1/*
2 * Copyright 2017-2022 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright 2014 Cryptography Research, Inc.
4 *
5 * Licensed under the Apache License 2.0 (the "License").  You may not use
6 * this file except in compliance with the License.  You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
9 *
10 * Originally written by Mike Hamburg
11 */
12
13#include "e_os.h"
14#include <openssl/macros.h>
15#include "internal/numbers.h"
16
17#ifndef UINT128_MAX
18/* No support for 128 bit ints, so do nothing here */
19NON_EMPTY_TRANSLATION_UNIT
20#else
21
22# include "../field.h"
23
24void gf_mul(gf_s * RESTRICT cs, const gf as, const gf bs)
25{
26    const uint64_t *a = as->limb, *b = bs->limb;
27    uint64_t *c = cs->limb;
28    uint128_t accum0 = 0, accum1 = 0, accum2;
29    uint64_t mask = (1ULL << 56) - 1;
30    uint64_t aa[4], bb[4], bbb[4];
31    unsigned int i, j;
32
33    for (i = 0; i < 4; i++) {
34        aa[i] = a[i] + a[i + 4];
35        bb[i] = b[i] + b[i + 4];
36        bbb[i] = bb[i] + b[i + 4];
37    }
38
39    for (i = 0; i < 4; i++) {
40        accum2 = 0;
41
42        for (j = 0; j <= i; j++) {
43            accum2 += widemul(a[j], b[i - j]);
44            accum1 += widemul(aa[j], bb[i - j]);
45            accum0 += widemul(a[j + 4], b[i - j + 4]);
46        }
47        for (; j < 4; j++) {
48            accum2 += widemul(a[j], b[i - j + 8]);
49            accum1 += widemul(aa[j], bbb[i - j + 4]);
50            accum0 += widemul(a[j + 4], bb[i - j + 4]);
51        }
52
53        accum1 -= accum2;
54        accum0 += accum2;
55
56        c[i] = ((uint64_t)(accum0)) & mask;
57        c[i + 4] = ((uint64_t)(accum1)) & mask;
58
59        accum0 >>= 56;
60        accum1 >>= 56;
61    }
62
63    accum0 += accum1;
64    accum0 += c[4];
65    accum1 += c[0];
66    c[4] = ((uint64_t)(accum0)) & mask;
67    c[0] = ((uint64_t)(accum1)) & mask;
68
69    accum0 >>= 56;
70    accum1 >>= 56;
71
72    c[5] += ((uint64_t)(accum0));
73    c[1] += ((uint64_t)(accum1));
74}
75
76void gf_mulw_unsigned(gf_s * RESTRICT cs, const gf as, uint32_t b)
77{
78    const uint64_t *a = as->limb;
79    uint64_t *c = cs->limb;
80    uint128_t accum0 = 0, accum4 = 0;
81    uint64_t mask = (1ULL << 56) - 1;
82    int i;
83
84    for (i = 0; i < 4; i++) {
85        accum0 += widemul(b, a[i]);
86        accum4 += widemul(b, a[i + 4]);
87        c[i] = accum0 & mask;
88        accum0 >>= 56;
89        c[i + 4] = accum4 & mask;
90        accum4 >>= 56;
91    }
92
93    accum0 += accum4 + c[4];
94    c[4] = accum0 & mask;
95    c[5] += accum0 >> 56;
96
97    accum4 += c[0];
98    c[0] = accum4 & mask;
99    c[1] += accum4 >> 56;
100}
101
102void gf_sqr(gf_s * RESTRICT cs, const gf as)
103{
104    const uint64_t *a = as->limb;
105    uint64_t *c = cs->limb;
106    uint128_t accum0 = 0, accum1 = 0, accum2;
107    uint64_t mask = (1ULL << 56) - 1;
108    uint64_t aa[4];
109    unsigned int i;
110
111    /* For some reason clang doesn't vectorize this without prompting? */
112    for (i = 0; i < 4; i++)
113        aa[i] = a[i] + a[i + 4];
114
115    accum2 = widemul(a[0], a[3]);
116    accum0 = widemul(aa[0], aa[3]);
117    accum1 = widemul(a[4], a[7]);
118
119    accum2 += widemul(a[1], a[2]);
120    accum0 += widemul(aa[1], aa[2]);
121    accum1 += widemul(a[5], a[6]);
122
123    accum0 -= accum2;
124    accum1 += accum2;
125
126    c[3] = ((uint64_t)(accum1)) << 1 & mask;
127    c[7] = ((uint64_t)(accum0)) << 1 & mask;
128
129    accum0 >>= 55;
130    accum1 >>= 55;
131
132    accum0 += widemul(2 * aa[1], aa[3]);
133    accum1 += widemul(2 * a[5], a[7]);
134    accum0 += widemul(aa[2], aa[2]);
135    accum1 += accum0;
136
137    accum0 -= widemul(2 * a[1], a[3]);
138    accum1 += widemul(a[6], a[6]);
139
140    accum2 = widemul(a[0], a[0]);
141    accum1 -= accum2;
142    accum0 += accum2;
143
144    accum0 -= widemul(a[2], a[2]);
145    accum1 += widemul(aa[0], aa[0]);
146    accum0 += widemul(a[4], a[4]);
147
148    c[0] = ((uint64_t)(accum0)) & mask;
149    c[4] = ((uint64_t)(accum1)) & mask;
150
151    accum0 >>= 56;
152    accum1 >>= 56;
153
154    accum2 = widemul(2 * aa[2], aa[3]);
155    accum0 -= widemul(2 * a[2], a[3]);
156    accum1 += widemul(2 * a[6], a[7]);
157
158    accum1 += accum2;
159    accum0 += accum2;
160
161    accum2 = widemul(2 * a[0], a[1]);
162    accum1 += widemul(2 * aa[0], aa[1]);
163    accum0 += widemul(2 * a[4], a[5]);
164
165    accum1 -= accum2;
166    accum0 += accum2;
167
168    c[1] = ((uint64_t)(accum0)) & mask;
169    c[5] = ((uint64_t)(accum1)) & mask;
170
171    accum0 >>= 56;
172    accum1 >>= 56;
173
174    accum2 = widemul(aa[3], aa[3]);
175    accum0 -= widemul(a[3], a[3]);
176    accum1 += widemul(a[7], a[7]);
177
178    accum1 += accum2;
179    accum0 += accum2;
180
181    accum2 = widemul(2 * a[0], a[2]);
182    accum1 += widemul(2 * aa[0], aa[2]);
183    accum0 += widemul(2 * a[4], a[6]);
184
185    accum2 += widemul(a[1], a[1]);
186    accum1 += widemul(aa[1], aa[1]);
187    accum0 += widemul(a[5], a[5]);
188
189    accum1 -= accum2;
190    accum0 += accum2;
191
192    c[2] = ((uint64_t)(accum0)) & mask;
193    c[6] = ((uint64_t)(accum1)) & mask;
194
195    accum0 >>= 56;
196    accum1 >>= 56;
197
198    accum0 += c[3];
199    accum1 += c[7];
200    c[3] = ((uint64_t)(accum0)) & mask;
201    c[7] = ((uint64_t)(accum1)) & mask;
202
203    /* we could almost stop here, but it wouldn't be stable, so... */
204
205    accum0 >>= 56;
206    accum1 >>= 56;
207    c[4] += ((uint64_t)(accum0)) + ((uint64_t)(accum1));
208    c[0] += ((uint64_t)(accum1));
209}
210#endif
211