1 /* $NetBSD: softfloat-specialize,v 1.2 2008/04/28 20:23:04 martin Exp $ */ 2 3 /* This is a derivative work. */ 4 5 /*- 6 * Copyright (c) 2001 The NetBSD Foundation, Inc. 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to The NetBSD Foundation 10 * by Ross Harvey. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 23 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31 * POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 /* 35 =============================================================================== 36 37 This C source fragment is part of the SoftFloat IEC/IEEE Floating-point 38 Arithmetic Package, Release 2a. 39 40 Written by John R. Hauser. This work was made possible in part by the 41 International Computer Science Institute, located at Suite 600, 1947 Center 42 Street, Berkeley, California 94704. Funding was partially provided by the 43 National Science Foundation under grant MIP-9311980. The original version 44 of this code was written as part of a project to build a fixed-point vector 45 processor in collaboration with the University of California at Berkeley, 46 overseen by Profs. Nelson Morgan and John Wawrzynek. More information 47 is available through the Web page `http://HTTP.CS.Berkeley.EDU/~jhauser/ 48 arithmetic/SoftFloat.html'. 49 50 THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort 51 has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT 52 TIMES RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO 53 PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY 54 AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE. 55 56 Derivative works are acceptable, even for commercial purposes, so long as 57 (1) they include prominent notice that the work is derivative, and (2) they 58 include prominent notice akin to these four paragraphs for those parts of 59 this code that are retained. 60 61 =============================================================================== 62 */ 63 64 /* 65 ------------------------------------------------------------------------------- 66 Underflow tininess-detection mode, statically initialized to default value. 67 ------------------------------------------------------------------------------- 68 */ 69 int float_detect_tininess = float_tininess_after_rounding; 70 71 /* 72 ------------------------------------------------------------------------------- 73 Raises the exceptions specified by `flags'. Floating-point traps can be 74 defined here if desired. It is currently not possible for such a trap 75 to substitute a result value. If traps are not implemented, this routine 76 should be simply `float_exception_flags |= flags;'. 77 ------------------------------------------------------------------------------- 78 */ 79 void float_raise( int flags ) 80 { 81 82 float_exception_flags |= flags; 83 84 } 85 86 /* 87 ------------------------------------------------------------------------------- 88 Internal canonical NaN format. 89 ------------------------------------------------------------------------------- 90 */ 91 typedef struct { 92 flag sign; 93 bits64 high, low; 94 } commonNaNT; 95 96 /* 97 ------------------------------------------------------------------------------- 98 The pattern for a default generated single-precision NaN. 99 ------------------------------------------------------------------------------- 100 */ 101 #define float32_default_nan 0xFFC00000 102 103 /* 104 ------------------------------------------------------------------------------- 105 Returns 1 if the single-precision floating-point value `a' is a NaN; 106 otherwise returns 0. 107 ------------------------------------------------------------------------------- 108 */ 109 static flag float32_is_nan( float32 a ) 110 { 111 112 return ( 0xFF000000 < (bits32) ( a<<1 ) ); 113 114 } 115 116 /* 117 ------------------------------------------------------------------------------- 118 Returns 1 if the single-precision floating-point value `a' is a signaling 119 NaN; otherwise returns 0. 120 ------------------------------------------------------------------------------- 121 */ 122 flag float32_is_signaling_nan( float32 a ) 123 { 124 125 return ( ( ( a>>22 ) & 0x1FF ) == 0x1FE ) && ( a & 0x003FFFFF ); 126 127 } 128 129 /* 130 ------------------------------------------------------------------------------- 131 Returns the result of converting the single-precision floating-point NaN 132 `a' to the canonical NaN format. If `a' is a signaling NaN, the invalid 133 exception is raised. 134 ------------------------------------------------------------------------------- 135 */ 136 static commonNaNT float32ToCommonNaN( float32 a ) 137 { 138 commonNaNT z; 139 140 if ( float32_is_signaling_nan( a ) ) float_raise( float_flag_invalid ); 141 z.sign = a>>31; 142 z.low = 0; 143 z.high = ( (bits64) a )<<41; 144 return z; 145 146 } 147 148 /* 149 ------------------------------------------------------------------------------- 150 Returns the result of converting the canonical NaN `a' to the single- 151 precision floating-point format. 152 ------------------------------------------------------------------------------- 153 */ 154 static float32 commonNaNToFloat32( commonNaNT a ) 155 { 156 157 return ( ( (bits32) a.sign )<<31 ) | 0x7FC00000 | ( a.high>>41 ); 158 159 } 160 161 /* 162 ------------------------------------------------------------------------------- 163 Takes two single-precision floating-point values `a' and `b', one of which 164 is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a 165 signaling NaN, the invalid exception is raised. 166 ------------------------------------------------------------------------------- 167 */ 168 static float32 propagateFloat32NaN( float32 a, float32 b ) 169 { 170 flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN; 171 172 aIsNaN = float32_is_nan( a ); 173 aIsSignalingNaN = float32_is_signaling_nan( a ); 174 bIsNaN = float32_is_nan( b ); 175 bIsSignalingNaN = float32_is_signaling_nan( b ); 176 a |= 0x00400000; 177 b |= 0x00400000; 178 if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid ); 179 if ( aIsSignalingNaN ) { 180 if ( bIsSignalingNaN ) goto returnLargerSignificand; 181 return bIsNaN ? b : a; 182 } 183 else if ( aIsNaN ) { 184 if ( bIsSignalingNaN | ! bIsNaN ) return a; 185 returnLargerSignificand: 186 if ( (bits32) ( a<<1 ) < (bits32) ( b<<1 ) ) return b; 187 if ( (bits32) ( b<<1 ) < (bits32) ( a<<1 ) ) return a; 188 return ( a < b ) ? a : b; 189 } 190 else { 191 return b; 192 } 193 194 } 195 196 /* 197 ------------------------------------------------------------------------------- 198 The pattern for a default generated double-precision NaN. 199 ------------------------------------------------------------------------------- 200 */ 201 #define float64_default_nan LIT64( 0xFFF8000000000000 ) 202 203 /* 204 ------------------------------------------------------------------------------- 205 Returns 1 if the double-precision floating-point value `a' is a NaN; 206 otherwise returns 0. 207 ------------------------------------------------------------------------------- 208 */ 209 static flag float64_is_nan( float64 a ) 210 { 211 212 return ( LIT64( 0xFFE0000000000000 ) < (bits64) ( a<<1 ) ); 213 214 } 215 216 /* 217 ------------------------------------------------------------------------------- 218 Returns 1 if the double-precision floating-point value `a' is a signaling 219 NaN; otherwise returns 0. 220 ------------------------------------------------------------------------------- 221 */ 222 flag float64_is_signaling_nan( float64 a ) 223 { 224 225 return 226 ( ( ( a>>51 ) & 0xFFF ) == 0xFFE ) 227 && ( a & LIT64( 0x0007FFFFFFFFFFFF ) ); 228 229 } 230 231 /* 232 ------------------------------------------------------------------------------- 233 Returns the result of converting the double-precision floating-point NaN 234 `a' to the canonical NaN format. If `a' is a signaling NaN, the invalid 235 exception is raised. 236 ------------------------------------------------------------------------------- 237 */ 238 static commonNaNT float64ToCommonNaN( float64 a ) 239 { 240 commonNaNT z; 241 242 if ( float64_is_signaling_nan( a ) ) float_raise( float_flag_invalid ); 243 z.sign = a>>63; 244 z.low = 0; 245 z.high = a<<12; 246 return z; 247 248 } 249 250 /* 251 ------------------------------------------------------------------------------- 252 Returns the result of converting the canonical NaN `a' to the double- 253 precision floating-point format. 254 ------------------------------------------------------------------------------- 255 */ 256 static float64 commonNaNToFloat64( commonNaNT a ) 257 { 258 259 return 260 ( ( (bits64) a.sign )<<63 ) 261 | LIT64( 0x7FF8000000000000 ) 262 | ( a.high>>12 ); 263 264 } 265 266 /* 267 ------------------------------------------------------------------------------- 268 Takes two double-precision floating-point values `a' and `b', one of which 269 is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a 270 signaling NaN, the invalid exception is raised. 271 ------------------------------------------------------------------------------- 272 */ 273 static float64 propagateFloat64NaN( float64 a, float64 b ) 274 { 275 flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN; 276 277 aIsNaN = float64_is_nan( a ); 278 aIsSignalingNaN = float64_is_signaling_nan( a ); 279 bIsNaN = float64_is_nan( b ); 280 bIsSignalingNaN = float64_is_signaling_nan( b ); 281 a |= LIT64( 0x0008000000000000 ); 282 b |= LIT64( 0x0008000000000000 ); 283 if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid ); 284 if ( aIsSignalingNaN ) { 285 if ( bIsSignalingNaN ) goto returnLargerSignificand; 286 return bIsNaN ? b : a; 287 } 288 else if ( aIsNaN ) { 289 if ( bIsSignalingNaN | ! bIsNaN ) return a; 290 returnLargerSignificand: 291 if ( (bits64) ( a<<1 ) < (bits64) ( b<<1 ) ) return b; 292 if ( (bits64) ( b<<1 ) < (bits64) ( a<<1 ) ) return a; 293 return ( a < b ) ? a : b; 294 } 295 else { 296 return b; 297 } 298 299 } 300 301 #ifdef FLOATX80 302 303 /* 304 ------------------------------------------------------------------------------- 305 The pattern for a default generated extended double-precision NaN. The 306 `high' and `low' values hold the most- and least-significant bits, 307 respectively. 308 ------------------------------------------------------------------------------- 309 */ 310 #define floatx80_default_nan_high 0xFFFF 311 #define floatx80_default_nan_low LIT64( 0xC000000000000000 ) 312 313 /* 314 ------------------------------------------------------------------------------- 315 Returns 1 if the extended double-precision floating-point value `a' is a 316 NaN; otherwise returns 0. 317 ------------------------------------------------------------------------------- 318 */ 319 static flag floatx80_is_nan( floatx80 a ) 320 { 321 322 return ( ( a.high & 0x7FFF ) == 0x7FFF ) && (bits64) ( a.low<<1 ); 323 324 } 325 326 /* 327 ------------------------------------------------------------------------------- 328 Returns 1 if the extended double-precision floating-point value `a' is a 329 signaling NaN; otherwise returns 0. 330 ------------------------------------------------------------------------------- 331 */ 332 flag floatx80_is_signaling_nan( floatx80 a ) 333 { 334 bits64 aLow; 335 336 aLow = a.low & ~ LIT64( 0x4000000000000000 ); 337 return 338 ( ( a.high & 0x7FFF ) == 0x7FFF ) 339 && (bits64) ( aLow<<1 ) 340 && ( a.low == aLow ); 341 342 } 343 344 /* 345 ------------------------------------------------------------------------------- 346 Returns the result of converting the extended double-precision floating- 347 point NaN `a' to the canonical NaN format. If `a' is a signaling NaN, the 348 invalid exception is raised. 349 ------------------------------------------------------------------------------- 350 */ 351 static commonNaNT floatx80ToCommonNaN( floatx80 a ) 352 { 353 commonNaNT z; 354 355 if ( floatx80_is_signaling_nan( a ) ) float_raise( float_flag_invalid ); 356 z.sign = a.high>>15; 357 z.low = 0; 358 z.high = a.low<<1; 359 return z; 360 361 } 362 363 /* 364 ------------------------------------------------------------------------------- 365 Returns the result of converting the canonical NaN `a' to the extended 366 double-precision floating-point format. 367 ------------------------------------------------------------------------------- 368 */ 369 static floatx80 commonNaNToFloatx80( commonNaNT a ) 370 { 371 floatx80 z; 372 373 z.low = LIT64( 0xC000000000000000 ) | ( a.high>>1 ); 374 z.high = ( ( (bits16) a.sign )<<15 ) | 0x7FFF; 375 return z; 376 377 } 378 379 /* 380 ------------------------------------------------------------------------------- 381 Takes two extended double-precision floating-point values `a' and `b', one 382 of which is a NaN, and returns the appropriate NaN result. If either `a' or 383 `b' is a signaling NaN, the invalid exception is raised. 384 ------------------------------------------------------------------------------- 385 */ 386 static floatx80 propagateFloatx80NaN( floatx80 a, floatx80 b ) 387 { 388 flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN; 389 390 aIsNaN = floatx80_is_nan( a ); 391 aIsSignalingNaN = floatx80_is_signaling_nan( a ); 392 bIsNaN = floatx80_is_nan( b ); 393 bIsSignalingNaN = floatx80_is_signaling_nan( b ); 394 a.low |= LIT64( 0xC000000000000000 ); 395 b.low |= LIT64( 0xC000000000000000 ); 396 if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid ); 397 if ( aIsSignalingNaN ) { 398 if ( bIsSignalingNaN ) goto returnLargerSignificand; 399 return bIsNaN ? b : a; 400 } 401 else if ( aIsNaN ) { 402 if ( bIsSignalingNaN | ! bIsNaN ) return a; 403 returnLargerSignificand: 404 if ( a.low < b.low ) return b; 405 if ( b.low < a.low ) return a; 406 return ( a.high < b.high ) ? a : b; 407 } 408 else { 409 return b; 410 } 411 412 } 413 414 #endif 415 416 #ifdef FLOAT128 417 418 /* 419 ------------------------------------------------------------------------------- 420 The pattern for a default generated quadruple-precision NaN. The `high' and 421 `low' values hold the most- and least-significant bits, respectively. 422 ------------------------------------------------------------------------------- 423 */ 424 #define float128_default_nan_high LIT64( 0xFFFF800000000000 ) 425 #define float128_default_nan_low LIT64( 0x0000000000000000 ) 426 427 /* 428 ------------------------------------------------------------------------------- 429 Returns 1 if the quadruple-precision floating-point value `a' is a NaN; 430 otherwise returns 0. 431 ------------------------------------------------------------------------------- 432 */ 433 flag float128_is_nan( float128 a ) 434 { 435 436 return 437 ( LIT64( 0xFFFE000000000000 ) <= (bits64) ( a.high<<1 ) ) 438 && ( a.low || ( a.high & LIT64( 0x0000FFFFFFFFFFFF ) ) ); 439 440 } 441 442 /* 443 ------------------------------------------------------------------------------- 444 Returns 1 if the quadruple-precision floating-point value `a' is a 445 signaling NaN; otherwise returns 0. 446 ------------------------------------------------------------------------------- 447 */ 448 flag float128_is_signaling_nan( float128 a ) 449 { 450 451 return 452 ( ( ( a.high>>47 ) & 0xFFFF ) == 0xFFFE ) 453 && ( a.low || ( a.high & LIT64( 0x00007FFFFFFFFFFF ) ) ); 454 455 } 456 457 /* 458 ------------------------------------------------------------------------------- 459 Returns the result of converting the quadruple-precision floating-point NaN 460 `a' to the canonical NaN format. If `a' is a signaling NaN, the invalid 461 exception is raised. 462 ------------------------------------------------------------------------------- 463 */ 464 static commonNaNT float128ToCommonNaN( float128 a ) 465 { 466 commonNaNT z; 467 468 if ( float128_is_signaling_nan( a ) ) float_raise( float_flag_invalid ); 469 z.sign = a.high>>63; 470 shortShift128Left( a.high, a.low, 16, &z.high, &z.low ); 471 return z; 472 473 } 474 475 /* 476 ------------------------------------------------------------------------------- 477 Returns the result of converting the canonical NaN `a' to the quadruple- 478 precision floating-point format. 479 ------------------------------------------------------------------------------- 480 */ 481 static float128 commonNaNToFloat128( commonNaNT a ) 482 { 483 float128 z; 484 485 shift128Right( a.high, a.low, 16, &z.high, &z.low ); 486 z.high |= ( ( (bits64) a.sign )<<63 ) | LIT64( 0x7FFF800000000000 ); 487 return z; 488 489 } 490 491 /* 492 ------------------------------------------------------------------------------- 493 Takes two quadruple-precision floating-point values `a' and `b', one of 494 which is a NaN, and returns the appropriate NaN result. If either `a' or 495 `b' is a signaling NaN, the invalid exception is raised. 496 ------------------------------------------------------------------------------- 497 */ 498 static float128 propagateFloat128NaN( float128 a, float128 b ) 499 { 500 flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN; 501 502 aIsNaN = float128_is_nan( a ); 503 aIsSignalingNaN = float128_is_signaling_nan( a ); 504 bIsNaN = float128_is_nan( b ); 505 bIsSignalingNaN = float128_is_signaling_nan( b ); 506 a.high |= LIT64( 0x0000800000000000 ); 507 b.high |= LIT64( 0x0000800000000000 ); 508 if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid ); 509 if ( aIsSignalingNaN ) { 510 if ( bIsSignalingNaN ) goto returnLargerSignificand; 511 return bIsNaN ? b : a; 512 } 513 else if ( aIsNaN ) { 514 if ( bIsSignalingNaN | ! bIsNaN ) return a; 515 returnLargerSignificand: 516 if ( lt128( a.high<<1, a.low, b.high<<1, b.low ) ) return b; 517 if ( lt128( b.high<<1, b.low, a.high<<1, a.low ) ) return a; 518 return ( a.high < b.high ) ? a : b; 519 } 520 else { 521 return b; 522 } 523 524 } 525 526 #endif 527 528
Indexes created Mon Sep 22 13:09:51 GMT 2025