1  /* mpz_get_str (string, base, mp_src) -- Convert the multiple precision
       2     number MP_SRC to a string STRING of base BASE.  If STRING is NULL
       3     allocate space for the result.  In any case, return a pointer to the
       4     result.  If STRING is not NULL, the caller must ensure enough space is
       5     available to store the result.
       6  
       7  Copyright 1991, 1993, 1994, 1996, 2000-2002, 2005, 2012, 2017 Free
       8  Software Foundation, Inc.
       9  
      10  This file is part of the GNU MP Library.
      11  
      12  The GNU MP Library is free software; you can redistribute it and/or modify
      13  it under the terms of either:
      14  
      15    * the GNU Lesser General Public License as published by the Free
      16      Software Foundation; either version 3 of the License, or (at your
      17      option) any later version.
      18  
      19  or
      20  
      21    * the GNU General Public License as published by the Free Software
      22      Foundation; either version 2 of the License, or (at your option) any
      23      later version.
      24  
      25  or both in parallel, as here.
      26  
      27  The GNU MP Library is distributed in the hope that it will be useful, but
      28  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      29  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      30  for more details.
      31  
      32  You should have received copies of the GNU General Public License and the
      33  GNU Lesser General Public License along with the GNU MP Library.  If not,
      34  see https://www.gnu.org/licenses/.  */
      35  
      36  #include <string.h> /* for strlen */
      37  #include "gmp-impl.h"
      38  #include "longlong.h"
      39  
      40  char *
      41  mpz_get_str (char *res_str, int base, mpz_srcptr x)
      42  {
      43    mp_ptr xp;
      44    mp_size_t x_size = SIZ (x);
      45    char *return_str;
      46    size_t str_size;
      47    size_t alloc_size = 0;
      48    const char *num_to_text;
      49    int i;
      50    TMP_DECL;
      51  
      52    num_to_text = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
      53    if (base > 1)
      54      {
      55        if (base <= 36)
      56  	num_to_text = "0123456789abcdefghijklmnopqrstuvwxyz";
      57        else if (UNLIKELY (base > 62))
      58  	return NULL;
      59      }
      60    else if (base > -2)
      61      {
      62        base = 10;
      63      }
      64    else
      65      {
      66        base = -base;
      67        if (UNLIKELY (base > 36))
      68  	return NULL;
      69      }
      70  
      71    /* allocate string for the user if necessary */
      72    if (res_str == NULL)
      73      {
      74        /* digits, null terminator, possible minus sign */
      75        MPN_SIZEINBASE (alloc_size, PTR(x), ABS(x_size), base);
      76        alloc_size += 1 + (x_size<0);
      77        res_str = __GMP_ALLOCATE_FUNC_TYPE (alloc_size, char);
      78      }
      79    return_str = res_str;
      80  
      81    if (x_size < 0)
      82      {
      83        *res_str++ = '-';
      84        x_size = -x_size;
      85      }
      86  
      87    /* mpn_get_str clobbers its input on non power-of-2 bases */
      88    TMP_MARK;
      89    xp = PTR (x);
      90    if (! POW2_P (base))
      91      {
      92        xp = TMP_ALLOC_LIMBS (x_size | 1);  /* |1 in case x_size==0 */
      93        MPN_COPY (xp, PTR (x), x_size);
      94      }
      95  
      96    str_size = mpn_get_str ((unsigned char *) res_str, base, xp, x_size);
      97    ASSERT (alloc_size == 0 || str_size <= alloc_size - (SIZ(x) < 0));
      98  
      99    /* Convert result to printable chars.  */
     100    for (i = 0; i < str_size; i++)
     101      res_str[i] = num_to_text[(int) res_str[i]];
     102    res_str[str_size] = 0;
     103  
     104    TMP_FREE;
     105  
     106    /* if allocated then resize down to the actual space required */
     107    if (alloc_size != 0)
     108      {
     109        size_t  actual_size = str_size + 1 + (res_str - return_str);
     110        ASSERT (actual_size == strlen (return_str) + 1);
     111        __GMP_REALLOCATE_FUNC_MAYBE_TYPE (return_str, alloc_size, actual_size,
     112  					char);
     113      }
     114    return return_str;
     115  }