annotate bn_mp_mod.c @ 1:22d5cf7d4b1a libtommath

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author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:23:46 +0000
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1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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2 *
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3 * LibTomMath is a library that provides multiple-precision
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4 * integer arithmetic as well as number theoretic functionality.
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5 *
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6 * The library was designed directly after the MPI library by
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7 * Michael Fromberger but has been written from scratch with
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8 * additional optimizations in place.
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9 *
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10 * The library is free for all purposes without any express
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11 * guarantee it works.
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12 *
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13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
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14 */
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15 #include <tommath.h>
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16
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17 /* c = a mod b, 0 <= c < b */
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18 int
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19 mp_mod (mp_int * a, mp_int * b, mp_int * c)
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20 {
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21 mp_int t;
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22 int res;
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23
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24 if ((res = mp_init (&t)) != MP_OKAY) {
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25 return res;
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26 }
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27
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28 if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) {
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29 mp_clear (&t);
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30 return res;
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31 }
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32
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33 if (t.sign != b->sign) {
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34 res = mp_add (b, &t, c);
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35 } else {
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36 res = MP_OKAY;
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37 mp_exch (&t, c);
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38 }
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39
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40 mp_clear (&t);
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41 return res;
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42 }