qemu

1
/*
2
 * Carry-less multiply operations.
3
 * SPDX-License-Identifier: GPL-2.0-or-later
4
 *
5
 * Copyright (C) 2023 Linaro, Ltd.
6
 */
7

8
#include "qemu/osdep.h"
9
#include "crypto/clmul.h"
10

11
uint64_t clmul_8x8_low(uint64_t n, uint64_t m)
12
{
13
    uint64_t r = 0;
14

15
    for (int i = 0; i < 8; ++i) {
16
        uint64_t mask = (n & 0x0101010101010101ull) * 0xff;
17
        r ^= m & mask;
18
        m = (m << 1) & 0xfefefefefefefefeull;
19
        n >>= 1;
20
    }
21
    return r;
22
}
23

24
static uint64_t clmul_8x4_even_int(uint64_t n, uint64_t m)
25
{
26
    uint64_t r = 0;
27

28
    for (int i = 0; i < 8; ++i) {
29
        uint64_t mask = (n & 0x0001000100010001ull) * 0xffff;
30
        r ^= m & mask;
31
        n >>= 1;
32
        m <<= 1;
33
    }
34
    return r;
35
}
36

37
uint64_t clmul_8x4_even(uint64_t n, uint64_t m)
38
{
39
    n &= 0x00ff00ff00ff00ffull;
40
    m &= 0x00ff00ff00ff00ffull;
41
    return clmul_8x4_even_int(n, m);
42
}
43

44
uint64_t clmul_8x4_odd(uint64_t n, uint64_t m)
45
{
46
    return clmul_8x4_even(n >> 8, m >> 8);
47
}
48

49
static uint64_t unpack_8_to_16(uint64_t x)
50
{
51
    return  (x & 0x000000ff)
52
         | ((x & 0x0000ff00) << 8)
53
         | ((x & 0x00ff0000) << 16)
54
         | ((x & 0xff000000) << 24);
55
}
56

57
uint64_t clmul_8x4_packed(uint32_t n, uint32_t m)
58
{
59
    return clmul_8x4_even_int(unpack_8_to_16(n), unpack_8_to_16(m));
60
}
61

62
uint64_t clmul_16x2_even(uint64_t n, uint64_t m)
63
{
64
    uint64_t r = 0;
65

66
    n &= 0x0000ffff0000ffffull;
67
    m &= 0x0000ffff0000ffffull;
68

69
    for (int i = 0; i < 16; ++i) {
70
        uint64_t mask = (n & 0x0000000100000001ull) * 0xffffffffull;
71
        r ^= m & mask;
72
        n >>= 1;
73
        m <<= 1;
74
    }
75
    return r;
76
}
77

78
uint64_t clmul_16x2_odd(uint64_t n, uint64_t m)
79
{
80
    return clmul_16x2_even(n >> 16, m >> 16);
81
}
82

83
uint64_t clmul_32(uint32_t n, uint32_t m32)
84
{
85
    uint64_t r = 0;
86
    uint64_t m = m32;
87

88
    for (int i = 0; i < 32; ++i) {
89
        r ^= n & 1 ? m : 0;
90
        n >>= 1;
91
        m <<= 1;
92
    }
93
    return r;
94
}
95

96
Int128 clmul_64_gen(uint64_t n, uint64_t m)
97
{
98
    uint64_t rl = 0, rh = 0;
99

100
    /* Bit 0 can only influence the low 64-bit result.  */
101
    if (n & 1) {
102
        rl = m;
103
    }
104

105
    for (int i = 1; i < 64; ++i) {
106
        uint64_t mask = -((n >> i) & 1);
107
        rl ^= (m << i) & mask;
108
        rh ^= (m >> (64 - i)) & mask;
109
    }
110
    return int128_make128(rl, rh);
111
}
112