1 use crate::util::crc8;
2 use crc_catalog::Algorithm;
3
4 mod bytewise;
5 mod nolookup;
6 mod slice16;
7
init(algorithm: &Algorithm<u8>, initial: u8) -> u88 const fn init(algorithm: &Algorithm<u8>, initial: u8) -> u8 {
9 if algorithm.refin {
10 initial.reverse_bits() >> (8u8 - algorithm.width)
11 } else {
12 initial << (8u8 - algorithm.width)
13 }
14 }
15
finalize(algorithm: &Algorithm<u8>, mut crc: u8) -> u816 const fn finalize(algorithm: &Algorithm<u8>, mut crc: u8) -> u8 {
17 if algorithm.refin ^ algorithm.refout {
18 crc = crc.reverse_bits();
19 }
20 if !algorithm.refout {
21 crc >>= 8u8 - algorithm.width;
22 }
23 crc ^ algorithm.xorout
24 }
25
update_nolookup(mut crc: u8, algorithm: &Algorithm<u8>, bytes: &[u8]) -> u826 const fn update_nolookup(mut crc: u8, algorithm: &Algorithm<u8>, bytes: &[u8]) -> u8 {
27 let poly = if algorithm.refin {
28 let poly = algorithm.poly.reverse_bits();
29 poly >> (8u8 - algorithm.width)
30 } else {
31 algorithm.poly << (8u8 - algorithm.width)
32 };
33
34 let mut i = 0;
35
36 while i < bytes.len() {
37 crc = crc8(poly, algorithm.refin, crc ^ bytes[i]);
38 i += 1;
39 }
40
41 crc
42 }
43
update_bytewise(mut crc: u8, table: &[u8; 256], bytes: &[u8]) -> u844 const fn update_bytewise(mut crc: u8, table: &[u8; 256], bytes: &[u8]) -> u8 {
45 let mut i = 0;
46
47 while i < bytes.len() {
48 crc = table[(crc ^ bytes[i]) as usize];
49 i += 1;
50 }
51
52 crc
53 }
54
update_slice16(mut crc: u8, table: &[[u8; 256]; 16], bytes: &[u8]) -> u855 const fn update_slice16(mut crc: u8, table: &[[u8; 256]; 16], bytes: &[u8]) -> u8 {
56 let len = bytes.len();
57 let mut i = 0;
58
59 while i + 16 <= len {
60 crc = table[0][bytes[i + 15] as usize]
61 ^ table[1][bytes[i + 14] as usize]
62 ^ table[2][bytes[i + 13] as usize]
63 ^ table[3][bytes[i + 12] as usize]
64 ^ table[4][bytes[i + 11] as usize]
65 ^ table[5][bytes[i + 10] as usize]
66 ^ table[6][bytes[i + 9] as usize]
67 ^ table[7][bytes[i + 8] as usize]
68 ^ table[8][bytes[i + 7] as usize]
69 ^ table[9][bytes[i + 6] as usize]
70 ^ table[10][bytes[i + 5] as usize]
71 ^ table[11][bytes[i + 4] as usize]
72 ^ table[12][bytes[i + 3] as usize]
73 ^ table[13][bytes[i + 2] as usize]
74 ^ table[14][bytes[i + 1] as usize]
75 ^ table[15][(bytes[i] ^ crc) as usize];
76
77 i += 16;
78 }
79
80 while i < len {
81 crc = table[0][(crc ^ bytes[i]) as usize];
82 i += 1;
83 }
84
85 crc
86 }
87
88 #[cfg(test)]
89 mod test {
90 use crate::*;
91 use crc_catalog::{Algorithm, CRC_8_BLUETOOTH};
92
93 /// Test this optimized version against the well known implementation to ensure correctness
94 #[test]
correctness()95 fn correctness() {
96 let data: &[&str] = &[
97 "",
98 "1",
99 "1234",
100 "123456789",
101 "0123456789ABCDE",
102 "01234567890ABCDEFGHIJK",
103 "01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK",
104 ];
105
106 pub const CRC_8_BLUETOOTH_NONREFLEX: Algorithm<u8> = Algorithm {
107 width: 8,
108 poly: 0xa7,
109 init: 0x00,
110 refin: false,
111 refout: true,
112 xorout: 0x00,
113 check: 0x26,
114 residue: 0x00,
115 };
116
117 let algs_to_test = [&CRC_8_BLUETOOTH, &CRC_8_BLUETOOTH_NONREFLEX];
118
119 for alg in algs_to_test {
120 for data in data {
121 let crc_slice16 = Crc::<u8, Table<16>>::new(alg);
122 let crc_nolookup = Crc::<u8, NoTable>::new(alg);
123 let expected = Crc::<u8, Table<1>>::new(alg).checksum(data.as_bytes());
124
125 // Check that doing all at once works as expected
126 assert_eq!(crc_slice16.checksum(data.as_bytes()), expected);
127 assert_eq!(crc_nolookup.checksum(data.as_bytes()), expected);
128
129 let mut digest = crc_slice16.digest();
130 digest.update(data.as_bytes());
131 assert_eq!(digest.finalize(), expected);
132
133 let mut digest = crc_nolookup.digest();
134 digest.update(data.as_bytes());
135 assert_eq!(digest.finalize(), expected);
136
137 // Check that we didn't break updating from multiple sources
138 if data.len() > 2 {
139 let data = data.as_bytes();
140 let data1 = &data[..data.len() / 2];
141 let data2 = &data[data.len() / 2..];
142 let mut digest = crc_slice16.digest();
143 digest.update(data1);
144 digest.update(data2);
145 assert_eq!(digest.finalize(), expected);
146 let mut digest = crc_nolookup.digest();
147 digest.update(data1);
148 digest.update(data2);
149 assert_eq!(digest.finalize(), expected);
150 }
151 }
152 }
153 }
154 }
155