1 /* $NetBSD: bn_mp_toradix_n.c,v 1.1.1.2 2014/04/24 12:45:31 pettai Exp $ */
2
3 #include <tommath.h>
4 #ifdef BN_MP_TORADIX_N_C
5 /* LibTomMath, multiple-precision integer library -- Tom St Denis
6 *
7 * LibTomMath is a library that provides multiple-precision
8 * integer arithmetic as well as number theoretic functionality.
9 *
10 * The library was designed directly after the MPI library by
11 * Michael Fromberger but has been written from scratch with
12 * additional optimizations in place.
13 *
14 * The library is free for all purposes without any express
15 * guarantee it works.
16 *
17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
18 */
19
20 /* stores a bignum as a ASCII string in a given radix (2..64)
21 *
22 * Stores upto maxlen-1 chars and always a NULL byte
23 */
mp_toradix_n(mp_int * a,char * str,int radix,int maxlen)24 int mp_toradix_n(mp_int * a, char *str, int radix, int maxlen)
25 {
26 int res, digs;
27 mp_int t;
28 mp_digit d;
29 char *_s = str;
30
31 /* check range of the maxlen, radix */
32 if (maxlen < 2 || radix < 2 || radix > 64) {
33 return MP_VAL;
34 }
35
36 /* quick out if its zero */
37 if (mp_iszero(a) == MP_YES) {
38 *str++ = '0';
39 *str = '\0';
40 return MP_OKAY;
41 }
42
43 if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
44 return res;
45 }
46
47 /* if it is negative output a - */
48 if (t.sign == MP_NEG) {
49 /* we have to reverse our digits later... but not the - sign!! */
50 ++_s;
51
52 /* store the flag and mark the number as positive */
53 *str++ = '-';
54 t.sign = MP_ZPOS;
55
56 /* subtract a char */
57 --maxlen;
58 }
59
60 digs = 0;
61 while (mp_iszero (&t) == 0) {
62 if (--maxlen < 1) {
63 /* no more room */
64 break;
65 }
66 if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
67 mp_clear (&t);
68 return res;
69 }
70 *str++ = mp_s_rmap[d];
71 ++digs;
72 }
73
74 /* reverse the digits of the string. In this case _s points
75 * to the first digit [exluding the sign] of the number
76 */
77 bn_reverse ((unsigned char *)_s, digs);
78
79 /* append a NULL so the string is properly terminated */
80 *str = '\0';
81
82 mp_clear (&t);
83 return MP_OKAY;
84 }
85
86 #endif
87
88 /* Source: /cvs/libtom/libtommath/bn_mp_toradix_n.c,v */
89 /* Revision: 1.5 */
90 /* Date: 2006/12/28 01:25:13 */
91