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Commit 5d240522 authored by Nick Terrell's avatar Nick Terrell Committed by Chris Mason
Browse files

lib: Add xxhash module 

Adds xxhash kernel module with xxh32 and xxh64 hashes. xxhash is an
extremely fast non-cryptographic hash algorithm for checksumming.
The zstd compression and decompression modules added in the next patch
require xxhash. I extracted it out from zstd since it is useful on its
own. I copied the code from the upstream XXHash source repository and
translated it into kernel style. I ran benchmarks and tests in the kernel
and tests in userland.

I benchmarked xxhash as a special character device. I ran in four modes,
no-op, xxh32, xxh64, and crc32. The no-op mode simply copies the data to
kernel space and ignores it. The xxh32, xxh64, and crc32 modes compute
hashes on the copied data. I also ran it with four different buffer sizes.
The benchmark file is located in the upstream zstd source repository under
`contrib/linux-kernel/xxhash_test.c` [1].

I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
16 GB of RAM, and a SSD. I benchmarked using the file `filesystem.squashfs`
from `ubuntu-16.10-desktop-amd64.iso`, which is 1,536,217,088 B large.
Run the following commands for the benchmark:

    modprobe xxhash_test
    mknod xxhash_test c 245 0
    time cp filesystem.squashfs xxhash_test

The time is reported by the time of the userland `cp`.
The GB/s is computed with

    1,536,217,008 B / time(buffer size, hash)

which includes the time to copy from userland.
The Normalized GB/s is computed with

    1,536,217,088 B / (time(buffer size, hash) - time(buffer size, none)).

| Buffer Size (B) | Hash  | Time (s) | GB/s | Adjusted GB/s |
|-----------------|-------|----------|------|---------------|
|            1024 | none  |    0.408 | 3.77 |             - |
|            1024 | xxh32 |    0.649 | 2.37 |          6.37 |
|            1024 | xxh64 |    0.542 | 2.83 |         11.46 |
|            1024 | crc32 |    1.290 | 1.19 |          1.74 |
|            4096 | none  |    0.380 | 4.04 |             - |
|            4096 | xxh32 |    0.645 | 2.38 |          5.79 |
|            4096 | xxh64 |    0.500 | 3.07 |         12.80 |
|            4096 | crc32 |    1.168 | 1.32 |          1.95 |
|            8192 | none  |    0.351 | 4.38 |             - |
|            8192 | xxh32 |    0.614 | 2.50 |          5.84 |
|            8192 | xxh64 |    0.464 | 3.31 |         13.60 |
|            8192 | crc32 |    1.163 | 1.32 |          1.89 |
|           16384 | none  |    0.346 | 4.43 |             - |
|           16384 | xxh32 |    0.590 | 2.60 |          6.30 |
|           16384 | xxh64 |    0.466 | 3.30 |         12.80 |
|           16384 | crc32 |    1.183 | 1.30 |          1.84 |

Tested in userland using the test-suite in the zstd repo under
`contrib/linux-kernel/test/XXHashUserlandTest.cpp` [2] by mocking the
kernel functions. A line in each branch of every function in `xxhash.c`
was commented out to ensure that the test-suite fails. Additionally
tested while testing zstd and with SMHasher [3].

[1] https://phabricator.intern.facebook.com/P57526246
[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/XXHashUserlandTest.cpp
[3] https://github.com/aappleby/smhasher

zstd source repository: https://github.com/facebook/zstd
XXHash source repository: https://github.com/cyan4973/xxhash



Signed-off-by: default avatarNick Terrell <terrelln@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent ef954844

include/linux/xxhash.h

0 → 100644
+236 −0
Original line number Diff line number Diff line 
/*

 * xxHash - Extremely Fast Hash algorithm

 * Copyright (C) 2012-2016, Yann Collet.

 *

 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are

 * met:

 *

 *   * Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *   * Redistributions in binary form must reproduce the above

 *     copyright notice, this list of conditions and the following disclaimer

 *     in the documentation and/or other materials provided with the

 *     distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * This program is free software; you can redistribute it and/or modify it under

 * the terms of the GNU General Public License version 2 as published by the

 * Free Software Foundation. This program is dual-licensed; you may select

 * either version 2 of the GNU General Public License ("GPL") or BSD license

 * ("BSD").

 *

 * You can contact the author at:

 * - xxHash homepage: http://cyan4973.github.io/xxHash/

 * - xxHash source repository: https://github.com/Cyan4973/xxHash

 */



/*

 * Notice extracted from xxHash homepage:

 *

 * xxHash is an extremely fast Hash algorithm, running at RAM speed limits.

 * It also successfully passes all tests from the SMHasher suite.

 *

 * Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2

 * Duo @3GHz)

 *

 * Name            Speed       Q.Score   Author

 * xxHash          5.4 GB/s     10

 * CrapWow         3.2 GB/s      2       Andrew

 * MumurHash 3a    2.7 GB/s     10       Austin Appleby

 * SpookyHash      2.0 GB/s     10       Bob Jenkins

 * SBox            1.4 GB/s      9       Bret Mulvey

 * Lookup3         1.2 GB/s      9       Bob Jenkins

 * SuperFastHash   1.2 GB/s      1       Paul Hsieh

 * CityHash64      1.05 GB/s    10       Pike & Alakuijala

 * FNV             0.55 GB/s     5       Fowler, Noll, Vo

 * CRC32           0.43 GB/s     9

 * MD5-32          0.33 GB/s    10       Ronald L. Rivest

 * SHA1-32         0.28 GB/s    10

 *

 * Q.Score is a measure of quality of the hash function.

 * It depends on successfully passing SMHasher test set.

 * 10 is a perfect score.

 *

 * A 64-bits version, named xxh64 offers much better speed,

 * but for 64-bits applications only.

 * Name     Speed on 64 bits    Speed on 32 bits

 * xxh64       13.8 GB/s            1.9 GB/s

 * xxh32        6.8 GB/s            6.0 GB/s

 */



#ifndef XXHASH_H

#define XXHASH_H



#include <linux/types.h>



/*-****************************

 * Simple Hash Functions

 *****************************/



/**

 * xxh32() - calculate the 32-bit hash of the input with a given seed.

 *

 * @input:  The data to hash.

 * @length: The length of the data to hash.

 * @seed:   The seed can be used to alter the result predictably.

 *

 * Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s

 *

 * Return:  The 32-bit hash of the data.

 */

uint32_t xxh32(const void *input, size_t length, uint32_t seed);



/**

 * xxh64() - calculate the 64-bit hash of the input with a given seed.

 *

 * @input:  The data to hash.

 * @length: The length of the data to hash.

 * @seed:   The seed can be used to alter the result predictably.

 *

 * This function runs 2x faster on 64-bit systems, but slower on 32-bit systems.

 *

 * Return:  The 64-bit hash of the data.

 */

uint64_t xxh64(const void *input, size_t length, uint64_t seed);



/*-****************************

 * Streaming Hash Functions

 *****************************/



/*

 * These definitions are only meant to allow allocation of XXH state

 * statically, on stack, or in a struct for example.

 * Do not use members directly.

 */



/**

 * struct xxh32_state - private xxh32 state, do not use members directly

 */

struct xxh32_state {

	uint32_t total_len_32;

	uint32_t large_len;

	uint32_t v1;

	uint32_t v2;

	uint32_t v3;

	uint32_t v4;

	uint32_t mem32[4];

	uint32_t memsize;

};



/**

 * struct xxh32_state - private xxh64 state, do not use members directly

 */

struct xxh64_state {

	uint64_t total_len;

	uint64_t v1;

	uint64_t v2;

	uint64_t v3;

	uint64_t v4;

	uint64_t mem64[4];

	uint32_t memsize;

};



/**

 * xxh32_reset() - reset the xxh32 state to start a new hashing operation

 *

 * @state: The xxh32 state to reset.

 * @seed:  Initialize the hash state with this seed.

 *

 * Call this function on any xxh32_state to prepare for a new hashing operation.

 */

void xxh32_reset(struct xxh32_state *state, uint32_t seed);



/**

 * xxh32_update() - hash the data given and update the xxh32 state

 *

 * @state:  The xxh32 state to update.

 * @input:  The data to hash.

 * @length: The length of the data to hash.

 *

 * After calling xxh32_reset() call xxh32_update() as many times as necessary.

 *

 * Return:  Zero on success, otherwise an error code.

 */

int xxh32_update(struct xxh32_state *state, const void *input, size_t length);



/**

 * xxh32_digest() - produce the current xxh32 hash

 *

 * @state: Produce the current xxh32 hash of this state.

 *

 * A hash value can be produced at any time. It is still possible to continue

 * inserting input into the hash state after a call to xxh32_digest(), and

 * generate new hashes later on, by calling xxh32_digest() again.

 *

 * Return: The xxh32 hash stored in the state.

 */

uint32_t xxh32_digest(const struct xxh32_state *state);



/**

 * xxh64_reset() - reset the xxh64 state to start a new hashing operation

 *

 * @state: The xxh64 state to reset.

 * @seed:  Initialize the hash state with this seed.

 */

void xxh64_reset(struct xxh64_state *state, uint64_t seed);



/**

 * xxh64_update() - hash the data given and update the xxh64 state

 * @state:  The xxh64 state to update.

 * @input:  The data to hash.

 * @length: The length of the data to hash.

 *

 * After calling xxh64_reset() call xxh64_update() as many times as necessary.

 *

 * Return:  Zero on success, otherwise an error code.

 */

int xxh64_update(struct xxh64_state *state, const void *input, size_t length);



/**

 * xxh64_digest() - produce the current xxh64 hash

 *

 * @state: Produce the current xxh64 hash of this state.

 *

 * A hash value can be produced at any time. It is still possible to continue

 * inserting input into the hash state after a call to xxh64_digest(), and

 * generate new hashes later on, by calling xxh64_digest() again.

 *

 * Return: The xxh64 hash stored in the state.

 */

uint64_t xxh64_digest(const struct xxh64_state *state);



/*-**************************

 * Utils

 ***************************/



/**

 * xxh32_copy_state() - copy the source state into the destination state

 *

 * @src: The source xxh32 state.

 * @dst: The destination xxh32 state.

 */

void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src);



/**

 * xxh64_copy_state() - copy the source state into the destination state

 *

 * @src: The source xxh64 state.

 * @dst: The destination xxh64 state.

 */

void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src);



#endif /* XXHASH_H */

lib/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -192,6 +192,9 @@ config CRC8 
	  when they need to do cyclic redundancy check according CRC8

	  algorithm. Module will be called crc8.



config XXHASH

	tristate



config AUDIT_GENERIC

	bool

	depends on AUDIT && !AUDIT_ARCH

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -102,6 +102,7 @@ obj-$(CONFIG_CRC4) += crc4.o 
obj-$(CONFIG_CRC7)	+= crc7.o

obj-$(CONFIG_LIBCRC32C)	+= libcrc32c.o

obj-$(CONFIG_CRC8)	+= crc8.o

obj-$(CONFIG_XXHASH)	+= xxhash.o

obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o



obj-$(CONFIG_842_COMPRESS) += 842/

lib/xxhash.c

0 → 100644
+500 −0
Original line number Diff line number Diff line 
/*

 * xxHash - Extremely Fast Hash algorithm

 * Copyright (C) 2012-2016, Yann Collet.

 *

 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are

 * met:

 *

 *   * Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *   * Redistributions in binary form must reproduce the above

 *     copyright notice, this list of conditions and the following disclaimer

 *     in the documentation and/or other materials provided with the

 *     distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * This program is free software; you can redistribute it and/or modify it under

 * the terms of the GNU General Public License version 2 as published by the

 * Free Software Foundation. This program is dual-licensed; you may select

 * either version 2 of the GNU General Public License ("GPL") or BSD license

 * ("BSD").

 *

 * You can contact the author at:

 * - xxHash homepage: http://cyan4973.github.io/xxHash/

 * - xxHash source repository: https://github.com/Cyan4973/xxHash

 */



#include <asm/unaligned.h>

#include <linux/errno.h>

#include <linux/compiler.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/string.h>

#include <linux/xxhash.h>



/*-*************************************

 * Macros

 **************************************/

#define xxh_rotl32(x, r) ((x << r) | (x >> (32 - r)))

#define xxh_rotl64(x, r) ((x << r) | (x >> (64 - r)))



#ifdef __LITTLE_ENDIAN

# define XXH_CPU_LITTLE_ENDIAN 1

#else

# define XXH_CPU_LITTLE_ENDIAN 0

#endif



/*-*************************************

 * Constants

 **************************************/

static const uint32_t PRIME32_1 = 2654435761U;

static const uint32_t PRIME32_2 = 2246822519U;

static const uint32_t PRIME32_3 = 3266489917U;

static const uint32_t PRIME32_4 =  668265263U;

static const uint32_t PRIME32_5 =  374761393U;



static const uint64_t PRIME64_1 = 11400714785074694791ULL;

static const uint64_t PRIME64_2 = 14029467366897019727ULL;

static const uint64_t PRIME64_3 =  1609587929392839161ULL;

static const uint64_t PRIME64_4 =  9650029242287828579ULL;

static const uint64_t PRIME64_5 =  2870177450012600261ULL;



/*-**************************

 *  Utils

 ***************************/

void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src)

{

	memcpy(dst, src, sizeof(*dst));

}

EXPORT_SYMBOL(xxh32_copy_state);



void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src)

{

	memcpy(dst, src, sizeof(*dst));

}

EXPORT_SYMBOL(xxh64_copy_state);



/*-***************************

 * Simple Hash Functions

 ****************************/

static uint32_t xxh32_round(uint32_t seed, const uint32_t input)

{

	seed += input * PRIME32_2;

	seed = xxh_rotl32(seed, 13);

	seed *= PRIME32_1;

	return seed;

}



uint32_t xxh32(const void *input, const size_t len, const uint32_t seed)

{

	const uint8_t *p = (const uint8_t *)input;

	const uint8_t *b_end = p + len;

	uint32_t h32;



	if (len >= 16) {

		const uint8_t *const limit = b_end - 16;

		uint32_t v1 = seed + PRIME32_1 + PRIME32_2;

		uint32_t v2 = seed + PRIME32_2;

		uint32_t v3 = seed + 0;

		uint32_t v4 = seed - PRIME32_1;



		do {

			v1 = xxh32_round(v1, get_unaligned_le32(p));

			p += 4;

			v2 = xxh32_round(v2, get_unaligned_le32(p));

			p += 4;

			v3 = xxh32_round(v3, get_unaligned_le32(p));

			p += 4;

			v4 = xxh32_round(v4, get_unaligned_le32(p));

			p += 4;

		} while (p <= limit);



		h32 = xxh_rotl32(v1, 1) + xxh_rotl32(v2, 7) +

			xxh_rotl32(v3, 12) + xxh_rotl32(v4, 18);

	} else {

		h32 = seed + PRIME32_5;

	}



	h32 += (uint32_t)len;



	while (p + 4 <= b_end) {

		h32 += get_unaligned_le32(p) * PRIME32_3;

		h32 = xxh_rotl32(h32, 17) * PRIME32_4;

		p += 4;

	}



	while (p < b_end) {

		h32 += (*p) * PRIME32_5;

		h32 = xxh_rotl32(h32, 11) * PRIME32_1;

		p++;

	}



	h32 ^= h32 >> 15;

	h32 *= PRIME32_2;

	h32 ^= h32 >> 13;

	h32 *= PRIME32_3;

	h32 ^= h32 >> 16;



	return h32;

}

EXPORT_SYMBOL(xxh32);



static uint64_t xxh64_round(uint64_t acc, const uint64_t input)

{

	acc += input * PRIME64_2;

	acc = xxh_rotl64(acc, 31);

	acc *= PRIME64_1;

	return acc;

}



static uint64_t xxh64_merge_round(uint64_t acc, uint64_t val)

{

	val = xxh64_round(0, val);

	acc ^= val;

	acc = acc * PRIME64_1 + PRIME64_4;

	return acc;

}



uint64_t xxh64(const void *input, const size_t len, const uint64_t seed)

{

	const uint8_t *p = (const uint8_t *)input;

	const uint8_t *const b_end = p + len;

	uint64_t h64;



	if (len >= 32) {

		const uint8_t *const limit = b_end - 32;

		uint64_t v1 = seed + PRIME64_1 + PRIME64_2;

		uint64_t v2 = seed + PRIME64_2;

		uint64_t v3 = seed + 0;

		uint64_t v4 = seed - PRIME64_1;



		do {

			v1 = xxh64_round(v1, get_unaligned_le64(p));

			p += 8;

			v2 = xxh64_round(v2, get_unaligned_le64(p));

			p += 8;

			v3 = xxh64_round(v3, get_unaligned_le64(p));

			p += 8;

			v4 = xxh64_round(v4, get_unaligned_le64(p));

			p += 8;

		} while (p <= limit);



		h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +

			xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);

		h64 = xxh64_merge_round(h64, v1);

		h64 = xxh64_merge_round(h64, v2);

		h64 = xxh64_merge_round(h64, v3);

		h64 = xxh64_merge_round(h64, v4);



	} else {

		h64  = seed + PRIME64_5;

	}



	h64 += (uint64_t)len;



	while (p + 8 <= b_end) {

		const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));



		h64 ^= k1;

		h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;

		p += 8;

	}



	if (p + 4 <= b_end) {

		h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;

		h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;

		p += 4;

	}



	while (p < b_end) {

		h64 ^= (*p) * PRIME64_5;

		h64 = xxh_rotl64(h64, 11) * PRIME64_1;

		p++;

	}



	h64 ^= h64 >> 33;

	h64 *= PRIME64_2;

	h64 ^= h64 >> 29;

	h64 *= PRIME64_3;

	h64 ^= h64 >> 32;



	return h64;

}

EXPORT_SYMBOL(xxh64);



/*-**************************************************

 * Advanced Hash Functions

 ***************************************************/

void xxh32_reset(struct xxh32_state *statePtr, const uint32_t seed)

{

	/* use a local state for memcpy() to avoid strict-aliasing warnings */

	struct xxh32_state state;



	memset(&state, 0, sizeof(state));

	state.v1 = seed + PRIME32_1 + PRIME32_2;

	state.v2 = seed + PRIME32_2;

	state.v3 = seed + 0;

	state.v4 = seed - PRIME32_1;

	memcpy(statePtr, &state, sizeof(state));

}

EXPORT_SYMBOL(xxh32_reset);



void xxh64_reset(struct xxh64_state *statePtr, const uint64_t seed)

{

	/* use a local state for memcpy() to avoid strict-aliasing warnings */

	struct xxh64_state state;



	memset(&state, 0, sizeof(state));

	state.v1 = seed + PRIME64_1 + PRIME64_2;

	state.v2 = seed + PRIME64_2;

	state.v3 = seed + 0;

	state.v4 = seed - PRIME64_1;

	memcpy(statePtr, &state, sizeof(state));

}

EXPORT_SYMBOL(xxh64_reset);



int xxh32_update(struct xxh32_state *state, const void *input, const size_t len)

{

	const uint8_t *p = (const uint8_t *)input;

	const uint8_t *const b_end = p + len;



	if (input == NULL)

		return -EINVAL;



	state->total_len_32 += (uint32_t)len;

	state->large_len |= (len >= 16) | (state->total_len_32 >= 16);



	if (state->memsize + len < 16) { /* fill in tmp buffer */

		memcpy((uint8_t *)(state->mem32) + state->memsize, input, len);

		state->memsize += (uint32_t)len;

		return 0;

	}



	if (state->memsize) { /* some data left from previous update */

		const uint32_t *p32 = state->mem32;



		memcpy((uint8_t *)(state->mem32) + state->memsize, input,

			16 - state->memsize);



		state->v1 = xxh32_round(state->v1, get_unaligned_le32(p32));

		p32++;

		state->v2 = xxh32_round(state->v2, get_unaligned_le32(p32));

		p32++;

		state->v3 = xxh32_round(state->v3, get_unaligned_le32(p32));

		p32++;

		state->v4 = xxh32_round(state->v4, get_unaligned_le32(p32));

		p32++;



		p += 16-state->memsize;

		state->memsize = 0;

	}



	if (p <= b_end - 16) {

		const uint8_t *const limit = b_end - 16;

		uint32_t v1 = state->v1;

		uint32_t v2 = state->v2;

		uint32_t v3 = state->v3;

		uint32_t v4 = state->v4;



		do {

			v1 = xxh32_round(v1, get_unaligned_le32(p));

			p += 4;

			v2 = xxh32_round(v2, get_unaligned_le32(p));

			p += 4;

			v3 = xxh32_round(v3, get_unaligned_le32(p));

			p += 4;

			v4 = xxh32_round(v4, get_unaligned_le32(p));

			p += 4;

		} while (p <= limit);



		state->v1 = v1;

		state->v2 = v2;

		state->v3 = v3;

		state->v4 = v4;

	}



	if (p < b_end) {

		memcpy(state->mem32, p, (size_t)(b_end-p));

		state->memsize = (uint32_t)(b_end-p);

	}



	return 0;

}

EXPORT_SYMBOL(xxh32_update);



uint32_t xxh32_digest(const struct xxh32_state *state)

{

	const uint8_t *p = (const uint8_t *)state->mem32;

	const uint8_t *const b_end = (const uint8_t *)(state->mem32) +

		state->memsize;

	uint32_t h32;



	if (state->large_len) {

		h32 = xxh_rotl32(state->v1, 1) + xxh_rotl32(state->v2, 7) +

			xxh_rotl32(state->v3, 12) + xxh_rotl32(state->v4, 18);

	} else {

		h32 = state->v3 /* == seed */ + PRIME32_5;

	}



	h32 += state->total_len_32;



	while (p + 4 <= b_end) {

		h32 += get_unaligned_le32(p) * PRIME32_3;

		h32 = xxh_rotl32(h32, 17) * PRIME32_4;

		p += 4;

	}



	while (p < b_end) {

		h32 += (*p) * PRIME32_5;

		h32 = xxh_rotl32(h32, 11) * PRIME32_1;

		p++;

	}



	h32 ^= h32 >> 15;

	h32 *= PRIME32_2;

	h32 ^= h32 >> 13;

	h32 *= PRIME32_3;

	h32 ^= h32 >> 16;



	return h32;

}

EXPORT_SYMBOL(xxh32_digest);



int xxh64_update(struct xxh64_state *state, const void *input, const size_t len)

{

	const uint8_t *p = (const uint8_t *)input;

	const uint8_t *const b_end = p + len;



	if (input == NULL)

		return -EINVAL;



	state->total_len += len;



	if (state->memsize + len < 32) { /* fill in tmp buffer */

		memcpy(((uint8_t *)state->mem64) + state->memsize, input, len);

		state->memsize += (uint32_t)len;

		return 0;

	}



	if (state->memsize) { /* tmp buffer is full */

		uint64_t *p64 = state->mem64;



		memcpy(((uint8_t *)p64) + state->memsize, input,

			32 - state->memsize);



		state->v1 = xxh64_round(state->v1, get_unaligned_le64(p64));

		p64++;

		state->v2 = xxh64_round(state->v2, get_unaligned_le64(p64));

		p64++;

		state->v3 = xxh64_round(state->v3, get_unaligned_le64(p64));

		p64++;

		state->v4 = xxh64_round(state->v4, get_unaligned_le64(p64));



		p += 32 - state->memsize;

		state->memsize = 0;

	}



	if (p + 32 <= b_end) {

		const uint8_t *const limit = b_end - 32;

		uint64_t v1 = state->v1;

		uint64_t v2 = state->v2;

		uint64_t v3 = state->v3;

		uint64_t v4 = state->v4;



		do {

			v1 = xxh64_round(v1, get_unaligned_le64(p));

			p += 8;

			v2 = xxh64_round(v2, get_unaligned_le64(p));

			p += 8;

			v3 = xxh64_round(v3, get_unaligned_le64(p));

			p += 8;

			v4 = xxh64_round(v4, get_unaligned_le64(p));

			p += 8;

		} while (p <= limit);



		state->v1 = v1;

		state->v2 = v2;

		state->v3 = v3;

		state->v4 = v4;

	}



	if (p < b_end) {

		memcpy(state->mem64, p, (size_t)(b_end-p));

		state->memsize = (uint32_t)(b_end - p);

	}



	return 0;

}

EXPORT_SYMBOL(xxh64_update);



uint64_t xxh64_digest(const struct xxh64_state *state)

{

	const uint8_t *p = (const uint8_t *)state->mem64;

	const uint8_t *const b_end = (const uint8_t *)state->mem64 +

		state->memsize;

	uint64_t h64;



	if (state->total_len >= 32) {

		const uint64_t v1 = state->v1;

		const uint64_t v2 = state->v2;

		const uint64_t v3 = state->v3;

		const uint64_t v4 = state->v4;



		h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +

			xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);

		h64 = xxh64_merge_round(h64, v1);

		h64 = xxh64_merge_round(h64, v2);

		h64 = xxh64_merge_round(h64, v3);

		h64 = xxh64_merge_round(h64, v4);

	} else {

		h64  = state->v3 + PRIME64_5;

	}



	h64 += (uint64_t)state->total_len;



	while (p + 8 <= b_end) {

		const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));



		h64 ^= k1;

		h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;

		p += 8;

	}



	if (p + 4 <= b_end) {

		h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;

		h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;

		p += 4;

	}



	while (p < b_end) {

		h64 ^= (*p) * PRIME64_5;

		h64 = xxh_rotl64(h64, 11) * PRIME64_1;

		p++;

	}



	h64 ^= h64 >> 33;

	h64 *= PRIME64_2;

	h64 ^= h64 >> 29;

	h64 *= PRIME64_3;

	h64 ^= h64 >> 32;



	return h64;

}

EXPORT_SYMBOL(xxh64_digest);



MODULE_LICENSE("Dual BSD/GPL");

MODULE_DESCRIPTION("xxHash");