460b9539 |
1 | /* |
2 | * This file is part of DisOrder. |
3 | * Copyright (C) 2005 Richard Kettlewell |
4 | * |
5 | * This program is free software; you can redistribute it and/or modify |
6 | * it under the terms of the GNU General Public License as published by |
7 | * the Free Software Foundation; either version 2 of the License, or |
8 | * (at your option) any later version. |
9 | * |
10 | * This program is distributed in the hope that it will be useful, but |
11 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | * General Public License for more details. |
14 | * |
15 | * You should have received a copy of the GNU General Public License |
16 | * along with this program; if not, write to the Free Software |
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 |
18 | * USA |
19 | */ |
20 | |
21 | #include <config.h> |
22 | #include "types.h" |
23 | |
24 | #include <string.h> |
25 | |
26 | #include "basen.h" |
27 | |
28 | /* test whether v is 0 */ |
29 | static int zero(const unsigned long *v, int nwords) { |
30 | int n; |
31 | |
32 | for(n = 0; n < nwords && !v[n]; ++n) |
33 | ; |
34 | return n == nwords; |
35 | } |
36 | |
37 | /* divide v by m returning the remainder */ |
38 | static unsigned divide(unsigned long *v, int nwords, unsigned long m) { |
39 | unsigned long r = 0, a, b; |
40 | int n; |
41 | |
42 | /* we do the divide 16 bits at a time */ |
43 | for(n = 0; n < nwords; ++n) { |
44 | a = v[n] >> 16; |
45 | b = v[n] & 0xFFFF; |
46 | a += r << 16; |
47 | r = a % m; |
48 | a /= m; |
49 | b += r << 16; |
50 | r = b % m; |
51 | b /= m; |
52 | v[n] = (a << 16) + b; |
53 | } |
54 | return r; |
55 | } |
56 | |
57 | int basen(unsigned long *v, |
58 | int nwords, |
59 | char buffer[], |
60 | size_t bufsize, |
61 | unsigned base) { |
62 | size_t i = bufsize; |
63 | static const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; |
64 | |
65 | do { |
66 | if(i <= 1) return -1; /* overflow */ |
67 | buffer[--i] = chars[divide(v, nwords, base)]; |
68 | } while(!zero(v, nwords)); |
69 | memmove(buffer, buffer + i, bufsize - i); |
70 | buffer[bufsize - i] = 0; |
71 | return 0; |
72 | } |
73 | |
74 | /* |
75 | Local Variables: |
76 | c-basic-offset:2 |
77 | comment-column:40 |
78 | fill-column:79 |
79 | End: |
80 | */ |