annotate bn_mp_copy.c @ 1:22d5cf7d4b1a libtommath

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author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:23:46 +0000
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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 /* copy, b = a */
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18 int
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19 mp_copy (mp_int * a, mp_int * b)
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20 {
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21 int res, n;
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22
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23 /* if dst == src do nothing */
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24 if (a == b) {
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25 return MP_OKAY;
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26 }
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27
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28 /* grow dest */
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29 if (b->alloc < a->used) {
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30 if ((res = mp_grow (b, a->used)) != MP_OKAY) {
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31 return res;
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32 }
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33 }
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34
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35 /* zero b and copy the parameters over */
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36 {
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37 register mp_digit *tmpa, *tmpb;
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38
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39 /* pointer aliases */
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40
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41 /* source */
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42 tmpa = a->dp;
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43
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44 /* destination */
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45 tmpb = b->dp;
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46
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47 /* copy all the digits */
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48 for (n = 0; n < a->used; n++) {
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49 *tmpb++ = *tmpa++;
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50 }
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51
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52 /* clear high digits */
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53 for (; n < b->used; n++) {
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54 *tmpb++ = 0;
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55 }
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56 }
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57
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58 /* copy used count and sign */
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59 b->used = a->used;
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60 b->sign = a->sign;
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61 return MP_OKAY;
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62 }