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comparison bn_mp_toradix_n.c @ 282:91fbc376f010 libtommath-orig libtommath-0.35

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Import of libtommath 0.35 From ltm-0.35.tar.bz2 SHA1 of 3f193dbae9351e92d02530994fa18236f7fde01c
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:16:18 +0000
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children 97db060d0ef5
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-1:000000000000 282:91fbc376f010
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.org
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 < 3 || radix < 2 || radix > 64) {
31 return MP_VAL;
32 }
33
34 /* quick out if its zero */
35 if (mp_iszero(a) == 1) {
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 ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
61 mp_clear (&t);
62 return res;
63 }
64 *str++ = mp_s_rmap[d];
65 ++digs;
66
67 if (--maxlen == 1) {
68 /* no more room */
69 break;
70 }
71 }
72
73 /* reverse the digits of the string. In this case _s points
74 * to the first digit [exluding the sign] of the number]
75 */
76 bn_reverse ((unsigned char *)_s, digs);
77
78 /* append a NULL so the string is properly terminated */
79 *str = '\0';
80
81 mp_clear (&t);
82 return MP_OKAY;
83 }
84
85 #endif