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Annotation of OpenXM_contrib/gmp/mpq/set_d.c, Revision 1.1

1.1     ! maekawa     1: /* mpq_set_d(mpq_t q, double d) -- Set q to d without rounding.
        !             2:
        !             3: Copyright (C) 2000 Free Software Foundation, Inc.
        !             4:
        !             5: This file is part of the GNU MP Library.
        !             6:
        !             7: The GNU MP Library is free software; you can redistribute it and/or modify
        !             8: it under the terms of the GNU Lesser General Public License as published by
        !             9: the Free Software Foundation; either version 2.1 of the License, or (at your
        !            10: option) any later version.
        !            11:
        !            12: The GNU MP Library is distributed in the hope that it will be useful, but
        !            13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Lesser General Public License
        !            18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            20: MA 02111-1307, USA. */
        !            21:
        !            22: #include "gmp.h"
        !            23: #include "gmp-impl.h"
        !            24: #include "longlong.h"
        !            25:
        !            26: #if BITS_PER_MP_LIMB != 32 && BITS_PER_MP_LIMB != 64
        !            27: This file does not handle any the used BITS_PER_MP_LIMB.
        !            28: #endif
        !            29:
        !            30: void
        !            31: #if __STDC__
        !            32: mpq_set_d (mpq_ptr dest, double d)
        !            33: #else
        !            34: mpq_set_d (dest, d)
        !            35:      mpq_ptr dest;
        !            36:      double d;
        !            37: #endif
        !            38: {
        !            39:   int negative;
        !            40:   mp_exp_t exp;
        !            41:   mp_limb_t tp[3];
        !            42:   mp_ptr np, dp;
        !            43:   mp_size_t nn, dn;
        !            44:   int c;
        !            45:
        !            46:   negative = d < 0;
        !            47:   d = ABS (d);
        !            48:
        !            49:   exp = __gmp_extract_double (tp, d);
        !            50:
        !            51:   /* There are two main version of the conversion.  The `then' arm handles
        !            52:      things that have a fractional part, while the `else' part handles
        !            53:      only integers.  */
        !            54: #if BITS_PER_MP_LIMB == 32
        !            55:   if (exp <= 1 || (exp == 2 && tp[0] != 0))
        !            56: #else
        !            57:   if (exp <= 1)
        !            58: #endif
        !            59:     {
        !            60:       if (d == 0.0)
        !            61:        {
        !            62:          SIZ(&(dest->_mp_num)) = 0;
        !            63:          SIZ(&(dest->_mp_den)) = 1;
        !            64:          PTR(&(dest->_mp_den))[0] = 1;
        !            65:          return;
        !            66:        }
        !            67:
        !            68:       dn = -exp;
        !            69:       if (dest->_mp_num._mp_alloc < 3)
        !            70:        _mpz_realloc (&(dest->_mp_num), 3);
        !            71:       np = PTR(&(dest->_mp_num));
        !            72: #if BITS_PER_MP_LIMB == 32
        !            73:       if ((tp[0] | tp[1]) == 0)
        !            74:        np[0] = tp[2], nn = 1;
        !            75:       else if (tp[0] == 0)
        !            76:        np[1] = tp[2], np[0] = tp[1], nn = 2;
        !            77:       else
        !            78:        np[2] = tp[2], np[1] = tp[1], np[0] = tp[0], nn = 3;
        !            79: #else
        !            80:       if (tp[0] == 0)
        !            81:        np[0] = tp[1], nn = 1;
        !            82:       else
        !            83:        np[1] = tp[1], np[0] = tp[0], nn = 2;
        !            84: #endif
        !            85:       dn += nn + 1;
        !            86:       if (dest->_mp_den._mp_alloc < dn)
        !            87:        _mpz_realloc (&(dest->_mp_den), dn);
        !            88:       dp = PTR(&(dest->_mp_den));
        !            89:       MPN_ZERO (dp, dn - 1);
        !            90:       dp[dn - 1] = 1;
        !            91:       count_trailing_zeros (c, np[0] | dp[0]);
        !            92:       if (c != 0)
        !            93:        {
        !            94:          mpn_rshift (np, np, nn, c);
        !            95:          nn -= np[nn - 1] == 0;
        !            96:          mpn_rshift (dp, dp, dn, c);
        !            97:          dn -= dp[dn - 1] == 0;
        !            98:        }
        !            99:       SIZ(&(dest->_mp_den)) = dn;
        !           100:       SIZ(&(dest->_mp_num)) = negative ? -nn : nn;
        !           101:     }
        !           102:   else
        !           103:     {
        !           104:       nn = exp;
        !           105:       if (dest->_mp_num._mp_alloc < nn)
        !           106:        _mpz_realloc (&(dest->_mp_num), nn);
        !           107:       np = PTR(&(dest->_mp_num));
        !           108: #if BITS_PER_MP_LIMB == 32
        !           109:       switch (nn)
        !           110:         {
        !           111:        default:
        !           112:           MPN_ZERO (np, nn - 3);
        !           113:           np += nn - 3;
        !           114:          /* fall through */
        !           115:        case 3:
        !           116:          np[2] = tp[2], np[1] = tp[1], np[0] = tp[0];
        !           117:          break;
        !           118:        case 2:
        !           119:          np[1] = tp[2], np[0] = tp[1];
        !           120:          break;
        !           121:        }
        !           122: #else
        !           123:       switch (nn)
        !           124:         {
        !           125:        default:
        !           126:          MPN_ZERO (np, nn - 2);
        !           127:          np += nn - 2;
        !           128:          /* fall through */
        !           129:        case 2:
        !           130:          np[1] = tp[1], np[0] = tp[0];
        !           131:          break;
        !           132:        }
        !           133: #endif
        !           134:       dp = PTR(&(dest->_mp_den));
        !           135:       dp[0] = 1;
        !           136:       SIZ(&(dest->_mp_den)) = 1;
        !           137:       SIZ(&(dest->_mp_num)) = negative ? -nn : nn;
        !           138:     }
        !           139: }