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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 /* c = a mod b, 0 <= c < b */ |
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18 int |
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19 mp_mod (mp_int * a, mp_int * b, mp_int * c) |
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20 { |
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21 mp_int t; |
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22 int res; |
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23 |
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24 if ((res = mp_init (&t)) != MP_OKAY) { |
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25 return res; |
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26 } |
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27 |
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28 if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) { |
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29 mp_clear (&t); |
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30 return res; |
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31 } |
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32 |
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33 if (t.sign != b->sign) { |
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34 res = mp_add (b, &t, c); |
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35 } else { |
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36 res = MP_OKAY; |
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37 mp_exch (&t, c); |
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38 } |
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39 |
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40 mp_clear (&t); |
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41 return res; |
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42 } |
