Mercurial > dropbear
comparison bn_mp_toradix_n.c @ 282:91fbc376f010 libtommath-orig libtommath-0.35
Import of libtommath 0.35
From ltm-0.35.tar.bz2 SHA1 of 3f193dbae9351e92d02530994fa18236f7fde01c
author | Matt Johnston <matt@ucc.asn.au> |
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date | Wed, 08 Mar 2006 13:16:18 +0000 |
parents | |
children | 97db060d0ef5 |
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-1:000000000000 | 282:91fbc376f010 |
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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 |