gcc/realmpfr.c

   1 /* Conversion routines from GCC internal float representation to MPFR.
   2    Copyright (C) 2010-2015 Free Software Foundation, Inc.
   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 "input.h"
  25 #include "alias.h"
  26 #include "symtab.h"
  27 #include "options.h"
  28 #include "tree.h"       /* For TYPE_MODE in real_from_mpfr.  */
  29 #include "stor-layout.h"
  30
  31 /* Convert from REAL_VALUE_TYPE to MPFR.  The caller is responsible
  32    for initializing and clearing the MPFR parameter.  */
  33
  34 void
  35 mpfr_from_real (mpfr_ptr m, const REAL_VALUE_TYPE *r, mp_rnd_t rndmode)
  36 {
  37   /* We use a string as an intermediate type.  */
  38   char buf[128];
  39   int ret;
  40
  41   /* Take care of Infinity and NaN.  */
  42   if (r->cl == rvc_inf)
  43     {
  44       mpfr_set_inf (m, r->sign == 1 ? -1 : 1);
  45       return;
  46     }
  47
  48   if (r->cl == rvc_nan)
  49     {
  50       mpfr_set_nan (m);
  51       return;
  52     }
  53
  54   real_to_hexadecimal (buf, r, sizeof (buf), 0, 1);
  55   /* mpfr_set_str() parses hexadecimal floats from strings in the same
  56      format that GCC will output them.  Nothing extra is needed.  */
  57   ret = mpfr_set_str (m, buf, 16, rndmode);
  58   gcc_assert (ret == 0);
  59 }
  60
  61 /* Convert from MPFR to REAL_VALUE_TYPE, for a given type TYPE and rounding
  62    mode RNDMODE.  TYPE is only relevant if M is a NaN.  */
  63
  64 void
  65 real_from_mpfr (REAL_VALUE_TYPE *r, mpfr_srcptr m, tree type, mp_rnd_t rndmode)
  66 {
  67   /* We use a string as an intermediate type.  */
  68   char buf[128], *rstr;
  69   mp_exp_t exp;
  70
  71   /* Take care of Infinity and NaN.  */
  72   if (mpfr_inf_p (m))
  73     {
  74       real_inf (r);
  75       if (mpfr_sgn (m) < 0)
  76         *r = real_value_negate (r);
  77       return;
  78     }
  79
  80   if (mpfr_nan_p (m))
  81     {
  82       real_nan (r, "", 1, TYPE_MODE (type));
  83       return;
  84     }
  85
  86   rstr = mpfr_get_str (NULL, &exp, 16, 0, m, rndmode);
  87
  88   /* The additional 12 chars add space for the sprintf below.  This
  89      leaves 6 digits for the exponent which is supposedly enough.  */
  90   gcc_assert (rstr != NULL && strlen (rstr) < sizeof (buf) - 12);
  91
  92   /* REAL_VALUE_ATOF expects the exponent for mantissa * 2**exp,
  93      mpfr_get_str returns the exponent for mantissa * 16**exp, adjust
  94      for that.  */
  95   exp *= 4;
  96
  97   if (rstr[0] == '-')
  98     sprintf (buf, "-0x.%sp%d", &rstr[1], (int) exp);
  99   else
 100     sprintf (buf, "0x.%sp%d", rstr, (int) exp);
 101
 102   mpfr_free_str (rstr);
 103
 104   real_from_string (r, buf);
 105 }
 106