" : : "m" (__env))
100 #define	__fldenvx(__env)	__asm __volatile("fldenv %0" : : "m" (__env)  \
101 				: "st", "st(1)", "st(2)", "st(3)", "st(4)",   \
102 				"st(5)", "st(6)", "st(7)")
103 #define	__fnclex()		__asm __volatile("fnclex")
104 #define	__fnstenv(__env)	__asm __volatile("fnstenv %0" : "=m" (*(__env)))
105 #define	__fnstcw(__cw)		__asm __volatile("fnstcw %0" : "=m" (*(__cw)))
106 #define	__fnstsw(__sw)		__asm __volatile("fnstsw %0" : "=am" (*(__sw)))
107 #define	__fwait()		__asm __volatile("fwait")
108 #define	__ldmxcsr(__csr)	__asm __volatile("ldmxcsr %0" : : "m" (__csr))
109 #define	__stmxcsr(__csr)	__asm __volatile("stmxcsr %0" : "=m" (*(__csr)))
110 
111 int fegetenv(fenv_t *__envp);
112 int feholdexcept(fenv_t *__envp);
113 int fesetexceptflag(const fexcept_t *__flagp, int __excepts);
114 int feraiseexcept(int __excepts);
115 int feupdateenv(const fenv_t *__envp);
116 
117 __fenv_static inline int
118 fegetround(void)
119 {
120 	__uint16_t __control;
121 
122 	/*
123 	 * We assume that the x87 and the SSE unit agree on the
124 	 * rounding mode.  Reading the control word on the x87 turns
125 	 * out to be about 5 times faster than reading it on the SSE
126 	 * unit on an Opteron 244.
127 	 */
128 	__fnstcw(&__control);
129 	return (__control & _ROUND_MASK);
130 }
131 
132 #if __BSD_VISIBLE
133 
134 int feenableexcept(int __mask);
135 int fedisableexcept(int __mask);
136 
137 /* We currently provide no external definition of fegetexcept(). */
138 static inline int
139 fegetexcept(void)
140 {
141 	__uint16_t __control;
142 
143 	/*
144 	 * We assume that the masks for the x87 and the SSE unit are
145 	 * the same.
146 	 */
147 	__fnstcw(&__control);
148 	return (~__control & FE_ALL_EXCEPT);
149 }
150 
151 #endif /* __BSD_VISIBLE */
152 
153 #ifdef __i386__
154 
155 /* After testing for SSE support once, we cache the result in __has_sse. */
156 enum __sse_support { __SSE_YES, __SSE_NO, __SSE_UNK };
157 extern enum __sse_support __has_sse;
158 int __test_sse(void);
159 #ifdef __SSE__
160 #define	__HAS_SSE()	1
161 #else
162 #define	__HAS_SSE()	(__has_sse == __SSE_YES ||			\
163 			 (__has_sse == __SSE_UNK && __test_sse()))
164 #endif
165 
166 #define	__get_mxcsr(env)	(((env).__mxcsr_hi << 16) |	\
167 				 ((env).__mxcsr_lo))
168 #define	__set_mxcsr(env, x)	do {				\
169 	(env).__mxcsr_hi = (__uint32_t)(x) >> 16;		\
170 	(env).__mxcsr_lo = (__uint16_t)(x);			\
171 } while (0)
172 
173 __fenv_static inline int
174 feclearexcept(int __excepts)
175 {
176 	fenv_t __env;
177 	__uint32_t __mxcsr;
178 
179 	if (__excepts == FE_ALL_EXCEPT) {
180 		__fnclex();
181 	} else {
182 		__fnstenv(&__env);
183 		__env.__status &= ~__excepts;
184 		__fldenv(__env);
185 	}
186 	if (__HAS_SSE()) {
187 		__stmxcsr(&__mxcsr);
188 		__mxcsr &= ~__excepts;
189 		__ldmxcsr(__mxcsr);
190 	}
191 	return (0);
192 }
193 
194 __fenv_static inline int
195 fegetexceptflag(fexcept_t *__flagp, int __excepts)
196 {
197 	__uint32_t __mxcsr;
198 	__uint16_t __status;
199 
200 	__fnstsw(&__status);
201 	if (__HAS_SSE())
202 		__stmxcsr(&__mxcsr);
203 	else
204 		__mxcsr = 0;
205 	*__flagp = (__mxcsr | __status) & __excepts;
206 	return (0);
207 }
208 
209 __fenv_static inline int
210 fetestexcept(int __excepts)
211 {
212 	__uint32_t __mxcsr;
213 	__uint16_t __status;
214 
215 	__fnstsw(&__status);
216 	if (__HAS_SSE())
217 		__stmxcsr(&__mxcsr);
218 	else
219 		__mxcsr = 0;
220 	return ((__status | __mxcsr) & __excepts);
221 }
222 
223 __fenv_static inline int
224 fesetround(int __round)
225 {
226 	__uint32_t __mxcsr;
227 	__uint16_t __control;
228 
229 	if (__round & ~_ROUND_MASK)
230 		return (-1);
231 
232 	__fnstcw(&__control);
233 	__control &= ~_ROUND_MASK;
234 	__control |= __round;
235 	__fldcw(__control);
236 
237 	if (__HAS_SSE()) {
238 		__stmxcsr(&__mxcsr);
239 		__mxcsr &= ~(_ROUND_MASK << _SSE_ROUND_SHIFT);
240 		__mxcsr |= __round << _SSE_ROUND_SHIFT;
241 		__ldmxcsr(__mxcsr);
242 	}
243 
244 	return (0);
245 }
246 
247 __fenv_static inline int
248 fesetenv(const fenv_t *__envp)
249 {
250 	fenv_t __env = *__envp;
251 	__uint32_t __mxcsr;
252 
253 	__mxcsr = __get_mxcsr(__env);
254 	__set_mxcsr(__env, 0xffffffff);
255 	/*
256 	 * XXX Using fldenvx() instead of fldenv() tells the compiler that this
257 	 * instruction clobbers the i387 register stack.  This happens because
258 	 * we restore the tag word from the saved environment.  Normally, this
259 	 * would happen anyway and we wouldn't care, because the ABI allows
260 	 * function calls to clobber the i387 regs.  However, fesetenv() is
261 	 * inlined, so we need to be more careful.
262 	 */
263 	__fldenvx(__env);
264 	if (__HAS_SSE())
265 		__ldmxcsr(__mxcsr);
266 	return (0);
267 }
268 
269 #else /* __amd64__ */
270 
271 __fenv_static inline int
272 feclearexcept(int __excepts)
273 {
274 	fenv_t __env;
275 
276 	if (__excepts == FE_ALL_EXCEPT) {
277 		__fnclex();
278 	} else {
279 		__fnstenv(&__env.__x87);
280 		__env.__x87.__status &= ~__excepts;
281 		__fldenv(__env.__x87);
282 	}
283 	__stmxcsr(&__env.__mxcsr);
284 	__env.__mxcsr &= ~__excepts;
285 	__ldmxcsr(__env.__mxcsr);
286 	return (0);
287 }
288 
289 __fenv_static inline int
290 fegetexceptflag(fexcept_t *__flagp, int __excepts)
291 {
292 	__uint32_t __mxcsr;
293 	__uint16_t __status;
294 
295 	__stmxcsr(&__mxcsr);
296 	__fnstsw(&__status);
297 	*__flagp = (__mxcsr | __status) & __excepts;
298 	return (0);
299 }
300 
301 __fenv_static inline int
302 fetestexcept(int __excepts)
303 {
304 	__uint32_t __mxcsr;
305 	__uint16_t __status;
306 
307 	__stmxcsr(&__mxcsr);
308 	__fnstsw(&__status);
309 	return ((__status | __mxcsr) & __excepts);
310 }
311 
312 __fenv_static inline int
313 fesetround(int __round)
314 {
315 	__uint32_t __mxcsr;
316 	__uint16_t __control;
317 
318 	if (__round & ~_ROUND_MASK)
319 		return (-1);
320 
321 	__fnstcw(&__control);
322 	__control &= ~_ROUND_MASK;
323 	__control |= __round;
324 	__fldcw(__control);
325 
326 	__stmxcsr(&__mxcsr);
327 	__mxcsr &= ~(_ROUND_MASK << _SSE_ROUND_SHIFT);
328 	__mxcsr |= __round << _SSE_ROUND_SHIFT;
329 	__ldmxcsr(__mxcsr);
330 
331 	return (0);
332 }
333 
334 __fenv_static inline int
335 fesetenv(const fenv_t *__envp)
336 {
337 
338 	/*
339 	 * XXX Using fldenvx() instead of fldenv() tells the compiler that this
340 	 * instruction clobbers the i387 register stack.  This happens because
341 	 * we restore the tag word from the saved environment.  Normally, this
342 	 * would happen anyway and we wouldn't care, because the ABI allows
343 	 * function calls to clobber the i387 regs.  However, fesetenv() is
344 	 * inlined, so we need to be more careful.
345 	 */
346 	__fldenvx(__envp->__x87);
347 	__ldmxcsr(__envp->__mxcsr);
348 	return (0);
349 }
350 
351 #endif /* __i386__ */
352 
353 __END_DECLS
354 
355 #endif	/* !_FENV_H_ */
356