souphash 0.1.0

SoupHash: an order-indipendent hash function, based on SipHash
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

use crate::bytes_to_u64;

#[derive(Clone, Debug)]
pub(crate) struct Buffer {
    data: u64,
    len: usize,
}

impl Buffer {
    const CAPACITY: usize = 8;

    #[inline]
    #[must_use]
    pub(crate) const fn new() -> Self {
        Self { data: 0, len: 0 }
    }

    #[inline]
    #[must_use]
    pub(crate) const fn is_empty(&self) -> bool {
        self.len == 0
    }

    #[inline]
    #[must_use]
    pub(crate) const fn available(&self) -> usize {
        Self::CAPACITY - self.len
    }

    #[inline]
    #[must_use]
    pub(crate) const fn take(&mut self) -> u64 {
        let data = self.data;
        self.len = 0;
        self.data = 0;
        data
    }

    #[inline]
    #[must_use]
    pub(crate) const fn write(&mut self, x: u64, size: usize) -> Option<u64> {
        debug_assert!(size <= Self::CAPACITY);
        debug_assert!(self.len < Self::CAPACITY);
        if size < Self::CAPACITY {
            // Ensure the input is zero-padded
            debug_assert!(x >> (size * 8) == 0);
        }

        let len = self.len + size;
        let data = self.data | (x << (self.len * 8));

        if len >= 8 {
            self.len = len - 8;
            self.data = x.unbounded_shr((size - self.len) as u32 * 8);
            Some(data)
        } else {
            self.len = len;
            self.data = data;
            None
        }
    }

    #[inline]
    #[must_use]
    pub(crate) const fn write_bytes(&mut self, bytes: &[u8]) -> Option<u64> {
        let x = bytes_to_u64(bytes);
        self.write(x, bytes.len())
    }
}

impl Default for Buffer {
    #[inline]
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use crate::buffer::Buffer;

    #[test]
    fn write_u8() {
        let mut buf = Buffer::default();
        assert_eq!(buf.write(0x11, 1), None);
        assert_eq!(buf.write(0x22, 1), None);
        assert_eq!(buf.write(0x33, 1), None);
        assert_eq!(buf.write(0x44, 1), None);
        assert_eq!(buf.write(0x55, 1), None);
        assert_eq!(buf.write(0x66, 1), None);
        assert_eq!(buf.write(0x77, 1), None);
        assert_eq!(buf.write(0x88, 1), Some(0x8877665544332211));
        assert_eq!(buf.take(), 0);
    }

    #[test]
    fn write_u16() {
        let mut buf = Buffer::default();
        assert_eq!(buf.write(0x1111, 2), None);
        assert_eq!(buf.write(0x2222, 2), None);
        assert_eq!(buf.write(0x3333, 2), None);
        assert_eq!(buf.write(0x4444, 2), Some(0x4444333322221111));
        assert_eq!(buf.take(), 0);
    }

    #[test]
    fn write_u32() {
        let mut buf = Buffer::default();
        assert_eq!(buf.write(0x11111111, 4), None);
        assert_eq!(buf.write(0x44444444, 4), Some(0x4444444411111111));
        assert_eq!(buf.take(), 0);
    }

    #[test]
    fn write_u64() {
        let mut buf = Buffer::default();
        assert_eq!(buf.write(0x1111111111111111, 8), Some(0x1111111111111111));
        assert_eq!(buf.take(), 0);
    }

    #[test]
    fn write_mixed() {
        let mut buf = Buffer::default();
        assert_eq!(buf.write(0x11, 1), None);
        assert_eq!(buf.write(0x2222, 2), None);
        assert_eq!(buf.write(0x44444444, 4), None);
        assert_eq!(buf.write(0x5555555555555555, 8), Some(0x5544444444222211));
        assert_eq!(buf.take(), 0x55555555555555);
    }
}