// SPDX-License-Identifier: GPL-2.0-or-later

  /* 
   * 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 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.

   */

  #include <crypto/hash.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/crc32c.h>

  static struct crypto_shash *tfm;

  u32 crc32c(u32 crc, const void *address, unsigned int length)

  {

  	SHASH_DESC_ON_STACK(shash, tfm);

  	u32 ret, *ctx = (u32 *)shash_desc_ctx(shash);

  	int err;

  	shash->tfm = tfm;

  	*ctx = crc;

  	err = crypto_shash_update(shash, address, length);

  	BUG_ON(err);

  	ret = *ctx;
  	barrier_data(ctx);
  	return ret;

  }

  EXPORT_SYMBOL(crc32c);

  static int __init libcrc32c_mod_init(void)

  {

  	tfm = crypto_alloc_shash("crc32c", 0, 0);

  	return PTR_ERR_OR_ZERO(tfm);

  }

  static void __exit libcrc32c_mod_fini(void)

  {

  	crypto_free_shash(tfm);

  }

  const char *crc32c_impl(void)
  {
  	return crypto_shash_driver_name(tfm);
  }
  EXPORT_SYMBOL(crc32c_impl);

  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");

  MODULE_SOFTDEP("pre: crc32c");