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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 } |
