Mercurial > dropbear

annotate libtommath/bn_mp_reduce_is_2k_l.c @ 691:e698d1a9f428

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Some changes since 2012.55
author Matt Johnston <matt@ucc.asn.au>
date Fri, 22 Feb 2013 23:54:47 +0800
parents 5ff8218bcee9
children 60fc6476e044
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1 #include <tommath.h>
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2 #ifdef BN_MP_REDUCE_IS_2K_L_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.com
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16 */
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17
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18 /* determines if reduce_2k_l can be used */
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19 int mp_reduce_is_2k_l(mp_int *a)
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20 {
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21 int ix, iy;
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22
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23 if (a->used == 0) {
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24 return MP_NO;
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25 } else if (a->used == 1) {
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26 return MP_YES;
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27 } else if (a->used > 1) {
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28 /* if more than half of the digits are -1 we're sold */
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29 for (iy = ix = 0; ix < a->used; ix++) {
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30 if (a->dp[ix] == MP_MASK) {
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31 ++iy;
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32 }
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33 }
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34 return (iy >= (a->used/2)) ? MP_YES : MP_NO;
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35
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36 }
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37 return MP_NO;
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38 }
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39
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40 #endif
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41
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42 /* $Source: /cvs/libtom/libtommath/bn_mp_reduce_is_2k_l.c,v $ */
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43 /* $Revision: 1.3 $ */
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44 /* $Date: 2006/03/31 14:18:44 $ */