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142
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1 #include <tommath.h> |
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2 #ifdef BN_MP_GET_INT_C |
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2
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis |
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4 * |
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5 * LibTomMath is a library that provides multiple-precision |
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6 * integer arithmetic as well as number theoretic functionality. |
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7 * |
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8 * The library was designed directly after the MPI library by |
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9 * Michael Fromberger but has been written from scratch with |
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10 * additional optimizations in place. |
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11 * |
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12 * The library is free for all purposes without any express |
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13 * guarantee it works. |
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14 * |
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15 * Tom St Denis, [email protected], http://math.libtomcrypt.org |
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16 */ |
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17 |
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18 /* get the lower 32-bits of an mp_int */ |
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19 unsigned long mp_get_int(mp_int * a) |
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20 { |
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21 int i; |
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22 unsigned long res; |
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23 |
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24 if (a->used == 0) { |
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25 return 0; |
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26 } |
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27 |
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28 /* get number of digits of the lsb we have to read */ |
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29 i = MIN(a->used,(int)((sizeof(unsigned long)*CHAR_BIT+DIGIT_BIT-1)/DIGIT_BIT))-1; |
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30 |
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31 /* get most significant digit of result */ |
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32 res = DIGIT(a,i); |
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33 |
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34 while (--i >= 0) { |
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35 res = (res << DIGIT_BIT) | DIGIT(a,i); |
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36 } |
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37 |
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38 /* force result to 32-bits always so it is consistent on non 32-bit platforms */ |
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39 return res & 0xFFFFFFFFUL; |
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40 } |
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142
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41 #endif |
