lib/libm/arch/sparc64/fenv.c

   1 /*      $NetBSD: fenv.c,v 1.2 2011/05/20 21:42:49 nakayama 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 1.2 2011/05/20 21:42:49 nakayama Exp $");
  28
  29 #include <assert.h>
  30 #include <fenv.h>
  31
  32 #ifdef __arch64__
  33
  34 /* Load floating-point state register (all 64bits) */
  35 #define __ldxfsr(__r)   __asm__ __volatile__            \
  36         ("ldx %0, %%fsr" : : "m" (__r))
  37
  38 /* Save floating-point state register (all 64bits) */
  39 #define __stxfsr(__r)   __asm__ __volatile__            \
  40         ("stx %%fsr, %0" : "=m" (*(__r)))
  41
  42 #else /* !__arch64__ */
  43
  44 /* Load floating-point state register (32bits) */
  45 #define __ldxfsr(__r)   __asm__ __volatile__            \
  46         ("ld %0, %%fsr" : : "m" (__r))
  47
  48 /* Save floating-point state register (32bits) */
  49 #define __stxfsr(__r)   __asm__ __volatile__            \
  50         ("st %%fsr, %0" : "=m" (*(__r)))
  51
  52 #endif /* __arch64__ */
  53
  54 /*
  55  * The feclearexcept() function clears the supported floating-point exceptions
  56  * represented by `excepts'.
  57  */
  58 int
  59 feclearexcept(int excepts)
  60 {
  61         fexcept_t r;
  62         int ex;
  63
  64         _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
  65
  66         ex = excepts & FE_ALL_EXCEPT;
  67
  68         __stxfsr(&r);
  69         r &= ~ex;
  70         __ldxfsr(r);
  71
  72         /* Success */
  73         return 0;
  74 }
  75
  76 /*
  77  * The fegetexceptflag() function stores an implementation-defined
  78  * representation of the states of the floating-point status flags indicated
  79  * by the argument excepts in the object pointed to by the argument flagp.
  80  */
  81 int
  82 fegetexceptflag(fexcept_t *flagp, int excepts)
  83 {
  84         fexcept_t r;
  85         int ex;
  86
  87         _DIAGASSERT(flagp != NULL);
  88         _DIAGASSERT((excepts & ~_FE_ALL_EXCEPT) == 0);
  89
  90         ex = excepts & FE_ALL_EXCEPT;
  91
  92         __stxfsr(&r);
  93         *flagp = r & ex;
  94
  95         /* Success */
  96         return 0;
  97 }
  98
  99
 100 /*
 101  * This function sets the floating-point status flags indicated by the argument
 102  * `excepts' to the states stored in the object pointed to by `flagp'. It does
 103  * NOT raise any floating-point exceptions, but only sets the state of the flags.
 104  */
 105 int
 106 fesetexceptflag(const fexcept_t *flagp, int excepts)
 107 {
 108         fexcept_t r;
 109         int ex;
 110
 111         _DIAGASSERT(flagp != NULL);
 112         _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
 113
 114         ex = excepts & FE_ALL_EXCEPT;
 115
 116         __stxfsr(&r);
 117         r &= ~ex;
 118         r |= *flagp & ex;
 119         __ldxfsr(r);
 120
 121         /* Success */
 122         return 0;
 123 }
 124
 125 /*
 126  * The feraiseexcept() function raises the supported floating-point exceptions
 127  * represented by the argument `excepts'.
 128  *
 129  * The order in which these floating-point exceptions are raised is unspecified
 130  * (by the standard).
 131  */
 132 int
 133 feraiseexcept(int excepts)
 134 {
 135         volatile double d;
 136         int ex;
 137
 138         _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
 139
 140         ex = excepts & FE_ALL_EXCEPT;
 141
 142         /*
 143          * With a compiler that supports the FENV_ACCESS pragma properly, simple
 144          * expressions like '0.0 / 0.0' should be sufficient to generate traps.
 145          * Unfortunately, we need to bring a volatile variable into the equation
 146          * to prevent incorrect optimizations.
 147          */
 148         if (ex & FE_INVALID) {
 149                 d = 0.0;
 150                 d = 0.0 / d;
 151         }
 152         if (ex & FE_DIVBYZERO) {
 153                 d = 0.0;
 154                 d = 1.0 / d;
 155         }
 156         if (ex & FE_OVERFLOW) {
 157                 d = 0x1.ffp1023;
 158                 d *= 2.0;
 159         }
 160         if (ex & FE_UNDERFLOW) {
 161                 d = 0x1p-1022;
 162                 d /= 0x1p1023;
 163         }
 164         if (ex & FE_INEXACT) {
 165                 d = 0x1p-1022;
 166                 d += 1.0;
 167         }
 168
 169         /* Success */
 170         return 0;
 171 }
 172
 173 /*
 174  * The fetestexcept() function determines which of a specified subset of the
 175  * floating-point exception flags are currently set. The `excepts' argument
 176  * specifies the floating-point status flags to be queried.
 177  */
 178 int
 179 fetestexcept(int excepts)
 180 {
 181         fexcept_t r;
 182
 183         _DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
 184
 185         __stxfsr(&r);
 186
 187         return r & (excepts & FE_ALL_EXCEPT);
 188 }
 189
 190 /*
 191  * The fegetround() function gets the current rounding direction.
 192  */
 193 int
 194 fegetround(void)
 195 {
 196         fenv_t r;
 197
 198         __stxfsr(&r);
 199
 200         return (r >> _ROUND_SHIFT) & _ROUND_MASK;
 201 }
 202
 203 /*
 204  * The fesetround() function establishes the rounding direction represented by
 205  * its argument `round'. If the argument is not equal to the value of a rounding
 206  * direction macro, the rounding direction is not changed.
 207  */
 208 int
 209 fesetround(int round)
 210 {
 211         fenv_t r;
 212
 213         _DIAGASSERT((round & ~_ROUND_MASK) == 0);
 214         if (round & ~_ROUND_MASK)
 215                 return -1;
 216
 217         __stxfsr(&r);
 218         r &= ~(_ROUND_MASK << _ROUND_SHIFT);
 219         r |= round << _ROUND_SHIFT;
 220         __ldxfsr(r);
 221
 222         /* Success */
 223         return 0;
 224 }
 225
 226 /*
 227  * The fegetenv() function attempts to store the current floating-point
 228  * environment in the object pointed to by envp.
 229  */
 230 int
 231 fegetenv(fenv_t *envp)
 232 {
 233         _DIAGASSERT(envp != NULL);
 234
 235         __stxfsr(envp);
 236
 237         /* Success */
 238         return 0;
 239 }
 240
 241
 242 /*
 243  * The feholdexcept() function saves the current floating-point environment
 244  * in the object pointed to by envp, clears the floating-point status flags, and
 245  * then installs a non-stop (continue on floating-point exceptions) mode, if
 246  * available, for all floating-point exceptions.
 247  */
 248 int
 249 feholdexcept(fenv_t *envp)
 250 {
 251         fenv_t r;
 252
 253         _DIAGASSERT(envp != NULL);
 254
 255         __stxfsr(&r);
 256         *envp = r;
 257         r &= ~(FE_ALL_EXCEPT | _ENABLE_MASK);
 258         __ldxfsr(r);
 259
 260         /* Success */
 261         return 0;
 262 }
 263
 264 /*
 265  * The fesetenv() function attempts to establish the floating-point environment
 266  * represented by the object pointed to by envp. The argument `envp' points
 267  * to an object set by a call to fegetenv() or feholdexcept(), or equal a
 268  * floating-point environment macro. The fesetenv() function does not raise
 269  * floating-point exceptions, but only installs the state of the floating-point
 270  * status flags represented through its argument.
 271  */
 272 int
 273 fesetenv(const fenv_t *envp)
 274 {
 275         _DIAGASSERT(envp != NULL);
 276
 277         __ldxfsr(*envp);
 278
 279         /* Success */
 280         return 0;
 281 }
 282
 283
 284 /*
 285  * The feupdateenv() function saves the currently raised floating-point
 286  * exceptions in its automatic storage, installs the floating-point environment
 287  * represented by the object pointed to by `envp', and then raises the saved
 288  * floating-point exceptions. The argument `envp' shall point to an object set
 289  * by a call to feholdexcept() or fegetenv(), or equal a floating-point
 290  * environment macro.
 291  */
 292 int
 293 feupdateenv(const fenv_t *envp)
 294 {
 295         fexcept_t r;
 296
 297         _DIAGASSERT(envp != NULL);
 298
 299         __stxfsr(&r);
 300         __ldxfsr(*envp);
 301
 302         _DIAGASSERT((r & ~FE_ALL_EXCEPT) == 0);
 303         feraiseexcept(r & FE_ALL_EXCEPT);
 304
 305         /* Success */
 306         return 0;
 307 }
 308
 309 /*
 310  * The following functions are extentions to the standard
 311  */
 312 int
 313 feenableexcept(int mask)
 314 {
 315         fenv_t old_r, new_r;
 316
 317         __stxfsr(&old_r);
 318         new_r = old_r | ((mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT);
 319         __ldxfsr(new_r);
 320
 321         return (old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT;
 322 }
 323
 324 int
 325 fedisableexcept(int mask)
 326 {
 327         fenv_t old_r, new_r;
 328
 329         __stxfsr(&old_r);
 330         new_r = old_r & ~((mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT);
 331         __ldxfsr(new_r);
 332
 333         return (old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT;
 334 }
 335
 336 int
 337 fegetexcept(void)
 338 {
 339         fenv_t r;
 340
 341         __stxfsr(&r);
 342         return (r & _ENABLE_MASK) >> _FPUSW_SHIFT;
 343 }