Line data    Source code

       1             : #include "tommath_private.h"
       2             : #ifdef BN_MP_TO_RADIX_C
       3             : /* LibTomMath, multiple-precision integer library -- Tom St Denis */
       4             : /* SPDX-License-Identifier: Unlicense */
       5             : 
       6             : /* stores a bignum as a ASCII string in a given radix (2..64)
       7             :  *
       8             :  * Stores upto "size - 1" chars and always a NULL byte, puts the number of characters
       9             :  * written, including the '\0', in "written".
      10             :  */
      11           0 : mp_err mp_to_radix(const mp_int *a, char *str, size_t maxlen, size_t *written, int radix)
      12             : {
      13             :    size_t  digs;
      14             :    mp_err  err;
      15             :    mp_int  t;
      16             :    mp_digit d;
      17           0 :    char   *_s = str;
      18             : 
      19             :    /* check range of radix and size*/
      20           0 :    if (maxlen < 2u) {
      21           0 :       return MP_BUF;
      22             :    }
      23           0 :    if ((radix < 2) || (radix > 64)) {
      24           0 :       return MP_VAL;
      25             :    }
      26             : 
      27             :    /* quick out if its zero */
      28           0 :    if (MP_IS_ZERO(a)) {
      29           0 :       *str++ = '0';
      30           0 :       *str = '\0';
      31           0 :       if (written != NULL) {
      32           0 :          *written = 2u;
      33             :       }
      34           0 :       return MP_OKAY;
      35             :    }
      36             : 
      37           0 :    if ((err = mp_init_copy(&t, a)) != MP_OKAY) {
      38           0 :       return err;
      39             :    }
      40             : 
      41             :    /* if it is negative output a - */
      42           0 :    if (t.sign == MP_NEG) {
      43             :       /* we have to reverse our digits later... but not the - sign!! */
      44           0 :       ++_s;
      45             : 
      46             :       /* store the flag and mark the number as positive */
      47           0 :       *str++ = '-';
      48           0 :       t.sign = MP_ZPOS;
      49             : 
      50             :       /* subtract a char */
      51           0 :       --maxlen;
      52             :    }
      53           0 :    digs = 0u;
      54           0 :    while (!MP_IS_ZERO(&t)) {
      55           0 :       if (--maxlen < 1u) {
      56             :          /* no more room */
      57           0 :          err = MP_BUF;
      58           0 :          goto LBL_ERR;
      59             :       }
      60           0 :       if ((err = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) {
      61           0 :          goto LBL_ERR;
      62             :       }
      63           0 :       *str++ = mp_s_rmap[d];
      64           0 :       ++digs;
      65             :    }
      66             :    /* reverse the digits of the string.  In this case _s points
      67             :     * to the first digit [exluding the sign] of the number
      68             :     */
      69           0 :    s_mp_reverse((unsigned char *)_s, digs);
      70             : 
      71             :    /* append a NULL so the string is properly terminated */
      72           0 :    *str = '\0';
      73           0 :    digs++;
      74             : 
      75           0 :    if (written != NULL) {
      76           0 :       *written = (a->sign == MP_NEG) ? (digs + 1u): digs;
      77             :    }
      78             : 
      79           0 : LBL_ERR:
      80           0 :    mp_clear(&t);
      81           0 :    return err;
      82             : }
      83             : 
      84             : #endif