Coverage Report

Created: 2025-07-18 06:31

/rust/registry/src/index.crates.io-6f17d22bba15001f/crc32fast-1.5.0/src/baseline.rs
Line
Count
Source (jump to first uncovered line)
1
use crate::table::CRC32_TABLE;
2
3
#[derive(Clone)]
4
pub struct State {
5
    state: u32,
6
}
7
8
impl State {
9
0
    pub fn new(state: u32) -> Self {
10
0
        State { state }
11
0
    }
12
13
0
    pub fn update(&mut self, buf: &[u8]) {
14
0
        self.state = update_fast_16(self.state, buf);
15
0
    }
16
17
0
    pub fn finalize(self) -> u32 {
18
0
        self.state
19
0
    }
20
21
0
    pub fn reset(&mut self) {
22
0
        self.state = 0;
23
0
    }
24
25
0
    pub fn combine(&mut self, other: u32, amount: u64) {
26
0
        self.state = crate::combine::combine(self.state, other, amount);
27
0
    }
28
}
29
30
28.0k
pub(crate) fn update_fast_16(prev: u32, mut buf: &[u8]) -> u32 {
31
    const UNROLL: usize = 4;
32
    const BYTES_AT_ONCE: usize = 16 * UNROLL;
33
34
28.0k
    let mut crc = !prev;
35
36
31.0k
    while buf.len() >= BYTES_AT_ONCE {
37
14.9k
        for _ in 0..UNROLL {
38
11.9k
            crc = CRC32_TABLE[0x0][buf[0xf] as usize]
39
11.9k
                ^ CRC32_TABLE[0x1][buf[0xe] as usize]
40
11.9k
                ^ CRC32_TABLE[0x2][buf[0xd] as usize]
41
11.9k
                ^ CRC32_TABLE[0x3][buf[0xc] as usize]
42
11.9k
                ^ CRC32_TABLE[0x4][buf[0xb] as usize]
43
11.9k
                ^ CRC32_TABLE[0x5][buf[0xa] as usize]
44
11.9k
                ^ CRC32_TABLE[0x6][buf[0x9] as usize]
45
11.9k
                ^ CRC32_TABLE[0x7][buf[0x8] as usize]
46
11.9k
                ^ CRC32_TABLE[0x8][buf[0x7] as usize]
47
11.9k
                ^ CRC32_TABLE[0x9][buf[0x6] as usize]
48
11.9k
                ^ CRC32_TABLE[0xa][buf[0x5] as usize]
49
11.9k
                ^ CRC32_TABLE[0xb][buf[0x4] as usize]
50
11.9k
                ^ CRC32_TABLE[0xc][buf[0x3] as usize ^ ((crc >> 0x18) & 0xFF) as usize]
51
11.9k
                ^ CRC32_TABLE[0xd][buf[0x2] as usize ^ ((crc >> 0x10) & 0xFF) as usize]
52
11.9k
                ^ CRC32_TABLE[0xe][buf[0x1] as usize ^ ((crc >> 0x08) & 0xFF) as usize]
53
11.9k
                ^ CRC32_TABLE[0xf][buf[0x0] as usize ^ (crc & 0xFF) as usize];
54
11.9k
            buf = &buf[16..];
55
11.9k
        }
56
    }
57
58
28.0k
    update_slow(!crc, buf)
59
28.0k
}
60
61
28.0k
pub(crate) fn update_slow(prev: u32, buf: &[u8]) -> u32 {
62
28.0k
    let mut crc = !prev;
63
64
334k
    for &byte in buf.iter() {
65
334k
        crc = CRC32_TABLE[0][((crc as u8) ^ byte) as usize] ^ (crc >> 8);
66
334k
    }
67
68
28.0k
    !crc
69
28.0k
}
70
71
#[cfg(test)]
72
mod test {
73
    #[test]
74
    fn slow() {
75
        assert_eq!(super::update_slow(0, b""), 0);
76
77
        // test vectors from the iPXE project (input and output are bitwise negated)
78
        assert_eq!(super::update_slow(!0x12345678, b""), !0x12345678);
79
        assert_eq!(super::update_slow(!0xffffffff, b"hello world"), !0xf2b5ee7a);
80
        assert_eq!(super::update_slow(!0xffffffff, b"hello"), !0xc9ef5979);
81
        assert_eq!(super::update_slow(!0xc9ef5979, b" world"), !0xf2b5ee7a);
82
83
        // Some vectors found on Rosetta code
84
        assert_eq!(super::update_slow(0, b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"), 0x190A55AD);
85
        assert_eq!(super::update_slow(0, b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF"), 0xFF6CAB0B);
86
        assert_eq!(super::update_slow(0, b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F"), 0x91267E8A);
87
    }
88
89
    quickcheck::quickcheck! {
90
        fn fast_16_is_the_same_as_slow(crc: u32, bytes: Vec<u8>) -> bool {
91
            super::update_fast_16(crc, &bytes) == super::update_slow(crc, &bytes)
92
        }
93
    }
94
}