1 /* $NetBSD: sfdiv.c,v 1.4 2007/02/22 05:46:30 thorpej Exp $ */ 2 3 /* $OpenBSD: sfdiv.c,v 1.4 2001/03/29 03:58:19 mickey Exp $ */ 4 5 /* 6 * Copyright 1996 1995 by Open Software Foundation, Inc. 7 * All Rights Reserved 8 * 9 * Permission to use, copy, modify, and distribute this software and 10 * its documentation for any purpose and without fee is hereby granted, 11 * provided that the above copyright notice appears in all copies and 12 * that both the copyright notice and this permission notice appear in 13 * supporting documentation. 14 * 15 * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE 16 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 17 * FOR A PARTICULAR PURPOSE. 18 * 19 * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR 20 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 21 * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, 22 * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION 23 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 24 * 25 */ 26 /* 27 * pmk1.1 28 */ 29 /* 30 * (c) Copyright 1986 HEWLETT-PACKARD COMPANY 31 * 32 * To anyone who acknowledges that this file is provided "AS IS" 33 * without any express or implied warranty: 34 * permission to use, copy, modify, and distribute this file 35 * for any purpose is hereby granted without fee, provided that 36 * the above copyright notice and this notice appears in all 37 * copies, and that the name of Hewlett-Packard Company not be 38 * used in advertising or publicity pertaining to distribution 39 * of the software without specific, written prior permission. 40 * Hewlett-Packard Company makes no representations about the 41 * suitability of this software for any purpose. 42 */ 43 44 #include <sys/cdefs.h> 45 __KERNEL_RCSID(0, "$NetBSD: sfdiv.c,v 1.4 2007/02/22 05:46:30 thorpej Exp $"); 46 47 #include "../spmath/float.h" 48 #include "../spmath/sgl_float.h" 49 50 /* 51 * Single Precision Floating-point Divide 52 */ 53 int 54 sgl_fdiv(srcptr1,srcptr2,dstptr,status) 55 56 sgl_floating_point *srcptr1, *srcptr2, *dstptr; 57 unsigned int *status; 58 { 59 register unsigned int opnd1, opnd2, opnd3, result; 60 register int dest_exponent, count; 61 register int inexact = false, guardbit = false, stickybit = false; 62 int is_tiny; 63 64 opnd1 = *srcptr1; 65 opnd2 = *srcptr2; 66 /* 67 * set sign bit of result 68 */ 69 if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result); 70 else Sgl_setzero(result); 71 /* 72 * check first operand for NaN's or infinity 73 */ 74 if (Sgl_isinfinity_exponent(opnd1)) { 75 if (Sgl_iszero_mantissa(opnd1)) { 76 if (Sgl_isnotnan(opnd2)) { 77 if (Sgl_isinfinity(opnd2)) { 78 /* 79 * invalid since both operands 80 * are infinity 81 */ 82 if (Is_invalidtrap_enabled()) 83 return(INVALIDEXCEPTION); 84 Set_invalidflag(); 85 Sgl_makequietnan(result); 86 *dstptr = result; 87 return(NOEXCEPTION); 88 } 89 /* 90 * return infinity 91 */ 92 Sgl_setinfinity_exponentmantissa(result); 93 *dstptr = result; 94 return(NOEXCEPTION); 95 } 96 } 97 else { 98 /* 99 * is NaN; signaling or quiet? 100 */ 101 if (Sgl_isone_signaling(opnd1)) { 102 /* trap if INVALIDTRAP enabled */ 103 if (Is_invalidtrap_enabled()) 104 return(INVALIDEXCEPTION); 105 /* make NaN quiet */ 106 Set_invalidflag(); 107 Sgl_set_quiet(opnd1); 108 } 109 /* 110 * is second operand a signaling NaN? 111 */ 112 else if (Sgl_is_signalingnan(opnd2)) { 113 /* trap if INVALIDTRAP enabled */ 114 if (Is_invalidtrap_enabled()) 115 return(INVALIDEXCEPTION); 116 /* make NaN quiet */ 117 Set_invalidflag(); 118 Sgl_set_quiet(opnd2); 119 *dstptr = opnd2; 120 return(NOEXCEPTION); 121 } 122 /* 123 * return quiet NaN 124 */ 125 *dstptr = opnd1; 126 return(NOEXCEPTION); 127 } 128 } 129 /* 130 * check second operand for NaN's or infinity 131 */ 132 if (Sgl_isinfinity_exponent(opnd2)) { 133 if (Sgl_iszero_mantissa(opnd2)) { 134 /* 135 * return zero 136 */ 137 Sgl_setzero_exponentmantissa(result); 138 *dstptr = result; 139 return(NOEXCEPTION); 140 } 141 /* 142 * is NaN; signaling or quiet? 143 */ 144 if (Sgl_isone_signaling(opnd2)) { 145 /* trap if INVALIDTRAP enabled */ 146 if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); 147 /* make NaN quiet */ 148 Set_invalidflag(); 149 Sgl_set_quiet(opnd2); 150 } 151 /* 152 * return quiet NaN 153 */ 154 *dstptr = opnd2; 155 return(NOEXCEPTION); 156 } 157 /* 158 * check for division by zero 159 */ 160 if (Sgl_iszero_exponentmantissa(opnd2)) { 161 if (Sgl_iszero_exponentmantissa(opnd1)) { 162 /* invalid since both operands are zero */ 163 if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); 164 Set_invalidflag(); 165 Sgl_makequietnan(result); 166 *dstptr = result; 167 return(NOEXCEPTION); 168 } 169 if (Is_divisionbyzerotrap_enabled()) 170 return(DIVISIONBYZEROEXCEPTION); 171 Set_divisionbyzeroflag(); 172 Sgl_setinfinity_exponentmantissa(result); 173 *dstptr = result; 174 return(NOEXCEPTION); 175 } 176 /* 177 * Generate exponent 178 */ 179 dest_exponent = Sgl_exponent(opnd1) - Sgl_exponent(opnd2) + SGL_BIAS; 180 181 /* 182 * Generate mantissa 183 */ 184 if (Sgl_isnotzero_exponent(opnd1)) { 185 /* set hidden bit */ 186 Sgl_clear_signexponent_set_hidden(opnd1); 187 } 188 else { 189 /* check for zero */ 190 if (Sgl_iszero_mantissa(opnd1)) { 191 Sgl_setzero_exponentmantissa(result); 192 *dstptr = result; 193 return(NOEXCEPTION); 194 } 195 /* is denormalized; want to normalize */ 196 Sgl_clear_signexponent(opnd1); 197 Sgl_leftshiftby1(opnd1); 198 Sgl_normalize(opnd1,dest_exponent); 199 } 200 /* opnd2 needs to have hidden bit set with msb in hidden bit */ 201 if (Sgl_isnotzero_exponent(opnd2)) { 202 Sgl_clear_signexponent_set_hidden(opnd2); 203 } 204 else { 205 /* is denormalized; want to normalize */ 206 Sgl_clear_signexponent(opnd2); 207 Sgl_leftshiftby1(opnd2); 208 while(Sgl_iszero_hiddenhigh7mantissa(opnd2)) { 209 Sgl_leftshiftby8(opnd2); 210 dest_exponent += 8; 211 } 212 if(Sgl_iszero_hiddenhigh3mantissa(opnd2)) { 213 Sgl_leftshiftby4(opnd2); 214 dest_exponent += 4; 215 } 216 while(Sgl_iszero_hidden(opnd2)) { 217 Sgl_leftshiftby1(opnd2); 218 dest_exponent += 1; 219 } 220 } 221 222 /* Divide the source mantissas */ 223 224 /* 225 * A non_restoring divide algorithm is used. 226 */ 227 Sgl_subtract(opnd1,opnd2,opnd1); 228 Sgl_setzero(opnd3); 229 for (count=1;count<=SGL_P && Sgl_all(opnd1);count++) { 230 Sgl_leftshiftby1(opnd1); 231 Sgl_leftshiftby1(opnd3); 232 if (Sgl_iszero_sign(opnd1)) { 233 Sgl_setone_lowmantissa(opnd3); 234 Sgl_subtract(opnd1,opnd2,opnd1); 235 } 236 else Sgl_addition(opnd1,opnd2,opnd1); 237 } 238 if (count <= SGL_P) { 239 Sgl_leftshiftby1(opnd3); 240 Sgl_setone_lowmantissa(opnd3); 241 Sgl_leftshift(opnd3,SGL_P-count); 242 if (Sgl_iszero_hidden(opnd3)) { 243 Sgl_leftshiftby1(opnd3); 244 dest_exponent--; 245 } 246 } 247 else { 248 if (Sgl_iszero_hidden(opnd3)) { 249 /* need to get one more bit of result */ 250 Sgl_leftshiftby1(opnd1); 251 Sgl_leftshiftby1(opnd3); 252 if (Sgl_iszero_sign(opnd1)) { 253 Sgl_setone_lowmantissa(opnd3); 254 Sgl_subtract(opnd1,opnd2,opnd1); 255 } 256 else Sgl_addition(opnd1,opnd2,opnd1); 257 dest_exponent--; 258 } 259 if (Sgl_iszero_sign(opnd1)) guardbit = true; 260 stickybit = Sgl_all(opnd1); 261 } 262 inexact = guardbit | stickybit; 263 264 /* 265 * round result 266 */ 267 if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) { 268 Sgl_clear_signexponent(opnd3); 269 switch (Rounding_mode()) { 270 case ROUNDPLUS: 271 if (Sgl_iszero_sign(result)) 272 Sgl_increment_mantissa(opnd3); 273 break; 274 case ROUNDMINUS: 275 if (Sgl_isone_sign(result)) 276 Sgl_increment_mantissa(opnd3); 277 break; 278 case ROUNDNEAREST: 279 if (guardbit && 280 (stickybit || Sgl_isone_lowmantissa(opnd3))) 281 Sgl_increment_mantissa(opnd3); 282 } 283 if (Sgl_isone_hidden(opnd3)) dest_exponent++; 284 } 285 Sgl_set_mantissa(result,opnd3); 286 287 /* 288 * Test for overflow 289 */ 290 if (dest_exponent >= SGL_INFINITY_EXPONENT) { 291 /* trap if OVERFLOWTRAP enabled */ 292 if (Is_overflowtrap_enabled()) { 293 /* 294 * Adjust bias of result 295 */ 296 Sgl_setwrapped_exponent(result,dest_exponent,ovfl); 297 *dstptr = result; 298 if (inexact) { 299 if (Is_inexacttrap_enabled()) 300 return(OVERFLOWEXCEPTION | INEXACTEXCEPTION); 301 else Set_inexactflag(); 302 } 303 return(OVERFLOWEXCEPTION); 304 } 305 Set_overflowflag(); 306 /* set result to infinity or largest number */ 307 Sgl_setoverflow(result); 308 inexact = true; 309 } 310 /* 311 * Test for underflow 312 */ 313 else if (dest_exponent <= 0) { 314 /* trap if UNDERFLOWTRAP enabled */ 315 if (Is_underflowtrap_enabled()) { 316 /* 317 * Adjust bias of result 318 */ 319 Sgl_setwrapped_exponent(result,dest_exponent,unfl); 320 *dstptr = result; 321 if (inexact) { 322 if (Is_inexacttrap_enabled()) 323 return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION); 324 else Set_inexactflag(); 325 } 326 return(UNDERFLOWEXCEPTION); 327 } 328 329 /* Determine if should set underflow flag */ 330 is_tiny = true; 331 if (dest_exponent == 0 && inexact) { 332 switch (Rounding_mode()) { 333 case ROUNDPLUS: 334 if (Sgl_iszero_sign(result)) { 335 Sgl_increment(opnd3); 336 if (Sgl_isone_hiddenoverflow(opnd3)) 337 is_tiny = false; 338 Sgl_decrement(opnd3); 339 } 340 break; 341 case ROUNDMINUS: 342 if (Sgl_isone_sign(result)) { 343 Sgl_increment(opnd3); 344 if (Sgl_isone_hiddenoverflow(opnd3)) 345 is_tiny = false; 346 Sgl_decrement(opnd3); 347 } 348 break; 349 case ROUNDNEAREST: 350 if (guardbit && (stickybit || 351 Sgl_isone_lowmantissa(opnd3))) { 352 Sgl_increment(opnd3); 353 if (Sgl_isone_hiddenoverflow(opnd3)) 354 is_tiny = false; 355 Sgl_decrement(opnd3); 356 } 357 break; 358 } 359 } 360 361 /* 362 * denormalize result or set to signed zero 363 */ 364 stickybit = inexact; 365 Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact); 366 367 /* return rounded number */ 368 if (inexact) { 369 switch (Rounding_mode()) { 370 case ROUNDPLUS: 371 if (Sgl_iszero_sign(result)) { 372 Sgl_increment(opnd3); 373 } 374 break; 375 case ROUNDMINUS: 376 if (Sgl_isone_sign(result)) { 377 Sgl_increment(opnd3); 378 } 379 break; 380 case ROUNDNEAREST: 381 if (guardbit && (stickybit || 382 Sgl_isone_lowmantissa(opnd3))) { 383 Sgl_increment(opnd3); 384 } 385 break; 386 } 387 if (is_tiny) Set_underflowflag(); 388 } 389 Sgl_set_exponentmantissa(result,opnd3); 390 } 391 else Sgl_set_exponent(result,dest_exponent); 392 *dstptr = result; 393 /* check for inexact */ 394 if (inexact) { 395 if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); 396 else Set_inexactflag(); 397 } 398 return(NOEXCEPTION); 399 } 400