blob: 2c317384fa63663bd51d4654b3b6a65bc1f62bae (
plain) (
blame)
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
|
/*
* Copied from Linux kernel crypto/crc32c.c
* Copyright (c) 2004 Cisco Systems, Inc.
* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
/*
* This is the CRC-32C table
* Generated with:
* width = 32 bits
* poly = 0x1EDC6F41
* reflect input bytes = true
* reflect output bytes = true
*/
static u32 crc32c_table[256];
/*
* Steps through buffer one byte at at time, calculates reflected
* crc using table.
*/
static inline u32 crc32c_le(u32 crc, const char *data, size_t length)
{
while (length--)
crc = crc32c_table[(u8)(crc ^ *data++)] ^ (crc >> 8);
return crc;
}
static inline void btrfs_init_crc32c(void)
{
int i, j;
u32 v;
const u32 poly = 0x82F63B78; /* Bit-reflected CRC32C polynomial */
for (i = 0; i < 256; i++) {
v = i;
for (j = 0; j < 8; j++) {
v = (v >> 1) ^ ((v & 1) ? poly : 0);
}
crc32c_table[i] = v;
}
}
|
