contrib/gmp/mpz/get_str.c

   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, 2001, 2002, 2005 Free Software
   8 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 the GNU Lesser General Public License as published by
  14 the Free Software Foundation; either version 3 of the License, or (at your
  15 option) any later version.
  16
  17 The GNU MP Library is distributed in the hope that it will be useful, but
  18 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  20 License for more details.
  21
  22 You should have received a copy of the GNU Lesser General Public License
  23 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  24
  25 #include <string.h> /* for strlen */
  26 #include "gmp.h"
  27 #include "gmp-impl.h"
  28 #include "longlong.h"
  29
  30 char *
  31 mpz_get_str (char *res_str, int base, mpz_srcptr x)
  32 {
  33   mp_ptr xp;
  34   mp_size_t x_size = x->_mp_size;
  35   char *str;
  36   char *return_str;
  37   size_t str_size;
  38   size_t alloc_size = 0;
  39   char *num_to_text;
  40   int i;
  41   TMP_DECL;
  42
  43   if (base >= 0)
  44     {
  45       num_to_text = "0123456789abcdefghijklmnopqrstuvwxyz";
  46       if (base == 0)
  47         base = 10;
  48       else if (base > 36)
  49         {
  50           num_to_text = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  51           if (base > 62)
  52             return NULL;
  53         }
  54     }
  55   else
  56     {
  57       base = -base;
  58       num_to_text = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  59     }
  60
  61   /* allocate string for the user if necessary */
  62   if (res_str == NULL)
  63     {
  64       /* digits, null terminator, possible minus sign */
  65       MPN_SIZEINBASE (alloc_size, PTR(x), ABS(x_size), base);
  66       alloc_size += 1 + (x_size<0);
  67       res_str = (char *) (*__gmp_allocate_func) (alloc_size);
  68     }
  69   return_str = res_str;
  70
  71   if (x_size < 0)
  72     {
  73       *res_str++ = '-';
  74       x_size = -x_size;
  75     }
  76
  77   /* mpn_get_str clobbers its input on non power-of-2 bases */
  78   TMP_MARK;
  79   xp = x->_mp_d;
  80   if (! POW2_P (base))
  81     {
  82       xp = TMP_ALLOC_LIMBS (x_size + 1);  /* +1 in case x_size==0 */
  83       MPN_COPY (xp, x->_mp_d, x_size);
  84     }
  85
  86   str_size = mpn_get_str ((unsigned char *) res_str, base, xp, x_size);
  87   ASSERT (alloc_size == 0 || str_size <= alloc_size - (SIZ(x) < 0));
  88
  89   /* might have a leading zero, skip it */
  90   str = res_str;
  91   if (*res_str == 0 && str_size != 1)
  92     {
  93       str_size--;
  94       str++;
  95       ASSERT (*str != 0);  /* at most one leading zero */
  96     }
  97
  98   /* Convert result to printable chars, and move down if there was a leading
  99      zero.  */
 100   for (i = 0; i < str_size; i++)
 101     res_str[i] = num_to_text[(int) 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 }