xref: /openssl/crypto/ec/curve448/arch_32/f_impl32.c (revision da1c088f)
1 /*
2  * Copyright 2017-2023 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 "internal/e_os.h"
14 #include <openssl/macros.h>
15 #include "internal/numbers.h"
16 
17 #ifdef UINT128_MAX
18 /* We have support for 128 bit ints, so do nothing here */
19 NON_EMPTY_TRANSLATION_UNIT
20 #else
21 
22 # include "../field.h"
23 
24 void ossl_gf_mul(gf_s * RESTRICT cs, const gf as, const gf bs)
25 {
26     const uint32_t *a = as->limb, *b = bs->limb;
27     uint32_t *c = cs->limb;
28     uint64_t accum0 = 0, accum1 = 0, accum2 = 0;
29     uint32_t mask = (1 << 28) - 1;
30     uint32_t aa[8], bb[8];
31     int i, j;
32 
33     for (i = 0; i < 8; i++) {
34         aa[i] = a[i] + a[i + 8];
35         bb[i] = b[i] + b[i + 8];
36     }
37 
38     for (j = 0; j < 8; j++) {
39         accum2 = 0;
40         for (i = 0; i < j + 1; i++) {
41             accum2 += widemul(a[j - i], b[i]);
42             accum1 += widemul(aa[j - i], bb[i]);
43             accum0 += widemul(a[8 + j - i], b[8 + i]);
44         }
45         accum1 -= accum2;
46         accum0 += accum2;
47         accum2 = 0;
48         for (i = j + 1; i < 8; i++) {
49             accum0 -= widemul(a[8 + j - i], b[i]);
50             accum2 += widemul(aa[8 + j - i], bb[i]);
51             accum1 += widemul(a[16 + j - i], b[8 + i]);
52         }
53         accum1 += accum2;
54         accum0 += accum2;
55         c[j] = ((uint32_t)(accum0)) & mask;
56         c[j + 8] = ((uint32_t)(accum1)) & mask;
57         accum0 >>= 28;
58         accum1 >>= 28;
59     }
60 
61     accum0 += accum1;
62     accum0 += c[8];
63     accum1 += c[0];
64     c[8] = ((uint32_t)(accum0)) & mask;
65     c[0] = ((uint32_t)(accum1)) & mask;
66 
67     accum0 >>= 28;
68     accum1 >>= 28;
69     c[9] += ((uint32_t)(accum0));
70     c[1] += ((uint32_t)(accum1));
71 }
72 
73 void ossl_gf_mulw_unsigned(gf_s * RESTRICT cs, const gf as, uint32_t b)
74 {
75     const uint32_t *a = as->limb;
76     uint32_t *c = cs->limb;
77     uint64_t accum0 = 0, accum8 = 0;
78     uint32_t mask = (1 << 28) - 1;
79     int i;
80 
81     assert(b <= mask);
82 
83     for (i = 0; i < 8; i++) {
84         accum0 += widemul(b, a[i]);
85         accum8 += widemul(b, a[i + 8]);
86         c[i] = accum0 & mask;
87         accum0 >>= 28;
88         c[i + 8] = accum8 & mask;
89         accum8 >>= 28;
90     }
91 
92     accum0 += accum8 + c[8];
93     c[8] = ((uint32_t)accum0) & mask;
94     c[9] += (uint32_t)(accum0 >> 28);
95 
96     accum8 += c[0];
97     c[0] = ((uint32_t)accum8) & mask;
98     c[1] += (uint32_t)(accum8 >> 28);
99 }
100 
101 void ossl_gf_sqr(gf_s * RESTRICT cs, const gf as)
102 {
103     ossl_gf_mul(cs, as, as);         /* Performs better with a dedicated square */
104 }
105 #endif
106