mpfr-2.4.1/set_d64.c

/* mpfr_set_decimal64 -- convert a IEEE 754r decimal64 float to
                         a multiple precision floating-point number

See http://gcc.gnu.org/ml/gcc/2006-06/msg00691.html,
http://gcc.gnu.org/onlinedocs/gcc/Decimal-Float.html,
and TR 24732 <http://www.open-std.org/jtc1/sc22/wg14/www/projects#24732>.

Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
Contributed by the Arenaire and Cacao projects, INRIA.

This file is part of the GNU MPFR Library.

The GNU MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.

The GNU MPFR Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MPFR Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301, USA. */

#define MPFR_NEED_LONGLONG_H
#include "mpfr-impl.h"

#ifdef MPFR_WANT_DECIMAL_FLOATS

#ifdef DPD_FORMAT
  /* conversion 10-bits to 3 digits */
static unsigned int T[1024] = {
  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 80, 81, 800, 801, 880, 881, 10, 11, 12, 13,
  14, 15, 16, 17, 18, 19, 90, 91, 810, 811, 890, 891, 20, 21, 22, 23, 24, 25,
  26, 27, 28, 29, 82, 83, 820, 821, 808, 809, 30, 31, 32, 33, 34, 35, 36, 37,
  38, 39, 92, 93, 830, 831, 818, 819, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
  84, 85, 840, 841, 88, 89, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 94, 95,
  850, 851, 98, 99, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 86, 87, 860, 861,
  888, 889, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 96, 97, 870, 871, 898,
  899, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 180, 181, 900, 901,
  980, 981, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 190, 191, 910,
  911, 990, 991, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 182, 183,
  920, 921, 908, 909, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 192,
  193, 930, 931, 918, 919, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149,
  184, 185, 940, 941, 188, 189, 150, 151, 152, 153, 154, 155, 156, 157, 158,
  159, 194, 195, 950, 951, 198, 199, 160, 161, 162, 163, 164, 165, 166, 167,
  168, 169, 186, 187, 960, 961, 988, 989, 170, 171, 172, 173, 174, 175, 176,
  177, 178, 179, 196, 197, 970, 971, 998, 999, 200, 201, 202, 203, 204, 205,
  206, 207, 208, 209, 280, 281, 802, 803, 882, 883, 210, 211, 212, 213, 214,
  215, 216, 217, 218, 219, 290, 291, 812, 813, 892, 893, 220, 221, 222, 223,
  224, 225, 226, 227, 228, 229, 282, 283, 822, 823, 828, 829, 230, 231, 232,
  233, 234, 235, 236, 237, 238, 239, 292, 293, 832, 833, 838, 839, 240, 241,
  242, 243, 244, 245, 246, 247, 248, 249, 284, 285, 842, 843, 288, 289, 250,
  251, 252, 253, 254, 255, 256, 257, 258, 259, 294, 295, 852, 853, 298, 299,
  260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 286, 287, 862, 863, 888,
  889, 270, 271, 272, 273, 274, 275, 276, 277, 278, 279, 296, 297, 872, 873,
  898, 899, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 380, 381, 902,
  903, 982, 983, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 390, 391,
  912, 913, 992, 993, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 382,
  383, 922, 923, 928, 929, 330, 331, 332, 333, 334, 335, 336, 337, 338, 339,
  392, 393, 932, 933, 938, 939, 340, 341, 342, 343, 344, 345, 346, 347, 348,
  349, 384, 385, 942, 943, 388, 389, 350, 351, 352, 353, 354, 355, 356, 357,
  358, 359, 394, 395, 952, 953, 398, 399, 360, 361, 362, 363, 364, 365, 366,
  367, 368, 369, 386, 387, 962, 963, 988, 989, 370, 371, 372, 373, 374, 375,
  376, 377, 378, 379, 396, 397, 972, 973, 998, 999, 400, 401, 402, 403, 404,
  405, 406, 407, 408, 409, 480, 481, 804, 805, 884, 885, 410, 411, 412, 413,
  414, 415, 416, 417, 418, 419, 490, 491, 814, 815, 894, 895, 420, 421, 422,
  423, 424, 425, 426, 427, 428, 429, 482, 483, 824, 825, 848, 849, 430, 431,
  432, 433, 434, 435, 436, 437, 438, 439, 492, 493, 834, 835, 858, 859, 440,
  441, 442, 443, 444, 445, 446, 447, 448, 449, 484, 485, 844, 845, 488, 489,
  450, 451, 452, 453, 454, 455, 456, 457, 458, 459, 494, 495, 854, 855, 498,
  499, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469, 486, 487, 864, 865,
  888, 889, 470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 496, 497, 874,
  875, 898, 899, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 580, 581,
  904, 905, 984, 985, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 590,
  591, 914, 915, 994, 995, 520, 521, 522, 523, 524, 525, 526, 527, 528, 529,
  582, 583, 924, 925, 948, 949, 530, 531, 532, 533, 534, 535, 536, 537, 538,
  539, 592, 593, 934, 935, 958, 959, 540, 541, 542, 543, 544, 545, 546, 547,
  548, 549, 584, 585, 944, 945, 588, 589, 550, 551, 552, 553, 554, 555, 556,
  557, 558, 559, 594, 595, 954, 955, 598, 599, 560, 561, 562, 563, 564, 565,
  566, 567, 568, 569, 586, 587, 964, 965, 988, 989, 570, 571, 572, 573, 574,
  575, 576, 577, 578, 579, 596, 597, 974, 975, 998, 999, 600, 601, 602, 603,
  604, 605, 606, 607, 608, 609, 680, 681, 806, 807, 886, 887, 610, 611, 612,
  613, 614, 615, 616, 617, 618, 619, 690, 691, 816, 817, 896, 897, 620, 621,
  622, 623, 624, 625, 626, 627, 628, 629, 682, 683, 826, 827, 868, 869, 630,
  631, 632, 633, 634, 635, 636, 637, 638, 639, 692, 693, 836, 837, 878, 879,
  640, 641, 642, 643, 644, 645, 646, 647, 648, 649, 684, 685, 846, 847, 688,
  689, 650, 651, 652, 653, 654, 655, 656, 657, 658, 659, 694, 695, 856, 857,
  698, 699, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 686, 687, 866,
  867, 888, 889, 670, 671, 672, 673, 674, 675, 676, 677, 678, 679, 696, 697,
  876, 877, 898, 899, 700, 701, 702, 703, 704, 705, 706, 707, 708, 709, 780,
  781, 906, 907, 986, 987, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719,
  790, 791, 916, 917, 996, 997, 720, 721, 722, 723, 724, 725, 726, 727, 728,
  729, 782, 783, 926, 927, 968, 969, 730, 731, 732, 733, 734, 735, 736, 737,
  738, 739, 792, 793, 936, 937, 978, 979, 740, 741, 742, 743, 744, 745, 746,
  747, 748, 749, 784, 785, 946, 947, 788, 789, 750, 751, 752, 753, 754, 755,
  756, 757, 758, 759, 794, 795, 956, 957, 798, 799, 760, 761, 762, 763, 764,
  765, 766, 767, 768, 769, 786, 787, 966, 967, 988, 989, 770, 771, 772, 773,
  774, 775, 776, 777, 778, 779, 796, 797, 976, 977, 998, 999 };
#endif

/* Convert d to a decimal string (one-to-one correspondence, no rounding).
   The string s needs to have at least 23 characters.
 */
static void
decimal64_to_string (char *s, _Decimal64 d)
{
  union ieee_double_extract x;
  union ieee_double_decimal64 y;
  char *t;
  unsigned int Gh; /* most 5 significant bits from combination field */
  int exp; /* exponent */
  mp_limb_t rp[2];
  mp_size_t rn = 2;
  unsigned int i;
#ifdef DPD_FORMAT
  unsigned int d0, d1, d2, d3, d4, d5;
#endif

  /* now convert BID or DPD to string */
  y.d64 = d;
  x.d = y.d;
  Gh = x.s.exp >> 6;
  if (Gh == 31)
    {
      sprintf (s, "NaN");
      return;
    }
  else if (Gh == 30)
    {
      if (x.s.sig == 0)
        sprintf (s, "Inf");
      else
        sprintf (s, "-Inf");
      return;
    }
  t = s;
  if (x.s.sig)
    *t++ = '-';

#ifdef DPD_FORMAT
  if (Gh < 24)
    {
      exp = (x.s.exp >> 1) & 768;
      d0 = Gh & 7;
    }
  else
    {
      exp = (x.s.exp & 384) << 1;
      d0 = 8 | (Gh & 1);
    }
  exp |= (x.s.exp & 63) << 2;
  exp |= x.s.manh >> 18;
  d1 = (x.s.manh >> 8) & 1023;
  d2 = ((x.s.manh << 2) | (x.s.manl >> 30)) & 1023;
  d3 = (x.s.manl >> 20) & 1023;
  d4 = (x.s.manl >> 10) & 1023;
  d5 = x.s.manl & 1023;
  sprintf (t, "%1u%3u%3u%3u%3u%3u", d0, T[d1], T[d2], T[d3], T[d4], T[d5]);
  /* Warning: some characters may be blank */
  for (i = 0; i < 16; i++)
    if (t[i] == ' ')
      t[i] = '0';
  t += 16;
#else /* BID */
  if (Gh < 24)
    {
      /* the biased exponent E is formed from G[0] to G[9] and the
         significand from bits G[10] through the end of the decoding */
      exp = x.s.exp >> 1;
      /* manh has 20 bits, manl has 32 bits */
      rp[1] = ((x.s.exp & 1) << 20) | x.s.manh;
      rp[0] = x.s.manl;
    }
  else
    {
      /* the biased exponent is formed from G[2] to G[11] */
      exp = (x.s.exp & 511) << 1;
      rp[1] = x.s.manh;
      rp[0] = x.s.manl;
      exp |= rp[1] >> 19;
      rp[1] &= 524287; /* 2^19-1: cancel G[11] */
      rp[1] |= 2097152; /* add 2^21 */
    }
#if BITS_PER_MP_LIMB >= 54
  rp[0] |= rp[1] << 32;
  rn = 1;
#endif
  while (rn > 0 && rp[rn - 1] == 0)
    rn --;
  if (rn == 0)
    {
      *t = 0;
      i = 1;
    }
  else
    {
      i = mpn_get_str (t, 10, rp, rn);
    }
  while (i-- > 0)
    *t++ += '0';
#endif /* DPD or BID */

  exp -= 398; /* unbiased exponent */
  t += sprintf (t, "E%d", exp);
}

int
mpfr_set_decimal64 (mpfr_ptr r, _Decimal64 d, mp_rnd_t rnd_mode)
{
  char s[23]; /* need 1 character for sign,
                     16 characters for mantissa,
                      1 character for exponent,
                      4 characters for exponent (including sign),
                      1 character for terminating \0. */

  decimal64_to_string (s, d);
  return mpfr_set_str (r, s, 10, rnd_mode);
}

#endif /* MPFR_WANT_DECIMAL_FLOATS */