Mercurial > dropbear

annotate libtommath/bn_mp_reduce_setup.c @ 330:5488db2e9e4e

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merge of 332f709a4cb39cde4cedab7c3be89e05f3023067 and ca4ca78b82c5d430c69ce01bf794e8886ce81431
author Matt Johnston <matt@ucc.asn.au>
date Sat, 10 Jun 2006 16:39:40 +0000
parents eed26cff980b
children 5ff8218bcee9
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1 #include <tommath.h>
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2 #ifdef BN_MP_REDUCE_SETUP_C
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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 /* pre-calculate the value required for Barrett reduction
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19 * For a given modulus "b" it calulates the value required in "a"
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20 */
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21 int mp_reduce_setup (mp_int * a, mp_int * b)
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22 {
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23 int res;
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24
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25 if ((res = mp_2expt (a, b->used * 2 * DIGIT_BIT)) != MP_OKAY) {
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26 return res;
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27 }
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28 return mp_div (a, b, a, NULL);
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29 }
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30 #endif