annotate bn_mp_read_unsigned_bin.c @ 386:97db060d0ef5 libtommath-orig libtommath-0.40

Update to LibTomMath 0.40
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 03:11:15 +0000
parents 91fbc376f010
children
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1 #include <tommath.h>
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2 #ifdef BN_MP_READ_UNSIGNED_BIN_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 /* reads a unsigned char array, assumes the msb is stored first [big endian] */
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19 int mp_read_unsigned_bin (mp_int * a, const unsigned char *b, int c)
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20 {
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21 int res;
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22
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23 /* make sure there are at least two digits */
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24 if (a->alloc < 2) {
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25 if ((res = mp_grow(a, 2)) != MP_OKAY) {
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26 return res;
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27 }
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28 }
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29
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30 /* zero the int */
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31 mp_zero (a);
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32
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33 /* read the bytes in */
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34 while (c-- > 0) {
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35 if ((res = mp_mul_2d (a, 8, a)) != MP_OKAY) {
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36 return res;
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37 }
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38
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39 #ifndef MP_8BIT
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40 a->dp[0] |= *b++;
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41 a->used += 1;
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42 #else
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43 a->dp[0] = (*b & MP_MASK);
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44 a->dp[1] |= ((*b++ >> 7U) & 1);
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45 a->used += 2;
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46 #endif
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47 }
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48 mp_clamp (a);
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49 return MP_OKAY;
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50 }
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51 #endif
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52
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53 /* $Source: /cvs/libtom/libtommath/bn_mp_read_unsigned_bin.c,v $ */
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54 /* $Revision: 1.4 $ */
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55 /* $Date: 2006/03/31 14:18:44 $ */