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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
#![warn(unsafe_op_in_unsafe_fn)]
use crate::CRC32_INITIAL_VALUE;
#[cfg(target_arch = "aarch64")]
pub(crate) mod acle;
mod braid;
mod combine;
#[cfg(target_arch = "x86_64")]
mod pclmulqdq;
pub use combine::crc32_combine;
pub fn crc32(start: u32, buf: &[u8]) -> u32 {
/* For lens < 64, crc32_braid method is faster. The CRC32 instruction for
* these short lengths might also prove to be effective */
if buf.len() < 64 {
return crc32_braid(start, buf);
}
let mut crc_state = Crc32Fold::new_with_initial(start);
crc_state.fold(buf, start);
crc_state.finish()
}
pub fn crc32_braid(start: u32, buf: &[u8]) -> u32 {
braid::crc32_braid::<5>(start, buf)
}
#[derive(Debug, Clone, Copy)]
pub struct Crc32Fold {
#[cfg(target_arch = "x86_64")]
fold: pclmulqdq::Accumulator,
value: u32,
}
impl Default for Crc32Fold {
fn default() -> Self {
Self::new()
}
}
impl Crc32Fold {
pub const fn new() -> Self {
Self::new_with_initial(CRC32_INITIAL_VALUE)
}
pub const fn new_with_initial(initial: u32) -> Self {
Self {
#[cfg(target_arch = "x86_64")]
fold: pclmulqdq::Accumulator::new(),
value: initial,
}
}
pub fn fold(&mut self, src: &[u8], _start: u32) {
#[cfg(target_arch = "x86_64")]
if crate::cpu_features::is_enabled_pclmulqdq() {
return unsafe { self.fold.fold(src, _start) };
}
#[cfg(target_arch = "aarch64")]
if crate::cpu_features::is_enabled_crc() {
self.value = unsafe { self::acle::crc32_acle_aarch64(self.value, src) };
return;
}
// in this case the start value is ignored
self.value = braid::crc32_braid::<5>(self.value, src);
}
pub fn fold_copy(&mut self, dst: &mut [u8], src: &[u8]) {
#[cfg(target_arch = "x86_64")]
if crate::cpu_features::is_enabled_pclmulqdq() {
return unsafe { self.fold.fold_copy(dst, src) };
}
self.fold(src, 0);
dst[..src.len()].copy_from_slice(src);
}
pub fn finish(self) -> u32 {
#[cfg(target_arch = "x86_64")]
if crate::cpu_features::is_enabled_pclmulqdq() {
return unsafe { self.fold.finish() };
}
self.value
}
}
#[cfg(test)]
mod test {
use test::braid::crc32_braid;
use super::*;
const INPUT: [u8; 1024] = {
let mut array = [0; 1024];
let mut i = 0;
while i < array.len() {
array[i] = i as u8;
i += 1;
}
array
};
#[test]
fn test_crc32_fold() {
// input large enough to trigger the SIMD
let mut h = crc32fast::Hasher::new_with_initial(CRC32_INITIAL_VALUE);
h.update(&INPUT);
assert_eq!(crc32(CRC32_INITIAL_VALUE, &INPUT), h.finalize());
}
#[test]
fn test_crc32_fold_align() {
// SIMD algorithm is sensitive to alignment;
for i in 0..16 {
for start in [CRC32_INITIAL_VALUE, 42] {
let mut h = crc32fast::Hasher::new_with_initial(start);
h.update(&INPUT[i..]);
assert_eq!(
crc32(start, &INPUT[i..]),
h.finalize(),
"offset = {i}, start = {start}"
);
}
}
}
quickcheck::quickcheck! {
fn crc_fold_is_crc32fast(v: Vec<u8>, start: u32) -> bool {
let mut h = crc32fast::Hasher::new_with_initial(start);
h.update(&v);
let a = crc32(start, &v) ;
let b = h.finalize();
a == b
}
}
#[test]
fn chunked() {
const INPUT: &[&[u8]] = &[
&[116],
&[111, 107, 105, 111, 44, 32, 97, 115],
&[121, 110, 99, 45, 115, 116, 100, 44],
&[32, 97, 110, 100, 32, 115, 109, 111],
&[108, 46, 32, 89, 111, 117, 226, 128],
&[153, 118, 101, 32, 112, 114, 111, 98],
&[97, 98, 108, 121, 32, 117, 115, 101],
&[100, 32, 116, 104, 101, 109, 32, 97],
&[116, 32, 115, 111, 109, 101, 32, 112],
&[111, 105, 110, 116, 44, 32, 101, 105],
&[116, 104, 101, 114, 32, 100, 105, 114],
&[101, 99, 116, 108, 121, 32, 111, 114],
&[0],
];
const START: u32 = 2380683574;
let mut in_chunks = START;
for chunk in INPUT {
in_chunks = crc32(in_chunks, chunk);
}
let flattened: Vec<_> = INPUT.iter().copied().flatten().copied().collect();
let flat = crc32(START, &flattened);
assert_eq!(in_chunks, flat);
}
#[test]
fn nasty_alignment() {
const START: u32 = 2380683574;
const FLAT: &[u8] = &[
116, 111, 107, 105, 111, 44, 32, 97, 115, 121, 110, 99, 45, 115, 116, 100, 44, 32, 97,
110, 100, 32, 115, 109, 111, 108, 46, 32, 89, 111, 117, 226, 128, 153, 118, 101, 32,
112, 114, 111, 98, 97, 98, 108, 121, 32, 117, 115, 101, 100, 32, 116, 104, 101, 109,
32, 97, 116, 32, 115, 111, 109, 101, 32, 112, 111, 105, 110, 116, 44, 32, 101, 105,
116, 104, 101, 114, 32, 100, 105, 114, 101, 99, 116, 108, 121, 32, 111, 114, 0,
];
let mut i = 0;
let mut flat = FLAT.to_vec();
while flat[i..].as_ptr() as usize % 16 != 15 {
flat.insert(0, 0);
i += 1;
}
let flat = &flat[i..];
assert_eq!(crc32_braid::<5>(START, flat), crc32(START, flat));
assert_eq!(crc32(2380683574, flat), 1175758345);
}
}
|
