1/* xtom -- convert a hexadecimal string to a MINT, and return a pointer to
2   the MINT.
3
4Copyright 1991, 1994, 1995, 1996, 2000, 2001, 2002, 2005 Free Software
5Foundation, Inc.
6
7This file is part of the GNU MP Library.
8
9The GNU MP Library is free software; you can redistribute it and/or modify
10it under the terms of the GNU Lesser General Public License as published by
11the Free Software Foundation; either version 3 of the License, or (at your
12option) any later version.
13
14The GNU MP Library is distributed in the hope that it will be useful, but
15WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
17License for more details.
18
19You should have received a copy of the GNU Lesser General Public License
20along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
21
22#include <string.h>
23#include <ctype.h>
24#include "mp.h"
25#include "gmp.h"
26#include "gmp-impl.h"
27
28extern const unsigned char __gmp_digit_value_tab[];
29#define digit_value __gmp_digit_value_tab
30
31MINT *
32xtom (const char *str)
33{
34  size_t str_size;
35  char *s, *begs;
36  size_t i;
37  mp_size_t xsize;
38  int c;
39  int negative;
40  MINT *x = (MINT *) (*__gmp_allocate_func) (sizeof (MINT));
41  TMP_DECL;
42
43  /* Skip whitespace.  */
44  do
45    c = (unsigned char) *str++;
46  while (isspace (c));
47
48  negative = 0;
49  if (c == '-')
50    {
51      negative = 1;
52      c = (unsigned char) *str++;
53    }
54
55  if (digit_value[c] >= 16)
56    return 0;			/* error if no digits */
57
58  TMP_MARK;
59  str_size = strlen (str - 1);
60  s = begs = (char *) TMP_ALLOC (str_size + 1);
61
62  for (i = 0; i < str_size; i++)
63    {
64      if (!isspace (c))
65	{
66	  int dig = digit_value[c];
67	  if (dig >= 16)
68	    {
69	      TMP_FREE;
70	      return 0;
71	    }
72	  *s++ = dig;
73	}
74      c = (unsigned char) *str++;
75    }
76
77  str_size = s - begs;
78
79  xsize = str_size / mp_bases[16].chars_per_limb + 1;
80  x->_mp_alloc = xsize;
81  x->_mp_d = (mp_ptr) (*__gmp_allocate_func) (xsize * BYTES_PER_MP_LIMB);
82
83  xsize = mpn_set_str (x->_mp_d, (unsigned char *) begs, str_size, 16);
84  x->_mp_size = negative ? -xsize : xsize;
85
86  TMP_FREE;
87  return x;
88}
89