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annotate bn_mp_clamp.c @ 283:bd240aa12ba7 libtommath-dropbear

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* Changes imported from Dropbear 0.47. * bn_mp_clear.c is changed so that some vars are volatile, so that the compiler won't optimise away
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:22:52 +0000
parents 91fbc376f010
children 97db060d0ef5
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1 #include <tommath.h>
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2 #ifdef BN_MP_CLAMP_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 /* trim unused digits
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19 *
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20 * This is used to ensure that leading zero digits are
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21 * trimed and the leading "used" digit will be non-zero
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22 * Typically very fast. Also fixes the sign if there
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23 * are no more leading digits
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24 */
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25 void
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26 mp_clamp (mp_int * a)
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27 {
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28 /* decrease used while the most significant digit is
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29 * zero.
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30 */
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31 while (a->used > 0 && a->dp[a->used - 1] == 0) {
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32 --(a->used);
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33 }
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34
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35 /* reset the sign flag if used == 0 */
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36 if (a->used == 0) {
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37 a->sign = MP_ZPOS;
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38 }
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39 }
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40 #endif