devela/data/codec/hash/
pengy.rs

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1// devela::data::codec::hash::pengy
2//
3//! Based on pengyhash v0.2 LICENSED as BSD-2.
4//
5
6use crate::{ConstDefault, Hasher};
7
8/// A fast 64-bit non-cryptographic hash algorithm.
9///
10#[doc = crate::doc_!(vendor: "pengyhash")]
11pub struct HasherPengy {
12    state: [u64; 4],
13    seed: u64,
14}
15
16impl ConstDefault for HasherPengy {
17    const DEFAULT: Self = Self { state: [0; 4], seed: 0 };
18}
19impl Default for HasherPengy {
20    fn default() -> Self {
21        Self::DEFAULT
22    }
23}
24
25impl HasherPengy {
26    /// Returns a default pengy hasher.
27    pub const fn new() -> Self {
28        Self::DEFAULT
29    }
30
31    /// Returns a new pengy hasher with the given `seed`.
32    pub const fn with_seed(seed: u64) -> Self {
33        Self { state: [0; 4], seed }
34    }
35
36    /// Checks whether the current state is uninitialized (or unchanged from default).
37    pub const fn is_empty(&self) -> bool {
38        let [a, b, c, d] = self.state;
39        a + b + c + d == 0
40    }
41
42    /// Resets the internal state to its initial default values without changing the seed.
43    pub const fn reset(&mut self) {
44        self.state = [0; 4];
45    }
46
47    /// Resets both the state and seed for full reinitialization.
48    pub const fn clear(&mut self) {
49        self.state = [0; 4];
50        self.seed = 0;
51    }
52
53    /// Processes the given data slice, updating the internal state.
54    pub const fn process(&mut self, data: &[u8]) {
55        let mut b: [u64; 4] = [0; 4];
56        let mut s: [u64; 4] = [0, 0, 0, data.len() as u64];
57        let mut remaining = data;
58
59        // Process 32-byte chunks into 64-bit words
60        while remaining.len() >= 32 {
61            let mut i = 0;
62            while i < 4 {
63                let (_, rest) = remaining.split_at(i * 8);
64                let (chunk, _) = rest.split_at(8);
65                b[i] = u64::from_le_bytes(Self::make_byte_array(chunk));
66
67                i += 1;
68            }
69            let (_left, right) = remaining.split_at(32);
70            remaining = right;
71
72            s[0] = s[0].wrapping_add(s[1]).wrapping_add(b[3]);
73            s[1] = s[0].wrapping_add(s[1].wrapping_shl(14) | s[1].wrapping_shr(50));
74            s[2] = s[2].wrapping_add(s[3]).wrapping_add(b[2]);
75            s[3] = s[2].wrapping_add(s[3].wrapping_shl(23) | s[3].wrapping_shr(41));
76            s[0] = s[0].wrapping_add(s[3]).wrapping_add(b[1]);
77            s[3] = s[0] ^ (s[3].wrapping_shl(16) | s[3].wrapping_shr(48));
78            s[2] = s[2].wrapping_add(s[1]).wrapping_add(b[0]);
79            s[1] = s[2] ^ (s[1].wrapping_shl(40) | s[1].wrapping_shr(24));
80        }
81
82        let mut tmp = [0u8; 32];
83        let mut i = 0;
84        while i < remaining.len() {
85            if i < tmp.len() {
86                tmp[i] = remaining[i];
87            }
88            i += 1;
89        }
90
91        let mut i = 0;
92        while i < 4 {
93            let (_, rest) = tmp.split_at(i * 8);
94            let (chunk, _) = rest.split_at(8);
95            b[i] = u64::from_le_bytes(Self::make_byte_array(chunk));
96            i += 1;
97        }
98
99        // Perform final mixing of state with seed and remaining data
100        let mut _i = 0;
101        while _i < 6 {
102            s[0] = s[0].wrapping_add(s[1]).wrapping_add(b[3]);
103            s[1] = s[0]
104                .wrapping_add(s[1].wrapping_shl(14) | s[1].wrapping_shr(50))
105                .wrapping_add(self.seed);
106            s[2] = s[2].wrapping_add(s[3]).wrapping_add(b[2]);
107            s[3] = s[2].wrapping_add(s[3].wrapping_shl(23) | s[3].wrapping_shr(41));
108            s[0] = s[0].wrapping_add(s[3]).wrapping_add(b[1]);
109            s[3] = s[0] ^ (s[3].wrapping_shl(16) | s[3].wrapping_shr(48));
110            s[2] = s[2].wrapping_add(s[1]).wrapping_add(b[0]);
111            s[1] = s[2] ^ (s[1].wrapping_shl(40) | s[1].wrapping_shr(24));
112            _i += 1;
113        }
114
115        self.state[0] = s[0];
116        self.state[1] = s[1];
117        self.state[2] = s[2];
118        self.state[3] = s[3];
119    }
120
121    const fn make_byte_array(chunk: &[u8]) -> [u8; 8] {
122        let mut byte_array = [0; 8];
123        let mut j = 0;
124        while j < chunk.len() {
125            byte_array[j] = chunk[j];
126            j += 1;
127        }
128        byte_array
129    }
130
131    /// Produces the final hash value based on the internal state.
132    pub const fn digest(&self) -> u64 {
133        self.state[0]
134            .wrapping_add(self.state[1])
135            .wrapping_add(self.state[2])
136            .wrapping_add(self.state[3])
137    }
138}
139
140impl Hasher for HasherPengy {
141    fn write(&mut self, data: &[u8]) {
142        self.process(data);
143    }
144    fn finish(&self) -> u64 {
145        self.digest()
146    }
147}
devela/data/codec/hash/pengy.rs

devela/data/codec/hash/
pengy.rs
