lib: update LZ4 compressor module

Patch series "Update LZ4 compressor module", v7.

This patchset updates the LZ4 compression module to a version based on
LZ4 v1.7.3 allowing to use the fast compression algorithm aka LZ4 fast
which provides an "acceleration" parameter as a tradeoff between high
compression ratio and high compression speed.

We want to use LZ4 fast in order to support compression in lustre and
(mostly, based on that) investigate data reduction techniques in behalf
of storage systems.

Also, it will be useful for other users of LZ4 compression, as with LZ4
fast it is possible to enable applications to use fast and/or high
compression depending on the usecase.  For instance, ZRAM is offering a
LZ4 backend and could benefit from an updated LZ4 in the kernel.

LZ4 homepage: http://www.lz4.org/
LZ4 source repository: https://github.com/lz4/lz4 Source version: 1.7.3

Benchmark (taken from [1], Core i5-4300U @1.9GHz):
----------------|--------------|----------------|----------
Compressor      | Compression  | Decompression  | Ratio
----------------|--------------|----------------|----------
memcpy          |  4200 MB/s   |  4200 MB/s     | 1.000
LZ4 fast 50     |  1080 MB/s   |  2650 MB/s     | 1.375
LZ4 fast 17     |   680 MB/s   |  2220 MB/s     | 1.607
LZ4 fast 5      |   475 MB/s   |  1920 MB/s     | 1.886
LZ4 default     |   385 MB/s   |  1850 MB/s     | 2.101

[1] http://fastcompression.blogspot.de/2015/04/sampling-or-faster-lz4.html

[PATCH 1/5] lib: Update LZ4 compressor module
[PATCH 2/5] lib/decompress_unlz4: Change module to work with new LZ4 module version
[PATCH 3/5] crypto: Change LZ4 modules to work with new LZ4 module version
[PATCH 4/5] fs/pstore: fs/squashfs: Change usage of LZ4 to work with new LZ4 version
[PATCH 5/5] lib/lz4: Remove back-compat wrappers

This patch (of 5):

Update the LZ4 kernel module to LZ4 v1.7.3 by Yann Collet.  The kernel
module is inspired by the previous work by Chanho Min.  The updated LZ4
module will not break existing code since the patchset contains
appropriate changes.

API changes:

New method LZ4_compress_fast which differs from the variant available in
kernel by the new acceleration parameter, allowing to trade compression
ratio for more compression speed and vice versa.

LZ4_decompress_fast is the respective decompression method, featuring a
very fast decoder (multiple GB/s per core), able to reach RAM speed in
multi-core systems.  The decompressor allows to decompress data
compressed with LZ4 fast as well as the LZ4 HC (high compression)
algorithm.

Also the useful functions LZ4_decompress_safe_partial and
LZ4_compress_destsize were added.  The latter reverses the logic by
trying to compress as much data as possible from source to dest while
the former aims to decompress partial blocks of data.

A bunch of streaming functions were also added which allow
compressig/decompressing data in multiple steps (so called "streaming
mode").

The methods lz4_compress and lz4_decompress_unknownoutputsize are now
known as LZ4_compress_default respectivley LZ4_decompress_safe.  The old
methods will be removed since there's no callers left in the code.

[arnd@arndb.de: fix KERNEL_LZ4 support]
  Link: http://lkml.kernel.org/r/20170208211946.2839649-1-arnd@arndb.de
[akpm@linux-foundation.org: simplify]
[akpm@linux-foundation.org: fix the simplification]
[4sschmid@informatik.uni-hamburg.de: fix performance regressions]
  Link: http://lkml.kernel.org/r/1486898178-17125-2-git-send-email-4sschmid@informatik.uni-hamburg.de
[4sschmid@informatik.uni-hamburg.de: v8]
  Link: http://lkml.kernel.org/r/1487182598-15351-2-git-send-email-4sschmid@informatik.uni-hamburg.de
Link: http://lkml.kernel.org/r/1486321748-19085-2-git-send-email-4sschmid@informatik.uni-hamburg.de
Signed-off-by: Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Bongkyu Kim <bongkyu.kim@lge.com>
Cc: Rui Salvaterra <rsalvaterra@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@davemloft.net>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 560 insertions, 307 deletions

diff --git a/lib/lz4/lz4hc_compress.c b/lib/lz4/lz4hc_compress.c
index f344f76b6559..e1fbf1561e55 100644
--- a/lib/lz4/lz4hc_compress.c
+++ b/lib/lz4/lz4hc_compress.c
@@ -1,19 +1,17 @@
 /*
  * LZ4 HC - High Compression Mode of LZ4
- * Copyright (C) 2011-2012, Yann Collet.
- * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ * Copyright (C) 2011-2015, 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
+ *	* 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
@@ -25,323 +23,361 @@
  * 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.
- *
  * You can contact the author at :
- * - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
- * - LZ4 source repository : http://code.google.com/p/lz4/
+ *	- LZ4 homepage : http://www.lz4.org
+ *	- LZ4 source repository : https://github.com/lz4/lz4
  *
- *  Changed for kernel use by:
- *  Chanho Min <chanho.min@lge.com>
+ *	Changed for kernel usage by:
+ *	Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
  */
 
-#include <linux/module.h>
-#include <linux/kernel.h>
+/*-************************************
+ *	Dependencies
+ **************************************/
 #include <linux/lz4.h>
-#include <asm/unaligned.h>
 #include "lz4defs.h"
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/string.h> /* memset */
+
+/* *************************************
+ *	Local Constants and types
+ ***************************************/
 
-struct lz4hc_data {
-	const u8 *base;
-	HTYPE hashtable[HASHTABLESIZE];
-	u16 chaintable[MAXD];
-	const u8 *nexttoupdate;
-} __attribute__((__packed__));
+#define OPTIMAL_ML (int)((ML_MASK - 1) + MINMATCH)
 
-static inline int lz4hc_init(struct lz4hc_data *hc4, const u8 *base)
+#define HASH_FUNCTION(i)	(((i) * 2654435761U) \
+	>> ((MINMATCH*8) - LZ4HC_HASH_LOG))
+#define DELTANEXTU16(p)	chainTable[(U16)(p)] /* faster */
+
+static U32 LZ4HC_hashPtr(const void *ptr)
+{
+	return HASH_FUNCTION(LZ4_read32(ptr));
+}
+
+/**************************************
+ *	HC Compression
+ **************************************/
+static void LZ4HC_init(LZ4HC_CCtx_internal *hc4, const BYTE *start)
 {
-	memset((void *)hc4->hashtable, 0, sizeof(hc4->hashtable));
-	memset(hc4->chaintable, 0xFF, sizeof(hc4->chaintable));
-
-#if LZ4_ARCH64
-	hc4->nexttoupdate = base + 1;
-#else
-	hc4->nexttoupdate = base;
-#endif
-	hc4->base = base;
-	return 1;
+	memset((void *)hc4->hashTable, 0, sizeof(hc4->hashTable));
+	memset(hc4->chainTable, 0xFF, sizeof(hc4->chainTable));
+	hc4->nextToUpdate = 64 * KB;
+	hc4->base = start - 64 * KB;
+	hc4->end = start;
+	hc4->dictBase = start - 64 * KB;
+	hc4->dictLimit = 64 * KB;
+	hc4->lowLimit = 64 * KB;
 }
 
 /* Update chains up to ip (excluded) */
-static inline void lz4hc_insert(struct lz4hc_data *hc4, const u8 *ip)
+static FORCE_INLINE void LZ4HC_Insert(LZ4HC_CCtx_internal *hc4,
+	const BYTE *ip)
 {
-	u16 *chaintable = hc4->chaintable;
-	HTYPE *hashtable  = hc4->hashtable;
-#if LZ4_ARCH64
+	U16 * const chainTable = hc4->chainTable;
+	U32 * const hashTable	= hc4->hashTable;
 	const BYTE * const base = hc4->base;
-#else
-	const int base = 0;
-#endif
+	U32 const target = (U32)(ip - base);
+	U32 idx = hc4->nextToUpdate;
+
+	while (idx < target) {
+		U32 const h = LZ4HC_hashPtr(base + idx);
+		size_t delta = idx - hashTable[h];
 
-	while (hc4->nexttoupdate < ip) {
-		const u8 *p = hc4->nexttoupdate;
-		size_t delta = p - (hashtable[HASH_VALUE(p)] + base);
 		if (delta > MAX_DISTANCE)
 			delta = MAX_DISTANCE;
-		chaintable[(size_t)(p) & MAXD_MASK] = (u16)delta;
-		hashtable[HASH_VALUE(p)] = (p) - base;
-		hc4->nexttoupdate++;
-	}
-}
 
-static inline size_t lz4hc_commonlength(const u8 *p1, const u8 *p2,
-		const u8 *const matchlimit)
-{
-	const u8 *p1t = p1;
-
-	while (p1t < matchlimit - (STEPSIZE - 1)) {
-#if LZ4_ARCH64
-		u64 diff = A64(p2) ^ A64(p1t);
-#else
-		u32 diff = A32(p2) ^ A32(p1t);
-#endif
-		if (!diff) {
-			p1t += STEPSIZE;
-			p2 += STEPSIZE;
-			continue;
-		}
-		p1t += LZ4_NBCOMMONBYTES(diff);
-		return p1t - p1;
-	}
-#if LZ4_ARCH64
-	if ((p1t < (matchlimit-3)) && (A32(p2) == A32(p1t))) {
-		p1t += 4;
-		p2 += 4;
-	}
-#endif
+		DELTANEXTU16(idx) = (U16)delta;
 
-	if ((p1t < (matchlimit - 1)) && (A16(p2) == A16(p1t))) {
-		p1t += 2;
-		p2 += 2;
+		hashTable[h] = idx;
+		idx++;
 	}
-	if ((p1t < matchlimit) && (*p2 == *p1t))
-		p1t++;
-	return p1t - p1;
+
+	hc4->nextToUpdate = target;
 }
 
-static inline int lz4hc_insertandfindbestmatch(struct lz4hc_data *hc4,
-		const u8 *ip, const u8 *const matchlimit, const u8 **matchpos)
+static FORCE_INLINE int LZ4HC_InsertAndFindBestMatch(
+	LZ4HC_CCtx_internal *hc4, /* Index table will be updated */
+	const BYTE *ip,
+	const BYTE * const iLimit,
+	const BYTE **matchpos,
+	const int maxNbAttempts)
 {
-	u16 *const chaintable = hc4->chaintable;
-	HTYPE *const hashtable = hc4->hashtable;
-	const u8 *ref;
-#if LZ4_ARCH64
+	U16 * const chainTable = hc4->chainTable;
+	U32 * const HashTable = hc4->hashTable;
 	const BYTE * const base = hc4->base;
-#else
-	const int base = 0;
-#endif
-	int nbattempts = MAX_NB_ATTEMPTS;
-	size_t repl = 0, ml = 0;
-	u16 delta;
+	const BYTE * const dictBase = hc4->dictBase;
+	const U32 dictLimit = hc4->dictLimit;
+	const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base))
+		? hc4->lowLimit
+		: (U32)(ip - base) - (64 * KB - 1);
+	U32 matchIndex;
+	int nbAttempts = maxNbAttempts;
+	size_t ml = 0;
 
 	/* HC4 match finder */
-	lz4hc_insert(hc4, ip);
-	ref = hashtable[HASH_VALUE(ip)] + base;
-
-	/* potential repetition */
-	if (ref >= ip-4) {
-		/* confirmed */
-		if (A32(ref) == A32(ip)) {
-			delta = (u16)(ip-ref);
-			repl = ml  = lz4hc_commonlength(ip + MINMATCH,
-					ref + MINMATCH, matchlimit) + MINMATCH;
-			*matchpos = ref;
-		}
-		ref -= (size_t)chaintable[(size_t)(ref) & MAXD_MASK];
-	}
+	LZ4HC_Insert(hc4, ip);
+	matchIndex = HashTable[LZ4HC_hashPtr(ip)];
+
+	while ((matchIndex >= lowLimit)
+		&& (nbAttempts)) {
+		nbAttempts--;
+		if (matchIndex >= dictLimit) {
+			const BYTE * const match = base + matchIndex;
+
+			if (*(match + ml) == *(ip + ml)
+				&& (LZ4_read32(match) == LZ4_read32(ip))) {
+				size_t const mlt = LZ4_count(ip + MINMATCH,
+					match + MINMATCH, iLimit) + MINMATCH;
 
-	while ((ref >= ip - MAX_DISTANCE) && nbattempts) {
-		nbattempts--;
-		if (*(ref + ml) == *(ip + ml)) {
-			if (A32(ref) == A32(ip)) {
-				size_t mlt =
-					lz4hc_commonlength(ip + MINMATCH,
-					ref + MINMATCH, matchlimit) + MINMATCH;
 				if (mlt > ml) {
 					ml = mlt;
-					*matchpos = ref;
+					*matchpos = match;
+				}
+			}
+		} else {
+			const BYTE * const match = dictBase + matchIndex;
+
+			if (LZ4_read32(match) == LZ4_read32(ip)) {
+				size_t mlt;
+				const BYTE *vLimit = ip
+					+ (dictLimit - matchIndex);
+
+				if (vLimit > iLimit)
+					vLimit = iLimit;
+				mlt = LZ4_count(ip + MINMATCH,
+					match + MINMATCH, vLimit) + MINMATCH;
+				if ((ip + mlt == vLimit)
+					&& (vLimit < iLimit))
+					mlt += LZ4_count(ip + mlt,
+						base + dictLimit,
+						iLimit);
+				if (mlt > ml) {
+					/* virtual matchpos */
+					ml = mlt;
+					*matchpos = base + matchIndex;
 				}
 			}
 		}
-		ref -= (size_t)chaintable[(size_t)(ref) & MAXD_MASK];
-	}
-
-	/* Complete table */
-	if (repl) {
-		const BYTE *ptr = ip;
-		const BYTE *end;
-		end = ip + repl - (MINMATCH-1);
-		/* Pre-Load */
-		while (ptr < end - delta) {
-			chaintable[(size_t)(ptr) & MAXD_MASK] = delta;
-			ptr++;
-		}
-		do {
-			chaintable[(size_t)(ptr) & MAXD_MASK] = delta;
-			/* Head of chain */
-			hashtable[HASH_VALUE(ptr)] = (ptr) - base;
-			ptr++;
-		} while (ptr < end);
-		hc4->nexttoupdate = end;
+		matchIndex -= DELTANEXTU16(matchIndex);
 	}
 
 	return (int)ml;
 }
 
-static inline int lz4hc_insertandgetwidermatch(struct lz4hc_data *hc4,
-	const u8 *ip, const u8 *startlimit, const u8 *matchlimit, int longest,
-	const u8 **matchpos, const u8 **startpos)
+static FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch(
+	LZ4HC_CCtx_internal *hc4,
+	const BYTE * const ip,
+	const BYTE * const iLowLimit,
+	const BYTE * const iHighLimit,
+	int longest,
+	const BYTE **matchpos,
+	const BYTE **startpos,
+	const int maxNbAttempts)
 {
-	u16 *const chaintable = hc4->chaintable;
-	HTYPE *const hashtable = hc4->hashtable;
-#if LZ4_ARCH64
+	U16 * const chainTable = hc4->chainTable;
+	U32 * const HashTable = hc4->hashTable;
 	const BYTE * const base = hc4->base;
-#else
-	const int base = 0;
-#endif
-	const u8 *ref;
-	int nbattempts = MAX_NB_ATTEMPTS;
-	int delta = (int)(ip - startlimit);
+	const U32 dictLimit = hc4->dictLimit;
+	const BYTE * const lowPrefixPtr = base + dictLimit;
+	const U32 lowLimit = (hc4->lowLimit + 64 * KB > (U32)(ip - base))
+		? hc4->lowLimit
+		: (U32)(ip - base) - (64 * KB - 1);
+	const BYTE * const dictBase = hc4->dictBase;
+	U32 matchIndex;
+	int nbAttempts = maxNbAttempts;
+	int delta = (int)(ip - iLowLimit);
 
 	/* First Match */
-	lz4hc_insert(hc4, ip);
-	ref = hashtable[HASH_VALUE(ip)] + base;
-
-	while ((ref >= ip - MAX_DISTANCE) && (ref >= hc4->base)
-		&& (nbattempts)) {
-		nbattempts--;
-		if (*(startlimit + longest) == *(ref - delta + longest)) {
-			if (A32(ref) == A32(ip)) {
-				const u8 *reft = ref + MINMATCH;
-				const u8 *ipt = ip + MINMATCH;
-				const u8 *startt = ip;
-
-				while (ipt < matchlimit-(STEPSIZE - 1)) {
-					#if LZ4_ARCH64
-					u64 diff = A64(reft) ^ A64(ipt);
-					#else
-					u32 diff = A32(reft) ^ A32(ipt);
-					#endif
-
-					if (!diff) {
-						ipt += STEPSIZE;
-						reft += STEPSIZE;
-						continue;
+	LZ4HC_Insert(hc4, ip);
+	matchIndex = HashTable[LZ4HC_hashPtr(ip)];
+
+	while ((matchIndex >= lowLimit)
+		&& (nbAttempts)) {
+		nbAttempts--;
+		if (matchIndex >= dictLimit) {
+			const BYTE *matchPtr = base + matchIndex;
+
+			if (*(iLowLimit + longest)
+				== *(matchPtr - delta + longest)) {
+				if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
+					int mlt = MINMATCH + LZ4_count(
+						ip + MINMATCH,
+						matchPtr + MINMATCH,
+						iHighLimit);
+					int back = 0;
+
+					while ((ip + back > iLowLimit)
+						&& (matchPtr + back > lowPrefixPtr)
+						&& (ip[back - 1] == matchPtr[back - 1]))
+						back--;
+
+					mlt -= back;
+
+					if (mlt > longest) {
+						longest = (int)mlt;
+						*matchpos = matchPtr + back;
+						*startpos = ip + back;
 					}
-					ipt += LZ4_NBCOMMONBYTES(diff);
-					goto _endcount;
-				}
-				#if LZ4_ARCH64
-				if ((ipt < (matchlimit - 3))
-					&& (A32(reft) == A32(ipt))) {
-					ipt += 4;
-					reft += 4;
 				}
-				ipt += 2;
-				#endif
-				if ((ipt < (matchlimit - 1))
-					&& (A16(reft) == A16(ipt))) {
-					reft += 2;
-				}
-				if ((ipt < matchlimit) && (*reft == *ipt))
-					ipt++;
-_endcount:
-				reft = ref;
-
-				while ((startt > startlimit)
-					&& (reft > hc4->base)
-					&& (startt[-1] == reft[-1])) {
-					startt--;
-					reft--;
-				}
-
-				if ((ipt - startt) > longest) {
-					longest = (int)(ipt - startt);
-					*matchpos = reft;
-					*startpos = startt;
+			}
+		} else {
+			const BYTE * const matchPtr = dictBase + matchIndex;
+
+			if (LZ4_read32(matchPtr) == LZ4_read32(ip)) {
+				size_t mlt;
+				int back = 0;
+				const BYTE *vLimit = ip + (dictLimit - matchIndex);
+
+				if (vLimit > iHighLimit)
+					vLimit = iHighLimit;
+
+				mlt = LZ4_count(ip + MINMATCH,
+					matchPtr + MINMATCH, vLimit) + MINMATCH;
+
+				if ((ip + mlt == vLimit) && (vLimit < iHighLimit))
+					mlt += LZ4_count(ip + mlt, base + dictLimit,
+						iHighLimit);
+				while ((ip + back > iLowLimit)
+					&& (matchIndex + back > lowLimit)
+					&& (ip[back - 1] == matchPtr[back - 1]))
+					back--;
+
+				mlt -= back;
+
+				if ((int)mlt > longest) {
+					longest = (int)mlt;
+					*matchpos = base + matchIndex + back;
+					*startpos = ip + back;
 				}
 			}
 		}
-		ref -= (size_t)chaintable[(size_t)(ref) & MAXD_MASK];
+
+		matchIndex -= DELTANEXTU16(matchIndex);
 	}
+
 	return longest;
 }
 
-static inline int lz4_encodesequence(const u8 **ip, u8 **op, const u8 **anchor,
-		int ml, const u8 *ref)
+static FORCE_INLINE int LZ4HC_encodeSequence(
+	const BYTE **ip,
+	BYTE **op,
+	const BYTE **anchor,
+	int matchLength,
+	const BYTE * const match,
+	limitedOutput_directive limitedOutputBuffer,
+	BYTE *oend)
 {
-	int length, len;
-	u8 *token;
+	int length;
+	BYTE *token;
 
 	/* Encode Literal length */
 	length = (int)(*ip - *anchor);
 	token = (*op)++;
+
+	if ((limitedOutputBuffer)
+		&& ((*op + (length>>8)
+			+ length + (2 + 1 + LASTLITERALS)) > oend)) {
+		/* Check output limit */
+		return 1;
+	}
 	if (length >= (int)RUN_MASK) {
-		*token = (RUN_MASK << ML_BITS);
+		int len;
+
+		*token = (RUN_MASK<<ML_BITS);
 		len = length - RUN_MASK;
 		for (; len > 254 ; len -= 255)
 			*(*op)++ = 255;
-		*(*op)++ = (u8)len;
+		*(*op)++ = (BYTE)len;
 	} else
-		*token = (length << ML_BITS);
+		*token = (BYTE)(length<<ML_BITS);
 
 	/* Copy Literals */
-	LZ4_BLINDCOPY(*anchor, *op, length);
+	LZ4_wildCopy(*op, *anchor, (*op) + length);
+	*op += length;
 
 	/* Encode Offset */
-	LZ4_WRITE_LITTLEENDIAN_16(*op, (u16)(*ip - ref));
+	LZ4_writeLE16(*op, (U16)(*ip - match));
+	*op += 2;
 
 	/* Encode MatchLength */
-	len = (int)(ml - MINMATCH);
-	if (len >= (int)ML_MASK) {
+	length = (int)(matchLength - MINMATCH);
+
+	if ((limitedOutputBuffer)
+		&& (*op + (length>>8)
+			+ (1 + LASTLITERALS) > oend)) {
+		/* Check output limit */
+		return 1;
+	}
+
+	if (length >= (int)ML_MASK) {
 		*token += ML_MASK;
-		len -= ML_MASK;
-		for (; len > 509 ; len -= 510) {
+		length -= ML_MASK;
+
+		for (; length > 509 ; length -= 510) {
 			*(*op)++ = 255;
 			*(*op)++ = 255;
 		}
-		if (len > 254) {
-			len -= 255;
+
+		if (length > 254) {
+			length -= 255;
 			*(*op)++ = 255;
 		}
-		*(*op)++ = (u8)len;
+
+		*(*op)++ = (BYTE)length;
 	} else
-		*token += len;
+		*token += (BYTE)(length);
 
 	/* Prepare next loop */
-	*ip += ml;
+	*ip += matchLength;
 	*anchor = *ip;
 
 	return 0;
 }
 
-static int lz4_compresshcctx(struct lz4hc_data *ctx,
-		const char *source,
-		char *dest,
-		int isize)
+static int LZ4HC_compress_generic(
+	LZ4HC_CCtx_internal *const ctx,
+	const char * const source,
+	char * const dest,
+	int const inputSize,
+	int const maxOutputSize,
+	int compressionLevel,
+	limitedOutput_directive limit
+	)
 {
-	const u8 *ip = (const u8 *)source;
-	const u8 *anchor = ip;
-	const u8 *const iend = ip + isize;
-	const u8 *const mflimit = iend - MFLIMIT;
-	const u8 *const matchlimit = (iend - LASTLITERALS);
+	const BYTE *ip = (const BYTE *) source;
+	const BYTE *anchor = ip;
+	const BYTE * const iend = ip + inputSize;
+	const BYTE * const mflimit = iend - MFLIMIT;
+	const BYTE * const matchlimit = (iend - LASTLITERALS);
 
-	u8 *op = (u8 *)dest;
+	BYTE *op = (BYTE *) dest;
+	BYTE * const oend = op + maxOutputSize;
 
+	unsigned int maxNbAttempts;
 	int ml, ml2, ml3, ml0;
-	const u8 *ref = NULL;
-	const u8 *start2 = NULL;
-	const u8 *ref2 = NULL;
-	const u8 *start3 = NULL;
-	const u8 *ref3 = NULL;
-	const u8 *start0;
-	const u8 *ref0;
-	int lastrun;
+	const BYTE *ref = NULL;
+	const BYTE *start2 = NULL;
+	const BYTE *ref2 = NULL;
+	const BYTE *start3 = NULL;
+	const BYTE *ref3 = NULL;
+	const BYTE *start0;
+	const BYTE *ref0;
+
+	/* init */
+	if (compressionLevel > LZ4HC_MAX_CLEVEL)
+		compressionLevel = LZ4HC_MAX_CLEVEL;
+	if (compressionLevel < 1)
+		compressionLevel = LZ4HC_DEFAULT_CLEVEL;
+	maxNbAttempts = 1 << (compressionLevel - 1);
+	ctx->end += inputSize;
 
 	ip++;
 
 	/* Main Loop */
 	while (ip < mflimit) {
-		ml = lz4hc_insertandfindbestmatch(ctx, ip, matchlimit, (&ref));
+		ml = LZ4HC_InsertAndFindBestMatch(ctx, ip,
+			matchlimit, (&ref), maxNbAttempts);
 		if (!ml) {
 			ip++;
 			continue;
@@ -351,51 +387,59 @@ static int lz4_compresshcctx(struct lz4hc_data *ctx,
 		start0 = ip;
 		ref0 = ref;
 		ml0 = ml;
-_search2:
-		if (ip+ml < mflimit)
-			ml2 = lz4hc_insertandgetwidermatch(ctx, ip + ml - 2,
-				ip + 1, matchlimit, ml, &ref2, &start2);
+
+_Search2:
+		if (ip + ml < mflimit)
+			ml2 = LZ4HC_InsertAndGetWiderMatch(ctx,
+				ip + ml - 2, ip + 0,
+				matchlimit, ml, &ref2,
+				&start2, maxNbAttempts);
 		else
 			ml2 = ml;
-		/* No better match */
+
 		if (ml2 == ml) {
-			lz4_encodesequence(&ip, &op, &anchor, ml, ref);
+			/* No better match */
+			if (LZ4HC_encodeSequence(&ip, &op,
+				&anchor, ml, ref, limit, oend))
+				return 0;
 			continue;
 		}
 
 		if (start0 < ip) {
-			/* empirical */
 			if (start2 < ip + ml0) {
+				/* empirical */
 				ip = start0;
 				ref = ref0;
 				ml = ml0;
 			}
 		}
-		/*
-		 * Here, start0==ip
-		 * First Match too small : removed
-		 */
+
+		/* Here, start0 == ip */
 		if ((start2 - ip) < 3) {
+			/* First Match too small : removed */
 			ml = ml2;
 			ip = start2;
 			ref = ref2;
-			goto _search2;
+			goto _Search2;
 		}
 
-_search3:
+_Search3:
 		/*
-		 * Currently we have :
-		 * ml2 > ml1, and
-		 * ip1+3 <= ip2 (usually < ip1+ml1)
-		 */
+		* Currently we have :
+		* ml2 > ml1, and
+		* ip1 + 3 <= ip2 (usually < ip1 + ml1)
+		*/
 		if ((start2 - ip) < OPTIMAL_ML) {
 			int correction;
 			int new_ml = ml;
+
 			if (new_ml > OPTIMAL_ML)
 				new_ml = OPTIMAL_ML;
 			if (ip + new_ml > start2 + ml2 - MINMATCH)
 				new_ml = (int)(start2 - ip) + ml2 - MINMATCH;
+
 			correction = new_ml - (int)(start2 - ip);
+
 			if (correction > 0) {
 				start2 += correction;
 				ref2 += correction;
@@ -403,39 +447,44 @@ _search3:
 			}
 		}
 		/*
-		 * Now, we have start2 = ip+new_ml,
-		 * with new_ml=min(ml, OPTIMAL_ML=18)
+		 * Now, we have start2 = ip + new_ml,
+		 * with new_ml = min(ml, OPTIMAL_ML = 18)
 		 */
+
 		if (start2 + ml2 < mflimit)
-			ml3 = lz4hc_insertandgetwidermatch(ctx,
-				start2 + ml2 - 3, start2, matchlimit,
-				ml2, &ref3, &start3);
+			ml3 = LZ4HC_InsertAndGetWiderMatch(ctx,
+				start2 + ml2 - 3, start2,
+				matchlimit, ml2, &ref3, &start3,
+				maxNbAttempts);
 		else
 			ml3 = ml2;
 
-		/* No better match : 2 sequences to encode */
 		if (ml3 == ml2) {
+			/* No better match : 2 sequences to encode */
 			/* ip & ref are known; Now for ml */
-			if (start2 < ip+ml)
+			if (start2 < ip + ml)
 				ml = (int)(start2 - ip);
-
 			/* Now, encode 2 sequences */
-			lz4_encodesequence(&ip, &op, &anchor, ml, ref);
+			if (LZ4HC_encodeSequence(&ip, &op, &anchor,
+				ml, ref, limit, oend))
+				return 0;
 			ip = start2;
-			lz4_encodesequence(&ip, &op, &anchor, ml2, ref2);
+			if (LZ4HC_encodeSequence(&ip, &op, &anchor,
+				ml2, ref2, limit, oend))
+				return 0;
 			continue;
 		}
 
-		/* Not enough space for match 2 : remove it */
 		if (start3 < ip + ml + 3) {
-			/*
-			 * can write Seq1 immediately ==> Seq2 is removed,
-			 * so Seq3 becomes Seq1
-			 */
+			/* Not enough space for match 2 : remove it */
 			if (start3 >= (ip + ml)) {
+				/* can write Seq1 immediately
+				 * ==> Seq2 is removed,
+				 * so Seq3 becomes Seq1
+				 */
 				if (start2 < ip + ml) {
-					int correction =
-						(int)(ip + ml - start2);
+					int correction = (int)(ip + ml - start2);
+
 					start2 += correction;
 					ref2 += correction;
 					ml2 -= correction;
@@ -446,35 +495,38 @@ _search3:
 					}
 				}
 
-				lz4_encodesequence(&ip, &op, &anchor, ml, ref);
-				ip  = start3;
+				if (LZ4HC_encodeSequence(&ip, &op, &anchor,
+					ml, ref, limit, oend))
+					return 0;
+				ip = start3;
 				ref = ref3;
-				ml  = ml3;
+				ml = ml3;
 
 				start0 = start2;
 				ref0 = ref2;
 				ml0 = ml2;
-				goto _search2;
+				goto _Search2;
 			}
 
 			start2 = start3;
 			ref2 = ref3;
 			ml2 = ml3;
-			goto _search3;
+			goto _Search3;
 		}
 
 		/*
-		 * OK, now we have 3 ascending matches; let's write at least
-		 * the first one ip & ref are known; Now for ml
-		 */
+		* OK, now we have 3 ascending matches;
+		* let's write at least the first one
+		* ip & ref are known; Now for ml
+		*/
 		if (start2 < ip + ml) {
 			if ((start2 - ip) < (int)ML_MASK) {
 				int correction;
+
 				if (ml > OPTIMAL_ML)
 					ml = OPTIMAL_ML;
 				if (ip + ml > start2 + ml2 - MINMATCH)
-					ml = (int)(start2 - ip) + ml2
-						- MINMATCH;
+					ml = (int)(start2 - ip) + ml2 - MINMATCH;
 				correction = ml - (int)(start2 - ip);
 				if (correction > 0) {
 					start2 += correction;
@@ -484,7 +536,9 @@ _search3:
 			} else
 				ml = (int)(start2 - ip);
 		}
-		lz4_encodesequence(&ip, &op, &anchor, ml, ref);
+		if (LZ4HC_encodeSequence(&ip, &op, &anchor, ml,
+			ref, limit, oend))
+			return 0;
 
 		ip = start2;
 		ref = ref2;
@@ -494,46 +548,245 @@ _search3:
 		ref2 = ref3;
 		ml2 = ml3;
 
-		goto _search3;
+		goto _Search3;
 	}
 
 	/* Encode Last Literals */
-	lastrun = (int)(iend - anchor);
-	if (lastrun >= (int)RUN_MASK) {
-		*op++ = (RUN_MASK << ML_BITS);
-		lastrun -= RUN_MASK;
-		for (; lastrun > 254 ; lastrun -= 255)
-			*op++ = 255;
-		*op++ = (u8) lastrun;
-	} else
-		*op++ = (lastrun << ML_BITS);
-	memcpy(op, anchor, iend - anchor);
-	op += iend - anchor;
+	{
+		int lastRun = (int)(iend - anchor);
+
+		if ((limit)
+			&& (((char *)op - dest) + lastRun + 1
+				+ ((lastRun + 255 - RUN_MASK)/255)
+					> (U32)maxOutputSize)) {
+			/* Check output limit */
+			return 0;
+		}
+		if (lastRun >= (int)RUN_MASK) {
+			*op++ = (RUN_MASK<<ML_BITS);
+			lastRun -= RUN_MASK;
+			for (; lastRun > 254 ; lastRun -= 255)
+				*op++ = 255;
+			*op++ = (BYTE) lastRun;
+		} else
+			*op++ = (BYTE)(lastRun<<ML_BITS);
+		memcpy(op, anchor, iend - anchor);
+		op += iend - anchor;
+	}
+
 	/* End */
 	return (int) (((char *)op) - dest);
 }
 
-int lz4hc_compress(const unsigned char *src, size_t src_len,
-			unsigned char *dst, size_t *dst_len, void *wrkmem)
+static int LZ4_compress_HC_extStateHC(
+	void *state,
+	const char *src,
+	char *dst,
+	int srcSize,
+	int maxDstSize,
+	int compressionLevel)
 {
-	int ret = -1;
-	int out_len = 0;
+	LZ4HC_CCtx_internal *ctx = &((LZ4_streamHC_t *)state)->internal_donotuse;
 
-	struct lz4hc_data *hc4 = (struct lz4hc_data *)wrkmem;
-	lz4hc_init(hc4, (const u8 *)src);
-	out_len = lz4_compresshcctx((struct lz4hc_data *)hc4, (const u8 *)src,
-		(char *)dst, (int)src_len);
+	if (((size_t)(state)&(sizeof(void *) - 1)) != 0) {
+		/* Error : state is not aligned
+		 * for pointers (32 or 64 bits)
+		 */
+		return 0;
+	}
 
-	if (out_len < 0)
-		goto exit;
+	LZ4HC_init(ctx, (const BYTE *)src);
 
-	*dst_len = out_len;
-	return 0;
+	if (maxDstSize < LZ4_compressBound(srcSize))
+		return LZ4HC_compress_generic(ctx, src, dst,
+			srcSize, maxDstSize, compressionLevel, limitedOutput);
+	else
+		return LZ4HC_compress_generic(ctx, src, dst,
+			srcSize, maxDstSize, compressionLevel, noLimit);
+}
+
+int LZ4_compress_HC(const char *src, char *dst, int srcSize,
+	int maxDstSize, int compressionLevel, void *wrkmem)
+{
+	return LZ4_compress_HC_extStateHC(wrkmem, src, dst,
+		srcSize, maxDstSize, compressionLevel);
+}
+EXPORT_SYMBOL(LZ4_compress_HC);
+
+/**************************************
+ *	Streaming Functions
+ **************************************/
+void LZ4_resetStreamHC(LZ4_streamHC_t *LZ4_streamHCPtr, int compressionLevel)
+{
+	LZ4_streamHCPtr->internal_donotuse.base = NULL;
+	LZ4_streamHCPtr->internal_donotuse.compressionLevel = (unsigned int)compressionLevel;
+}
+
+int LZ4_loadDictHC(LZ4_streamHC_t *LZ4_streamHCPtr,
+	const char *dictionary,
+	int dictSize)
+{
+	LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
+
+	if (dictSize > 64 * KB) {
+		dictionary += dictSize - 64 * KB;
+		dictSize = 64 * KB;
+	}
+	LZ4HC_init(ctxPtr, (const BYTE *)dictionary);
+	if (dictSize >= 4)
+		LZ4HC_Insert(ctxPtr, (const BYTE *)dictionary + (dictSize - 3));
+	ctxPtr->end = (const BYTE *)dictionary + dictSize;
+	return dictSize;
+}
+EXPORT_SYMBOL(LZ4_loadDictHC);
+
+/* compression */
+
+static void LZ4HC_setExternalDict(
+	LZ4HC_CCtx_internal *ctxPtr,
+	const BYTE *newBlock)
+{
+	if (ctxPtr->end >= ctxPtr->base + 4) {
+		/* Referencing remaining dictionary content */
+		LZ4HC_Insert(ctxPtr, ctxPtr->end - 3);
+	}
+
+	/*
+	 * Only one memory segment for extDict,
+	 * so any previous extDict is lost at this stage
+	 */
+	ctxPtr->lowLimit	= ctxPtr->dictLimit;
+	ctxPtr->dictLimit = (U32)(ctxPtr->end - ctxPtr->base);
+	ctxPtr->dictBase	= ctxPtr->base;
+	ctxPtr->base = newBlock - ctxPtr->dictLimit;
+	ctxPtr->end	= newBlock;
+	/* match referencing will resume from there */
+	ctxPtr->nextToUpdate = ctxPtr->dictLimit;
+}
+EXPORT_SYMBOL(LZ4HC_setExternalDict);
+
+static int LZ4_compressHC_continue_generic(
+	LZ4_streamHC_t *LZ4_streamHCPtr,
+	const char *source,
+	char *dest,
+	int inputSize,
+	int maxOutputSize,
+	limitedOutput_directive limit)
+{
+	LZ4HC_CCtx_internal *ctxPtr = &LZ4_streamHCPtr->internal_donotuse;
+
+	/* auto - init if forgotten */
+	if (ctxPtr->base == NULL)
+		LZ4HC_init(ctxPtr, (const BYTE *) source);
+
+	/* Check overflow */
+	if ((size_t)(ctxPtr->end - ctxPtr->base) > 2 * GB) {
+		size_t dictSize = (size_t)(ctxPtr->end - ctxPtr->base)
+			- ctxPtr->dictLimit;
+		if (dictSize > 64 * KB)
+			dictSize = 64 * KB;
+		LZ4_loadDictHC(LZ4_streamHCPtr,
+			(const char *)(ctxPtr->end) - dictSize, (int)dictSize);
+	}
+
+	/* Check if blocks follow each other */
+	if ((const BYTE *)source != ctxPtr->end)
+		LZ4HC_setExternalDict(ctxPtr, (const BYTE *)source);
+
+	/* Check overlapping input/dictionary space */
+	{
+		const BYTE *sourceEnd = (const BYTE *) source + inputSize;
+		const BYTE * const dictBegin = ctxPtr->dictBase + ctxPtr->lowLimit;
+		const BYTE * const dictEnd = ctxPtr->dictBase + ctxPtr->dictLimit;
+
+		if ((sourceEnd > dictBegin)
+			&& ((const BYTE *)source < dictEnd)) {
+			if (sourceEnd > dictEnd)
+				sourceEnd = dictEnd;
+			ctxPtr->lowLimit = (U32)(sourceEnd - ctxPtr->dictBase);
+
+			if (ctxPtr->dictLimit - ctxPtr->lowLimit < 4)
+				ctxPtr->lowLimit = ctxPtr->dictLimit;
+		}
+	}
+
+	return LZ4HC_compress_generic(ctxPtr, source, dest,
+		inputSize, maxOutputSize, ctxPtr->compressionLevel, limit);
+}
+
+int LZ4_compress_HC_continue(
+	LZ4_streamHC_t *LZ4_streamHCPtr,
+	const char *source,
+	char *dest,
+	int inputSize,
+	int maxOutputSize)
+{
+	if (maxOutputSize < LZ4_compressBound(inputSize))
+		return LZ4_compressHC_continue_generic(LZ4_streamHCPtr,
+			source, dest, inputSize, maxOutputSize, limitedOutput);
+	else
+		return LZ4_compressHC_continue_generic(LZ4_streamHCPtr,
+			source, dest, inputSize, maxOutputSize, noLimit);
+}
+EXPORT_SYMBOL(LZ4_compress_HC_continue);
+
+/* dictionary saving */
+
+int LZ4_saveDictHC(
+	LZ4_streamHC_t *LZ4_streamHCPtr,
+	char *safeBuffer,
+	int dictSize)
+{
+	LZ4HC_CCtx_internal *const streamPtr = &LZ4_streamHCPtr->internal_donotuse;
+	int const prefixSize = (int)(streamPtr->end
+		- (streamPtr->base + streamPtr->dictLimit));
+
+	if (dictSize > 64 * KB)
+		dictSize = 64 * KB;
+	if (dictSize < 4)
+		dictSize = 0;
+	if (dictSize > prefixSize)
+		dictSize = prefixSize;
+
+	memmove(safeBuffer, streamPtr->end - dictSize, dictSize);
 
-exit:
-	return ret;
+	{
+		U32 const endIndex = (U32)(streamPtr->end - streamPtr->base);
+
+		streamPtr->end = (const BYTE *)safeBuffer + dictSize;
+		streamPtr->base = streamPtr->end - endIndex;
+		streamPtr->dictLimit = endIndex - dictSize;
+		streamPtr->lowLimit = endIndex - dictSize;
+
+		if (streamPtr->nextToUpdate < streamPtr->dictLimit)
+			streamPtr->nextToUpdate = streamPtr->dictLimit;
+	}
+	return dictSize;
+}
+EXPORT_SYMBOL(LZ4_saveDictHC);
+
+/*-******************************
+ *	For backwards compatibility
+ ********************************/
+int lz4hc_compress(const unsigned char *src, size_t src_len,
+	unsigned char *dst, size_t *dst_len, void *wrkmem)
+{
+	*dst_len = LZ4_compress_HC(src, dst, src_len,
+		*dst_len, LZ4HC_DEFAULT_CLEVEL, wrkmem);
+
+	/*
+	 * Prior lz4hc_compress will return -1 in case of error
+	 * and 0 on success
+	 * while new LZ4_compress_HC
+	 * returns 0 in case of error
+	 * and the output length on success
+	 */
+	if (!*dst_len)
+		return -1;
+	else
+		return 0;
 }
 EXPORT_SYMBOL(lz4hc_compress);
 
 MODULE_LICENSE("Dual BSD/GPL");
-MODULE_DESCRIPTION("LZ4HC compressor");
+MODULE_DESCRIPTION("LZ4 HC compressor");