annotate bn_mp_mul_d.c @ 142:d29b64170cf0 libtommath-orig

import of libtommath 0.32
author Matt Johnston <matt@ucc.asn.au>
date Sun, 19 Dec 2004 11:33:56 +0000
parents 86e0b50a9b58
children d8254fc979e9
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
142
d29b64170cf0 import of libtommath 0.32
Matt Johnston <matt@ucc.asn.au>
parents: 2
diff changeset
1 #include <tommath.h>
d29b64170cf0 import of libtommath 0.32
Matt Johnston <matt@ucc.asn.au>
parents: 2
diff changeset
2 #ifdef BN_MP_MUL_D_C
2
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
4 *
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
5 * LibTomMath is a library that provides multiple-precision
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
6 * integer arithmetic as well as number theoretic functionality.
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
7 *
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
8 * The library was designed directly after the MPI library by
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
9 * Michael Fromberger but has been written from scratch with
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
10 * additional optimizations in place.
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
11 *
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
12 * The library is free for all purposes without any express
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
13 * guarantee it works.
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
14 *
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
16 */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
17
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
18 /* multiply by a digit */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
19 int
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
20 mp_mul_d (mp_int * a, mp_digit b, mp_int * c)
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
21 {
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
22 mp_digit u, *tmpa, *tmpc;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
23 mp_word r;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
24 int ix, res, olduse;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
25
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
26 /* make sure c is big enough to hold a*b */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
27 if (c->alloc < a->used + 1) {
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
28 if ((res = mp_grow (c, a->used + 1)) != MP_OKAY) {
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
29 return res;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
30 }
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
31 }
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
32
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
33 /* get the original destinations used count */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
34 olduse = c->used;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
35
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
36 /* set the sign */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
37 c->sign = a->sign;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
38
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
39 /* alias for a->dp [source] */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
40 tmpa = a->dp;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
41
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
42 /* alias for c->dp [dest] */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
43 tmpc = c->dp;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
44
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
45 /* zero carry */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
46 u = 0;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
47
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
48 /* compute columns */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
49 for (ix = 0; ix < a->used; ix++) {
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
50 /* compute product and carry sum for this term */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
51 r = ((mp_word) u) + ((mp_word)*tmpa++) * ((mp_word)b);
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
52
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
53 /* mask off higher bits to get a single digit */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
54 *tmpc++ = (mp_digit) (r & ((mp_word) MP_MASK));
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
55
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
56 /* send carry into next iteration */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
57 u = (mp_digit) (r >> ((mp_word) DIGIT_BIT));
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
58 }
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
59
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
60 /* store final carry [if any] */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
61 *tmpc++ = u;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
62
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
63 /* now zero digits above the top */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
64 while (ix++ < olduse) {
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
65 *tmpc++ = 0;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
66 }
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
67
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
68 /* set used count */
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
69 c->used = a->used + 1;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
70 mp_clamp(c);
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
71
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
72 return MP_OKAY;
86e0b50a9b58 ltm 0.30 orig import
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
73 }
142
d29b64170cf0 import of libtommath 0.32
Matt Johnston <matt@ucc.asn.au>
parents: 2
diff changeset
74 #endif