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comparison bn_mp_toom_sqr.c @ 1:22d5cf7d4b1a libtommath

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Renaming branch
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:23:46 +0000
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children d29b64170cf0
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-1:000000000000 1:22d5cf7d4b1a
1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
2 *
3 * LibTomMath is a library that provides multiple-precision
4 * integer arithmetic as well as number theoretic functionality.
5 *
6 * The library was designed directly after the MPI library by
7 * Michael Fromberger but has been written from scratch with
8 * additional optimizations in place.
9 *
10 * The library is free for all purposes without any express
11 * guarantee it works.
12 *
13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
14 */
15 #include <tommath.h>
16
17 /* squaring using Toom-Cook 3-way algorithm */
18 int
19 mp_toom_sqr(mp_int *a, mp_int *b)
20 {
21 mp_int w0, w1, w2, w3, w4, tmp1, a0, a1, a2;
22 int res, B;
23
24 /* init temps */
25 if ((res = mp_init_multi(&w0, &w1, &w2, &w3, &w4, &a0, &a1, &a2, &tmp1, NULL)) != MP_OKAY) {
26 return res;
27 }
28
29 /* B */
30 B = a->used / 3;
31
32 /* a = a2 * B**2 + a1 * B + a0 */
33 if ((res = mp_mod_2d(a, DIGIT_BIT * B, &a0)) != MP_OKAY) {
34 goto ERR;
35 }
36
37 if ((res = mp_copy(a, &a1)) != MP_OKAY) {
38 goto ERR;
39 }
40 mp_rshd(&a1, B);
41 mp_mod_2d(&a1, DIGIT_BIT * B, &a1);
42
43 if ((res = mp_copy(a, &a2)) != MP_OKAY) {
44 goto ERR;
45 }
46 mp_rshd(&a2, B*2);
47
48 /* w0 = a0*a0 */
49 if ((res = mp_sqr(&a0, &w0)) != MP_OKAY) {
50 goto ERR;
51 }
52
53 /* w4 = a2 * a2 */
54 if ((res = mp_sqr(&a2, &w4)) != MP_OKAY) {
55 goto ERR;
56 }
57
58 /* w1 = (a2 + 2(a1 + 2a0))**2 */
59 if ((res = mp_mul_2(&a0, &tmp1)) != MP_OKAY) {
60 goto ERR;
61 }
62 if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
63 goto ERR;
64 }
65 if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
66 goto ERR;
67 }
68 if ((res = mp_add(&tmp1, &a2, &tmp1)) != MP_OKAY) {
69 goto ERR;
70 }
71
72 if ((res = mp_sqr(&tmp1, &w1)) != MP_OKAY) {
73 goto ERR;
74 }
75
76 /* w3 = (a0 + 2(a1 + 2a2))**2 */
77 if ((res = mp_mul_2(&a2, &tmp1)) != MP_OKAY) {
78 goto ERR;
79 }
80 if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
81 goto ERR;
82 }
83 if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
84 goto ERR;
85 }
86 if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
87 goto ERR;
88 }
89
90 if ((res = mp_sqr(&tmp1, &w3)) != MP_OKAY) {
91 goto ERR;
92 }
93
94
95 /* w2 = (a2 + a1 + a0)**2 */
96 if ((res = mp_add(&a2, &a1, &tmp1)) != MP_OKAY) {
97 goto ERR;
98 }
99 if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
100 goto ERR;
101 }
102 if ((res = mp_sqr(&tmp1, &w2)) != MP_OKAY) {
103 goto ERR;
104 }
105
106 /* now solve the matrix
107
108 0 0 0 0 1
109 1 2 4 8 16
110 1 1 1 1 1
111 16 8 4 2 1
112 1 0 0 0 0
113
114 using 12 subtractions, 4 shifts, 2 small divisions and 1 small multiplication.
115 */
116
117 /* r1 - r4 */
118 if ((res = mp_sub(&w1, &w4, &w1)) != MP_OKAY) {
119 goto ERR;
120 }
121 /* r3 - r0 */
122 if ((res = mp_sub(&w3, &w0, &w3)) != MP_OKAY) {
123 goto ERR;
124 }
125 /* r1/2 */
126 if ((res = mp_div_2(&w1, &w1)) != MP_OKAY) {
127 goto ERR;
128 }
129 /* r3/2 */
130 if ((res = mp_div_2(&w3, &w3)) != MP_OKAY) {
131 goto ERR;
132 }
133 /* r2 - r0 - r4 */
134 if ((res = mp_sub(&w2, &w0, &w2)) != MP_OKAY) {
135 goto ERR;
136 }
137 if ((res = mp_sub(&w2, &w4, &w2)) != MP_OKAY) {
138 goto ERR;
139 }
140 /* r1 - r2 */
141 if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
142 goto ERR;
143 }
144 /* r3 - r2 */
145 if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
146 goto ERR;
147 }
148 /* r1 - 8r0 */
149 if ((res = mp_mul_2d(&w0, 3, &tmp1)) != MP_OKAY) {
150 goto ERR;
151 }
152 if ((res = mp_sub(&w1, &tmp1, &w1)) != MP_OKAY) {
153 goto ERR;
154 }
155 /* r3 - 8r4 */
156 if ((res = mp_mul_2d(&w4, 3, &tmp1)) != MP_OKAY) {
157 goto ERR;
158 }
159 if ((res = mp_sub(&w3, &tmp1, &w3)) != MP_OKAY) {
160 goto ERR;
161 }
162 /* 3r2 - r1 - r3 */
163 if ((res = mp_mul_d(&w2, 3, &w2)) != MP_OKAY) {
164 goto ERR;
165 }
166 if ((res = mp_sub(&w2, &w1, &w2)) != MP_OKAY) {
167 goto ERR;
168 }
169 if ((res = mp_sub(&w2, &w3, &w2)) != MP_OKAY) {
170 goto ERR;
171 }
172 /* r1 - r2 */
173 if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
174 goto ERR;
175 }
176 /* r3 - r2 */
177 if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
178 goto ERR;
179 }
180 /* r1/3 */
181 if ((res = mp_div_3(&w1, &w1, NULL)) != MP_OKAY) {
182 goto ERR;
183 }
184 /* r3/3 */
185 if ((res = mp_div_3(&w3, &w3, NULL)) != MP_OKAY) {
186 goto ERR;
187 }
188
189 /* at this point shift W[n] by B*n */
190 if ((res = mp_lshd(&w1, 1*B)) != MP_OKAY) {
191 goto ERR;
192 }
193 if ((res = mp_lshd(&w2, 2*B)) != MP_OKAY) {
194 goto ERR;
195 }
196 if ((res = mp_lshd(&w3, 3*B)) != MP_OKAY) {
197 goto ERR;
198 }
199 if ((res = mp_lshd(&w4, 4*B)) != MP_OKAY) {
200 goto ERR;
201 }
202
203 if ((res = mp_add(&w0, &w1, b)) != MP_OKAY) {
204 goto ERR;
205 }
206 if ((res = mp_add(&w2, &w3, &tmp1)) != MP_OKAY) {
207 goto ERR;
208 }
209 if ((res = mp_add(&w4, &tmp1, &tmp1)) != MP_OKAY) {
210 goto ERR;
211 }
212 if ((res = mp_add(&tmp1, b, b)) != MP_OKAY) {
213 goto ERR;
214 }
215
216 ERR:
217 mp_clear_multi(&w0, &w1, &w2, &w3, &w4, &a0, &a1, &a2, &tmp1, NULL);
218 return res;
219 }
220