gcc/realmpfr.c

   1 /* Conversion routines from GCC internal float representation to MPFR.
   2    Copyright (C) 2010-2019 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 "tree.h"
  24 #include "realmpfr.h"
  25 #include "stor-layout.h"
  26
  27 /* Convert from REAL_VALUE_TYPE to MPFR.  The caller is responsible
  28    for initializing and clearing the MPFR parameter.  */
  29
  30 void
  31 mpfr_from_real (mpfr_ptr m, const REAL_VALUE_TYPE *r, mp_rnd_t rndmode)
  32 {
  33   /* We use a string as an intermediate type.  */
  34   char buf[128];
  35   int ret;
  36
  37   /* Take care of Infinity and NaN.  */
  38   if (r->cl == rvc_inf)
  39     {
  40       mpfr_set_inf (m, r->sign == 1 ? -1 : 1);
  41       return;
  42     }
  43
  44   if (r->cl == rvc_nan)
  45     {
  46       mpfr_set_nan (m);
  47       return;
  48     }
  49
  50   real_to_hexadecimal (buf, r, sizeof (buf), 0, 1);
  51   /* mpfr_set_str() parses hexadecimal floats from strings in the same
  52      format that GCC will output them.  Nothing extra is needed.  */
  53   ret = mpfr_set_str (m, buf, 16, rndmode);
  54   gcc_assert (ret == 0);
  55 }
  56
  57 /* Convert from MPFR to REAL_VALUE_TYPE, for a given format FORMAT and
  58    rounding mode RNDMODE.  FORMAT is only relevant if M is a NaN.  */
  59
  60 void
  61 real_from_mpfr (REAL_VALUE_TYPE *r, mpfr_srcptr m, const real_format *format,
  62                 mp_rnd_t rndmode)
  63 {
  64   /* We use a string as an intermediate type.  */
  65   char buf[128], *rstr;
  66   mp_exp_t exp;
  67
  68   /* Take care of Infinity and NaN.  */
  69   if (mpfr_inf_p (m))
  70     {
  71       real_inf (r);
  72       if (mpfr_sgn (m) < 0)
  73         *r = real_value_negate (r);
  74       return;
  75     }
  76
  77   if (mpfr_nan_p (m))
  78     {
  79       real_nan (r, "", 1, format);
  80       return;
  81     }
  82
  83   rstr = mpfr_get_str (NULL, &exp, 16, 0, m, rndmode);
  84
  85   /* The additional 12 chars add space for the sprintf below.  This
  86      leaves 6 digits for the exponent which is supposedly enough.  */
  87   gcc_assert (rstr != NULL && strlen (rstr) < sizeof (buf) - 12);
  88
  89   /* REAL_VALUE_ATOF expects the exponent for mantissa * 2**exp,
  90      mpfr_get_str returns the exponent for mantissa * 16**exp, adjust
  91      for that.  */
  92   exp *= 4;
  93
  94   if (rstr[0] == '-')
  95     sprintf (buf, "-0x.%sp%d", &rstr[1], (int) exp);
  96   else
  97     sprintf (buf, "0x.%sp%d", rstr, (int) exp);
  98
  99   mpfr_free_str (rstr);
 100
 101   real_from_string (r, buf);
 102 }
 103
 104 /* Convert from MPFR to REAL_VALUE_TYPE, for a given type TYPE and rounding
 105    mode RNDMODE.  TYPE is only relevant if M is a NaN.  */
 106
 107 void
 108 real_from_mpfr (REAL_VALUE_TYPE *r, mpfr_srcptr m, tree type, mp_rnd_t rndmode)
 109 {
 110   real_from_mpfr (r, m, type ? REAL_MODE_FORMAT (TYPE_MODE (type)) : NULL,
 111                   rndmode);
 112 }
 113