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/*
* 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");
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