fpu/softfloat-macros.h

   1 /*
   2  * QEMU float support macros
   3  *
   4  * The code in this source file is derived from release 2a of the SoftFloat
   5  * IEC/IEEE Floating-point Arithmetic Package. Those parts of the code (and
   6  * some later contributions) are provided under that license, as detailed below.
   7  * It has subsequently been modified by contributors to the QEMU Project,
   8  * so some portions are provided under:
   9  *  the SoftFloat-2a license
  10  *  the BSD license
  11  *  GPL-v2-or-later
  12  *
  13  * Any future contributions to this file after December 1st 2014 will be
  14  * taken to be licensed under the Softfloat-2a license unless specifically
  15  * indicated otherwise.
  16  */
  17
  18 /*
  19 ===============================================================================
  20 This C source fragment is part of the SoftFloat IEC/IEEE Floating-point
  21 Arithmetic Package, Release 2a.
  22
  23 Written by John R. Hauser.  This work was made possible in part by the
  24 International Computer Science Institute, located at Suite 600, 1947 Center
  25 Street, Berkeley, California 94704.  Funding was partially provided by the
  26 National Science Foundation under grant MIP-9311980.  The original version
  27 of this code was written as part of a project to build a fixed-point vector
  28 processor in collaboration with the University of California at Berkeley,
  29 overseen by Profs. Nelson Morgan and John Wawrzynek.  More information
  30 is available through the Web page `http://HTTP.CS.Berkeley.EDU/~jhauser/
  31 arithmetic/SoftFloat.html'.
  32
  33 THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE.  Although reasonable effort
  34 has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
  35 TIMES RESULT IN INCORRECT BEHAVIOR.  USE OF THIS SOFTWARE IS RESTRICTED TO
  36 PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
  37 AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
  38
  39 Derivative works are acceptable, even for commercial purposes, so long as
  40 (1) they include prominent notice that the work is derivative, and (2) they
  41 include prominent notice akin to these four paragraphs for those parts of
  42 this code that are retained.
  43
  44 ===============================================================================
  45 */
  46
  47 /* BSD licensing:
  48  * Copyright (c) 2006, Fabrice Bellard
  49  * All rights reserved.
  50  *
  51  * Redistribution and use in source and binary forms, with or without
  52  * modification, are permitted provided that the following conditions are met:
  53  *
  54  * 1. Redistributions of source code must retain the above copyright notice,
  55  * this list of conditions and the following disclaimer.
  56  *
  57  * 2. Redistributions in binary form must reproduce the above copyright notice,
  58  * this list of conditions and the following disclaimer in the documentation
  59  * and/or other materials provided with the distribution.
  60  *
  61  * 3. Neither the name of the copyright holder nor the names of its contributors
  62  * may be used to endorse or promote products derived from this software without
  63  * specific prior written permission.
  64  *
  65  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  66  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  67  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  68  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  69  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  70  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  71  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  72  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  73  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  74  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  75  * THE POSSIBILITY OF SUCH DAMAGE.
  76  */
  77
  78 /* Portions of this work are licensed under the terms of the GNU GPL,
  79  * version 2 or later. See the COPYING file in the top-level directory.
  80  */
  81
  82 /*----------------------------------------------------------------------------
  83 | This macro tests for minimum version of the GNU C compiler.
  84 *----------------------------------------------------------------------------*/
  85 #if defined(__GNUC__) && defined(__GNUC_MINOR__)
  86 # define SOFTFLOAT_GNUC_PREREQ(maj, min) \
  87          ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
  88 #else
  89 # define SOFTFLOAT_GNUC_PREREQ(maj, min) 0
  90 #endif
  91
  92
  93 /*----------------------------------------------------------------------------
  94 | Shifts `a' right by the number of bits given in `count'.  If any nonzero
  95 | bits are shifted off, they are ``jammed'' into the least significant bit of
  96 | the result by setting the least significant bit to 1.  The value of `count'
  97 | can be arbitrarily large; in particular, if `count' is greater than 32, the
  98 | result will be either 0 or 1, depending on whether `a' is zero or nonzero.
  99 | The result is stored in the location pointed to by `zPtr'.
 100 *----------------------------------------------------------------------------*/
 101
 102 static inline void shift32RightJamming(uint32_t a, int_fast16_t count, uint32_t *zPtr)
 103 {
 104     uint32_t z;
 105
 106     if ( count == 0 ) {
 107         z = a;
 108     }
 109     else if ( count < 32 ) {
 110         z = ( a>>count ) | ( ( a<<( ( - count ) & 31 ) ) != 0 );
 111     }
 112     else {
 113         z = ( a != 0 );
 114     }
 115     *zPtr = z;
 116
 117 }
 118
 119 /*----------------------------------------------------------------------------
 120 | Shifts `a' right by the number of bits given in `count'.  If any nonzero
 121 | bits are shifted off, they are ``jammed'' into the least significant bit of
 122 | the result by setting the least significant bit to 1.  The value of `count'
 123 | can be arbitrarily large; in particular, if `count' is greater than 64, the
 124 | result will be either 0 or 1, depending on whether `a' is zero or nonzero.
 125 | The result is stored in the location pointed to by `zPtr'.
 126 *----------------------------------------------------------------------------*/
 127
 128 static inline void shift64RightJamming(uint64_t a, int_fast16_t count, uint64_t *zPtr)
 129 {
 130     uint64_t z;
 131
 132     if ( count == 0 ) {
 133         z = a;
 134     }
 135     else if ( count < 64 ) {
 136         z = ( a>>count ) | ( ( a<<( ( - count ) & 63 ) ) != 0 );
 137     }
 138     else {
 139         z = ( a != 0 );
 140     }
 141     *zPtr = z;
 142
 143 }
 144
 145 /*----------------------------------------------------------------------------
 146 | Shifts the 128-bit value formed by concatenating `a0' and `a1' right by 64
 147 | _plus_ the number of bits given in `count'.  The shifted result is at most
 148 | 64 nonzero bits; this is stored at the location pointed to by `z0Ptr'.  The
 149 | bits shifted off form a second 64-bit result as follows:  The _last_ bit
 150 | shifted off is the most-significant bit of the extra result, and the other
 151 | 63 bits of the extra result are all zero if and only if _all_but_the_last_
 152 | bits shifted off were all zero.  This extra result is stored in the location
 153 | pointed to by `z1Ptr'.  The value of `count' can be arbitrarily large.
 154 |     (This routine makes more sense if `a0' and `a1' are considered to form a
 155 | fixed-point value with binary point between `a0' and `a1'.  This fixed-point
 156 | value is shifted right by the number of bits given in `count', and the
 157 | integer part of the result is returned at the location pointed to by
 158 | `z0Ptr'.  The fractional part of the result may be slightly corrupted as
 159 | described above, and is returned at the location pointed to by `z1Ptr'.)
 160 *----------------------------------------------------------------------------*/
 161
 162 static inline void
 163  shift64ExtraRightJamming(
 164      uint64_t a0, uint64_t a1, int_fast16_t count, uint64_t *z0Ptr, uint64_t *z1Ptr)
 165 {
 166     uint64_t z0, z1;
 167     int8 negCount = ( - count ) & 63;
 168
 169     if ( count == 0 ) {
 170         z1 = a1;
 171         z0 = a0;
 172     }
 173     else if ( count < 64 ) {
 174         z1 = ( a0<<negCount ) | ( a1 != 0 );
 175         z0 = a0>>count;
 176     }
 177     else {
 178         if ( count == 64 ) {
 179             z1 = a0 | ( a1 != 0 );
 180         }
 181         else {
 182             z1 = ( ( a0 | a1 ) != 0 );
 183         }
 184         z0 = 0;
 185     }
 186     *z1Ptr = z1;
 187     *z0Ptr = z0;
 188
 189 }
 190
 191 /*----------------------------------------------------------------------------
 192 | Shifts the 128-bit value formed by concatenating `a0' and `a1' right by the
 193 | number of bits given in `count'.  Any bits shifted off are lost.  The value
 194 | of `count' can be arbitrarily large; in particular, if `count' is greater
 195 | than 128, the result will be 0.  The result is broken into two 64-bit pieces
 196 | which are stored at the locations pointed to by `z0Ptr' and `z1Ptr'.
 197 *----------------------------------------------------------------------------*/
 198
 199 static inline void
 200  shift128Right(
 201      uint64_t a0, uint64_t a1, int_fast16_t count, uint64_t *z0Ptr, uint64_t *z1Ptr)
 202 {
 203     uint64_t z0, z1;
 204     int8 negCount = ( - count ) & 63;
 205
 206     if ( count == 0 ) {
 207         z1 = a1;
 208         z0 = a0;
 209     }
 210     else if ( count < 64 ) {
 211         z1 = ( a0<<negCount ) | ( a1>>count );
 212         z0 = a0>>count;
 213     }
 214     else {
 215         z1 = (count < 128) ? (a0 >> (count & 63)) : 0;
 216         z0 = 0;
 217     }
 218     *z1Ptr = z1;
 219     *z0Ptr = z0;
 220
 221 }
 222
 223 /*----------------------------------------------------------------------------
 224 | Shifts the 128-bit value formed by concatenating `a0' and `a1' right by the
 225 | number of bits given in `count'.  If any nonzero bits are shifted off, they
 226 | are ``jammed'' into the least significant bit of the result by setting the
 227 | least significant bit to 1.  The value of `count' can be arbitrarily large;
 228 | in particular, if `count' is greater than 128, the result will be either
 229 | 0 or 1, depending on whether the concatenation of `a0' and `a1' is zero or
 230 | nonzero.  The result is broken into two 64-bit pieces which are stored at
 231 | the locations pointed to by `z0Ptr' and `z1Ptr'.
 232 *----------------------------------------------------------------------------*/
 233
 234 static inline void
 235  shift128RightJamming(
 236      uint64_t a0, uint64_t a1, int_fast16_t count, uint64_t *z0Ptr, uint64_t *z1Ptr)
 237 {
 238     uint64_t z0, z1;
 239     int8 negCount = ( - count ) & 63;
 240
 241     if ( count == 0 ) {
 242         z1 = a1;
 243         z0 = a0;
 244     }
 245     else if ( count < 64 ) {
 246         z1 = ( a0<<negCount ) | ( a1>>count ) | ( ( a1<<negCount ) != 0 );
 247         z0 = a0>>count;
 248     }
 249     else {
 250         if ( count == 64 ) {
 251             z1 = a0 | ( a1 != 0 );
 252         }
 253         else if ( count < 128 ) {
 254             z1 = ( a0>>( count & 63 ) ) | ( ( ( a0<<negCount ) | a1 ) != 0 );
 255         }
 256         else {
 257             z1 = ( ( a0 | a1 ) != 0 );
 258         }
 259         z0 = 0;
 260     }
 261     *z1Ptr = z1;
 262     *z0Ptr = z0;
 263
 264 }
 265
 266 /*----------------------------------------------------------------------------
 267 | Shifts the 192-bit value formed by concatenating `a0', `a1', and `a2' right
 268 | by 64 _plus_ the number of bits given in `count'.  The shifted result is
 269 | at most 128 nonzero bits; these are broken into two 64-bit pieces which are
 270 | stored at the locations pointed to by `z0Ptr' and `z1Ptr'.  The bits shifted
 271 | off form a third 64-bit result as follows:  The _last_ bit shifted off is
 272 | the most-significant bit of the extra result, and the other 63 bits of the
 273 | extra result are all zero if and only if _all_but_the_last_ bits shifted off
 274 | were all zero.  This extra result is stored in the location pointed to by
 275 | `z2Ptr'.  The value of `count' can be arbitrarily large.
 276 |     (This routine makes more sense if `a0', `a1', and `a2' are considered
 277 | to form a fixed-point value with binary point between `a1' and `a2'.  This
 278 | fixed-point value is shifted right by the number of bits given in `count',
 279 | and the integer part of the result is returned at the locations pointed to
 280 | by `z0Ptr' and `z1Ptr'.  The fractional part of the result may be slightly
 281 | corrupted as described above, and is returned at the location pointed to by
 282 | `z2Ptr'.)
 283 *----------------------------------------------------------------------------*/
 284
 285 static inline void
 286  shift128ExtraRightJamming(
 287      uint64_t a0,
 288      uint64_t a1,
 289      uint64_t a2,
 290      int_fast16_t count,
 291      uint64_t *z0Ptr,
 292      uint64_t *z1Ptr,
 293      uint64_t *z2Ptr
 294  )
 295 {
 296     uint64_t z0, z1, z2;
 297     int8 negCount = ( - count ) & 63;
 298
 299     if ( count == 0 ) {
 300         z2 = a2;
 301         z1 = a1;
 302         z0 = a0;
 303     }
 304     else {
 305         if ( count < 64 ) {
 306             z2 = a1<<negCount;
 307             z1 = ( a0<<negCount ) | ( a1>>count );
 308             z0 = a0>>count;
 309         }
 310         else {
 311             if ( count == 64 ) {
 312                 z2 = a1;
 313                 z1 = a0;
 314             }
 315             else {
 316                 a2 |= a1;
 317                 if ( count < 128 ) {
 318                     z2 = a0<<negCount;
 319                     z1 = a0>>( count & 63 );
 320                 }
 321                 else {
 322                     z2 = ( count == 128 ) ? a0 : ( a0 != 0 );
 323                     z1 = 0;
 324                 }
 325             }
 326             z0 = 0;
 327         }
 328         z2 |= ( a2 != 0 );
 329     }
 330     *z2Ptr = z2;
 331     *z1Ptr = z1;
 332     *z0Ptr = z0;
 333
 334 }
 335
 336 /*----------------------------------------------------------------------------
 337 | Shifts the 128-bit value formed by concatenating `a0' and `a1' left by the
 338 | number of bits given in `count'.  Any bits shifted off are lost.  The value
 339 | of `count' must be less than 64.  The result is broken into two 64-bit
 340 | pieces which are stored at the locations pointed to by `z0Ptr' and `z1Ptr'.
 341 *----------------------------------------------------------------------------*/
 342
 343 static inline void
 344  shortShift128Left(
 345      uint64_t a0, uint64_t a1, int_fast16_t count, uint64_t *z0Ptr, uint64_t *z1Ptr)
 346 {
 347
 348     *z1Ptr = a1<<count;
 349     *z0Ptr =
 350         ( count == 0 ) ? a0 : ( a0<<count ) | ( a1>>( ( - count ) & 63 ) );
 351
 352 }
 353
 354 /*----------------------------------------------------------------------------
 355 | Shifts the 192-bit value formed by concatenating `a0', `a1', and `a2' left
 356 | by the number of bits given in `count'.  Any bits shifted off are lost.
 357 | The value of `count' must be less than 64.  The result is broken into three
 358 | 64-bit pieces which are stored at the locations pointed to by `z0Ptr',
 359 | `z1Ptr', and `z2Ptr'.
 360 *----------------------------------------------------------------------------*/
 361
 362 static inline void
 363  shortShift192Left(
 364      uint64_t a0,
 365      uint64_t a1,
 366      uint64_t a2,
 367      int_fast16_t count,
 368      uint64_t *z0Ptr,
 369      uint64_t *z1Ptr,
 370      uint64_t *z2Ptr
 371  )
 372 {
 373     uint64_t z0, z1, z2;
 374     int8 negCount;
 375
 376     z2 = a2<<count;
 377     z1 = a1<<count;
 378     z0 = a0<<count;
 379     if ( 0 < count ) {
 380         negCount = ( ( - count ) & 63 );
 381         z1 |= a2>>negCount;
 382         z0 |= a1>>negCount;
 383     }
 384     *z2Ptr = z2;
 385     *z1Ptr = z1;
 386     *z0Ptr = z0;
 387
 388 }
 389
 390 /*----------------------------------------------------------------------------
 391 | Adds the 128-bit value formed by concatenating `a0' and `a1' to the 128-bit
 392 | value formed by concatenating `b0' and `b1'.  Addition is modulo 2^128, so
 393 | any carry out is lost.  The result is broken into two 64-bit pieces which
 394 | are stored at the locations pointed to by `z0Ptr' and `z1Ptr'.
 395 *----------------------------------------------------------------------------*/
 396
 397 static inline void
 398  add128(
 399      uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1, uint64_t *z0Ptr, uint64_t *z1Ptr )
 400 {
 401     uint64_t z1;
 402
 403     z1 = a1 + b1;
 404     *z1Ptr = z1;
 405     *z0Ptr = a0 + b0 + ( z1 < a1 );
 406
 407 }
 408
 409 /*----------------------------------------------------------------------------
 410 | Adds the 192-bit value formed by concatenating `a0', `a1', and `a2' to the
 411 | 192-bit value formed by concatenating `b0', `b1', and `b2'.  Addition is
 412 | modulo 2^192, so any carry out is lost.  The result is broken into three
 413 | 64-bit pieces which are stored at the locations pointed to by `z0Ptr',
 414 | `z1Ptr', and `z2Ptr'.
 415 *----------------------------------------------------------------------------*/
 416
 417 static inline void
 418  add192(
 419      uint64_t a0,
 420      uint64_t a1,
 421      uint64_t a2,
 422      uint64_t b0,
 423      uint64_t b1,
 424      uint64_t b2,
 425      uint64_t *z0Ptr,
 426      uint64_t *z1Ptr,
 427      uint64_t *z2Ptr
 428  )
 429 {
 430     uint64_t z0, z1, z2;
 431     int8 carry0, carry1;
 432
 433     z2 = a2 + b2;
 434     carry1 = ( z2 < a2 );
 435     z1 = a1 + b1;
 436     carry0 = ( z1 < a1 );
 437     z0 = a0 + b0;
 438     z1 += carry1;
 439     z0 += ( z1 < carry1 );
 440     z0 += carry0;
 441     *z2Ptr = z2;
 442     *z1Ptr = z1;
 443     *z0Ptr = z0;
 444
 445 }
 446
 447 /*----------------------------------------------------------------------------
 448 | Subtracts the 128-bit value formed by concatenating `b0' and `b1' from the
 449 | 128-bit value formed by concatenating `a0' and `a1'.  Subtraction is modulo
 450 | 2^128, so any borrow out (carry out) is lost.  The result is broken into two
 451 | 64-bit pieces which are stored at the locations pointed to by `z0Ptr' and
 452 | `z1Ptr'.
 453 *----------------------------------------------------------------------------*/
 454
 455 static inline void
 456  sub128(
 457      uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1, uint64_t *z0Ptr, uint64_t *z1Ptr )
 458 {
 459
 460     *z1Ptr = a1 - b1;
 461     *z0Ptr = a0 - b0 - ( a1 < b1 );
 462
 463 }
 464
 465 /*----------------------------------------------------------------------------
 466 | Subtracts the 192-bit value formed by concatenating `b0', `b1', and `b2'
 467 | from the 192-bit value formed by concatenating `a0', `a1', and `a2'.
 468 | Subtraction is modulo 2^192, so any borrow out (carry out) is lost.  The
 469 | result is broken into three 64-bit pieces which are stored at the locations
 470 | pointed to by `z0Ptr', `z1Ptr', and `z2Ptr'.
 471 *----------------------------------------------------------------------------*/
 472
 473 static inline void
 474  sub192(
 475      uint64_t a0,
 476      uint64_t a1,
 477      uint64_t a2,
 478      uint64_t b0,
 479      uint64_t b1,
 480      uint64_t b2,
 481      uint64_t *z0Ptr,
 482      uint64_t *z1Ptr,
 483      uint64_t *z2Ptr
 484  )
 485 {
 486     uint64_t z0, z1, z2;
 487     int8 borrow0, borrow1;
 488
 489     z2 = a2 - b2;
 490     borrow1 = ( a2 < b2 );
 491     z1 = a1 - b1;
 492     borrow0 = ( a1 < b1 );
 493     z0 = a0 - b0;
 494     z0 -= ( z1 < borrow1 );
 495     z1 -= borrow1;
 496     z0 -= borrow0;
 497     *z2Ptr = z2;
 498     *z1Ptr = z1;
 499     *z0Ptr = z0;
 500
 501 }
 502
 503 /*----------------------------------------------------------------------------
 504 | Multiplies `a' by `b' to obtain a 128-bit product.  The product is broken
 505 | into two 64-bit pieces which are stored at the locations pointed to by
 506 | `z0Ptr' and `z1Ptr'.
 507 *----------------------------------------------------------------------------*/
 508
 509 static inline void mul64To128( uint64_t a, uint64_t b, uint64_t *z0Ptr, uint64_t *z1Ptr )
 510 {
 511     uint32_t aHigh, aLow, bHigh, bLow;
 512     uint64_t z0, zMiddleA, zMiddleB, z1;
 513
 514     aLow = a;
 515     aHigh = a>>32;
 516     bLow = b;
 517     bHigh = b>>32;
 518     z1 = ( (uint64_t) aLow ) * bLow;
 519     zMiddleA = ( (uint64_t) aLow ) * bHigh;
 520     zMiddleB = ( (uint64_t) aHigh ) * bLow;
 521     z0 = ( (uint64_t) aHigh ) * bHigh;
 522     zMiddleA += zMiddleB;
 523     z0 += ( ( (uint64_t) ( zMiddleA < zMiddleB ) )<<32 ) + ( zMiddleA>>32 );
 524     zMiddleA <<= 32;
 525     z1 += zMiddleA;
 526     z0 += ( z1 < zMiddleA );
 527     *z1Ptr = z1;
 528     *z0Ptr = z0;
 529
 530 }
 531
 532 /*----------------------------------------------------------------------------
 533 | Multiplies the 128-bit value formed by concatenating `a0' and `a1' by
 534 | `b' to obtain a 192-bit product.  The product is broken into three 64-bit
 535 | pieces which are stored at the locations pointed to by `z0Ptr', `z1Ptr', and
 536 | `z2Ptr'.
 537 *----------------------------------------------------------------------------*/
 538
 539 static inline void
 540  mul128By64To192(
 541      uint64_t a0,
 542      uint64_t a1,
 543      uint64_t b,
 544      uint64_t *z0Ptr,
 545      uint64_t *z1Ptr,
 546      uint64_t *z2Ptr
 547  )
 548 {
 549     uint64_t z0, z1, z2, more1;
 550
 551     mul64To128( a1, b, &z1, &z2 );
 552     mul64To128( a0, b, &z0, &more1 );
 553     add128( z0, more1, 0, z1, &z0, &z1 );
 554     *z2Ptr = z2;
 555     *z1Ptr = z1;
 556     *z0Ptr = z0;
 557
 558 }
 559
 560 /*----------------------------------------------------------------------------
 561 | Multiplies the 128-bit value formed by concatenating `a0' and `a1' to the
 562 | 128-bit value formed by concatenating `b0' and `b1' to obtain a 256-bit
 563 | product.  The product is broken into four 64-bit pieces which are stored at
 564 | the locations pointed to by `z0Ptr', `z1Ptr', `z2Ptr', and `z3Ptr'.
 565 *----------------------------------------------------------------------------*/
 566
 567 static inline void
 568  mul128To256(
 569      uint64_t a0,
 570      uint64_t a1,
 571      uint64_t b0,
 572      uint64_t b1,
 573      uint64_t *z0Ptr,
 574      uint64_t *z1Ptr,
 575      uint64_t *z2Ptr,
 576      uint64_t *z3Ptr
 577  )
 578 {
 579     uint64_t z0, z1, z2, z3;
 580     uint64_t more1, more2;
 581
 582     mul64To128( a1, b1, &z2, &z3 );
 583     mul64To128( a1, b0, &z1, &more2 );
 584     add128( z1, more2, 0, z2, &z1, &z2 );
 585     mul64To128( a0, b0, &z0, &more1 );
 586     add128( z0, more1, 0, z1, &z0, &z1 );
 587     mul64To128( a0, b1, &more1, &more2 );
 588     add128( more1, more2, 0, z2, &more1, &z2 );
 589     add128( z0, z1, 0, more1, &z0, &z1 );
 590     *z3Ptr = z3;
 591     *z2Ptr = z2;
 592     *z1Ptr = z1;
 593     *z0Ptr = z0;
 594
 595 }
 596
 597 /*----------------------------------------------------------------------------
 598 | Returns an approximation to the 64-bit integer quotient obtained by dividing
 599 | `b' into the 128-bit value formed by concatenating `a0' and `a1'.  The
 600 | divisor `b' must be at least 2^63.  If q is the exact quotient truncated
 601 | toward zero, the approximation returned lies between q and q + 2 inclusive.
 602 | If the exact quotient q is larger than 64 bits, the maximum positive 64-bit
 603 | unsigned integer is returned.
 604 *----------------------------------------------------------------------------*/
 605
 606 static uint64_t estimateDiv128To64( uint64_t a0, uint64_t a1, uint64_t b )
 607 {
 608     uint64_t b0, b1;
 609     uint64_t rem0, rem1, term0, term1;
 610     uint64_t z;
 611
 612     if ( b <= a0 ) return LIT64( 0xFFFFFFFFFFFFFFFF );
 613     b0 = b>>32;
 614     z = ( b0<<32 <= a0 ) ? LIT64( 0xFFFFFFFF00000000 ) : ( a0 / b0 )<<32;
 615     mul64To128( b, z, &term0, &term1 );
 616     sub128( a0, a1, term0, term1, &rem0, &rem1 );
 617     while ( ( (int64_t) rem0 ) < 0 ) {
 618         z -= LIT64( 0x100000000 );
 619         b1 = b<<32;
 620         add128( rem0, rem1, b0, b1, &rem0, &rem1 );
 621     }
 622     rem0 = ( rem0<<32 ) | ( rem1>>32 );
 623     z |= ( b0<<32 <= rem0 ) ? 0xFFFFFFFF : rem0 / b0;
 624     return z;
 625
 626 }
 627
 628 /*----------------------------------------------------------------------------
 629 | Returns an approximation to the square root of the 32-bit significand given
 630 | by `a'.  Considered as an integer, `a' must be at least 2^31.  If bit 0 of
 631 | `aExp' (the least significant bit) is 1, the integer returned approximates
 632 | 2^31*sqrt(`a'/2^31), where `a' is considered an integer.  If bit 0 of `aExp'
 633 | is 0, the integer returned approximates 2^31*sqrt(`a'/2^30).  In either
 634 | case, the approximation returned lies strictly within +/-2 of the exact
 635 | value.
 636 *----------------------------------------------------------------------------*/
 637
 638 static uint32_t estimateSqrt32(int_fast16_t aExp, uint32_t a)
 639 {
 640     static const uint16_t sqrtOddAdjustments[] = {
 641         0x0004, 0x0022, 0x005D, 0x00B1, 0x011D, 0x019F, 0x0236, 0x02E0,
 642         0x039C, 0x0468, 0x0545, 0x0631, 0x072B, 0x0832, 0x0946, 0x0A67
 643     };
 644     static const uint16_t sqrtEvenAdjustments[] = {
 645         0x0A2D, 0x08AF, 0x075A, 0x0629, 0x051A, 0x0429, 0x0356, 0x029E,
 646         0x0200, 0x0179, 0x0109, 0x00AF, 0x0068, 0x0034, 0x0012, 0x0002
 647     };
 648     int8 index;
 649     uint32_t z;
 650
 651     index = ( a>>27 ) & 15;
 652     if ( aExp & 1 ) {
 653         z = 0x4000 + ( a>>17 ) - sqrtOddAdjustments[ (int)index ];
 654         z = ( ( a / z )<<14 ) + ( z<<15 );
 655         a >>= 1;
 656     }
 657     else {
 658         z = 0x8000 + ( a>>17 ) - sqrtEvenAdjustments[ (int)index ];
 659         z = a / z + z;
 660         z = ( 0x20000 <= z ) ? 0xFFFF8000 : ( z<<15 );
 661         if ( z <= a ) return (uint32_t) ( ( (int32_t) a )>>1 );
 662     }
 663     return ( (uint32_t) ( ( ( (uint64_t) a )<<31 ) / z ) ) + ( z>>1 );
 664
 665 }
 666
 667 /*----------------------------------------------------------------------------
 668 | Returns the number of leading 0 bits before the most-significant 1 bit of
 669 | `a'.  If `a' is zero, 32 is returned.
 670 *----------------------------------------------------------------------------*/
 671
 672 static int8 countLeadingZeros32( uint32_t a )
 673 {
 674 #if SOFTFLOAT_GNUC_PREREQ(3, 4)
 675     if (a) {
 676         return __builtin_clz(a);
 677     } else {
 678         return 32;
 679     }
 680 #else
 681     static const int8 countLeadingZerosHigh[] = {
 682         8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
 683         3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
 684         2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
 685         2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
 686         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 687         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 688         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 689         1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 690         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 691         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 692         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 693         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 694         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 695         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 696         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 697         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 698     };
 699     int8 shiftCount;
 700
 701     shiftCount = 0;
 702     if ( a < 0x10000 ) {
 703         shiftCount += 16;
 704         a <<= 16;
 705     }
 706     if ( a < 0x1000000 ) {
 707         shiftCount += 8;
 708         a <<= 8;
 709     }
 710     shiftCount += countLeadingZerosHigh[ a>>24 ];
 711     return shiftCount;
 712 #endif
 713 }
 714
 715 /*----------------------------------------------------------------------------
 716 | Returns the number of leading 0 bits before the most-significant 1 bit of
 717 | `a'.  If `a' is zero, 64 is returned.
 718 *----------------------------------------------------------------------------*/
 719
 720 static int8 countLeadingZeros64( uint64_t a )
 721 {
 722 #if SOFTFLOAT_GNUC_PREREQ(3, 4)
 723     if (a) {
 724         return __builtin_clzll(a);
 725     } else {
 726         return 64;
 727     }
 728 #else
 729     int8 shiftCount;
 730
 731     shiftCount = 0;
 732     if ( a < ( (uint64_t) 1 )<<32 ) {
 733         shiftCount += 32;
 734     }
 735     else {
 736         a >>= 32;
 737     }
 738     shiftCount += countLeadingZeros32( a );
 739     return shiftCount;
 740 #endif
 741 }
 742
 743 /*----------------------------------------------------------------------------
 744 | Returns 1 if the 128-bit value formed by concatenating `a0' and `a1'
 745 | is equal to the 128-bit value formed by concatenating `b0' and `b1'.
 746 | Otherwise, returns 0.
 747 *----------------------------------------------------------------------------*/
 748
 749 static inline flag eq128( uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1 )
 750 {
 751
 752     return ( a0 == b0 ) && ( a1 == b1 );
 753
 754 }
 755
 756 /*----------------------------------------------------------------------------
 757 | Returns 1 if the 128-bit value formed by concatenating `a0' and `a1' is less
 758 | than or equal to the 128-bit value formed by concatenating `b0' and `b1'.
 759 | Otherwise, returns 0.
 760 *----------------------------------------------------------------------------*/
 761
 762 static inline flag le128( uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1 )
 763 {
 764
 765     return ( a0 < b0 ) || ( ( a0 == b0 ) && ( a1 <= b1 ) );
 766
 767 }
 768
 769 /*----------------------------------------------------------------------------
 770 | Returns 1 if the 128-bit value formed by concatenating `a0' and `a1' is less
 771 | than the 128-bit value formed by concatenating `b0' and `b1'.  Otherwise,
 772 | returns 0.
 773 *----------------------------------------------------------------------------*/
 774
 775 static inline flag lt128( uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1 )
 776 {
 777
 778     return ( a0 < b0 ) || ( ( a0 == b0 ) && ( a1 < b1 ) );
 779
 780 }
 781
 782 /*----------------------------------------------------------------------------
 783 | Returns 1 if the 128-bit value formed by concatenating `a0' and `a1' is
 784 | not equal to the 128-bit value formed by concatenating `b0' and `b1'.
 785 | Otherwise, returns 0.
 786 *----------------------------------------------------------------------------*/
 787
 788 static inline flag ne128( uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1 )
 789 {
 790
 791     return ( a0 != b0 ) || ( a1 != b1 );
 792
 793 }