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53 lines
1.3 KiB
C
53 lines
1.3 KiB
C
#include <tommath.h>
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#ifdef BN_MP_REDUCE_IS_2K_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis
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*
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* LibTomMath is a library that provides multiple-precision
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* integer arithmetic as well as number theoretic functionality.
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*
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* The library was designed directly after the MPI library by
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* Michael Fromberger but has been written from scratch with
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* additional optimizations in place.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
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*/
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/* determines if mp_reduce_2k can be used */
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int mp_reduce_is_2k(mp_int *a)
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{
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int ix, iy, iw;
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mp_digit iz;
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if (a->used == 0) {
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return MP_NO;
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} else if (a->used == 1) {
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return MP_YES;
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} else if (a->used > 1) {
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iy = mp_count_bits(a);
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iz = 1;
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iw = 1;
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/* Test every bit from the second digit up, must be 1 */
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for (ix = DIGIT_BIT; ix < iy; ix++) {
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if ((a->dp[iw] & iz) == 0) {
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return MP_NO;
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}
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iz <<= 1;
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if (iz > (mp_digit)MP_MASK) {
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++iw;
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iz = 1;
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}
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}
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}
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return MP_YES;
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}
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#endif
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/* $Source: /cvs/libtom/libtommath/bn_mp_reduce_is_2k.c,v $ */
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/* $Revision: 1.3 $ */
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/* $Date: 2006/03/31 14:18:44 $ */
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