Linux Kernel  3.7.1
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
libcrc32c.c
Go to the documentation of this file.
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 
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 <[email protected]>");
80 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
81 MODULE_LICENSE("GPL");