lzma-rust2 0.16.2

LZMA / LZMA2 / LZIP / XZ compression ported from 'tukaani xz for java'
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

const CRC32_POLY: u32 = 0xEDB88320;

const fn make_crc32_table() -> [u32; 256] {
    let mut table = [0; 256];
    let mut i = 0;
    while i < 256 {
        let mut crc = i as u32;
        let mut j = 0;
        while j < 8 {
            if crc & 1 != 0 {
                crc = (crc >> 1) ^ CRC32_POLY;
            } else {
                crc >>= 1;
            }
            j += 1;
        }
        table[i] = crc;
        i += 1;
    }
    table
}

const CRC32_TABLE: [u32; 256] = make_crc32_table();

/// CRC_32_ISO_HDLC
#[derive(Clone, Copy)]
#[repr(transparent)]
pub(crate) struct Crc32 {
    state: u32,
}

impl Crc32 {
    pub(crate) fn new() -> Self {
        Self { state: 0xFFFFFFFF }
    }

    pub(crate) fn update(&mut self, data: &[u8]) {
        for &byte in data {
            let index = ((self.state ^ (byte as u32)) & 0xFF) as usize;
            self.state = (self.state >> 8) ^ CRC32_TABLE[index];
        }
    }

    pub(crate) fn finalize(self) -> u32 {
        self.state ^ 0xFFFFFFFF
    }

    pub(crate) fn checksum(data: &[u8]) -> u32 {
        let mut crc = Self::new();
        crc.update(data);
        crc.finalize()
    }
}

const CRC64_POLY: u64 = 0xC96C5795D7870F42;

const fn make_crc64_table() -> [u64; 256] {
    let mut table = [0; 256];
    let mut i = 0;
    while i < 256 {
        let mut crc = i as u64;
        let mut j = 0;
        while j < 8 {
            if crc & 1 != 0 {
                crc = (crc >> 1) ^ CRC64_POLY;
            } else {
                crc >>= 1;
            }
            j += 1;
        }
        table[i] = crc;
        i += 1;
    }
    table
}

const CRC64_TABLE: [u64; 256] = make_crc64_table();

/// CRC_64_XZ
#[derive(Clone, Copy)]
#[repr(transparent)]
pub(crate) struct Crc64 {
    state: u64,
}

impl Crc64 {
    pub(crate) fn new() -> Self {
        Self {
            state: 0xFFFFFFFFFFFFFFFF,
        }
    }

    pub(crate) fn update(&mut self, data: &[u8]) {
        for &byte in data {
            let index = ((self.state ^ (byte as u64)) & 0xFF) as usize;
            self.state = (self.state >> 8) ^ CRC64_TABLE[index];
        }
    }

    pub(crate) fn finalize(self) -> u64 {
        self.state ^ 0xFFFFFFFFFFFFFFFF
    }

    pub(crate) fn checksum(data: &[u8]) -> u64 {
        let mut crc = Self::new();
        crc.update(data);
        crc.finalize()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    const SIMPLE_DATA: &[u8] = &[1, 2, 3, 7, 16, 31, 64, 255];

    #[test]
    fn crc32_empty() {
        assert_eq!(Crc32::checksum(&[]), 0);
    }

    #[test]
    fn crc64_empty() {
        assert_eq!(Crc64::checksum(&[]), 0);
    }

    #[test]
    fn crc32_simple_data() {
        assert_eq!(Crc32::checksum(SIMPLE_DATA), 2428203834);
    }

    #[test]
    fn crc64_simple_data() {
        assert_eq!(Crc64::checksum(SIMPLE_DATA), 11721292222009571391);
    }
}