libquadmath/quadmath_io.c

   1 /* GCC Quad-Precision Math Library
   2    Copyright (C) 2010 Free Software Foundation, Inc.
   3    Written by Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
   4
   5 This file is part of the libiberty library.
   6 Libiberty is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public
   8 License as published by the Free Software Foundation; either
   9 version 2 of the License, or (at your option) any later version.
  10
  11 Libiberty is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with libiberty; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  19 Boston, MA 02110-1301, USA.  */
  20
  21 #include "quadmath.h"
  22 #include <stdio.h>
  23 #include <string.h>
  24
  25 #define ABS(x) ((x) >= 0 ? (x) : -(x))
  26
  27
  28
  29 static void
  30 format (char * res, const __float128 x, size_t n)
  31 {
  32   char buffer[1024];
  33   char *p;
  34
  35   memset (buffer, 0, sizeof(buffer));
  36
  37   g_Qfmt (buffer, &x, n + 1, sizeof(buffer) - 3);
  38   p = buffer + (*buffer == '-' ? 1 : 0);
  39
  40   // The sign is the easiest part
  41   res[0] = (signbitq (x) ? '-' : '+');
  42
  43   if (*p == '.')
  44   {
  45     // We have a number smaller than 1, without exponent
  46     int exp = 0;
  47     char *c;
  48
  49     for (c = p+1; *c == '0'; c++)
  50       exp++;
  51
  52     // We move the string "exp" characters left
  53     size_t l = strlen (p+1+exp);
  54     memcpy (res + 2, p + 1 + exp, l);
  55     memset (res + 2 + l, '0', n - l + 1);
  56     sprintf (res + n + 3, "e-%02d", exp + 1);
  57
  58     res[1] = res[2];
  59     res[2] = '.';
  60
  61     return;
  62   }
  63
  64   // Now, do we already have an exponent
  65   char *c;
  66   for (c = p; *c && *c != 'e'; c++)
  67     ;
  68   if (*c)
  69   {
  70     int exp = strtol (c + 1, NULL, 10);
  71
  72     size_t l = c - p;
  73
  74     memcpy (res + 1, p, l);
  75     if (l <= n + 1)
  76       memset (res + 1 + l, '0', (int) n - l + 2);
  77
  78     sprintf (res + n + 3, "e%c%02d", exp >= 0 ? '+' : '-', ABS(exp));
  79
  80     return;
  81   }
  82   else
  83   {
  84     // If we have no exponent, normalize and add the exponent
  85     for (c = p; *c && *c != '.'; c++)
  86       ;
  87
  88     res[1] = *p;
  89     res[2] = '.';
  90
  91     size_t l = c - p;
  92     memcpy (res + 3, p + 1, l);
  93     size_t l2 = strlen (c + 1);
  94     memcpy (res + 2 + l, c + 1, l2);
  95     memset (res + 2 + l + l2, '0', n - (l + l2) + 1);
  96     sprintf (res + n + 3, "e+%02d", l - 1);
  97
  98     return;
  99   }
 100 }
 101
 102
 103 void
 104 quadmath_dtoaq (char *s, size_t size, size_t n, __float128 x)
 105 {
 106   char buffer[1024];
 107   memset (buffer, 0, sizeof(buffer));
 108   format (buffer, x, n);
 109   memcpy (s, buffer, size);
 110 }