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comparison bn_mp_toradix_n.c @ 2:86e0b50a9b58 libtommath-orig ltm-0.30-orig

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ltm 0.30 orig import
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:25:22 +0000
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children d29b64170cf0
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-1:000000000000 2:86e0b50a9b58
1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
2 *
3 * LibTomMath is a library that provides multiple-precision
4 * integer arithmetic as well as number theoretic functionality.
5 *
6 * The library was designed directly after the MPI library by
7 * Michael Fromberger but has been written from scratch with
8 * additional optimizations in place.
9 *
10 * The library is free for all purposes without any express
11 * guarantee it works.
12 *
13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
14 */
15 #include <tommath.h>
16
17 /* stores a bignum as a ASCII string in a given radix (2..64)
18 *
19 * Stores upto maxlen-1 chars and always a NULL byte
20 */
21 int mp_toradix_n(mp_int * a, char *str, int radix, int maxlen)
22 {
23 int res, digs;
24 mp_int t;
25 mp_digit d;
26 char *_s = str;
27
28 /* check range of the maxlen, radix */
29 if (maxlen < 3 || radix < 2 || radix > 64) {
30 return MP_VAL;
31 }
32
33 /* quick out if its zero */
34 if (mp_iszero(a) == 1) {
35 *str++ = '0';
36 *str = '\0';
37 return MP_OKAY;
38 }
39
40 if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
41 return res;
42 }
43
44 /* if it is negative output a - */
45 if (t.sign == MP_NEG) {
46 /* we have to reverse our digits later... but not the - sign!! */
47 ++_s;
48
49 /* store the flag and mark the number as positive */
50 *str++ = '-';
51 t.sign = MP_ZPOS;
52
53 /* subtract a char */
54 --maxlen;
55 }
56
57 digs = 0;
58 while (mp_iszero (&t) == 0) {
59 if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
60 mp_clear (&t);
61 return res;
62 }
63 *str++ = mp_s_rmap[d];
64 ++digs;
65
66 if (--maxlen == 1) {
67 /* no more room */
68 break;
69 }
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