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annotate libtommath/bn_mp_reduce_2k.c @ 447:278805938dcf

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Patch from Nicolai Ehemann to try binding before going to the background, so that if it exits early (because something's already listening etc) then it will return an exitcode of 1.
author Matt Johnston <matt@ucc.asn.au>
date Thu, 19 Jul 2007 15:54:18 +0000
parents 5ff8218bcee9
children 60fc6476e044
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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1 #include <tommath.h>
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2 #ifdef BN_MP_REDUCE_2K_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 /* reduces a modulo n where n is of the form 2**p - d */
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19 int mp_reduce_2k(mp_int *a, mp_int *n, mp_digit d)
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20 {
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21 mp_int q;
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22 int p, res;
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23
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24 if ((res = mp_init(&q)) != MP_OKAY) {
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25 return res;
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26 }
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27
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28 p = mp_count_bits(n);
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29 top:
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30 /* q = a/2**p, a = a mod 2**p */
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31 if ((res = mp_div_2d(a, p, &q, a)) != MP_OKAY) {
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32 goto ERR;
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33 }
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34
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35 if (d != 1) {
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36 /* q = q * d */
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37 if ((res = mp_mul_d(&q, d, &q)) != MP_OKAY) {
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38 goto ERR;
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39 }
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40 }
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41
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42 /* a = a + q */
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43 if ((res = s_mp_add(a, &q, a)) != MP_OKAY) {
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44 goto ERR;
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45 }
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46
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47 if (mp_cmp_mag(a, n) != MP_LT) {
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48 s_mp_sub(a, n, a);
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49 goto top;
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50 }
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51
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52 ERR:
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53 mp_clear(&q);
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54 return res;
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55 }
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56
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57 #endif
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58
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59 /* $Source: /cvs/libtom/libtommath/bn_mp_reduce_2k.c,v $ */
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60 /* $Revision: 1.3 $ */
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61 /* $Date: 2006/03/31 14:18:44 $ */