annotate bn_mp_grow.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 /* grow as required */
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18 int mp_grow (mp_int * a, int size)
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19 {
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20 int i;
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21 mp_digit *tmp;
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22
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23 /* if the alloc size is smaller alloc more ram */
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24 if (a->alloc < size) {
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25 /* ensure there are always at least MP_PREC digits extra on top */
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26 size += (MP_PREC * 2) - (size % MP_PREC);
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27
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28 /* reallocate the array a->dp
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29 *
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30 * We store the return in a temporary variable
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31 * in case the operation failed we don't want
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32 * to overwrite the dp member of a.
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33 */
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34 tmp = OPT_CAST(mp_digit) XREALLOC (a->dp, sizeof (mp_digit) * size);
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35 if (tmp == NULL) {
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36 /* reallocation failed but "a" is still valid [can be freed] */
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37 return MP_MEM;
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38 }
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39
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40 /* reallocation succeeded so set a->dp */
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41 a->dp = tmp;
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42
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43 /* zero excess digits */
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44 i = a->alloc;
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45 a->alloc = size;
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46 for (; i < a->alloc; i++) {
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47 a->dp[i] = 0;
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48 }
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49 }
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50 return MP_OKAY;
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51 }