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comparison libtommath/bn_mp_reduce_is_2k_l.c @ 284:eed26cff980b

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propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583) to branch 'au.asn.ucc.matt.dropbear' (head fff0894a0399405a9410ea1c6d118f342cf2aa64)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:49 +0000
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children 5ff8218bcee9
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283:bd240aa12ba7 284:eed26cff980b
1 #include <tommath.h>
2 #ifdef BN_MP_REDUCE_IS_2K_L_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 *
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
7 *
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
11 *
12 * The library is free for all purposes without any express
13 * guarantee it works.
14 *
15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
16 */
17
18 /* determines if reduce_2k_l can be used */
19 int mp_reduce_is_2k_l(mp_int *a)
20 {
21 int ix, iy;
22
23 if (a->used == 0) {
24 return MP_NO;
25 } else if (a->used == 1) {
26 return MP_YES;
27 } else if (a->used > 1) {
28 /* if more than half of the digits are -1 we're sold */
29 for (iy = ix = 0; ix < a->used; ix++) {
30 if (a->dp[ix] == MP_MASK) {
31 ++iy;
32 }
33 }
34 return (iy >= (a->used/2)) ? MP_YES : MP_NO;
35
36 }
37 return MP_NO;
38 }
39
40 #endif