LXR linux/lib/libcrc32c.c

   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        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
  60EXPORT_SYMBOL(crc32c);
  61
  62static 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
  71static void __exit libcrc32c_mod_fini(void)
  72{
  73        crypto_free_shash(tfm);
  74}
  75
  76module_init(libcrc32c_mod_init);
  77module_exit(libcrc32c_mod_fini);
  78
  79MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
  80MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
  81MODULE_LICENSE("GPL");
  82