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
41static struct crypto_shash *tfm;
42
43u32 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
61EXPORT_SYMBOL(crc32c);
62
63static int __init libcrc32c_mod_init(void)
64{
65 tfm = crypto_alloc_shash("crc32c", 0, 0);
66 return PTR_ERR_OR_ZERO(tfm);
67}
68
69static void __exit libcrc32c_mod_fini(void)
70{
71 crypto_free_shash(tfm);
72}
73
74const char *crc32c_impl(void)
75{
76 return crypto_shash_driver_name(tfm);
77}
78EXPORT_SYMBOL(crc32c_impl);
79
80module_init(libcrc32c_mod_init);
81module_exit(libcrc32c_mod_fini);
82
83MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
84MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
85MODULE_LICENSE("GPL");
86MODULE_SOFTDEP("pre: crc32c");
87