annotate bn_mp_copy.c @ 283:bd240aa12ba7 libtommath-dropbear

* Changes imported from Dropbear 0.47. * bn_mp_clear.c is changed so that some vars are volatile, so that the compiler won't optimise away
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:22:52 +0000
parents 91fbc376f010
children 97db060d0ef5
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1 #include <tommath.h>
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2 #ifdef BN_MP_COPY_C
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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4 *
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5 * LibTomMath is a library that provides multiple-precision
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6 * integer arithmetic as well as number theoretic functionality.
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7 *
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8 * The library was designed directly after the MPI library by
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9 * Michael Fromberger but has been written from scratch with
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10 * additional optimizations in place.
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11 *
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12 * The library is free for all purposes without any express
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13 * guarantee it works.
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14 *
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15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
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16 */
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17
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18 /* copy, b = a */
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19 int
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20 mp_copy (mp_int * a, mp_int * b)
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21 {
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22 int res, n;
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23
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24 /* if dst == src do nothing */
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25 if (a == b) {
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26 return MP_OKAY;
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27 }
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28
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29 /* grow dest */
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30 if (b->alloc < a->used) {
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31 if ((res = mp_grow (b, a->used)) != MP_OKAY) {
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32 return res;
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33 }
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34 }
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35
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36 /* zero b and copy the parameters over */
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37 {
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38 register mp_digit *tmpa, *tmpb;
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39
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40 /* pointer aliases */
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41
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42 /* source */
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43 tmpa = a->dp;
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44
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45 /* destination */
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46 tmpb = b->dp;
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47
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48 /* copy all the digits */
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49 for (n = 0; n < a->used; n++) {
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50 *tmpb++ = *tmpa++;
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51 }
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52
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53 /* clear high digits */
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54 for (; n < b->used; n++) {
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55 *tmpb++ = 0;
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56 }
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57 }
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58
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59 /* copy used count and sign */
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60 b->used = a->used;
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61 b->sign = a->sign;
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62 return MP_OKAY;
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63 }
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64 #endif