annotate bn_mp_toradix.c @ 19:e1037a1e12e7 libtommath-orig

0.30 release of LibTomMath
author Matt Johnston <matt@ucc.asn.au>
date Tue, 15 Jun 2004 14:42:57 +0000
parents 86e0b50a9b58
children d29b64170cf0
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1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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2 *
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3 * LibTomMath is a library that provides multiple-precision
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4 * integer arithmetic as well as number theoretic functionality.
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5 *
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6 * The library was designed directly after the MPI library by
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7 * Michael Fromberger but has been written from scratch with
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8 * additional optimizations in place.
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9 *
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10 * The library is free for all purposes without any express
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11 * guarantee it works.
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12 *
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13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
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14 */
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15 #include <tommath.h>
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16
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17 /* stores a bignum as a ASCII string in a given radix (2..64) */
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18 int mp_toradix (mp_int * a, char *str, int radix)
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19 {
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20 int res, digs;
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21 mp_int t;
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22 mp_digit d;
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23 char *_s = str;
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24
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25 /* check range of the radix */
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26 if (radix < 2 || radix > 64) {
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27 return MP_VAL;
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28 }
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29
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30 /* quick out if its zero */
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31 if (mp_iszero(a) == 1) {
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32 *str++ = '0';
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33 *str = '\0';
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34 return MP_OKAY;
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35 }
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36
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37 if ((res = mp_init_copy (&t, a)) != MP_OKAY) {
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38 return res;
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39 }
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40
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41 /* if it is negative output a - */
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42 if (t.sign == MP_NEG) {
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43 ++_s;
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44 *str++ = '-';
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45 t.sign = MP_ZPOS;
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46 }
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47
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48 digs = 0;
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49 while (mp_iszero (&t) == 0) {
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50 if ((res = mp_div_d (&t, (mp_digit) radix, &t, &d)) != MP_OKAY) {
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51 mp_clear (&t);
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52 return res;
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53 }
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54 *str++ = mp_s_rmap[d];
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55 ++digs;
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56 }
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57
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58 /* reverse the digits of the string. In this case _s points
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59 * to the first digit [exluding the sign] of the number]
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60 */
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61 bn_reverse ((unsigned char *)_s, digs);
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62
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63 /* append a NULL so the string is properly terminated */
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64 *str = '\0';
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65
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66 mp_clear (&t);
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67 return MP_OKAY;
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68 }
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