1*4882a593Smuzhiyun /* mpi-mul.c - MPI functions
2*4882a593Smuzhiyun * Copyright (C) 1994, 1996, 1998, 2001, 2002,
3*4882a593Smuzhiyun * 2003 Free Software Foundation, Inc.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * This file is part of Libgcrypt.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Note: This code is heavily based on the GNU MP Library.
8*4882a593Smuzhiyun * Actually it's the same code with only minor changes in the
9*4882a593Smuzhiyun * way the data is stored; this is to support the abstraction
10*4882a593Smuzhiyun * of an optional secure memory allocation which may be used
11*4882a593Smuzhiyun * to avoid revealing of sensitive data due to paging etc.
12*4882a593Smuzhiyun */
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun #include "mpi-internal.h"
15*4882a593Smuzhiyun
mpi_mul(MPI w,MPI u,MPI v)16*4882a593Smuzhiyun void mpi_mul(MPI w, MPI u, MPI v)
17*4882a593Smuzhiyun {
18*4882a593Smuzhiyun mpi_size_t usize, vsize, wsize;
19*4882a593Smuzhiyun mpi_ptr_t up, vp, wp;
20*4882a593Smuzhiyun mpi_limb_t cy;
21*4882a593Smuzhiyun int usign, vsign, sign_product;
22*4882a593Smuzhiyun int assign_wp = 0;
23*4882a593Smuzhiyun mpi_ptr_t tmp_limb = NULL;
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun if (u->nlimbs < v->nlimbs) {
26*4882a593Smuzhiyun /* Swap U and V. */
27*4882a593Smuzhiyun usize = v->nlimbs;
28*4882a593Smuzhiyun usign = v->sign;
29*4882a593Smuzhiyun up = v->d;
30*4882a593Smuzhiyun vsize = u->nlimbs;
31*4882a593Smuzhiyun vsign = u->sign;
32*4882a593Smuzhiyun vp = u->d;
33*4882a593Smuzhiyun } else {
34*4882a593Smuzhiyun usize = u->nlimbs;
35*4882a593Smuzhiyun usign = u->sign;
36*4882a593Smuzhiyun up = u->d;
37*4882a593Smuzhiyun vsize = v->nlimbs;
38*4882a593Smuzhiyun vsign = v->sign;
39*4882a593Smuzhiyun vp = v->d;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun sign_product = usign ^ vsign;
42*4882a593Smuzhiyun wp = w->d;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun /* Ensure W has space enough to store the result. */
45*4882a593Smuzhiyun wsize = usize + vsize;
46*4882a593Smuzhiyun if (w->alloced < wsize) {
47*4882a593Smuzhiyun if (wp == up || wp == vp) {
48*4882a593Smuzhiyun wp = mpi_alloc_limb_space(wsize);
49*4882a593Smuzhiyun assign_wp = 1;
50*4882a593Smuzhiyun } else {
51*4882a593Smuzhiyun mpi_resize(w, wsize);
52*4882a593Smuzhiyun wp = w->d;
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun } else { /* Make U and V not overlap with W. */
55*4882a593Smuzhiyun if (wp == up) {
56*4882a593Smuzhiyun /* W and U are identical. Allocate temporary space for U. */
57*4882a593Smuzhiyun up = tmp_limb = mpi_alloc_limb_space(usize);
58*4882a593Smuzhiyun /* Is V identical too? Keep it identical with U. */
59*4882a593Smuzhiyun if (wp == vp)
60*4882a593Smuzhiyun vp = up;
61*4882a593Smuzhiyun /* Copy to the temporary space. */
62*4882a593Smuzhiyun MPN_COPY(up, wp, usize);
63*4882a593Smuzhiyun } else if (wp == vp) {
64*4882a593Smuzhiyun /* W and V are identical. Allocate temporary space for V. */
65*4882a593Smuzhiyun vp = tmp_limb = mpi_alloc_limb_space(vsize);
66*4882a593Smuzhiyun /* Copy to the temporary space. */
67*4882a593Smuzhiyun MPN_COPY(vp, wp, vsize);
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun if (!vsize)
72*4882a593Smuzhiyun wsize = 0;
73*4882a593Smuzhiyun else {
74*4882a593Smuzhiyun mpihelp_mul(wp, up, usize, vp, vsize, &cy);
75*4882a593Smuzhiyun wsize -= cy ? 0:1;
76*4882a593Smuzhiyun }
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun if (assign_wp)
79*4882a593Smuzhiyun mpi_assign_limb_space(w, wp, wsize);
80*4882a593Smuzhiyun w->nlimbs = wsize;
81*4882a593Smuzhiyun w->sign = sign_product;
82*4882a593Smuzhiyun if (tmp_limb)
83*4882a593Smuzhiyun mpi_free_limb_space(tmp_limb);
84*4882a593Smuzhiyun }
85*4882a593Smuzhiyun
mpi_mulm(MPI w,MPI u,MPI v,MPI m)86*4882a593Smuzhiyun void mpi_mulm(MPI w, MPI u, MPI v, MPI m)
87*4882a593Smuzhiyun {
88*4882a593Smuzhiyun mpi_mul(w, u, v);
89*4882a593Smuzhiyun mpi_tdiv_r(w, w, m);
90*4882a593Smuzhiyun }
91*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(mpi_mulm);
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