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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 /* set a 32-bit const */ |
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18 int mp_set_int (mp_int * a, unsigned long b) |
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19 { |
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20 int x, res; |
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21 |
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22 mp_zero (a); |
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23 |
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24 /* set four bits at a time */ |
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25 for (x = 0; x < 8; x++) { |
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26 /* shift the number up four bits */ |
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27 if ((res = mp_mul_2d (a, 4, a)) != MP_OKAY) { |
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28 return res; |
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29 } |
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30 |
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31 /* OR in the top four bits of the source */ |
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32 a->dp[0] |= (b >> 28) & 15; |
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33 |
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34 /* shift the source up to the next four bits */ |
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35 b <<= 4; |
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36 |
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37 /* ensure that digits are not clamped off */ |
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38 a->used += 1; |
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39 } |
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40 mp_clamp (a); |
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41 return MP_OKAY; |
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42 } |
