1#include <tommath.h>
2#ifdef BN_MP_TORADIX_N_C
3/* LibTomMath, multiple-precision integer library -- Tom St Denis
4 *
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
7 *
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
11 *
12 * The library is free for all purposes without any express
13 * guarantee it works.
14 *
15 * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
16 */
17
18/* stores a bignum as a ASCII string in a given radix (2..64)
19 *
20 * Stores upto maxlen-1 chars and always a NULL byte
21 */
22int mp_toradix_n(mp_int * a, char *str, int radix, int maxlen)
23{
24  int     res, digs;
25  mp_int  t;
26  mp_digit d;
27  char   *_s = str;
28
29  /* check range of the maxlen, radix */
30  if (maxlen < 2 || radix < 2 || radix > 64) {
31    return MP_VAL;
32  }
33
34  /* quick out if its zero */
35  if (mp_iszero(a) == MP_YES) {
36     *str++ = '0';
37     *str = '\0';
38     return MP_OKAY;
39  }
40
41  if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
42    return res;
43  }
44
45  /* if it is negative output a - */
46  if (t.sign == MP_NEG) {
47    /* we have to reverse our digits later... but not the - sign!! */
48    ++_s;
49
50    /* store the flag and mark the number as positive */
51    *str++ = '-';
52    t.sign = MP_ZPOS;
53
54    /* subtract a char */
55    --maxlen;
56  }
57
58  digs = 0;
59  while (mp_iszero (&t) == 0) {
60    if (--maxlen < 1) {
61       /* no more room */
62       break;
63    }
64    if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
65      mp_clear (&t);
66      return res;
67    }
68    *str++ = mp_s_rmap[d];
69    ++digs;
70  }
71
72  /* reverse the digits of the string.  In this case _s points
73   * to the first digit [exluding the sign] of the number
74   */
75  bn_reverse ((unsigned char *)_s, digs);
76
77  /* append a NULL so the string is properly terminated */
78  *str = '\0';
79
80  mp_clear (&t);
81  return MP_OKAY;
82}
83
84#endif
85
86/* $Source: /cvs/libtom/libtommath/bn_mp_toradix_n.c,v $ */
87/* $Revision: 1.4 $ */
88/* $Date: 2006/03/31 14:18:44 $ */
89