/src/dropbear/libtommath/bn_mp_to_radix.c
Line | Count | Source (jump to first uncovered line) |
1 | | #include "tommath_private.h" |
2 | | #ifdef BN_MP_TO_RADIX_C |
3 | | /* LibTomMath, multiple-precision integer library -- Tom St Denis */ |
4 | | /* SPDX-License-Identifier: Unlicense */ |
5 | | |
6 | | /* stores a bignum as a ASCII string in a given radix (2..64) |
7 | | * |
8 | | * Stores upto "size - 1" chars and always a NULL byte, puts the number of characters |
9 | | * written, including the '\0', in "written". |
10 | | */ |
11 | | mp_err mp_to_radix(const mp_int *a, char *str, size_t maxlen, size_t *written, int radix) |
12 | 0 | { |
13 | 0 | size_t digs; |
14 | 0 | mp_err err; |
15 | 0 | mp_int t; |
16 | 0 | mp_digit d; |
17 | 0 | char *_s = str; |
18 | | |
19 | | /* check range of radix and size*/ |
20 | 0 | if (maxlen < 2u) { |
21 | 0 | return MP_BUF; |
22 | 0 | } |
23 | 0 | if ((radix < 2) || (radix > 64)) { |
24 | 0 | return MP_VAL; |
25 | 0 | } |
26 | | |
27 | | /* quick out if its zero */ |
28 | 0 | if (MP_IS_ZERO(a)) { |
29 | 0 | *str++ = '0'; |
30 | 0 | *str = '\0'; |
31 | 0 | if (written != NULL) { |
32 | 0 | *written = 2u; |
33 | 0 | } |
34 | 0 | return MP_OKAY; |
35 | 0 | } |
36 | | |
37 | 0 | if ((err = mp_init_copy(&t, a)) != MP_OKAY) { |
38 | 0 | return err; |
39 | 0 | } |
40 | | |
41 | | /* if it is negative output a - */ |
42 | 0 | if (t.sign == MP_NEG) { |
43 | | /* we have to reverse our digits later... but not the - sign!! */ |
44 | 0 | ++_s; |
45 | | |
46 | | /* store the flag and mark the number as positive */ |
47 | 0 | *str++ = '-'; |
48 | 0 | t.sign = MP_ZPOS; |
49 | | |
50 | | /* subtract a char */ |
51 | 0 | --maxlen; |
52 | 0 | } |
53 | 0 | digs = 0u; |
54 | 0 | while (!MP_IS_ZERO(&t)) { |
55 | 0 | if (--maxlen < 1u) { |
56 | | /* no more room */ |
57 | 0 | err = MP_BUF; |
58 | 0 | goto LBL_ERR; |
59 | 0 | } |
60 | 0 | if ((err = mp_div_d(&t, (mp_digit)radix, &t, &d)) != MP_OKAY) { |
61 | 0 | goto LBL_ERR; |
62 | 0 | } |
63 | 0 | *str++ = mp_s_rmap[d]; |
64 | 0 | ++digs; |
65 | 0 | } |
66 | | /* reverse the digits of the string. In this case _s points |
67 | | * to the first digit [exluding the sign] of the number |
68 | | */ |
69 | 0 | s_mp_reverse((unsigned char *)_s, digs); |
70 | | |
71 | | /* append a NULL so the string is properly terminated */ |
72 | 0 | *str = '\0'; |
73 | 0 | digs++; |
74 | |
|
75 | 0 | if (written != NULL) { |
76 | 0 | *written = (a->sign == MP_NEG) ? (digs + 1u): digs; |
77 | 0 | } |
78 | |
|
79 | 0 | LBL_ERR: |
80 | 0 | mp_clear(&t); |
81 | 0 | return err; |
82 | 0 | } |
83 | | |
84 | | #endif |