gcc/realmpfr.c

   1 /* Conversion routines from GCC internal float representation to MPFR.
   2    Copyright (C) 2010
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify it under
   7    the terms of the GNU General Public License as published by the Free
   8    Software Foundation; either version 3, or (at your option) any later
   9    version.
  10
  11    GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12    WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14    for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GCC; see the file COPYING3.  If not see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "realmpfr.h"
  24 #include "tree.h"       /* For TYPE_MODE in real_from_mpfr.  */
  25
  26 /* Convert from REAL_VALUE_TYPE to MPFR.  The caller is responsible
  27    for initializing and clearing the MPFR parameter.  */
  28
  29 void
  30 mpfr_from_real (mpfr_ptr m, const REAL_VALUE_TYPE *r, mp_rnd_t rndmode)
  31 {
  32   /* We use a string as an intermediate type.  */
  33   char buf[128];
  34   int ret;
  35
  36   /* Take care of Infinity and NaN.  */
  37   if (r->cl == rvc_inf)
  38     {
  39       mpfr_set_inf (m, r->sign == 1 ? -1 : 1);
  40       return;
  41     }
  42
  43   if (r->cl == rvc_nan)
  44     {
  45       mpfr_set_nan (m);
  46       return;
  47     }
  48
  49   real_to_hexadecimal (buf, r, sizeof (buf), 0, 1);
  50   /* mpfr_set_str() parses hexadecimal floats from strings in the same
  51      format that GCC will output them.  Nothing extra is needed.  */
  52   ret = mpfr_set_str (m, buf, 16, rndmode);
  53   gcc_assert (ret == 0);
  54 }
  55
  56 /* Convert from MPFR to REAL_VALUE_TYPE, for a given type TYPE and rounding
  57    mode RNDMODE.  TYPE is only relevant if M is a NaN.  */
  58
  59 void
  60 real_from_mpfr (REAL_VALUE_TYPE *r, mpfr_srcptr m, tree type, mp_rnd_t rndmode)
  61 {
  62   /* We use a string as an intermediate type.  */
  63   char buf[128], *rstr;
  64   mp_exp_t exp;
  65
  66   /* Take care of Infinity and NaN.  */
  67   if (mpfr_inf_p (m))
  68     {
  69       real_inf (r);
  70       if (mpfr_sgn (m) < 0)
  71         *r = real_value_negate (r);
  72       return;
  73     }
  74
  75   if (mpfr_nan_p (m))
  76     {
  77       real_nan (r, "", 1, TYPE_MODE (type));
  78       return;
  79     }
  80
  81   rstr = mpfr_get_str (NULL, &exp, 16, 0, m, rndmode);
  82
  83   /* The additional 12 chars add space for the sprintf below.  This
  84      leaves 6 digits for the exponent which is supposedly enough.  */
  85   gcc_assert (rstr != NULL && strlen (rstr) < sizeof (buf) - 12);
  86
  87   /* REAL_VALUE_ATOF expects the exponent for mantissa * 2**exp,
  88      mpfr_get_str returns the exponent for mantissa * 16**exp, adjust
  89      for that.  */
  90   exp *= 4;
  91
  92   if (rstr[0] == '-')
  93     sprintf (buf, "-0x.%sp%d", &rstr[1], (int) exp);
  94   else
  95     sprintf (buf, "0x.%sp%d", rstr, (int) exp);
  96
  97   mpfr_free_str (rstr);
  98
  99   real_from_string (r, buf);
 100 }
 101