/*
   * Copyright (C) 2014 Filipe David Borba Manana <fdmanana@gmail.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   */
  
  #include <crypto/hash.h>
  #include <linux/err.h>
  #include "hash.h"
  
  static struct crypto_shash *tfm;
  
  int __init btrfs_hash_init(void)
  {
  	tfm = crypto_alloc_shash("crc32c", 0, 0);

  	return PTR_ERR_OR_ZERO(tfm);

  }

  const char* btrfs_crc32c_impl(void)
  {
  	return crypto_tfm_alg_driver_name(crypto_shash_tfm(tfm));
  }

  void btrfs_hash_exit(void)
  {
  	crypto_free_shash(tfm);
  }
  
  u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length)
  {

  	SHASH_DESC_ON_STACK(shash, tfm);
  	u32 *ctx = (u32 *)shash_desc_ctx(shash);

  	int err;

  	shash->tfm = tfm;
  	shash->flags = 0;
  	*ctx = crc;

  	err = crypto_shash_update(shash, address, length);

  	BUG_ON(err);

  	return *ctx;

  }