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 <stdint.h>
33 #include <sys/cdefs.h>
34 #include <sys/types.h>
35
36 typedef struct {
37 struct {
38 uint32_t __control;
39 uint32_t __status;
40 uint32_t __tag;
41 char __other[16];
42 } __x87;
43 uint32_t __mxcsr;
44 } fenv_t;
45
46 typedef uint16_t fexcept_t;
47
48 /* Exception flags */
49 #define FE_INVALID 0x01
50 #define FE_DENORMAL 0x02
51 #define FE_DIVBYZERO 0x04
52 #define FE_OVERFLOW 0x08
53 #define FE_UNDERFLOW 0x10
54 #define FE_INEXACT 0x20
55 #define FE_ALL_EXCEPT (FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
56 FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
57
58 /* Rounding modes */
59 #define FE_TONEAREST 0x0000
60 #define FE_DOWNWARD 0x0400
61 #define FE_UPWARD 0x0800
62 #define FE_TOWARDZERO 0x0c00
63 #define _ROUND_MASK (FE_TONEAREST | FE_DOWNWARD | \
64 FE_UPWARD | FE_TOWARDZERO)
65
66 /*
67 * As compared to the x87 control word, the SSE unit's control word
68 * has the rounding control bits offset by 3 and the exception mask
69 * bits offset by 7.
70 */
71 #define _SSE_ROUND_SHIFT 3
72 #define _SSE_EMASK_SHIFT 7
73
74 __BEGIN_DECLS
75
76 /* Default floating-point environment */
77 extern const fenv_t __fe_dfl_env;
78 #define FE_DFL_ENV (&__fe_dfl_env)
79
80 #define __fldcw(__cw) __asm __volatile("fldcw %0" : : "m" (__cw))
81 #define __fldenv(__env) __asm __volatile("fldenv %0" : : "m" (__env))
82 #define __fldenvx(__env) __asm __volatile("fldenv %0" : : "m" (__env) \
83 : "st", "st(1)", "st(2)", "st(3)", "st(4)", \
84 "st(5)", "st(6)", "st(7)")
85 #define __fnclex() __asm __volatile("fnclex")
86 #define __fnstenv(__env) __asm __volatile("fnstenv %0" : "=m" (*(__env)))
87 #define __fnstcw(__cw) __asm __volatile("fnstcw %0" : "=m" (*(__cw)))
88 #define __fnstsw(__sw) __asm __volatile("fnstsw %0" : "=am" (*(__sw)))
89 #define __fwait() __asm __volatile("fwait")
90 #define __ldmxcsr(__csr) __asm __volatile("ldmxcsr %0" : : "m" (__csr))
91 #define __stmxcsr(__csr) __asm __volatile("stmxcsr %0" : "=m" (*(__csr)))
92
93 static __inline int
feclearexcept(int __excepts)94 feclearexcept(int __excepts)
95 {
96 fenv_t __env;
97
98 if (__excepts == FE_ALL_EXCEPT) {
99 __fnclex();
100 } else {
101 __fnstenv(&__env.__x87);
102 __env.__x87.__status &= ~__excepts;
103 __fldenv(__env.__x87);
104 }
105 __stmxcsr(&__env.__mxcsr);
106 __env.__mxcsr &= ~__excepts;
107 __ldmxcsr(__env.__mxcsr);
108 return (0);
109 }
110
111 static __inline int
fegetexceptflag(fexcept_t * __flagp,int __excepts)112 fegetexceptflag(fexcept_t *__flagp, int __excepts)
113 {
114 uint32_t __mxcsr;
115 uint16_t __status;
116
117 __stmxcsr(&__mxcsr);
118 __fnstsw(&__status);
119 *__flagp = (__mxcsr | __status) & __excepts;
120 return (0);
121 }
122
123 int fesetexceptflag(const fexcept_t *__flagp, int __excepts);
124 int feraiseexcept(int __excepts);
125
126 static __inline int
fetestexcept(int __excepts)127 fetestexcept(int __excepts)
128 {
129 uint32_t __mxcsr;
130 uint16_t __status;
131
132 __stmxcsr(&__mxcsr);
133 __fnstsw(&__status);
134 return ((__status | __mxcsr) & __excepts);
135 }
136
137 static __inline int
fegetround(void)138 fegetround(void)
139 {
140 uint16_t __control;
141
142 /*
143 * We assume that the x87 and the SSE unit agree on the
144 * rounding mode. Reading the control word on the x87 turns
145 * out to be about 5 times faster than reading it on the SSE
146 * unit on an Opteron 244.
147 */
148 __fnstcw(&__control);
149 return (__control & _ROUND_MASK);
150 }
151
152 static __inline int
fesetround(int __round)153 fesetround(int __round)
154 {
155 uint32_t __mxcsr;
156 uint16_t __control;
157
158 if (__round & ~_ROUND_MASK)
159 return (-1);
160
161 __fnstcw(&__control);
162 __control &= ~_ROUND_MASK;
163 __control |= __round;
164 __fldcw(__control);
165
166 __stmxcsr(&__mxcsr);
167 __mxcsr &= ~(_ROUND_MASK << _SSE_ROUND_SHIFT);
168 __mxcsr |= __round << _SSE_ROUND_SHIFT;
169 __ldmxcsr(__mxcsr);
170
171 return (0);
172 }
173
174 int fegetenv(fenv_t *__envp);
175 int feholdexcept(fenv_t *__envp);
176
177 static __inline int
fesetenv(const fenv_t * __envp)178 fesetenv(const fenv_t *__envp)
179 {
180
181 /*
182 * XXX Using fldenvx() instead of fldenv() tells the compiler that this
183 * instruction clobbers the i387 register stack. This happens because
184 * we restore the tag word from the saved environment. Normally, this
185 * would happen anyway and we wouldn't care, because the ABI allows
186 * function calls to clobber the i387 regs. However, fesetenv() is
187 * inlined, so we need to be more careful.
188 */
189 __fldenvx(__envp->__x87);
190 __ldmxcsr(__envp->__mxcsr);
191 return (0);
192 }
193
194 int feupdateenv(const fenv_t *__envp);
195
196 #if __BSD_VISIBLE
197
198 int feenableexcept(int __mask);
199 int fedisableexcept(int __mask);
200
201 static __inline int
fegetexcept(void)202 fegetexcept(void)
203 {
204 uint16_t __control;
205
206 /*
207 * We assume that the masks for the x87 and the SSE unit are
208 * the same.
209 */
210 __fnstcw(&__control);
211 return (~__control & FE_ALL_EXCEPT);
212 }
213
214 #endif /* __BSD_VISIBLE */
215
216 __END_DECLS
217
218 #endif /* !_FENV_H_ */
219