Mercurial > dropbear

comparison libtommath/bn_mp_toradix_n.c @ 399:a707e6148060

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
merge of '5fdf69ca60d1683cdd9f4c2595134bed26394834' and '6b61c50f4cf888bea302ac8fcf5dbb573b443251'
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 08:20:34 +0000
parents 5ff8218bcee9
children 60fc6476e044
comparison
equal deleted inserted replaced
394:17d097fc111c 399:a707e6148060
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, [email protected], 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 */
22 int 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 $ */