lib/lz4/lz4_decompress.c - arm/linux - Git at Google

 /*
  * LZ4 - Fast LZ compression algorithm
  * Copyright (C) 2011 - 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.
  * You can contact the author at :
  *	- LZ4 homepage : http://www.lz4.org
  *	- LZ4 source repository : https://github.com/lz4/lz4
  *
  *	Changed for kernel usage by:
  *	Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
  */

 /*-************************************
  *	Dependencies
  **************************************/
 #include <linux/lz4.h>
 #include "lz4defs.h"
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <asm/unaligned.h>

 /*-*****************************
  *	Decompression functions
  *******************************/
 /* LZ4_decompress_generic() :
  * This generic decompression function cover all use cases.
  * It shall be instantiated several times, using different sets of directives
  * Note that it is important this generic function is really inlined,
  * in order to remove useless branches during compilation optimization.
  */
 static FORCE_INLINE int LZ4_decompress_generic(
 	 const char * const source,
 	 char * const dest,
 	 int inputSize,
 		/*
 		 * If endOnInput == endOnInputSize,
 		 * this value is the max size of Output Buffer.
 		 */
 	 int outputSize,
 	 /* endOnOutputSize, endOnInputSize */
 	 int endOnInput,
 	 /* full, partial */
 	 int partialDecoding,
 	 /* only used if partialDecoding == partial */
 	 int targetOutputSize,
 	 /* noDict, withPrefix64k, usingExtDict */
 	 int dict,
 	 /* == dest when no prefix */
 	 const BYTE * const lowPrefix,
 	 /* only if dict == usingExtDict */
 	 const BYTE * const dictStart,
 	 /* note : = 0 if noDict */
 	 const size_t dictSize
 	 )
 {
 	/* Local Variables */
 	const BYTE *ip = (const BYTE *) source;
 	const BYTE * const iend = ip + inputSize;

 	BYTE *op = (BYTE *) dest;
 	BYTE * const oend = op + outputSize;
 	BYTE *cpy;
 	BYTE *oexit = op + targetOutputSize;
 	const BYTE * const lowLimit = lowPrefix - dictSize;

 	const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
 	const unsigned int dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };
 	const int dec64table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };

 	const int safeDecode = (endOnInput == endOnInputSize);
 	const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));

 	/* Special cases */
 	/* targetOutputSize too high => decode everything */
 	if ((partialDecoding) && (oexit > oend - MFLIMIT))
 		oexit = oend - MFLIMIT;

 	/* Empty output buffer */
 	if ((endOnInput) && (unlikely(outputSize == 0)))
 		return ((inputSize == 1) && (*ip == 0)) ? 0 : -1;

 	if ((!endOnInput) && (unlikely(outputSize == 0)))
 		return (*ip == 0 ? 1 : -1);

 	/* Main Loop : decode sequences */
 	while (1) {
 		size_t length;
 		const BYTE *match;
 		size_t offset;

 		/* get literal length */
 		unsigned int const token = *ip++;

 		length = token>>ML_BITS;

 		if (length == RUN_MASK) {
 			unsigned int s;

 			do {
 				s = *ip++;
 				length += s;
 			} while (likely(endOnInput
 				? ip < iend - RUN_MASK
 				: 1) & (s == 255));

 			if ((safeDecode)
 				&& unlikely(
 					(size_t)(op + length) < (size_t)(op))) {
 				/* overflow detection */
 				goto _output_error;
 			}
 			if ((safeDecode)
 				&& unlikely(
 					(size_t)(ip + length) < (size_t)(ip))) {
 				/* overflow detection */
 				goto _output_error;
 			}
 		}

 		/* copy literals */
 		cpy = op + length;
 		if (((endOnInput) && ((cpy > (partialDecoding ? oexit : oend - MFLIMIT))
 			|| (ip + length > iend - (2 + 1 + LASTLITERALS))))
 			|| ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) {
 			if (partialDecoding) {
 				if (cpy > oend) {
 					/*
 					 * Error :
 					 * write attempt beyond end of output buffer
 					 */
 					goto _output_error;
 				}
 				if ((endOnInput)
 					&& (ip + length > iend)) {
 					/*
 					 * Error :
 					 * read attempt beyond
 					 * end of input buffer
 					 */
 					goto _output_error;
 				}
 			} else {
 				if ((!endOnInput)
 					&& (cpy != oend)) {
 					/*
 					 * Error :
 					 * block decoding must
 					 * stop exactly there
 					 */
 					goto _output_error;
 				}
 				if ((endOnInput)
 					&& ((ip + length != iend)
 					|| (cpy > oend))) {
 					/*
 					 * Error :
 					 * input must be consumed
 					 */
 					goto _output_error;
 				}
 			}

 			memcpy(op, ip, length);
 			ip += length;
 			op += length;
 			/* Necessarily EOF, due to parsing restrictions */
 			break;
 		}

 		LZ4_wildCopy(op, ip, cpy);
 		ip += length;
 		op = cpy;

 		/* get offset */
 		offset = LZ4_readLE16(ip);
 		ip += 2;
 		match = op - offset;

 		if ((checkOffset) && (unlikely(match < lowLimit))) {
 			/* Error : offset outside buffers */
 			goto _output_error;
 		}

 		/* costs ~1%; silence an msan warning when offset == 0 */
 		LZ4_write32(op, (U32)offset);

 		/* get matchlength */
 		length = token & ML_MASK;
 		if (length == ML_MASK) {
 			unsigned int s;

 			do {
 				s = *ip++;

 				if ((endOnInput) && (ip > iend - LASTLITERALS))
 					goto _output_error;

 				length += s;
 			} while (s == 255);

 			if ((safeDecode)
 				&& unlikely(
 					(size_t)(op + length) < (size_t)op)) {
 				/* overflow detection */
 				goto _output_error;
 			}
 		}

 		length += MINMATCH;

 		/* check external dictionary */
 		if ((dict == usingExtDict) && (match < lowPrefix)) {
 			if (unlikely(op + length > oend - LASTLITERALS)) {
 				/* doesn't respect parsing restriction */
 				goto _output_error;
 			}

 			if (length <= (size_t)(lowPrefix - match)) {
 				/*
 				 * match can be copied as a single segment
 				 * from external dictionary
 				 */
 				memmove(op, dictEnd - (lowPrefix - match),
 					length);
 				op += length;
 			} else {
 				/*
 				 * match encompass external
 				 * dictionary and current block
 				 */
 				size_t const copySize = (size_t)(lowPrefix - match);
 				size_t const restSize = length - copySize;

 				memcpy(op, dictEnd - copySize, copySize);
 				op += copySize;

 				if (restSize > (size_t)(op - lowPrefix)) {
 					/* overlap copy */
 					BYTE * const endOfMatch = op + restSize;
 					const BYTE *copyFrom = lowPrefix;

 					while (op < endOfMatch)
 						*op++ = *copyFrom++;
 				} else {
 					memcpy(op, lowPrefix, restSize);
 					op += restSize;
 				}
 			}

 			continue;
 		}

 		/* copy match within block */
 		cpy = op + length;

 		if (unlikely(offset < 8)) {
 			const int dec64 = dec64table[offset];

 			op[0] = match[0];
 			op[1] = match[1];
 			op[2] = match[2];
 			op[3] = match[3];
 			match += dec32table[offset];
 			memcpy(op + 4, match, 4);
 			match -= dec64;
 		} else {
 			LZ4_copy8(op, match);
 			match += 8;
 		}

 		op += 8;

 		if (unlikely(cpy > oend - 12)) {
 			BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);

 			if (cpy > oend - LASTLITERALS) {
 				/*
 				 * Error : last LASTLITERALS bytes
 				 * must be literals (uncompressed)
 				 */
 				goto _output_error;
 			}

 			if (op < oCopyLimit) {
 				LZ4_wildCopy(op, match, oCopyLimit);
 				match += oCopyLimit - op;
 				op = oCopyLimit;
 			}

 			while (op < cpy)
 				*op++ = *match++;
 		} else {
 			LZ4_copy8(op, match);

 			if (length > 16)
 				LZ4_wildCopy(op + 8, match + 8, cpy);
 		}

 		op = cpy; /* correction */
 	}

 	/* end of decoding */
 	if (endOnInput) {
 		/* Nb of output bytes decoded */
 		return (int) (((char *)op) - dest);
 	} else {
 		/* Nb of input bytes read */
 		return (int) (((const char *)ip) - source);
 	}

 	/* Overflow error detected */
 _output_error:
 	return -1;
 }

 int LZ4_decompress_safe(const char *source, char *dest,
 	int compressedSize, int maxDecompressedSize)
 {
 	return LZ4_decompress_generic(source, dest, compressedSize,
 		maxDecompressedSize, endOnInputSize, full, 0,
 		noDict, (BYTE *)dest, NULL, 0);
 }

 int LZ4_decompress_safe_partial(const char *source, char *dest,
 	int compressedSize, int targetOutputSize, int maxDecompressedSize)
 {
 	return LZ4_decompress_generic(source, dest, compressedSize,
 		maxDecompressedSize, endOnInputSize, partial,
 		targetOutputSize, noDict, (BYTE *)dest, NULL, 0);
 }

 int LZ4_decompress_fast(const char *source, char *dest, int originalSize)
 {
 	return LZ4_decompress_generic(source, dest, 0, originalSize,
 		endOnOutputSize, full, 0, withPrefix64k,
 		(BYTE *)(dest - 64 * KB), NULL, 64 * KB);
 }

 int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
 	const char *dictionary, int dictSize)
 {
 	LZ4_streamDecode_t_internal *lz4sd = (LZ4_streamDecode_t_internal *) LZ4_streamDecode;

 	lz4sd->prefixSize = (size_t) dictSize;
 	lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize;
 	lz4sd->externalDict = NULL;
 	lz4sd->extDictSize	= 0;
 	return 1;
 }

 /*
  * *_continue() :
  * These decoding functions allow decompression of multiple blocks
  * in "streaming" mode.
  * Previously decoded blocks must still be available at the memory
  * position where they were decoded.
  * If it's not possible, save the relevant part of
  * decoded data into a safe buffer,
  * and indicate where it stands using LZ4_setStreamDecode()
  */
 int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
 	const char *source, char *dest, int compressedSize, int maxOutputSize)
 {
 	LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
 	int result;

 	if (lz4sd->prefixEnd == (BYTE *)dest) {
 		result = LZ4_decompress_generic(source, dest,
 			compressedSize,
 			maxOutputSize,
 			endOnInputSize, full, 0,
 			usingExtDict, lz4sd->prefixEnd - lz4sd->prefixSize,
 			lz4sd->externalDict,
 			lz4sd->extDictSize);

 		if (result <= 0)
 			return result;

 		lz4sd->prefixSize += result;
 		lz4sd->prefixEnd	+= result;
 	} else {
 		lz4sd->extDictSize = lz4sd->prefixSize;
 		lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
 		result = LZ4_decompress_generic(source, dest,
 			compressedSize, maxOutputSize,
 			endOnInputSize, full, 0,
 			usingExtDict, (BYTE *)dest,
 			lz4sd->externalDict, lz4sd->extDictSize);
 		if (result <= 0)
 			return result;
 		lz4sd->prefixSize = result;
 		lz4sd->prefixEnd	= (BYTE *)dest + result;
 	}

 	return result;
 }

 int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
 	const char *source, char *dest, int originalSize)
 {
 	LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
 	int result;

 	if (lz4sd->prefixEnd == (BYTE *)dest) {
 		result = LZ4_decompress_generic(source, dest, 0, originalSize,
 			endOnOutputSize, full, 0,
 			usingExtDict,
 			lz4sd->prefixEnd - lz4sd->prefixSize,
 			lz4sd->externalDict, lz4sd->extDictSize);

 		if (result <= 0)
 			return result;

 		lz4sd->prefixSize += originalSize;
 		lz4sd->prefixEnd	+= originalSize;
 	} else {
 		lz4sd->extDictSize = lz4sd->prefixSize;
 		lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
 		result = LZ4_decompress_generic(source, dest, 0, originalSize,
 			endOnOutputSize, full, 0,
 			usingExtDict, (BYTE *)dest,
 			lz4sd->externalDict, lz4sd->extDictSize);
 		if (result <= 0)
 			return result;
 		lz4sd->prefixSize = originalSize;
 		lz4sd->prefixEnd	= (BYTE *)dest + originalSize;
 	}

 	return result;
 }

 /*
  * Advanced decoding functions :
  * *_usingDict() :
  * These decoding functions work the same as "_continue" ones,
  * the dictionary must be explicitly provided within parameters
  */
 static FORCE_INLINE int LZ4_decompress_usingDict_generic(const char *source,
 	char *dest, int compressedSize, int maxOutputSize, int safe,
 	const char *dictStart, int dictSize)
 {
 	if (dictSize == 0)
 		return LZ4_decompress_generic(source, dest,
 			compressedSize, maxOutputSize, safe, full, 0,
 			noDict, (BYTE *)dest, NULL, 0);
 	if (dictStart + dictSize == dest) {
 		if (dictSize >= (int)(64 * KB - 1))
 			return LZ4_decompress_generic(source, dest,
 				compressedSize, maxOutputSize, safe, full, 0,
 				withPrefix64k, (BYTE *)dest - 64 * KB, NULL, 0);
 		return LZ4_decompress_generic(source, dest, compressedSize,
 			maxOutputSize, safe, full, 0, noDict,
 			(BYTE *)dest - dictSize, NULL, 0);
 	}
 	return LZ4_decompress_generic(source, dest, compressedSize,
 		maxOutputSize, safe, full, 0, usingExtDict,
 		(BYTE *)dest, (const BYTE *)dictStart, dictSize);
 }

 int LZ4_decompress_safe_usingDict(const char *source, char *dest,
 	int compressedSize, int maxOutputSize,
 	const char *dictStart, int dictSize)
 {
 	return LZ4_decompress_usingDict_generic(source, dest,
 		compressedSize, maxOutputSize, 1, dictStart, dictSize);
 }

 int LZ4_decompress_fast_usingDict(const char *source, char *dest,
 	int originalSize, const char *dictStart, int dictSize)
 {
 	return LZ4_decompress_usingDict_generic(source, dest, 0,
 		originalSize, 0, dictStart, dictSize);
 }

 #ifndef STATIC
 EXPORT_SYMBOL(LZ4_decompress_safe);
 EXPORT_SYMBOL(LZ4_decompress_safe_partial);
 EXPORT_SYMBOL(LZ4_decompress_fast);
 EXPORT_SYMBOL(LZ4_setStreamDecode);
 EXPORT_SYMBOL(LZ4_decompress_safe_continue);
 EXPORT_SYMBOL(LZ4_decompress_fast_continue);
 EXPORT_SYMBOL(LZ4_decompress_safe_usingDict);
 EXPORT_SYMBOL(LZ4_decompress_fast_usingDict);

 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_DESCRIPTION("LZ4 decompressor");
 #endif
	/*
	* LZ4 - Fast LZ compression algorithm
	* Copyright (C) 2011 - 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.
	* You can contact the author at :
	* - LZ4 homepage : http://www.lz4.org
	* - LZ4 source repository : https://github.com/lz4/lz4
	*
	* Changed for kernel usage by:
	* Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
	*/

	/-***********************************
	* Dependencies
	**************************************/
	#include <linux/lz4.h>
	#include "lz4defs.h"
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <asm/unaligned.h>

	/-****************************
	* Decompression functions
	*******************************/
	/* LZ4_decompress_generic() :
	* This generic decompression function cover all use cases.
	* It shall be instantiated several times, using different sets of directives
	* Note that it is important this generic function is really inlined,
	* in order to remove useless branches during compilation optimization.
	*/
	static FORCE_INLINE int LZ4_decompress_generic(
	const char * const source,
	char * const dest,
	int inputSize,
	/*
	* If endOnInput == endOnInputSize,
	* this value is the max size of Output Buffer.
	*/
	int outputSize,
	/* endOnOutputSize, endOnInputSize */
	int endOnInput,
	/* full, partial */
	int partialDecoding,
	/* only used if partialDecoding == partial */
	int targetOutputSize,
	/* noDict, withPrefix64k, usingExtDict */
	int dict,
	/* == dest when no prefix */
	const BYTE * const lowPrefix,
	/* only if dict == usingExtDict */
	const BYTE * const dictStart,
	/* note : = 0 if noDict */
	const size_t dictSize
	)
	{
	/* Local Variables */
	const BYTE ip = (const BYTE ) source;
	const BYTE * const iend = ip + inputSize;

	BYTE op = (BYTE ) dest;
	BYTE * const oend = op + outputSize;
	BYTE *cpy;
	BYTE *oexit = op + targetOutputSize;
	const BYTE * const lowLimit = lowPrefix - dictSize;

	const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
	const unsigned int dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };
	const int dec64table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };

	const int safeDecode = (endOnInput == endOnInputSize);
	const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));

	/* Special cases */
	/* targetOutputSize too high => decode everything */
	if ((partialDecoding) && (oexit > oend - MFLIMIT))
	oexit = oend - MFLIMIT;

	/* Empty output buffer */
	if ((endOnInput) && (unlikely(outputSize == 0)))
	return ((inputSize == 1) && (*ip == 0)) ? 0 : -1;

	if ((!endOnInput) && (unlikely(outputSize == 0)))
	return (*ip == 0 ? 1 : -1);

	/* Main Loop : decode sequences */
	while (1) {
	size_t length;
	const BYTE *match;
	size_t offset;

	/* get literal length */
	unsigned int const token = *ip++;

	length = token>>ML_BITS;

	if (length == RUN_MASK) {
	unsigned int s;

	do {
	s = *ip++;
	length += s;
	} while (likely(endOnInput
	? ip < iend - RUN_MASK
	: 1) & (s == 255));

	if ((safeDecode)
	&& unlikely(
	(size_t)(op + length) < (size_t)(op))) {
	/* overflow detection */
	goto _output_error;
	}
	if ((safeDecode)
	&& unlikely(
	(size_t)(ip + length) < (size_t)(ip))) {
	/* overflow detection */
	goto _output_error;
	}
	}

	/* copy literals */
	cpy = op + length;
	if (((endOnInput) && ((cpy > (partialDecoding ? oexit : oend - MFLIMIT))
	\|\| (ip + length > iend - (2 + 1 + LASTLITERALS))))
	\|\| ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) {
	if (partialDecoding) {
	if (cpy > oend) {
	/*
	* Error :
	* write attempt beyond end of output buffer
	*/
	goto _output_error;
	}
	if ((endOnInput)
	&& (ip + length > iend)) {
	/*
	* Error :
	* read attempt beyond
	* end of input buffer
	*/
	goto _output_error;
	}
	} else {
	if ((!endOnInput)
	&& (cpy != oend)) {
	/*
	* Error :
	* block decoding must
	* stop exactly there
	*/
	goto _output_error;
	}
	if ((endOnInput)
	&& ((ip + length != iend)
	\|\| (cpy > oend))) {
	/*
	* Error :
	* input must be consumed
	*/
	goto _output_error;
	}
	}

	memcpy(op, ip, length);
	ip += length;
	op += length;
	/* Necessarily EOF, due to parsing restrictions */
	break;
	}

	LZ4_wildCopy(op, ip, cpy);
	ip += length;
	op = cpy;

	/* get offset */
	offset = LZ4_readLE16(ip);
	ip += 2;
	match = op - offset;

	if ((checkOffset) && (unlikely(match < lowLimit))) {
	/* Error : offset outside buffers */
	goto _output_error;
	}

	/* costs ~1%; silence an msan warning when offset == 0 */
	LZ4_write32(op, (U32)offset);

	/* get matchlength */
	length = token & ML_MASK;
	if (length == ML_MASK) {
	unsigned int s;

	do {
	s = *ip++;

	if ((endOnInput) && (ip > iend - LASTLITERALS))
	goto _output_error;

	length += s;
	} while (s == 255);

	if ((safeDecode)
	&& unlikely(
	(size_t)(op + length) < (size_t)op)) {
	/* overflow detection */
	goto _output_error;
	}
	}

	length += MINMATCH;

	/* check external dictionary */
	if ((dict == usingExtDict) && (match < lowPrefix)) {
	if (unlikely(op + length > oend - LASTLITERALS)) {
	/* doesn't respect parsing restriction */
	goto _output_error;
	}

	if (length <= (size_t)(lowPrefix - match)) {
	/*
	* match can be copied as a single segment
	* from external dictionary
	*/
	memmove(op, dictEnd - (lowPrefix - match),
	length);
	op += length;
	} else {
	/*
	* match encompass external
	* dictionary and current block
	*/
	size_t const copySize = (size_t)(lowPrefix - match);
	size_t const restSize = length - copySize;

	memcpy(op, dictEnd - copySize, copySize);
	op += copySize;

	if (restSize > (size_t)(op - lowPrefix)) {
	/* overlap copy */
	BYTE * const endOfMatch = op + restSize;
	const BYTE *copyFrom = lowPrefix;

	while (op < endOfMatch)
	op++ = copyFrom++;
	} else {
	memcpy(op, lowPrefix, restSize);
	op += restSize;
	}
	}

	continue;
	}

	/* copy match within block */
	cpy = op + length;

	if (unlikely(offset < 8)) {
	const int dec64 = dec64table[offset];

	op[0] = match[0];
	op[1] = match[1];
	op[2] = match[2];
	op[3] = match[3];
	match += dec32table[offset];
	memcpy(op + 4, match, 4);
	match -= dec64;
	} else {
	LZ4_copy8(op, match);
	match += 8;
	}

	op += 8;

	if (unlikely(cpy > oend - 12)) {
	BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);

	if (cpy > oend - LASTLITERALS) {
	/*
	* Error : last LASTLITERALS bytes
	* must be literals (uncompressed)
	*/
	goto _output_error;
	}

	if (op < oCopyLimit) {
	LZ4_wildCopy(op, match, oCopyLimit);
	match += oCopyLimit - op;
	op = oCopyLimit;
	}

	while (op < cpy)
	op++ = match++;
	} else {
	LZ4_copy8(op, match);

	if (length > 16)
	LZ4_wildCopy(op + 8, match + 8, cpy);
	}

	op = cpy; /* correction */
	}

	/* end of decoding */
	if (endOnInput) {
	/* Nb of output bytes decoded */
	return (int) (((char *)op) - dest);
	} else {
	/* Nb of input bytes read */
	return (int) (((const char *)ip) - source);
	}

	/* Overflow error detected */
	_output_error:
	return -1;
	}

	int LZ4_decompress_safe(const char source, char dest,
	int compressedSize, int maxDecompressedSize)
	{
	return LZ4_decompress_generic(source, dest, compressedSize,
	maxDecompressedSize, endOnInputSize, full, 0,
	noDict, (BYTE *)dest, NULL, 0);
	}

	int LZ4_decompress_safe_partial(const char source, char dest,
	int compressedSize, int targetOutputSize, int maxDecompressedSize)
	{
	return LZ4_decompress_generic(source, dest, compressedSize,
	maxDecompressedSize, endOnInputSize, partial,
	targetOutputSize, noDict, (BYTE *)dest, NULL, 0);
	}

	int LZ4_decompress_fast(const char source, char dest, int originalSize)
	{
	return LZ4_decompress_generic(source, dest, 0, originalSize,
	endOnOutputSize, full, 0, withPrefix64k,
	(BYTE )(dest - 64 KB), NULL, 64 * KB);
	}

	int LZ4_setStreamDecode(LZ4_streamDecode_t *LZ4_streamDecode,
	const char *dictionary, int dictSize)
	{
	LZ4_streamDecode_t_internal lz4sd = (LZ4_streamDecode_t_internal ) LZ4_streamDecode;

	lz4sd->prefixSize = (size_t) dictSize;
	lz4sd->prefixEnd = (const BYTE *) dictionary + dictSize;
	lz4sd->externalDict = NULL;
	lz4sd->extDictSize = 0;
	return 1;
	}

	/*
	* *_continue() :
	* These decoding functions allow decompression of multiple blocks
	* in "streaming" mode.
	* Previously decoded blocks must still be available at the memory
	* position where they were decoded.
	* If it's not possible, save the relevant part of
	* decoded data into a safe buffer,
	* and indicate where it stands using LZ4_setStreamDecode()
	*/
	int LZ4_decompress_safe_continue(LZ4_streamDecode_t *LZ4_streamDecode,
	const char source, char dest, int compressedSize, int maxOutputSize)
	{
	LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
	int result;

	if (lz4sd->prefixEnd == (BYTE *)dest) {
	result = LZ4_decompress_generic(source, dest,
	compressedSize,
	maxOutputSize,
	endOnInputSize, full, 0,
	usingExtDict, lz4sd->prefixEnd - lz4sd->prefixSize,
	lz4sd->externalDict,
	lz4sd->extDictSize);

	if (result <= 0)
	return result;

	lz4sd->prefixSize += result;
	lz4sd->prefixEnd += result;
	} else {
	lz4sd->extDictSize = lz4sd->prefixSize;
	lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
	result = LZ4_decompress_generic(source, dest,
	compressedSize, maxOutputSize,
	endOnInputSize, full, 0,
	usingExtDict, (BYTE *)dest,
	lz4sd->externalDict, lz4sd->extDictSize);
	if (result <= 0)
	return result;
	lz4sd->prefixSize = result;
	lz4sd->prefixEnd = (BYTE *)dest + result;
	}

	return result;
	}

	int LZ4_decompress_fast_continue(LZ4_streamDecode_t *LZ4_streamDecode,
	const char source, char dest, int originalSize)
	{
	LZ4_streamDecode_t_internal *lz4sd = &LZ4_streamDecode->internal_donotuse;
	int result;

	if (lz4sd->prefixEnd == (BYTE *)dest) {
	result = LZ4_decompress_generic(source, dest, 0, originalSize,
	endOnOutputSize, full, 0,
	usingExtDict,
	lz4sd->prefixEnd - lz4sd->prefixSize,
	lz4sd->externalDict, lz4sd->extDictSize);

	if (result <= 0)
	return result;

	lz4sd->prefixSize += originalSize;
	lz4sd->prefixEnd += originalSize;
	} else {
	lz4sd->extDictSize = lz4sd->prefixSize;
	lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
	result = LZ4_decompress_generic(source, dest, 0, originalSize,
	endOnOutputSize, full, 0,
	usingExtDict, (BYTE *)dest,
	lz4sd->externalDict, lz4sd->extDictSize);
	if (result <= 0)
	return result;
	lz4sd->prefixSize = originalSize;
	lz4sd->prefixEnd = (BYTE *)dest + originalSize;
	}

	return result;
	}

	/*
	* Advanced decoding functions :
	* *_usingDict() :
	* These decoding functions work the same as "_continue" ones,
	* the dictionary must be explicitly provided within parameters
	*/
	static FORCE_INLINE int LZ4_decompress_usingDict_generic(const char *source,
	char *dest, int compressedSize, int maxOutputSize, int safe,
	const char *dictStart, int dictSize)
	{
	if (dictSize == 0)
	return LZ4_decompress_generic(source, dest,
	compressedSize, maxOutputSize, safe, full, 0,
	noDict, (BYTE *)dest, NULL, 0);
	if (dictStart + dictSize == dest) {
	if (dictSize >= (int)(64 * KB - 1))
	return LZ4_decompress_generic(source, dest,
	compressedSize, maxOutputSize, safe, full, 0,
	withPrefix64k, (BYTE )dest - 64 KB, NULL, 0);
	return LZ4_decompress_generic(source, dest, compressedSize,
	maxOutputSize, safe, full, 0, noDict,
	(BYTE *)dest - dictSize, NULL, 0);
	}
	return LZ4_decompress_generic(source, dest, compressedSize,
	maxOutputSize, safe, full, 0, usingExtDict,
	(BYTE )dest, (const BYTE )dictStart, dictSize);
	}

	int LZ4_decompress_safe_usingDict(const char source, char dest,
	int compressedSize, int maxOutputSize,
	const char *dictStart, int dictSize)
	{
	return LZ4_decompress_usingDict_generic(source, dest,
	compressedSize, maxOutputSize, 1, dictStart, dictSize);
	}

	int LZ4_decompress_fast_usingDict(const char source, char dest,
	int originalSize, const char *dictStart, int dictSize)
	{
	return LZ4_decompress_usingDict_generic(source, dest, 0,
	originalSize, 0, dictStart, dictSize);
	}

	#ifndef STATIC
	EXPORT_SYMBOL(LZ4_decompress_safe);
	EXPORT_SYMBOL(LZ4_decompress_safe_partial);
	EXPORT_SYMBOL(LZ4_decompress_fast);
	EXPORT_SYMBOL(LZ4_setStreamDecode);
	EXPORT_SYMBOL(LZ4_decompress_safe_continue);
	EXPORT_SYMBOL(LZ4_decompress_fast_continue);
	EXPORT_SYMBOL(LZ4_decompress_safe_usingDict);
	EXPORT_SYMBOL(LZ4_decompress_fast_usingDict);

	MODULE_LICENSE("Dual BSD/GPL");
	MODULE_DESCRIPTION("LZ4 decompressor");
	#endif