2 #ifdef BN_MP_TOOM_SQR_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
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.
12 * The library is free for all purposes without any express
15 * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
18 /* squaring using Toom-Cook 3-way algorithm */
20 mp_toom_sqr(mp_int *a, mp_int *b)
22 mp_int w0, w1, w2, w3, w4, tmp1, a0, a1, a2;
26 if ((res = mp_init_multi(&w0, &w1, &w2, &w3, &w4, &a0, &a1, &a2, &tmp1, NULL)) != MP_OKAY) {
33 /* a = a2 * B**2 + a1 * B + a0 */
34 if ((res = mp_mod_2d(a, DIGIT_BIT * B, &a0)) != MP_OKAY) {
38 if ((res = mp_copy(a, &a1)) != MP_OKAY) {
42 mp_mod_2d(&a1, DIGIT_BIT * B, &a1);
44 if ((res = mp_copy(a, &a2)) != MP_OKAY) {
50 if ((res = mp_sqr(&a0, &w0)) != MP_OKAY) {
55 if ((res = mp_sqr(&a2, &w4)) != MP_OKAY) {
59 /* w1 = (a2 + 2(a1 + 2a0))**2 */
60 if ((res = mp_mul_2(&a0, &tmp1)) != MP_OKAY) {
63 if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
66 if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
69 if ((res = mp_add(&tmp1, &a2, &tmp1)) != MP_OKAY) {
73 if ((res = mp_sqr(&tmp1, &w1)) != MP_OKAY) {
77 /* w3 = (a0 + 2(a1 + 2a2))**2 */
78 if ((res = mp_mul_2(&a2, &tmp1)) != MP_OKAY) {
81 if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
84 if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
87 if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
91 if ((res = mp_sqr(&tmp1, &w3)) != MP_OKAY) {
96 /* w2 = (a2 + a1 + a0)**2 */
97 if ((res = mp_add(&a2, &a1, &tmp1)) != MP_OKAY) {
100 if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
103 if ((res = mp_sqr(&tmp1, &w2)) != MP_OKAY) {
107 /* now solve the matrix
115 using 12 subtractions, 4 shifts, 2 small divisions and 1 small multiplication.
119 if ((res = mp_sub(&w1, &w4, &w1)) != MP_OKAY) {
123 if ((res = mp_sub(&w3, &w0, &w3)) != MP_OKAY) {
127 if ((res = mp_div_2(&w1, &w1)) != MP_OKAY) {
131 if ((res = mp_div_2(&w3, &w3)) != MP_OKAY) {
135 if ((res = mp_sub(&w2, &w0, &w2)) != MP_OKAY) {
138 if ((res = mp_sub(&w2, &w4, &w2)) != MP_OKAY) {
142 if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
146 if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
150 if ((res = mp_mul_2d(&w0, 3, &tmp1)) != MP_OKAY) {
153 if ((res = mp_sub(&w1, &tmp1, &w1)) != MP_OKAY) {
157 if ((res = mp_mul_2d(&w4, 3, &tmp1)) != MP_OKAY) {
160 if ((res = mp_sub(&w3, &tmp1, &w3)) != MP_OKAY) {
164 if ((res = mp_mul_d(&w2, 3, &w2)) != MP_OKAY) {
167 if ((res = mp_sub(&w2, &w1, &w2)) != MP_OKAY) {
170 if ((res = mp_sub(&w2, &w3, &w2)) != MP_OKAY) {
174 if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
178 if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
182 if ((res = mp_div_3(&w1, &w1, NULL)) != MP_OKAY) {
186 if ((res = mp_div_3(&w3, &w3, NULL)) != MP_OKAY) {
190 /* at this point shift W[n] by B*n */
191 if ((res = mp_lshd(&w1, 1*B)) != MP_OKAY) {
194 if ((res = mp_lshd(&w2, 2*B)) != MP_OKAY) {
197 if ((res = mp_lshd(&w3, 3*B)) != MP_OKAY) {
200 if ((res = mp_lshd(&w4, 4*B)) != MP_OKAY) {
204 if ((res = mp_add(&w0, &w1, b)) != MP_OKAY) {
207 if ((res = mp_add(&w2, &w3, &tmp1)) != MP_OKAY) {
210 if ((res = mp_add(&w4, &tmp1, &tmp1)) != MP_OKAY) {
213 if ((res = mp_add(&tmp1, b, b)) != MP_OKAY) {
218 mp_clear_multi(&w0, &w1, &w2, &w3, &w4, &a0, &a1, &a2, &tmp1, NULL);
224 /* $Source: /cvs/libtom/libtommath/bn_mp_toom_sqr.c,v $ */
225 /* $Revision: 1.3 $ */
226 /* $Date: 2006/03/31 14:18:44 $ */