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1 | /* |
2 | * CRC32C |
3 | *@Article{castagnoli-crc, |
4 | * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman}, |
5 | * title = {{Optimization of Cyclic Redundancy-Check Codes with 24 |
6 | * and 32 Parity Bits}}, |
7 | * journal = IEEE Transactions on Communication, |
8 | * year = {1993}, |
9 | * volume = {41}, |
10 | * number = {6}, |
11 | * pages = {}, |
12 | * month = {June}, |
13 | *} |
14 | * Used by the iSCSI driver, possibly others, and derived from the |
15 | * the iscsi-crc.c module of the linux-iscsi driver at |
16 | * http://linux-iscsi.sourceforge.net. |
17 | * |
18 | * Following the example of lib/crc32, this function is intended to be |
19 | * flexible and useful for all users. Modules that currently have their |
20 | * own crc32c, but hopefully may be able to use this one are: |
21 | * net/sctp (please add all your doco to here if you change to |
22 | * use this one!) |
23 | * <endoflist> |
24 | * |
25 | * Copyright (c) 2004 Cisco Systems, Inc. |
26 | * |
27 | * This program is free software; you can redistribute it and/or modify it |
28 | * under the terms of the GNU General Public License as published by the Free |
29 | * Software Foundation; either version 2 of the License, or (at your option) |
30 | * any later version. |
31 | * |
32 | */ |
33 | |
34 | #include <crypto/hash.h> |
35 | #include <linux/err.h> |
36 | #include <linux/init.h> |
37 | #include <linux/kernel.h> |
38 | #include <linux/module.h> |
39 | |
40 | static struct crypto_shash *tfm; |
41 | |
42 | u32 crc32c(u32 crc, const void *address, unsigned int length) |
43 | { |
44 | struct { |
45 | struct shash_desc shash; |
46 | char ctx[crypto_shash_descsize(tfm)]; |
47 | } desc; |
48 | int err; |
49 | |
50 | desc.shash.tfm = tfm; |
51 | desc.shash.flags = 0; |
52 | *(u32 *)desc.ctx = crc; |
53 | |
54 | err = crypto_shash_update(&desc.shash, address, length); |
55 | BUG_ON(err); |
56 | |
57 | return *(u32 *)desc.ctx; |
58 | } |
59 | |
60 | EXPORT_SYMBOL(crc32c); |
61 | |
62 | static int __init libcrc32c_mod_init(void) |
63 | { |
64 | tfm = crypto_alloc_shash("crc32c", 0, 0); |
65 | if (IS_ERR(tfm)) |
66 | return PTR_ERR(tfm); |
67 | |
68 | return 0; |
69 | } |
70 | |
71 | static void __exit libcrc32c_mod_fini(void) |
72 | { |
73 | crypto_free_shash(tfm); |
74 | } |
75 | |
76 | module_init(libcrc32c_mod_init); |
77 | module_exit(libcrc32c_mod_fini); |
78 | |
79 | MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); |
80 | MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations"); |
81 | MODULE_LICENSE("GPL"); |
82 |
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