Mercurial > dropbear

comparison libtommath/bn_mp_read_radix.c @ 284:eed26cff980b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583) to branch 'au.asn.ucc.matt.dropbear' (head fff0894a0399405a9410ea1c6d118f342cf2aa64)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:49 +0000
parents
children 5ff8218bcee9
comparison
equal deleted inserted replaced
283:bd240aa12ba7 284:eed26cff980b
1 #include <tommath.h>
2 #ifdef BN_MP_READ_RADIX_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 /* read a string [ASCII] in a given radix */
19 int mp_read_radix (mp_int * a, const char *str, int radix)
20 {
21 int y, res, neg;
22 char ch;
23
24 /* make sure the radix is ok */
25 if (radix < 2 || radix > 64) {
26 return MP_VAL;
27 }
28
29 /* if the leading digit is a
30 * minus set the sign to negative.
31 */
32 if (*str == '-') {
33 ++str;
34 neg = MP_NEG;
35 } else {
36 neg = MP_ZPOS;
37 }
38
39 /* set the integer to the default of zero */
40 mp_zero (a);
41
42 /* process each digit of the string */
43 while (*str) {
44 /* if the radix < 36 the conversion is case insensitive
45 * this allows numbers like 1AB and 1ab to represent the same value
46 * [e.g. in hex]
47 */
48 ch = (char) ((radix < 36) ? toupper (*str) : *str);
49 for (y = 0; y < 64; y++) {
50 if (ch == mp_s_rmap[y]) {
51 break;
52 }
53 }
54
55 /* if the char was found in the map
56 * and is less than the given radix add it
57 * to the number, otherwise exit the loop.
58 */
59 if (y < radix) {
60 if ((res = mp_mul_d (a, (mp_digit) radix, a)) != MP_OKAY) {
61 return res;
62 }
63 if ((res = mp_add_d (a, (mp_digit) y, a)) != MP_OKAY) {
64 return res;
65 }
66 } else {
67 break;
68 }
69 ++str;
70 }
71
72 /* set the sign only if a != 0 */
73 if (mp_iszero(a) != 1) {
74 a->sign = neg;
75 }
76 return MP_OKAY;
77 }
78 #endif