path: root/lz4.c

/*

   LZ4 - Fast LZ compression algorithm

   Copyright (C) 2011-2012, 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://fastcompression.blogspot.com/p/lz4.html

   - LZ4 source repository : http://code.google.com/p/lz4/

*/

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

// Tuning parameters

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

// COMPRESSIONLEVEL :

// Increasing this value improves compression ratio

// Lowering this value reduces memory usage

// Reduced memory usage typically improves speed, due to cache effect (ex : L1 32KB for Intel, L1 64KB for AMD)

// Memory usage formula : N->2^(N+2) Bytes (examples : 12 -> 16KB ; 17 -> 512KB)

#define COMPRESSIONLEVEL 12


// NOTCOMPRESSIBLE_CONFIRMATION :

// Decreasing this value will make the algorithm skip faster data segments considered "incompressible"

// This may decrease compression ratio dramatically, but will be faster on incompressible data

// Increasing this value will make the algorithm search more before declaring a segment "incompressible"

// This could improve compression a bit, but will be slower on incompressible data

// The default value (6) is recommended

#define NOTCOMPRESSIBLE_CONFIRMATION 6


// LZ4_COMPRESSMIN :

// Compression function will *fail* if it is not successful at compressing input by at least LZ4_COMPRESSMIN bytes

// Since the compression function stops working prematurely, it results in a speed gain

// The output however is unusable. Compression function result will be zero.

// Default : 0 = disabled

#define LZ4_COMPRESSMIN 0


// BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE :

// This will provide a boost to performance for big endian cpu, but the resulting compressed stream will be incompatible with little-endian CPU.

// You can set this option to 1 in situations where data will stay within closed environment

// This option is useless on Little_Endian CPU (such as x86)

//#define BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE 1




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

// CPU Feature Detection

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

// 32 or 64 bits ?

#if (defined(__x86_64__) || defined(__x86_64) || defined(__amd64__) || defined(__amd64) || defined(__ppc64__) || defined(_WIN64) || defined(__LP64__) || defined(_LP64) )   // Detects 64 bits mode

#  define LZ4_ARCH64 1

#else

#  define LZ4_ARCH64 0

#endif


// Little Endian or Big Endian ?

// Note : overwrite the below #define if you know your architecture endianess

#if (defined(__BIG_ENDIAN__) || defined(__BIG_ENDIAN) || defined(_BIG_ENDIAN) || defined(_ARCH_PPC) || defined(__PPC__) || defined(__PPC) || defined(PPC) || defined(__powerpc__) || defined(__powerpc) || defined(powerpc) || ((defined(__BYTE_ORDER__)&&(__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))) )

#  define LZ4_BIG_ENDIAN 1

#else

// Little Endian assumed. PDP Endian and other very rare endian format are unsupported.

#endif


// Unaligned memory access is automatically enabled for "common" CPU, such as x86.

// For others CPU, the compiler will be more cautious, and insert extra code to ensure aligned access is respected

// If you know your target CPU supports unaligned memory access, you may want to force this option manually to improve performance

#if defined(__ARM_FEATURE_UNALIGNED)

#  define LZ4_FORCE_UNALIGNED_ACCESS 1

#endif


// Define this parameter if your target system or compiler does not support hardware bit count

#if defined(_MSC_VER) && defined(_WIN32_WCE)            // Visual Studio for Windows CE does not support Hardware bit count

#  define LZ4_FORCE_SW_BITCOUNT

#endif



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

// Compiler Options

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

#if __STDC_VERSION__ >= 199901L // C99

/* "restrict" is a known keyword */
#else

#  define restrict // Disable restrict

#endif


#define GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)


#ifdef _MSC_VER  // Visual Studio

#  define inline __forceinline           // Visual is not C99, but supports some kind of inline

#  if LZ4_ARCH64	// 64-bit

#    pragma intrinsic(_BitScanForward64) // For Visual 2005

#    pragma intrinsic(_BitScanReverse64) // For Visual 2005

#  else

#    pragma intrinsic(_BitScanForward)   // For Visual 2005

#    pragma intrinsic(_BitScanReverse)   // For Visual 2005

#  endif

#endif


#ifdef _MSC_VER

#  define lz4_bswap16(x) _byteswap_ushort(x)

#else

#  define lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8)))

#endif


#if (GCC_VERSION >= 302) || (__INTEL_COMPILER >= 800) || defined(__clang__)

#  define expect(expr,value)    (__builtin_expect ((expr),(value)) )

#else

#  define expect(expr,value)    (expr)

#endif


#define likely(expr)     expect((expr) != 0, 1)

#define unlikely(expr)   expect((expr) != 0, 0)



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

// Includes

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

#include <stdlib.h>   // for malloc

#include <string.h>   // for memset

#include "lz4.h"



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

// Basic Types

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

#if defined(_MSC_VER)    // Visual Studio does not support 'stdint' natively

#  define BYTE	unsigned __int8

#  define U16		unsigned __int16

#  define U32		unsigned __int32

#  define S32		__int32

#  define U64		unsigned __int64

#else

#  include <stdint.h>

#  define BYTE	uint8_t

#  define U16		uint16_t

#  define U32		uint32_t

#  define S32		int32_t

#  define U64		uint64_t

#endif


#ifndef LZ4_FORCE_UNALIGNED_ACCESS

#  pragma pack(push, 1)

#endif


typedef struct _U16_S { U16 v; } U16_S;
typedef struct _U32_S { U32 v; } U32_S;
typedef struct _U64_S { U64 v; } U64_S;

#ifndef LZ4_FORCE_UNALIGNED_ACCESS

#  pragma pack(pop)

#endif


#define A64(x) (((U64_S *)(x))->v)

#define A32(x) (((U32_S *)(x))->v)

#define A16(x) (((U16_S *)(x))->v)



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

// Constants

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

#define MINMATCH 4


#define HASH_LOG COMPRESSIONLEVEL

#define HASHTABLESIZE (1 << HASH_LOG)

#define HASH_MASK (HASHTABLESIZE - 1)


#define SKIPSTRENGTH (NOTCOMPRESSIBLE_CONFIRMATION>2?NOTCOMPRESSIBLE_CONFIRMATION:2)

#define STACKLIMIT 13

#define HEAPMODE (HASH_LOG>STACKLIMIT)  // Defines if memory is allocated into the stack (local variable), or into the heap (malloc()).

#define COPYLENGTH 8

#define LASTLITERALS 5

#define MFLIMIT (COPYLENGTH+MINMATCH)

#define MINLENGTH (MFLIMIT+1)


#define MAXD_LOG 16

#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)


#define ML_BITS 4

#define ML_MASK ((1U<<ML_BITS)-1)

#define RUN_BITS (8-ML_BITS)

#define RUN_MASK ((1U<<RUN_BITS)-1)



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

// Architecture-specific macros

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

#if LZ4_ARCH64	// 64-bit

#  define STEPSIZE 8

#  define UARCH U64

#  define AARCH A64

#  define LZ4_COPYSTEP(s,d)		A64(d) = A64(s); d+=8; s+=8;

#  define LZ4_COPYPACKET(s,d)		LZ4_COPYSTEP(s,d)

#  define LZ4_SECURECOPY(s,d,e)	if (d<e) LZ4_WILDCOPY(s,d,e)

#  define HTYPE U32

#  define INITBASE(base)			const BYTE* const base = ip

#else		// 32-bit

#  define STEPSIZE 4

#  define UARCH U32

#  define AARCH A32

#  define LZ4_COPYSTEP(s,d)		A32(d) = A32(s); d+=4; s+=4;

#  define LZ4_COPYPACKET(s,d)		LZ4_COPYSTEP(s,d); LZ4_COPYSTEP(s,d);

#  define LZ4_SECURECOPY			LZ4_WILDCOPY

#  define HTYPE const BYTE*

#  define INITBASE(base)			const int base = 0

#endif


#if (defined(LZ4_BIG_ENDIAN) && !defined(BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE))

#  define LZ4_READ_LITTLEENDIAN_16(d,s,p) { U16 v = A16(p); v = lz4_bswap16(v); d = (s) - v; }

#  define LZ4_WRITE_LITTLEENDIAN_16(p,i)  { U16 v = (U16)(i); v = lz4_bswap16(v); A16(p) = v; p+=2; }

#else		// Little Endian

#  define LZ4_READ_LITTLEENDIAN_16(d,s,p) { d = (s) - A16(p); }

#  define LZ4_WRITE_LITTLEENDIAN_16(p,v)  { A16(p) = v; p+=2; }

#endif



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

// Local structures

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

struct refTables
{
	HTYPE hashTable[HASHTABLESIZE];
};


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

// Macros

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

#define LZ4_HASH_FUNCTION(i)	(((i) * 2654435761U) >> ((MINMATCH*8)-HASH_LOG))

#define LZ4_HASH_VALUE(p)		LZ4_HASH_FUNCTION(A32(p))

#define LZ4_WILDCOPY(s,d,e)		do { LZ4_COPYPACKET(s,d) } while (d<e);

#define LZ4_BLINDCOPY(s,d,l)	{ BYTE* e=(d)+l; LZ4_WILDCOPY(s,d,e); d=e; }



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

// Private functions

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

#if LZ4_ARCH64


inline static int LZ4_NbCommonBytes (register U64 val)
{
#if defined(LZ4_BIG_ENDIAN)

    #if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)

    unsigned long r = 0;
    _BitScanReverse64( &r, val );
    return (int)(r>>3);
    #elif defined(__GNUC__) && (GCC_VERSION >= 304) && !defined(LZ4_FORCE_SW_BITCOUNT)

    return (__builtin_clzll(val) >> 3);
    #else

	int r;
	if (!(val>>32)) { r=4; } else { r=0; val>>=32; }
	if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; }
	r += (!val);
	return r;
    #endif

#else

    #if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)

    unsigned long r = 0;
    _BitScanForward64( &r, val );
    return (int)(r>>3);
    #elif defined(__GNUC__) && (GCC_VERSION >= 304) && !defined(LZ4_FORCE_SW_BITCOUNT)

    return (__builtin_ctzll(val) >> 3);
    #else

	static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5, 3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5, 5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4, 4, 5, 7, 2, 6, 5, 7, 6, 7, 7 };
	return DeBruijnBytePos[((U64)((val & -val) * 0x0218A392CDABBD3F)) >> 58];
    #endif

#endif

}

#else


inline static int LZ4_NbCommonBytes (register U32 val)
{
#if defined(LZ4_BIG_ENDIAN)

    #if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)

    unsigned long r = 0;
    _BitScanReverse( &r, val );
    return (int)(r>>3);
    #elif defined(__GNUC__) && (GCC_VERSION >= 304) && !defined(LZ4_FORCE_SW_BITCOUNT)

    return (__builtin_clz(val) >> 3);
    #else

	int r;
	if (!(val>>16)) { r=2; val>>=8; } else { r=0; val>>=24; }
	r += (!val);
	return r;
    #endif

#else

    #if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)

    unsigned long r = 0;
    _BitScanForward( &r, val );
    return (int)(r>>3);
    #elif defined(__GNUC__) && (GCC_VERSION >= 304) && !defined(LZ4_FORCE_SW_BITCOUNT)

    return (__builtin_ctz(val) >> 3);
    #else

	static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
	return DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27];
    #endif

#endif

}

#endif



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

// Public functions

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


int LZ4_compressBound(int isize)
{
	return (isize + (isize/255) + 16);
}



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

// Compression functions

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


int LZ4_compressCtx(void** ctx,
				 const char* source,
				 char* dest,
				 int isize)
{
#if HEAPMODE

	struct refTables *srt = (struct refTables *) (*ctx);
	HTYPE* HashTable;
#else

	HTYPE HashTable[HASHTABLESIZE] = {0};
#endif


	const BYTE* ip = (BYTE*) source;
	INITBASE(base);
	const BYTE* anchor = ip;
	const BYTE* const iend = ip + isize;
	const BYTE* const mflimit = iend - MFLIMIT;
#define matchlimit (iend - LASTLITERALS)


	BYTE* op = (BYTE*) dest;

	int len, length;
	const int skipStrength = SKIPSTRENGTH;
	U32 forwardH;


	// Init

	if (isize<MINLENGTH) goto _last_literals;
#if HEAPMODE

	if (*ctx == NULL)
	{
		srt = (struct refTables *) malloc ( sizeof(struct refTables) );
		*ctx = (void*) srt;
	}
	HashTable = (HTYPE*)(srt->hashTable);
	memset((void*)HashTable, 0, sizeof(srt->hashTable));
#else

	(void) ctx;
#endif



	// First Byte

	HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
	ip++; forwardH = LZ4_HASH_VALUE(ip);

	// Main Loop

    for ( ; ; )
	{
		int findMatchAttempts = (1U << skipStrength) + 3;
		const BYTE* forwardIp = ip;
		const BYTE* ref;
		BYTE* token;

		// Find a match

		do {
			U32 h = forwardH;
			int step = findMatchAttempts++ >> skipStrength;
			ip = forwardIp;
			forwardIp = ip + step;

			if unlikely(forwardIp > mflimit) { goto _last_literals; }

			forwardH = LZ4_HASH_VALUE(forwardIp);
			ref = base + HashTable[h];
			HashTable[h] = ip - base;

		} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));

		// Catch up

		while ((ip>anchor) && (ref>(BYTE*)source) && unlikely(ip[-1]==ref[-1])) { ip--; ref--; }

		// Encode Literal length

		length = ip - anchor;
		token = op++;
		if (length>=(int)RUN_MASK) { *token=(RUN_MASK<<ML_BITS); len = length-RUN_MASK; for(; len > 254 ; len-=255) *op++ = 255; *op++ = (BYTE)len; }
		else *token = (length<<ML_BITS);

		// Copy Literals

		LZ4_BLINDCOPY(anchor, op, length);

_next_match:
		// Encode Offset

		LZ4_WRITE_LITTLEENDIAN_16(op,ip-ref);

		// Start Counting

		ip+=MINMATCH; ref+=MINMATCH;   // MinMatch verified

		anchor = ip;
		while likely(ip<matchlimit-(STEPSIZE-1))
		{
			UARCH diff = AARCH(ref) ^ AARCH(ip);
			if (!diff) { ip+=STEPSIZE; ref+=STEPSIZE; continue; }
			ip += LZ4_NbCommonBytes(diff);
			goto _endCount;
		}
		if (LZ4_ARCH64) if ((ip<(matchlimit-3)) && (A32(ref) == A32(ip))) { ip+=4; ref+=4; }
		if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }
		if ((ip<matchlimit) && (*ref == *ip)) ip++;
_endCount:

		// Encode MatchLength

		len = (ip - anchor);
		if (len>=(int)ML_MASK) { *token+=ML_MASK; len-=ML_MASK; for(; len > 509 ; len-=510) { *op++ = 255; *op++ = 255; } if (len > 254) { len-=255; *op++ = 255; } *op++ = (BYTE)len; }
		else *token += len;

		// Test end of chunk

		if (ip > mflimit) { anchor = ip;  break; }

		// Fill table

		HashTable[LZ4_HASH_VALUE(ip-2)] = ip - 2 - base;

		// Test next position

		ref = base + HashTable[LZ4_HASH_VALUE(ip)];
		HashTable[LZ4_HASH_VALUE(ip)] = ip - base;
		if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) { token = op++; *token=0; goto _next_match; }

		// Prepare next loop

		anchor = ip++;
		forwardH = LZ4_HASH_VALUE(ip);
	}

_last_literals:
	// Encode Last Literals

	{
		int lastRun = iend - anchor;
		if ((LZ4_COMPRESSMIN>0) && (((op - (BYTE*)dest) + lastRun + 1 + ((lastRun-15)/255)) > isize - LZ4_COMPRESSMIN)) 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++ = (lastRun<<ML_BITS);
		memcpy(op, anchor, iend - anchor);
		op += iend-anchor;
	}

	// End

	return (int) (((char*)op)-dest);
}



// Note : this function is valid only if isize < LZ4_64KLIMIT

#define LZ4_64KLIMIT ((1<<16) + (MFLIMIT-1))

#define HASHLOG64K (HASH_LOG+1)

#define HASH64KTABLESIZE (1U<<HASHLOG64K)

#define LZ4_HASH64K_FUNCTION(i)	(((i) * 2654435761U) >> ((MINMATCH*8)-HASHLOG64K))

#define LZ4_HASH64K_VALUE(p)	LZ4_HASH64K_FUNCTION(A32(p))

int LZ4_compress64kCtx(void** ctx,
				 const char* source,
				 char* dest,
				 int isize)
{
#if HEAPMODE

	struct refTables *srt = (struct refTables *) (*ctx);
	U16* HashTable;
#else

	U16 HashTable[HASH64KTABLESIZE] = {0};
#endif


	const BYTE* ip = (BYTE*) source;
	const BYTE* anchor = ip;
	const BYTE* const base = ip;
	const BYTE* const iend = ip + isize;
	const BYTE* const mflimit = iend - MFLIMIT;
#define matchlimit (iend - LASTLITERALS)


	BYTE* op = (BYTE*) dest;

	int len, length;
	const int skipStrength = SKIPSTRENGTH;
	U32 forwardH;


	// Init

	if (isize<MINLENGTH) goto _last_literals;
#if HEAPMODE

	if (*ctx == NULL)
	{
		srt = (struct refTables *) malloc ( sizeof(struct refTables) );
		*ctx = (void*) srt;
	}
	HashTable = (U16*)(srt->hashTable);
	memset((void*)HashTable, 0, sizeof(srt->hashTable));
#else

	(void) ctx;
#endif



	// First Byte

	ip++; forwardH = LZ4_HASH64K_VALUE(ip);

	// Main Loop

    for ( ; ; )
	{
		int findMatchAttempts = (1U << skipStrength) + 3;
		const BYTE* forwardIp = ip;
		const BYTE* ref;
		BYTE* token;

		// Find a match

		do {
			U32 h = forwardH;
			int step = findMatchAttempts++ >> skipStrength;
			ip = forwardIp;
			forwardIp = ip + step;

			if (forwardIp > mflimit) { goto _last_literals; }

			forwardH = LZ4_HASH64K_VALUE(forwardIp);
			ref = base + HashTable[h];
			HashTable[h] = ip - base;

		} while (A32(ref) != A32(ip));

		// Catch up

		while ((ip>anchor) && (ref>(BYTE*)source) && (ip[-1]==ref[-1])) { ip--; ref--; }

		// Encode Literal length

		length = ip - anchor;
		token = op++;
		if (length>=(int)RUN_MASK) { *token=(RUN_MASK<<ML_BITS); len = length-RUN_MASK; for(; len > 254 ; len-=255) *op++ = 255; *op++ = (BYTE)len; }
		else *token = (length<<ML_BITS);

		// Copy Literals

		LZ4_BLINDCOPY(anchor, op, length);

_next_match:
		// Encode Offset

		LZ4_WRITE_LITTLEENDIAN_16(op,ip-ref);

		// Start Counting

		ip+=MINMATCH; ref+=MINMATCH;   // MinMatch verified

		anchor = ip;
		while (ip<matchlimit-(STEPSIZE-1))
		{
			UARCH diff = AARCH(ref) ^ AARCH(ip);
			if (!diff) { ip+=STEPSIZE; ref+=STEPSIZE; continue; }
			ip += LZ4_NbCommonBytes(diff);
			goto _endCount;
		}
		if (LZ4_ARCH64) if ((ip<(matchlimit-3)) && (A32(ref) == A32(ip))) { ip+=4; ref+=4; }
		if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }
		if ((ip<matchlimit) && (*ref == *ip)) ip++;
_endCount:

		// Encode MatchLength

		len = (ip - anchor);
		if (len>=(int)ML_MASK) { *token+=ML_MASK; len-=ML_MASK; for(; len > 509 ; len-=510) { *op++ = 255; *op++ = 255; } if (len > 254) { len-=255; *op++ = 255; } *op++ = (BYTE)len; }
		else *token += len;

		// Test end of chunk

		if (ip > mflimit) { anchor = ip;  break; }

		// Fill table

		HashTable[LZ4_HASH64K_VALUE(ip-2)] = ip - 2 - base;

		// Test next position

		ref = base + HashTable[LZ4_HASH64K_VALUE(ip)];
		HashTable[LZ4_HASH64K_VALUE(ip)] = ip - base;
		if (A32(ref) == A32(ip)) { token = op++; *token=0; goto _next_match; }

		// Prepare next loop

		anchor = ip++;
		forwardH = LZ4_HASH64K_VALUE(ip);
	}

_last_literals:
	// Encode Last Literals

	{
		int lastRun = iend - anchor;
		if ((LZ4_COMPRESSMIN>0) && (((op - (BYTE*)dest) + lastRun + 1 + ((lastRun-15)/255)) > isize - LZ4_COMPRESSMIN)) 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++ = (lastRun<<ML_BITS);
		memcpy(op, anchor, iend - anchor);
		op += iend-anchor;
	}

	// End

	return (int) (((char*)op)-dest);
}



int LZ4_compress(const char* source,
				 char* dest,
				 int isize)
{
#if HEAPMODE

	void* ctx = malloc(sizeof(struct refTables));
	int result;
	if (isize < LZ4_64KLIMIT)
		result = LZ4_compress64kCtx(&ctx, source, dest, isize);
	else result = LZ4_compressCtx(&ctx, source, dest, isize);
	free(ctx);
	return result;
#else

	if (isize < (int)LZ4_64KLIMIT) return LZ4_compress64kCtx(NULL, source, dest, isize);
	return LZ4_compressCtx(NULL, source, dest, isize);
#endif

}




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

// Decompression functions

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


// Note : The decoding functions LZ4_uncompress() and LZ4_uncompress_unknownOutputSize()

//		are safe against "buffer overflow" attack type.

//		They will never write nor read outside of the provided output buffers.

//      LZ4_uncompress_unknownOutputSize() also insures that it will never read outside of the input buffer.

//		A corrupted input will produce an error result, a negative int, indicating the position of the error within input stream.


int LZ4_uncompress(const char* source,
				 char* dest,
				 int osize)
{
	// Local Variables

	const BYTE* restrict ip = (const BYTE*) source;
	const BYTE* restrict ref;

	BYTE* restrict op = (BYTE*) dest;
	BYTE* const oend = op + osize;
	BYTE* cpy;

	BYTE token;

	int	len, length;
	size_t dec[] ={0, 3, 2, 3, 0, 0, 0, 0};


	// Main Loop

	while (1)
	{
		// get runlength

		token = *ip++;
		if ((length=(token>>ML_BITS)) == RUN_MASK)  { for (;(len=*ip++)==255;length+=255){} length += len; }

		// copy literals

		cpy = op+length;
		if unlikely(cpy>oend-COPYLENGTH)
		{
			if (cpy > oend) goto _output_error;          // Error : request to write beyond destination buffer

			memcpy(op, ip, length);
			ip += length;
			break;    // Necessarily EOF

		}
		LZ4_WILDCOPY(ip, op, cpy); ip -= (op-cpy); op = cpy;

		// get offset

		LZ4_READ_LITTLEENDIAN_16(ref,cpy,ip); ip+=2;
		if (ref < (BYTE* const)dest) goto _output_error;   // Error : offset create reference outside destination buffer


		// get matchlength

		if ((length=(token&ML_MASK)) == ML_MASK) { for (;*ip==255;length+=255) {ip++;} length += *ip++; }

		// copy repeated sequence

		if unlikely(op-ref<STEPSIZE)
		{
#if LZ4_ARCH64

			size_t dec2table[]={0, 0, 0, -1, 0, 1, 2, 3};
			size_t dec2 = dec2table[op-ref];
#else

			const int dec2 = 0;
#endif

			*op++ = *ref++;
			*op++ = *ref++;
			*op++ = *ref++;
			*op++ = *ref++;
			ref -= dec[op-ref];
			A32(op)=A32(ref); op += STEPSIZE-4;
			ref -= dec2;
		} else { LZ4_COPYSTEP(ref,op); }
		cpy = op + length - (STEPSIZE-4);
		if (cpy>oend-COPYLENGTH)
		{
			if (cpy > oend) goto _output_error;             // Error : request to write beyond destination buffer

			LZ4_SECURECOPY(ref, op, (oend-COPYLENGTH));
			while(op<cpy) *op++=*ref++;
			op=cpy;
			if (op == oend) break;    // Check EOF (should never happen, since last 5 bytes are supposed to be literals)

			continue;
		}
		LZ4_SECURECOPY(ref, op, cpy);
		op=cpy;		// correction

	}

	// end of decoding

	return (int) (((char*)ip)-source);

	// write overflow error detected

_output_error:
	return (int) (-(((char*)ip)-source));
}


int LZ4_uncompress_unknownOutputSize(
				const char* source,
				char* dest,
				int isize,
				int maxOutputSize)
{
	// Local Variables

	const BYTE* restrict ip = (const BYTE*) source;
	const BYTE* const iend = ip + isize;
	const BYTE* restrict ref;

	BYTE* restrict op = (BYTE*) dest;
	BYTE* const oend = op + maxOutputSize;
	BYTE* cpy;

	size_t dec[] ={0, 3, 2, 3, 0, 0, 0, 0};


	// Main Loop

	while (ip<iend)
	{
		BYTE token;
		int length;

		// get runlength

		token = *ip++;
		if ((length=(token>>ML_BITS)) == RUN_MASK) { int s=255; while ((ip<iend) && (s==255)) { s=*ip++; length += s; } }

		// copy literals

		cpy = op+length;
		if ((cpy>oend-COPYLENGTH) || (ip+length>iend-COPYLENGTH))
		{
			if (cpy > oend) goto _output_error;          // Error : request to write beyond destination buffer

			if (ip+length > iend) goto _output_error;    // Error : request to read beyond source buffer

			memcpy(op, ip, length);
			op += length;
			ip += length;
			if (ip<iend) goto _output_error;             // Error : LZ4 format violation

			break;    // Necessarily EOF, due to parsing restrictions

		}
		LZ4_WILDCOPY(ip, op, cpy); ip -= (op-cpy); op = cpy;

		// get offset

		LZ4_READ_LITTLEENDIAN_16(ref,cpy,ip); ip+=2;
		if (ref < (BYTE* const)dest) goto _output_error;   // Error : offset creates reference outside of destination buffer


		// get matchlength

		if ((length=(token&ML_MASK)) == ML_MASK) { while (ip<iend) { int s = *ip++; length +=s; if (s==255) continue; break; } }

		// copy repeated sequence

		if unlikely(op-ref<STEPSIZE)
		{
#if LZ4_ARCH64

			size_t dec2table[]={0, 0, 0, -1, 0, 1, 2, 3};
			size_t dec2 = dec2table[op-ref];
#else

			const int dec2 = 0;
#endif

			*op++ = *ref++;
			*op++ = *ref++;
			*op++ = *ref++;
			*op++ = *ref++;
			ref -= dec[op-ref];
			A32(op)=A32(ref); op += STEPSIZE-4;
			ref -= dec2;
		} else { LZ4_COPYSTEP(ref,op); }
		cpy = op + length - (STEPSIZE-4);
		if (cpy>oend-COPYLENGTH)
		{
			if (cpy > oend) goto _output_error;           // Error : request to write outside of destination buffer

			LZ4_SECURECOPY(ref, op, (oend-COPYLENGTH));
			while(op<cpy) *op++=*ref++;
			op=cpy;
			if (op == oend) break;    // Check EOF (should never happen, since last 5 bytes are supposed to be literals)

			continue;
		}
		LZ4_SECURECOPY(ref, op, cpy);
		op=cpy;		// correction

	}

	// end of decoding

	return (int) (((char*)op)-dest);

	// write overflow error detected

_output_error:
	return (int) (-(((char*)ip)-source));
}