/* 
   * CRC32C
   *@Article{castagnoli-crc,
   * author =       { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
   * title =        {{Optimization of Cyclic Redundancy-Check Codes with 24
   *                 and 32 Parity Bits}},
   * journal =      IEEE Transactions on Communication,
   * year =         {1993},
   * volume =       {41},
   * number =       {6},
   * pages =        {},
   * month =        {June},
   *}
   * Used by the iSCSI driver, possibly others, and derived from the
   * the iscsi-crc.c module of the linux-iscsi driver at
   * http://linux-iscsi.sourceforge.net.
   *
   * Following the example of lib/crc32, this function is intended to be
   * flexible and useful for all users.  Modules that currently have their
   * own crc32c, but hopefully may be able to use this one are:
   *  net/sctp (please add all your doco to here if you change to
   *            use this one!)
   *  <endoflist>
   *
   * Copyright (c) 2004 Cisco Systems, Inc.
   * 
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the Free
   * Software Foundation; either version 2 of the License, or (at your option) 
   * any later version.
   *
   */
  
  #include <crypto/hash.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  
  static struct crypto_shash *tfm;
  
  u32 crc32c(u32 crc, const void *address, unsigned int length)
  {
  	struct {
  		struct shash_desc shash;
  		char ctx[crypto_shash_descsize(tfm)];
  	} desc;
  	int err;
  
  	desc.shash.tfm = tfm;
  	desc.shash.flags = 0;
  	*(u32 *)desc.ctx = crc;
  
  	err = crypto_shash_update(&desc.shash, address, length);
  	BUG_ON(err);
  
  	return *(u32 *)desc.ctx;
  }
  
  EXPORT_SYMBOL(crc32c);
  
  static int __init libcrc32c_mod_init(void)
  {
  	tfm = crypto_alloc_shash("crc32c", 0, 0);
  	if (IS_ERR(tfm))
  		return PTR_ERR(tfm);
  
  	return 0;
  }
  
  static void __exit libcrc32c_mod_fini(void)
  {
  	crypto_free_shash(tfm);
  }
  
  module_init(libcrc32c_mod_init);
  module_exit(libcrc32c_mod_fini);
  
  MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
  MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
  MODULE_LICENSE("GPL");