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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 /* reads a unsigned char array, assumes the msb is stored first [big endian] */ |
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18 int |
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19 mp_read_unsigned_bin (mp_int * a, unsigned char *b, int c) |
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20 { |
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21 int res; |
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22 |
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23 /* make sure there are at least two digits */ |
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24 if (a->alloc < 2) { |
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25 if ((res = mp_grow(a, 2)) != MP_OKAY) { |
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26 return res; |
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27 } |
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28 } |
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29 |
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30 /* zero the int */ |
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31 mp_zero (a); |
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32 |
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33 /* read the bytes in */ |
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34 while (c-- > 0) { |
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35 if ((res = mp_mul_2d (a, 8, a)) != MP_OKAY) { |
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36 return res; |
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37 } |
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38 |
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39 #ifndef MP_8BIT |
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40 a->dp[0] |= *b++; |
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41 a->used += 1; |
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42 #else |
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43 a->dp[0] = (*b & MP_MASK); |
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44 a->dp[1] |= ((*b++ >> 7U) & 1); |
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45 a->used += 2; |
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46 #endif |
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47 } |
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48 mp_clamp (a); |
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49 return MP_OKAY; |
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50 } |
