1 /* $OpenBSD: fenv.c,v 1.6 2022/12/27 17:10:07 jmc Exp $ */ 2 3 /* 4 * Copyright (c) 2011 Martynas Venckus <martynas@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <fenv.h> 20 #include <machine/ieeefp.h> 21 22 extern fp_except _softfloat_float_exception_flags; 23 extern fp_except _softfloat_float_exception_mask; 24 extern fp_rnd _softfloat_float_rounding_mode; 25 26 /* 27 * The following constant represents the default floating-point environment 28 * (that is, the one installed at program startup) and has type pointer to 29 * const-qualified fenv_t. 30 * 31 * It can be used as an argument to the functions within the <fenv.h> header 32 * that manage the floating-point environment, namely fesetenv() and 33 * feupdateenv(). 34 */ 35 fenv_t __fe_dfl_env = { 36 0, 37 0, 38 0 39 }; 40 41 /* 42 * The feclearexcept() function clears the supported floating-point exceptions 43 * represented by `excepts'. 44 */ 45 int 46 feclearexcept(int excepts) 47 { 48 unsigned int fpscr; 49 50 excepts &= FE_ALL_EXCEPT; 51 52 /* Clear the requested floating-point exceptions */ 53 _softfloat_float_exception_flags &= ~excepts; 54 55 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 56 fpscr &= ~excepts; 57 __asm volatile("vmsr fpscr, %0" :: "r" (fpscr)); 58 59 return 0; 60 } 61 DEF_STD(feclearexcept); 62 63 /* 64 * The fegetexceptflag() function stores an implementation-defined 65 * representation of the states of the floating-point status flags indicated by 66 * the argument excepts in the object pointed to by the argument flagp. 67 */ 68 int 69 fegetexceptflag(fexcept_t *flagp, int excepts) 70 { 71 unsigned int fpscr; 72 73 excepts &= FE_ALL_EXCEPT; 74 75 /* Store the results in flagp */ 76 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 77 fpscr |= _softfloat_float_exception_flags; 78 *flagp = fpscr & excepts; 79 80 return 0; 81 } 82 83 /* 84 * The feraiseexcept() function raises the supported floating-point exceptions 85 * represented by the argument `excepts'. 86 */ 87 int 88 feraiseexcept(int excepts) 89 { 90 excepts &= FE_ALL_EXCEPT; 91 92 fesetexceptflag((fexcept_t *)&excepts, excepts); 93 94 return 0; 95 } 96 DEF_STD(feraiseexcept); 97 98 /* 99 * This function sets the floating-point status flags indicated by the argument 100 * `excepts' to the states stored in the object pointed to by `flagp'. It does 101 * NOT raise any floating-point exceptions, but only sets the state of the flags. 102 */ 103 int 104 fesetexceptflag(const fexcept_t *flagp, int excepts) 105 { 106 unsigned int fpscr; 107 108 excepts &= FE_ALL_EXCEPT; 109 110 /* Set the requested status flags */ 111 _softfloat_float_exception_flags &= ~excepts; 112 _softfloat_float_exception_flags |= *flagp & excepts; 113 114 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 115 fpscr &= ~excepts; 116 fpscr |= *flagp & excepts; 117 __asm volatile("vmsr fpscr, %0" :: "r" (fpscr)); 118 119 return 0; 120 } 121 DEF_STD(fesetexceptflag); 122 123 /* 124 * The fetestexcept() function determines which of a specified subset of the 125 * floating-point exception flags are currently set. The `excepts' argument 126 * specifies the floating-point status flags to be queried. 127 */ 128 int 129 fetestexcept(int excepts) 130 { 131 unsigned int fpscr; 132 133 excepts &= FE_ALL_EXCEPT; 134 135 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 136 fpscr |= _softfloat_float_exception_flags; 137 138 return fpscr & excepts; 139 } 140 DEF_STD(fetestexcept); 141 142 /* 143 * The fegetround() function gets the current rounding direction. 144 */ 145 int 146 fegetround(void) 147 { 148 unsigned int fpscr; 149 150 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 151 152 return (fpscr >> 22) & _ROUND_MASK; 153 } 154 DEF_STD(fegetround); 155 156 /* 157 * The fesetround() function establishes the rounding direction represented by 158 * its argument `round'. If the argument is not equal to the value of a rounding 159 * direction macro, the rounding direction is not changed. 160 */ 161 int 162 fesetround(int round) 163 { 164 unsigned int fpscr; 165 166 /* Check whether requested rounding direction is supported */ 167 if (round & ~_ROUND_MASK) 168 return -1; 169 170 /* Set the rounding direction */ 171 _softfloat_float_rounding_mode &= ~_ROUND_MASK; 172 _softfloat_float_rounding_mode |= round; 173 174 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 175 fpscr &= ~(_ROUND_MASK << 22); 176 fpscr |= round << 22; 177 __asm volatile("vmsr fpscr, %0" :: "r" (fpscr)); 178 179 return 0; 180 } 181 DEF_STD(fesetround); 182 183 /* 184 * The fegetenv() function attempts to store the current floating-point 185 * environment in the object pointed to by envp. 186 */ 187 int 188 fegetenv(fenv_t *envp) 189 { 190 unsigned int fpscr; 191 192 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 193 fpscr |= _softfloat_float_exception_flags; 194 195 /* Store the current floating-point sticky flags */ 196 envp->__sticky = fpscr & FE_ALL_EXCEPT; 197 198 /* Store the current floating-point masks */ 199 envp->__mask = 0; 200 201 /* Store the current floating-point control register */ 202 envp->__round = (fpscr >> 22) & _ROUND_MASK; 203 204 return 0; 205 } 206 DEF_STD(fegetenv); 207 208 /* 209 * The feholdexcept() function saves the current floating-point environment 210 * in the object pointed to by envp, clears the floating-point status flags, and 211 * then installs a non-stop (continue on floating-point exceptions) mode, if 212 * available, for all floating-point exceptions. 213 */ 214 int 215 feholdexcept(fenv_t *envp) 216 { 217 unsigned int fpscr; 218 219 /* Store the current floating-point environment */ 220 fegetenv(envp); 221 222 /* Clear exception flags */ 223 _softfloat_float_exception_flags &= ~FE_ALL_EXCEPT; 224 225 /* Mask all exceptions */ 226 _softfloat_float_exception_mask &= ~FE_ALL_EXCEPT; 227 228 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 229 fpscr &= ~(FE_ALL_EXCEPT << 8 | FE_ALL_EXCEPT); 230 __asm volatile("vmsr fpscr, %0" :: "r" (fpscr)); 231 232 return 0; 233 } 234 DEF_STD(feholdexcept); 235 236 /* 237 * The fesetenv() function attempts to establish the floating-point environment 238 * represented by the object pointed to by envp. The argument `envp' points 239 * to an object set by a call to fegetenv() or feholdexcept(), or equal a 240 * floating-point environment macro. The fesetenv() function does not raise 241 * floating-point exceptions, but only installs the state of the floating-point 242 * status flags represented through its argument. 243 */ 244 int 245 fesetenv(const fenv_t *envp) 246 { 247 unsigned int fpscr; 248 249 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 250 fpscr &= ~(_ROUND_MASK << 22 | FE_ALL_EXCEPT << 8 | FE_ALL_EXCEPT); 251 252 /* Load the floating-point sticky flags */ 253 fpscr |= envp->__sticky & FE_ALL_EXCEPT; 254 _softfloat_float_exception_flags = envp->__sticky & FE_ALL_EXCEPT; 255 256 /* Load the floating-point masks */ 257 fpscr |= (envp->__mask & FE_ALL_EXCEPT) << 8; 258 _softfloat_float_exception_mask = envp->__mask & FE_ALL_EXCEPT; 259 260 /* Load the floating-point rounding mode */ 261 fpscr |= (envp->__round & _ROUND_MASK) << 22; 262 _softfloat_float_rounding_mode = envp->__round & _ROUND_MASK; 263 264 __asm volatile("vmsr fpscr, %0" :: "r" (fpscr)); 265 266 return 0; 267 } 268 DEF_STD(fesetenv); 269 270 /* 271 * The feupdateenv() function saves the currently raised floating-point 272 * exceptions in its automatic storage, installs the floating-point environment 273 * represented by the object pointed to by `envp', and then raises the saved 274 * floating-point exceptions. The argument `envp' shall point to an object set 275 * by a call to feholdexcept() or fegetenv(), or equal a floating-point 276 * environment macro. 277 */ 278 int 279 feupdateenv(const fenv_t *envp) 280 { 281 unsigned int fpscr; 282 283 __asm volatile("vmrs %0, fpscr" : "=r" (fpscr)); 284 fpscr |= _softfloat_float_exception_flags; 285 286 /* Install new floating-point environment */ 287 fesetenv(envp); 288 289 /* Raise any previously accumulated exceptions */ 290 feraiseexcept(fpscr & FE_ALL_EXCEPT); 291 292 return 0; 293 } 294 DEF_STD(feupdateenv); 295 296 /* 297 * The following functions are extensions to the standard 298 */ 299 int 300 feenableexcept(int mask) 301 { 302 return -1; 303 } 304 305 int 306 fedisableexcept(int mask) 307 { 308 return 0; 309 } 310 311 int 312 fegetexcept(void) 313 { 314 return 0; 315 } 316