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