source/libs/mpfr/mpfr-3.1.3/src/modf.c

   1 /* mpfr_modf -- Integral and fractional part.
   2
   3 Copyright 2007-2015 Free Software Foundation, Inc.
   4 Contributed by the AriC and Caramel projects, INRIA.
   5
   6 This file is part of the GNU MPFR Library.
   7
   8 The GNU MPFR Library is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU Lesser General Public License as published by
  10 the Free Software Foundation; either version 3 of the License, or (at your
  11 option) any later version.
  12
  13 The GNU MPFR Library is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16 License for more details.
  17
  18 You should have received a copy of the GNU Lesser General Public License
  19 along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
  20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
  21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
  22
  23 #include "mpfr-impl.h"
  24
  25 #define INEXPOS(y) ((y) == 0 ? 0 : (((y) > 0) ? 1 : 2))
  26 #define INEX(y,z) (INEXPOS(y) | (INEXPOS(z) << 2))
  27
  28 /* Set iop to the integral part of op and fop to its fractional part */
  29 int
  30 mpfr_modf (mpfr_ptr iop, mpfr_ptr fop, mpfr_srcptr op, mpfr_rnd_t rnd_mode)
  31 {
  32   mpfr_exp_t ope;
  33   mpfr_prec_t opq;
  34   int inexi, inexf;
  35
  36   MPFR_LOG_FUNC
  37     (("op[%Pu]=%.*Rg rnd=%d",
  38       mpfr_get_prec (op), mpfr_log_prec, op, rnd_mode),
  39      ("iop[%Pu]=%.*Rg fop[%Pu]=%.*Rg",
  40       mpfr_get_prec (iop), mpfr_log_prec, iop,
  41       mpfr_get_prec (fop), mpfr_log_prec, fop));
  42
  43   MPFR_ASSERTN (iop != fop);
  44
  45   if ( MPFR_UNLIKELY (MPFR_IS_SINGULAR (op)) )
  46     {
  47       if (MPFR_IS_NAN (op))
  48         {
  49           MPFR_SET_NAN (iop);
  50           MPFR_SET_NAN (fop);
  51           MPFR_RET_NAN;
  52         }
  53       MPFR_SET_SAME_SIGN (iop, op);
  54       MPFR_SET_SAME_SIGN (fop, op);
  55       if (MPFR_IS_INF (op))
  56         {
  57           MPFR_SET_INF (iop);
  58           MPFR_SET_ZERO (fop);
  59           MPFR_RET (0);
  60         }
  61       else /* op is zero */
  62         {
  63           MPFR_ASSERTD (MPFR_IS_ZERO (op));
  64           MPFR_SET_ZERO (iop);
  65           MPFR_SET_ZERO (fop);
  66           MPFR_RET (0);
  67         }
  68     }
  69
  70   ope = MPFR_GET_EXP (op);
  71   opq = MPFR_PREC (op);
  72
  73   if (ope <= 0)   /* 0 < |op| < 1 */
  74     {
  75       inexf = (fop != op) ? mpfr_set (fop, op, rnd_mode) : 0;
  76       MPFR_SET_SAME_SIGN (iop, op);
  77       MPFR_SET_ZERO (iop);
  78       MPFR_RET (INEX(0, inexf));
  79     }
  80   else if (ope >= opq) /* op has no fractional part */
  81     {
  82       inexi = (iop != op) ? mpfr_set (iop, op, rnd_mode) : 0;
  83       MPFR_SET_SAME_SIGN (fop, op);
  84       MPFR_SET_ZERO (fop);
  85       MPFR_RET (INEX(inexi, 0));
  86     }
  87   else /* op has both integral and fractional parts */
  88     {
  89       if (iop != op)
  90         {
  91           inexi = mpfr_rint_trunc (iop, op, rnd_mode);
  92           inexf = mpfr_frac (fop, op, rnd_mode);
  93         }
  94       else
  95         {
  96           MPFR_ASSERTN (fop != op);
  97           inexf = mpfr_frac (fop, op, rnd_mode);
  98           inexi = mpfr_rint_trunc (iop, op, rnd_mode);
  99         }
 100       MPFR_RET (INEX(inexi, inexf));
 101     }
 102 }