Line data Source code
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://libtom.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 0 : 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 0 : char *_s = str;
28 :
29 : /* check range of the maxlen, radix */
30 0 : if (maxlen < 2 || radix < 2 || radix > 64) {
31 0 : return MP_VAL;
32 : }
33 :
34 : /* quick out if its zero */
35 0 : if (mp_iszero(a) == MP_YES) {
36 0 : *str++ = '0';
37 0 : *str = '\0';
38 0 : return MP_OKAY;
39 : }
40 :
41 0 : if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
42 0 : return res;
43 : }
44 :
45 : /* if it is negative output a - */
46 0 : if (t.sign == MP_NEG) {
47 : /* we have to reverse our digits later... but not the - sign!! */
48 0 : ++_s;
49 :
50 : /* store the flag and mark the number as positive */
51 0 : *str++ = '-';
52 0 : t.sign = MP_ZPOS;
53 :
54 : /* subtract a char */
55 0 : --maxlen;
56 : }
57 :
58 0 : digs = 0;
59 0 : while (mp_iszero (&t) == 0) {
60 0 : if (--maxlen < 1) {
61 : /* no more room */
62 0 : break;
63 : }
64 0 : if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
65 0 : mp_clear (&t);
66 0 : return res;
67 : }
68 0 : *str++ = mp_s_rmap[d];
69 0 : ++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 0 : bn_reverse ((unsigned char *)_s, digs);
76 :
77 : /* append a NULL so the string is properly terminated */
78 0 : *str = '\0';
79 :
80 0 : mp_clear (&t);
81 0 : return MP_OKAY;
82 : }
83 :
84 : #endif
85 :
86 : /* $Source: /cvs/libtom/libtommath/bn_mp_toradix_n.c,v $ */
87 : /* $Revision: 1.5 $ */
88 : /* $Date: 2006/12/28 01:25:13 $ */
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