Mercurial > dropbear

annotate libtommath/bn_mp_sqrt.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
284
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diff changeset
1 #include <tommath.h>
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diff changeset
2 #ifdef BN_MP_SQRT_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 *
389
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diff changeset
15 * Tom St Denis, [email protected], http://math.libtomcrypt.com
284
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16 */
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17
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diff changeset
18 /* this function is less generic than mp_n_root, simpler and faster */
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19 int mp_sqrt(mp_int *arg, mp_int *ret)
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20 {
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21 int res;
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22 mp_int t1,t2;
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23
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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24 /* must be positive */
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25 if (arg->sign == MP_NEG) {
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26 return MP_VAL;
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27 }
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28
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29 /* easy out */
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30 if (mp_iszero(arg) == MP_YES) {
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31 mp_zero(ret);
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32 return MP_OKAY;
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33 }
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34
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35 if ((res = mp_init_copy(&t1, arg)) != MP_OKAY) {
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36 return res;
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37 }
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38
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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39 if ((res = mp_init(&t2)) != MP_OKAY) {
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Matt Johnston <matt@ucc.asn.au>
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40 goto E2;
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41 }
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42
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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43 /* First approx. (not very bad for large arg) */
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diff changeset
44 mp_rshd (&t1,t1.used/2);
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45
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46 /* t1 > 0 */
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47 if ((res = mp_div(arg,&t1,&t2,NULL)) != MP_OKAY) {
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48 goto E1;
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49 }
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50 if ((res = mp_add(&t1,&t2,&t1)) != MP_OKAY) {
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51 goto E1;
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52 }
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53 if ((res = mp_div_2(&t1,&t1)) != MP_OKAY) {
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54 goto E1;
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55 }
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56 /* And now t1 > sqrt(arg) */
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57 do {
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diff changeset
58 if ((res = mp_div(arg,&t1,&t2,NULL)) != MP_OKAY) {
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59 goto E1;
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60 }
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parents:
diff changeset
61 if ((res = mp_add(&t1,&t2,&t1)) != MP_OKAY) {
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diff changeset
62 goto E1;
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parents:
diff changeset
63 }
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parents:
diff changeset
64 if ((res = mp_div_2(&t1,&t1)) != MP_OKAY) {
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parents:
diff changeset
65 goto E1;
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parents:
diff changeset
66 }
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parents:
diff changeset
67 /* t1 >= sqrt(arg) >= t2 at this point */
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68 } while (mp_cmp_mag(&t1,&t2) == MP_GT);
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parents:
diff changeset
69
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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parents:
diff changeset
70 mp_exch(&t1,ret);
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Matt Johnston <matt@ucc.asn.au>
parents:
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71
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
72 E1: mp_clear(&t2);
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
73 E2: mp_clear(&t1);
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
74 return res;
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
75 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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parents:
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76
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
77 #endif
389
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parents: 284
diff changeset
78
5ff8218bcee9 propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e)
Matt Johnston <matt@ucc.asn.au>
parents: 284
diff changeset
79 /* $Source: /cvs/libtom/libtommath/bn_mp_sqrt.c,v $ */
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Matt Johnston <matt@ucc.asn.au>
parents: 284
diff changeset
80 /* $Revision: 1.3 $ */
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parents: 284
diff changeset
81 /* $Date: 2006/03/31 14:18:44 $ */