2 * This file is part of DisOrder.
3 * Copyright (C) 2005 Richard Kettlewell
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.
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.
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
28 /** @brief Test whether v is 0
29 * @param v Pointer to bigendian bignum
30 * @param nwords Length of bignum
33 static int zero(const unsigned long *v, int nwords) {
36 for(n = 0; n < nwords && !v[n]; ++n)
41 /** @brief Divide v by m returning the remainder.
42 * @param v Pointer to bigendian bignum
43 * @param nwords Length of bignum
44 * @param m Divisor (must not be 0)
47 * The quotient is stored in @p v.
49 static unsigned divide(unsigned long *v, int nwords, unsigned long m) {
50 unsigned long r = 0, a, b;
53 /* we do the divide 16 bits at a time */
54 for(n = 0; n < nwords; ++n) {
68 /** @brief Convert v to a chosen base
69 * @param v Pointer to bigendian bignum
70 * @param nwords Length of bignum
71 * @param buffer Output buffer
72 * @param bufsize Size of output buffer
73 * @param base Number base (2..62)
74 * @return 0 on success, -1 if the buffer is too small
76 * Converts @p v to a string in the given base using decimal digits, lower case
77 * letter sand upper case letters as digits.
79 int basen(unsigned long *v,
85 static const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
88 if(i <= 1) return -1; /* overflow */
89 buffer[--i] = chars[divide(v, nwords, base)];
90 } while(!zero(v, nwords));
91 memmove(buffer, buffer + i, bufsize - i);
92 buffer[bufsize - i] = 0;