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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 | #include <linux/crc32c.h> | |
40 | ||
41 | static struct crypto_shash *tfm; | |
42 | ||
43 | u32 crc32c(u32 crc, const void *address, unsigned int length) | |
44 | { | |
45 | SHASH_DESC_ON_STACK(shash, tfm); | |
46 | u32 ret, *ctx = (u32 *)shash_desc_ctx(shash); | |
47 | int err; | |
48 | ||
49 | shash->tfm = tfm; | |
50 | shash->flags = 0; | |
51 | *ctx = crc; | |
52 | ||
53 | err = crypto_shash_update(shash, address, length); | |
54 | BUG_ON(err); | |
55 | ||
56 | ret = *ctx; | |
57 | barrier_data(ctx); | |
58 | return ret; | |
59 | } | |
60 | ||
61 | EXPORT_SYMBOL(crc32c); | |
62 | ||
63 | static int __init libcrc32c_mod_init(void) | |
64 | { | |
65 | tfm = crypto_alloc_shash("crc32c", 0, 0); | |
66 | return PTR_ERR_OR_ZERO(tfm); | |
67 | } | |
68 | ||
69 | static void __exit libcrc32c_mod_fini(void) | |
70 | { | |
71 | crypto_free_shash(tfm); | |
72 | } | |
73 | ||
74 | module_init(libcrc32c_mod_init); | |
75 | module_exit(libcrc32c_mod_fini); | |
76 | ||
77 | MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>"); | |
78 | MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations"); | |
79 | MODULE_LICENSE("GPL"); | |
80 | MODULE_SOFTDEP("pre: crc32c"); |