annotate libtommath/bn_mp_mul_2d.c @ 284:eed26cff980b

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
parents
children 5ff8218bcee9
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
284
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parents:
diff changeset
1 #include <tommath.h>
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diff changeset
2 #ifdef BN_MP_MUL_2D_C
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diff changeset
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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diff changeset
4 *
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
5 * LibTomMath is a library that provides multiple-precision
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
6 * integer arithmetic as well as number theoretic functionality.
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Matt Johnston <matt@ucc.asn.au>
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7 *
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
8 * The library was designed directly after the MPI library by
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diff changeset
9 * Michael Fromberger but has been written from scratch with
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
10 * additional optimizations in place.
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
11 *
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
12 * The library is free for all purposes without any express
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
13 * guarantee it works.
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
14 *
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
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16 */
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17
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
18 /* shift left by a certain bit count */
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
19 int mp_mul_2d (mp_int * a, int b, mp_int * c)
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
20 {
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
21 mp_digit d;
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
22 int res;
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23
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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24 /* copy */
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Matt Johnston <matt@ucc.asn.au>
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25 if (a != c) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
26 if ((res = mp_copy (a, c)) != MP_OKAY) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
27 return res;
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28 }
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29 }
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30
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
31 if (c->alloc < (int)(c->used + b/DIGIT_BIT + 1)) {
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
32 if ((res = mp_grow (c, c->used + b / DIGIT_BIT + 1)) != MP_OKAY) {
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
33 return res;
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34 }
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35 }
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36
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
37 /* shift by as many digits in the bit count */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
38 if (b >= (int)DIGIT_BIT) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
39 if ((res = mp_lshd (c, b / DIGIT_BIT)) != MP_OKAY) {
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
40 return res;
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Matt Johnston <matt@ucc.asn.au>
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41 }
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Matt Johnston <matt@ucc.asn.au>
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42 }
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43
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
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44 /* shift any bit count < DIGIT_BIT */
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
45 d = (mp_digit) (b % DIGIT_BIT);
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
46 if (d != 0) {
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
47 register mp_digit *tmpc, shift, mask, r, rr;
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
48 register int x;
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49
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
50 /* bitmask for carries */
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
51 mask = (((mp_digit)1) << d) - 1;
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52
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
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diff changeset
53 /* shift for msbs */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
54 shift = DIGIT_BIT - d;
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55
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
56 /* alias */
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
57 tmpc = c->dp;
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58
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
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59 /* carry */
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
60 r = 0;
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
61 for (x = 0; x < c->used; x++) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
62 /* get the higher bits of the current word */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
63 rr = (*tmpc >> shift) & mask;
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parents:
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64
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
65 /* shift the current word and OR in the carry */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
66 *tmpc = ((*tmpc << d) | r) & MP_MASK;
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
67 ++tmpc;
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
68
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
69 /* set the carry to the carry bits of the current word */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
70 r = rr;
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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>
parents:
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72
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
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73 /* set final carry */
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
74 if (r != 0) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
75 c->dp[(c->used)++] = r;
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Matt Johnston <matt@ucc.asn.au>
parents:
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76 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
77 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
78 mp_clamp (c);
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Matt Johnston <matt@ucc.asn.au>
parents:
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79 return MP_OKAY;
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
80 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
81 #endif