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