1 /* $NetBSD: fenv.c,v 1.4 2021/09/03 21:54:59 andvar Exp $ */
2
3 /*-
4 * Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 */
26 #include <sys/cdefs.h>
27 __RCSID("$NetBSD: fenv.c,v 1.4 2021/09/03 21:54:59 andvar Exp $");
28
29 #include "namespace.h"
30
31 #include <assert.h>
32 #include <fenv.h>
33
34 #ifdef __weak_alias
__weak_alias(feclearexcept,_feclearexcept)35 __weak_alias(feclearexcept,_feclearexcept)
36 __weak_alias(fedisableexcept,_fedisableexcept)
37 __weak_alias(feenableexcept,_feenableexcept)
38 __weak_alias(fegetenv,_fegetenv)
39 __weak_alias(fegetexcept,_fegetexcept)
40 __weak_alias(fegetexceptflag,_fegetexceptflag)
41 __weak_alias(fegetround,_fegetround)
42 __weak_alias(feholdexcept,_feholdexcept)
43 __weak_alias(feraiseexcept,_feraiseexcept)
44 __weak_alias(fesetenv,_fesetenv)
45 __weak_alias(fesetexceptflag,_fesetexceptflag)
46 __weak_alias(fesetround,_fesetround)
47 __weak_alias(fetestexcept,_fetestexcept)
48 __weak_alias(feupdateenv,_feupdateenv)
49 #endif
50
51 #ifdef __arch64__
52
53 /* Load floating-point state register (all 64bits) */
54 #define __ldxfsr(__r) __asm__ __volatile__ \
55 ("ldx %0, %%fsr" : : "m" (__r))
56
57 /* Save floating-point state register (all 64bits) */
58 #define __stxfsr(__r) __asm__ __volatile__ \
59 ("stx %%fsr, %0" : "=m" (*(__r)))
60
61 #else /* !__arch64__ */
62
63 /* Load floating-point state register (32bits) */
64 #define __ldxfsr(__r) __asm__ __volatile__ \
65 ("ld %0, %%fsr" : : "m" (__r))
66
67 /* Save floating-point state register (32bits) */
68 #define __stxfsr(__r) __asm__ __volatile__ \
69 ("st %%fsr, %0" : "=m" (*(__r)))
70
71 #endif /* __arch64__ */
72
73 /*
74 * The feclearexcept() function clears the supported floating-point exceptions
75 * represented by `excepts'.
76 */
77 int
78 feclearexcept(int excepts)
79 {
80 fexcept_t r;
81 int ex;
82
83 _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
84
85 ex = excepts & FE_ALL_EXCEPT;
86
87 __stxfsr(&r);
88 r &= ~ex;
89 __ldxfsr(r);
90
91 /* Success */
92 return 0;
93 }
94
95 /*
96 * The fegetexceptflag() function stores an implementation-defined
97 * representation of the states of the floating-point status flags indicated
98 * by the argument excepts in the object pointed to by the argument flagp.
99 */
100 int
fegetexceptflag(fexcept_t * flagp,int excepts)101 fegetexceptflag(fexcept_t *flagp, int excepts)
102 {
103 fexcept_t r;
104 int ex;
105
106 _DIAGASSERT(flagp != NULL);
107 _DIAGASSERT((excepts & ~_FE_ALL_EXCEPT) == 0);
108
109 ex = excepts & FE_ALL_EXCEPT;
110
111 __stxfsr(&r);
112 *flagp = r & ex;
113
114 /* Success */
115 return 0;
116 }
117
118
119 /*
120 * This function sets the floating-point status flags indicated by the argument
121 * `excepts' to the states stored in the object pointed to by `flagp'. It does
122 * NOT raise any floating-point exceptions, but only sets the state of the flags.
123 */
124 int
fesetexceptflag(const fexcept_t * flagp,int excepts)125 fesetexceptflag(const fexcept_t *flagp, int excepts)
126 {
127 fexcept_t r;
128 int ex;
129
130 _DIAGASSERT(flagp != NULL);
131 _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
132
133 ex = excepts & FE_ALL_EXCEPT;
134
135 __stxfsr(&r);
136 r &= ~ex;
137 r |= *flagp & ex;
138 __ldxfsr(r);
139
140 /* Success */
141 return 0;
142 }
143
144 /*
145 * The feraiseexcept() function raises the supported floating-point exceptions
146 * represented by the argument `excepts'.
147 *
148 * The order in which these floating-point exceptions are raised is unspecified
149 * (by the standard).
150 */
151 int
feraiseexcept(int excepts)152 feraiseexcept(int excepts)
153 {
154 volatile double d;
155 int ex;
156
157 _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
158
159 ex = excepts & FE_ALL_EXCEPT;
160
161 /*
162 * With a compiler that supports the FENV_ACCESS pragma properly, simple
163 * expressions like '0.0 / 0.0' should be sufficient to generate traps.
164 * Unfortunately, we need to bring a volatile variable into the equation
165 * to prevent incorrect optimizations.
166 */
167 if (ex & FE_INVALID) {
168 d = 0.0;
169 d = 0.0 / d;
170 }
171 if (ex & FE_DIVBYZERO) {
172 d = 0.0;
173 d = 1.0 / d;
174 }
175 if (ex & FE_OVERFLOW) {
176 d = 0x1.ffp1023;
177 d *= 2.0;
178 }
179 if (ex & FE_UNDERFLOW) {
180 d = 0x1p-1022;
181 d /= 0x1p1023;
182 }
183 if (ex & FE_INEXACT) {
184 d = 0x1p-1022;
185 d += 1.0;
186 }
187
188 /* Success */
189 return 0;
190 }
191
192 /*
193 * The fetestexcept() function determines which of a specified subset of the
194 * floating-point exception flags are currently set. The `excepts' argument
195 * specifies the floating-point status flags to be queried.
196 */
197 int
fetestexcept(int excepts)198 fetestexcept(int excepts)
199 {
200 fexcept_t r;
201
202 _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
203
204 __stxfsr(&r);
205
206 return r & (excepts & FE_ALL_EXCEPT);
207 }
208
209 /*
210 * The fegetround() function gets the current rounding direction.
211 */
212 int
fegetround(void)213 fegetround(void)
214 {
215 fenv_t r;
216
217 __stxfsr(&r);
218
219 return (r >> _ROUND_SHIFT) & _ROUND_MASK;
220 }
221
222 /*
223 * The fesetround() function establishes the rounding direction represented by
224 * its argument `round'. If the argument is not equal to the value of a rounding
225 * direction macro, the rounding direction is not changed.
226 */
227 int
fesetround(int round)228 fesetround(int round)
229 {
230 fenv_t r;
231
232 _DIAGASSERT((round & ~_ROUND_MASK) == 0);
233 if (round & ~_ROUND_MASK)
234 return -1;
235
236 __stxfsr(&r);
237 r &= ~(_ROUND_MASK << _ROUND_SHIFT);
238 r |= round << _ROUND_SHIFT;
239 __ldxfsr(r);
240
241 /* Success */
242 return 0;
243 }
244
245 /*
246 * The fegetenv() function attempts to store the current floating-point
247 * environment in the object pointed to by envp.
248 */
249 int
fegetenv(fenv_t * envp)250 fegetenv(fenv_t *envp)
251 {
252 _DIAGASSERT(envp != NULL);
253
254 __stxfsr(envp);
255
256 /* Success */
257 return 0;
258 }
259
260
261 /*
262 * The feholdexcept() function saves the current floating-point environment
263 * in the object pointed to by envp, clears the floating-point status flags, and
264 * then installs a non-stop (continue on floating-point exceptions) mode, if
265 * available, for all floating-point exceptions.
266 */
267 int
feholdexcept(fenv_t * envp)268 feholdexcept(fenv_t *envp)
269 {
270 fenv_t r;
271
272 _DIAGASSERT(envp != NULL);
273
274 __stxfsr(&r);
275 *envp = r;
276 r &= ~(FE_ALL_EXCEPT | _ENABLE_MASK);
277 __ldxfsr(r);
278
279 /* Success */
280 return 0;
281 }
282
283 /*
284 * The fesetenv() function attempts to establish the floating-point environment
285 * represented by the object pointed to by envp. The argument `envp' points
286 * to an object set by a call to fegetenv() or feholdexcept(), or equal a
287 * floating-point environment macro. The fesetenv() function does not raise
288 * floating-point exceptions, but only installs the state of the floating-point
289 * status flags represented through its argument.
290 */
291 int
fesetenv(const fenv_t * envp)292 fesetenv(const fenv_t *envp)
293 {
294 _DIAGASSERT(envp != NULL);
295
296 __ldxfsr(*envp);
297
298 /* Success */
299 return 0;
300 }
301
302
303 /*
304 * The feupdateenv() function saves the currently raised floating-point
305 * exceptions in its automatic storage, installs the floating-point environment
306 * represented by the object pointed to by `envp', and then raises the saved
307 * floating-point exceptions. The argument `envp' shall point to an object set
308 * by a call to feholdexcept() or fegetenv(), or equal a floating-point
309 * environment macro.
310 */
311 int
feupdateenv(const fenv_t * envp)312 feupdateenv(const fenv_t *envp)
313 {
314 fexcept_t r;
315
316 _DIAGASSERT(envp != NULL);
317
318 __stxfsr(&r);
319 __ldxfsr(*envp);
320
321 _DIAGASSERT((r & ~FE_ALL_EXCEPT) == 0);
322 feraiseexcept(r & FE_ALL_EXCEPT);
323
324 /* Success */
325 return 0;
326 }
327
328 /*
329 * The following functions are extensions to the standard
330 */
331 int
feenableexcept(int mask)332 feenableexcept(int mask)
333 {
334 fenv_t old_r, new_r;
335
336 __stxfsr(&old_r);
337 new_r = old_r | ((mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT);
338 __ldxfsr(new_r);
339
340 return (old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT;
341 }
342
343 int
fedisableexcept(int mask)344 fedisableexcept(int mask)
345 {
346 fenv_t old_r, new_r;
347
348 __stxfsr(&old_r);
349 new_r = old_r & ~((mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT);
350 __ldxfsr(new_r);
351
352 return (old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT;
353 }
354
355 int
fegetexcept(void)356 fegetexcept(void)
357 {
358 fenv_t r;
359
360 __stxfsr(&r);
361 return (r & _ENABLE_MASK) >> _FPUSW_SHIFT;
362 }
363