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Annotation of OpenXM_contrib/gmp/mpq/set_d.c, Revision 1.1.1.1

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: }