xtom.c
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上传日期:2022-08-06
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- /* xtom -- convert a hexadecimal string to a MINT, and return a pointer to
- the MINT.
- Copyright 1991, 1994, 1995, 1996, 2000, 2001, 2002, 2005 Free Software
- Foundation, Inc.
- This file is part of the GNU MP Library.
- The GNU MP Library is free software; you can redistribute it and/or modify
- it under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 3 of the License, or (at your
- option) any later version.
- The GNU MP Library is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
- #include <string.h>
- #include <ctype.h>
- #include "mp.h"
- #include "gmp.h"
- #include "gmp-impl.h"
- extern const unsigned char __gmp_digit_value_tab[];
- #define digit_value __gmp_digit_value_tab
- MINT *
- xtom (const char *str)
- {
- size_t str_size;
- char *s, *begs;
- size_t i;
- mp_size_t xsize;
- int c;
- int negative;
- MINT *x = (MINT *) (*__gmp_allocate_func) (sizeof (MINT));
- TMP_DECL;
- /* Skip whitespace. */
- do
- c = (unsigned char) *str++;
- while (isspace (c));
- negative = 0;
- if (c == '-')
- {
- negative = 1;
- c = (unsigned char) *str++;
- }
- if (digit_value[c] >= 16)
- return 0; /* error if no digits */
- TMP_MARK;
- str_size = strlen (str - 1);
- s = begs = (char *) TMP_ALLOC (str_size + 1);
- for (i = 0; i < str_size; i++)
- {
- if (!isspace (c))
- {
- int dig = digit_value[c];
- if (dig >= 16)
- {
- TMP_FREE;
- return 0;
- }
- *s++ = dig;
- }
- c = (unsigned char) *str++;
- }
- str_size = s - begs;
- xsize = str_size / mp_bases[16].chars_per_limb + 1;
- x->_mp_alloc = xsize;
- x->_mp_d = (mp_ptr) (*__gmp_allocate_func) (xsize * BYTES_PER_MP_LIMB);
- xsize = mpn_set_str (x->_mp_d, (unsigned char *) begs, str_size, 16);
- x->_mp_size = negative ? -xsize : xsize;
- TMP_FREE;
- return x;
- }