lz4.c

/*
   LZ4 - Fast LZ compression algorithm
   Copyright (C) 2011-2013, 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
//**************************************
// MEMORY_USAGE :
// Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
// Increasing memory usage improves compression ratio
// Reduced memory usage can improve speed, due to cache effect
// Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
#define MEMORY_USAGE 14

// HEAPMODE :
// Select how default compression functions will allocate memory for their hash table,
// in memory stack (0:default, fastest), or in memory heap (1:requires memory allocation (malloc)).
#define HEAPMODE 0


//**************************************
// CPU Feature Detection
//**************************************
// 32 or 64 bits ?
#if (defined(__x86_64__) || defined(_M_X64) || defined(_WIN64) \
  || defined(__powerpc64__) || defined(__ppc64__) || defined(__PPC64__) \
  || defined(__64BIT__) || defined(_LP64) || defined(__LP64__) \
  || defined(__ia64) || defined(__itanium__) || defined(_M_IA64) )   // Detects 64 bits mode
#  define LZ4_ARCH64 1
#else
#  define LZ4_ARCH64 0
#endif

// Little Endian or Big Endian ?
// Overwrite the #define below if you know your architecture endianess
#if defined (__GLIBC__)
#  include <endian.h>
#  if (__BYTE_ORDER == __BIG_ENDIAN)
#     define LZ4_BIG_ENDIAN 1
#  endif
#elif (defined(__BIG_ENDIAN__) || defined(__BIG_ENDIAN) || defined(_BIG_ENDIAN)) && !(defined(__LITTLE_ENDIAN__) || defined(__LITTLE_ENDIAN) || defined(_LITTLE_ENDIAN))
#  define LZ4_BIG_ENDIAN 1
#elif defined(__sparc) || defined(__sparc__) \
   || defined(__powerpc__) || defined(__ppc__) || defined(__PPC__) \
   || defined(__hpux)  || defined(__hppa) \
   || defined(_MIPSEB) || defined(__s390__)
#  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, such as ARM, the compiler may be more cautious, inserting unnecessary extra code to ensure aligned access property
// If you know your target CPU supports unaligned memory access, you 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

// BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE :
// This option may provide a small boost to performance for some big endian cpu, although probably modest.
// You may set this option to 1 if data will remain within closed environment.
// This option is useless on Little_Endian CPU (such as x86)
//#define BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE 1


//**************************************
// Compiler Options
//**************************************
#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)   // C99
/* "restrict" is a known keyword */
#else
#  define restrict // Disable restrict
#endif

#ifdef _MSC_VER    // Visual Studio
#  define FORCE_INLINE static __forceinline
#  include <intrin.h>                    // For Visual 2005
#  if LZ4_ARCH64   // 64-bits
#    pragma intrinsic(_BitScanForward64) // For Visual 2005
#    pragma intrinsic(_BitScanReverse64) // For Visual 2005
#  else            // 32-bits
#    pragma intrinsic(_BitScanForward)   // For Visual 2005
#    pragma intrinsic(_BitScanReverse)   // For Visual 2005
#  endif
#  pragma warning(disable : 4127)        // disable: C4127: conditional expression is constant
#else 
#  ifdef __GNUC__
#    define FORCE_INLINE static inline __attribute__((always_inline))
#  else
#    define FORCE_INLINE static inline
#  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

#define GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)

#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 (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L   // C99
# include <stdint.h>
  typedef  uint8_t BYTE;
  typedef uint16_t U16;
  typedef uint32_t U32;
  typedef  int32_t S32;
  typedef uint64_t U64;
#else
  typedef unsigned char       BYTE;
  typedef unsigned short      U16;
  typedef unsigned int        U32;
  typedef   signed int        S32;
  typedef unsigned long long  U64;
#endif

typedef const BYTE* Ptr;

#if defined(__GNUC__)  && !defined(LZ4_FORCE_UNALIGNED_ACCESS)
#  define _PACKED __attribute__ ((packed))
#else
#  define _PACKED
#endif

#if !defined(LZ4_FORCE_UNALIGNED_ACCESS) && !defined(__GNUC__)
#  ifdef __IBMC__
#    pragma pack(1)
#  else
#    pragma pack(push, 1)
#  endif
#endif

typedef struct { U16 v; }  _PACKED U16_S;
typedef struct { U32 v; }  _PACKED U32_S;
typedef struct { U64 v; }  _PACKED U64_S;
typedef struct {size_t v;} _PACKED size_t_S;

#if !defined(LZ4_FORCE_UNALIGNED_ACCESS) && !defined(__GNUC__)
#  pragma pack(pop)
#endif

#define A16(x)   (((U16_S *)(x))->v)
#define A32(x)   (((U32_S *)(x))->v)
#define A64(x)   (((U64_S *)(x))->v)
#define AARCH(x) (((size_t_S *)(x))->v)


//**************************************
// Constants
//**************************************
#define HASHTABLESIZE (1 << MEMORY_USAGE)

#define MINMATCH 4

#define COPYLENGTH 8
#define LASTLITERALS 5
#define MFLIMIT (COPYLENGTH+MINMATCH)
#define MINLENGTH (MFLIMIT+1)

#define LZ4_64KLIMIT ((1<<16) + (MFLIMIT-1))
#define SKIPSTRENGTH 6     // Increasing this value will make the compression run slower on incompressible data

#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
//**************************************
#define STEPSIZE                  sizeof(size_t)
#define LZ4_COPYSTEP(d,s)         { AARCH(d) = AARCH(s); d+=STEPSIZE; s+=STEPSIZE; }
#define LZ4_COPY8(d,s)            { LZ4_COPYSTEP(d,s); if (STEPSIZE<8) LZ4_COPYSTEP(d,s); }
#define LZ4_SECURECOPY(d,s,e)     { if ((STEPSIZE==4)||(d<e)) LZ4_WILDCOPY(d,s,e); }

#if LZ4_ARCH64   // 64-bit
#  define HTYPE                   U32
#  define INITBASE(base)          Ptr const base = ip
#else            // 32-bit
#  define HTYPE                   Ptr
#  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


//**************************************
// Macros
//**************************************
#define LZ4_WILDCOPY(d,s,e)     { do { LZ4_COPY8(d,s) } while (d<e); }           // at the end, d>=e;


//****************************
// Private functions
//****************************
#if LZ4_ARCH64

FORCE_INLINE 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 & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58];
#   endif
# endif
}

#else

FORCE_INLINE 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;
    _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


//****************************
// Compression functions
//****************************
#define LZ4_HASHLOG (MEMORY_USAGE-2)
typedef enum { notLimited = 0, limited = 1 } limitedOutput_directive;
typedef enum { byPtr, byU32, byU16 } tableType_t;

FORCE_INLINE int LZ4_hashSequence(U32 sequence, tableType_t tableType)
{
    if (tableType == byU16)
        return (((sequence) * 2654435761U) >> ((MINMATCH*8)-(LZ4_HASHLOG+1)));
    else
        return (((sequence) * 2654435761U) >> ((MINMATCH*8)-LZ4_HASHLOG));
}

FORCE_INLINE int LZ4_hashPosition(Ptr p, tableType_t tableType) { return LZ4_hashSequence(A32(p), tableType); }

FORCE_INLINE void LZ4_putPositionOnHash(Ptr p, U32 h, void* tableBase, tableType_t tableType, Ptr srcBase)
{
    switch (tableType)
    {
    case byPtr: { Ptr* hashTable = (Ptr*) tableBase; hashTable[h] = p; break; }
    case byU32: { U32* hashTable = (U32*) tableBase; hashTable[h] = p-srcBase; break; }
    case byU16: { U16* hashTable = (U16*) tableBase; hashTable[h] = (U16)(p-srcBase); break; }
    }
}

FORCE_INLINE void LZ4_putPosition(Ptr p, void* tableBase, tableType_t tableType, Ptr srcBase)
{
    U32 h = LZ4_hashPosition(p, tableType);
    LZ4_putPositionOnHash(p, h, tableBase, tableType, srcBase);
}

FORCE_INLINE Ptr LZ4_getPositionOnHash(U32 h, void* tableBase, tableType_t tableType, Ptr srcBase)
{
    if (tableType == byPtr) { Ptr* hashTable = (Ptr*) tableBase; return hashTable[h]; }
    if (tableType == byU32) { U32* hashTable = (U32*) tableBase; return hashTable[h] + srcBase; }
    { U16* hashTable = (U16*) tableBase; return hashTable[h] + srcBase; }   // default, to ensure a return
}

FORCE_INLINE Ptr LZ4_getPosition(Ptr p, void* tableBase, tableType_t tableType, Ptr srcBase)
{
    U32 h = LZ4_hashPosition(p, tableType);
    return LZ4_getPositionOnHash(h, tableBase, tableType, srcBase);
}


FORCE_INLINE int LZ4_compress_generic(
                 void* ctx,
                 const char* source,
                 char* dest,
                 int inputSize,
                 int maxOutputSize,

                 limitedOutput_directive limitedOutput,
                 tableType_t tableType)
{
    Ptr ip = (Ptr) source;
    Ptr const base = (Ptr) source;
    Ptr anchor = (Ptr) source;
    Ptr const iend = ip + inputSize;
    Ptr const mflimit = iend - MFLIMIT;
    Ptr const matchlimit = iend - LASTLITERALS;

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

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

    // Init conditions
    if (inputSize<MINLENGTH) goto _last_literals;
    if ((tableType == byU16) && (inputSize>=LZ4_64KLIMIT)) return 0;   // Size too large (not within 64K limit)

    // First Byte
    LZ4_putPosition(ip, ctx, tableType, base);
    ip++; forwardH = LZ4_hashPosition(ip, tableType);

    // Main Loop
    for ( ; ; )
    {
        int findMatchAttempts = (1U << skipStrength) + 3;
        Ptr forwardIp = ip;
        Ptr 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_hashPosition(forwardIp, tableType);
            ref = LZ4_getPositionOnHash(h, ctx, tableType, base);
            LZ4_putPositionOnHash(ip, h, ctx, tableType, base);

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

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

        // Encode Literal length
        length = (int)(ip - anchor);
        token = op++;
        if ((limitedOutput) && unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) > oend)) return 0;   // Check output limit
        if (length>=(int)RUN_MASK) 
        { 
            int len = length-RUN_MASK; 
            *token=(RUN_MASK<<ML_BITS); 
            for(; len >= 255 ; len-=255) *op++ = 255; 
            *op++ = (BYTE)len; 
        }
        else *token = (BYTE)(length<<ML_BITS);

        // Copy Literals
        { BYTE* end=(op)+(length); LZ4_WILDCOPY(op,anchor,end); op=end; }

_next_match:
        // Encode Offset
        LZ4_WRITE_LITTLEENDIAN_16(op,(U16)(ip-ref));

        // Start Counting
        ip+=MINMATCH; ref+=MINMATCH;    // MinMatch already verified
        anchor = ip;
        while likely(ip<matchlimit-(STEPSIZE-1))
        {
            size_t 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
        length = (int)(ip - anchor);
        if ((limitedOutput) && unlikely(op + (1 + LASTLITERALS) + (length>>8) > oend)) return 0;    // Check output limit
        if (length>=(int)ML_MASK) 
        { 
            *token += ML_MASK; 
            length -= ML_MASK; 
            for (; length > 509 ; length-=510) { *op++ = 255; *op++ = 255; } 
            if (length >= 255) { length-=255; *op++ = 255; } 
            *op++ = (BYTE)length; 
        }
        else *token += (BYTE)(length);

        // Test end of chunk
        if (ip > mflimit) { anchor = ip;  break; }

        // Fill table
        LZ4_putPosition(ip-2, ctx, tableType, base);

        // Test next position
        ref = LZ4_getPosition(ip, ctx, tableType, base); 
        LZ4_putPosition(ip, ctx, tableType, base);
        if ((ref + MAX_DISTANCE >= ip) && (A32(ref) == A32(ip))) { token = op++; *token=0; goto _next_match; }

        // Prepare next loop
        anchor = ip++;
        forwardH = LZ4_hashPosition(ip, tableType);
    }

_last_literals:
    // Encode Last Literals
    {
        int lastRun = (int)(iend - anchor);
        if ((limitedOutput) && (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize)) return 0;  // Check output limit
        if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun >= 255 ; 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 LZ4_compress(const char* source, char* dest, int inputSize)
{
#if (HEAPMODE)
    void* ctx = calloc(1U<<(MEMORY_USAGE-2), 4);   // Aligned on 4-bytes boundaries
#else
    U32 ctx[1U<<(MEMORY_USAGE-2)] = {0};           // Ensure data is aligned on 4-bytes boundaries
#endif
    int result;

    if (inputSize < (int)LZ4_64KLIMIT)
        result = LZ4_compress_generic((void*)ctx, source, dest, inputSize, 0, notLimited, byU16);
    else
        result = LZ4_compress_generic((void*)ctx, source, dest, inputSize, 0, notLimited, (sizeof(void*)==8) ? byU32 : byPtr);

#if (HEAPMODE)
    free(ctx);
#endif
    return result;
}


int LZ4_compress_limitedOutput(const char* source, char* dest, int inputSize, int maxOutputSize)
{
#if (HEAPMODE)
    void* ctx = calloc(1U<<(MEMORY_USAGE-2), 4);   // Aligned on 4-bytes boundaries
#else
    U32 ctx[1U<<(MEMORY_USAGE-2)] = {0};           // Ensure data is aligned on 4-bytes boundaries
#endif
    int result;

    if (inputSize < (int)LZ4_64KLIMIT)
        result = LZ4_compress_generic((void*)ctx, source, dest, inputSize, maxOutputSize, limited, byU16);
    else
        result = LZ4_compress_generic((void*)ctx, source, dest, inputSize, maxOutputSize, limited, (sizeof(void*)==8) ? byU32 : byPtr);

#if (HEAPMODE)
    free(ctx);
#endif
    return result;
}



//****************************
// Decompression functions
//****************************

typedef enum { noPrefix = 0, withPrefix = 1 } prefix64k_directive;
typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
typedef enum { full = 0, partial = 1 } earlyEnd_directive;


// This generic decompression function cover all use cases.
// It shall be instanciated several times, using different sets of directives
// Note that it is essential this generic function is really inlined, 
// in order to remove useless branches during compilation optimisation.
FORCE_INLINE int LZ4_decompress_generic(
                 const char* source,
                 char* dest,
                 int inputSize,          //
                 int outputSize,         // OutputSize must be != 0; if endOnInput==endOnInputSize, this value is the max size of Output Buffer.

                 int endOnInput,         // endOnOutputSize, endOnInputSize
                 int prefix64k,          // noPrefix, withPrefix
                 int partialDecoding,    // full, partial
                 int targetOutputSize    // only used if partialDecoding==partial
                 )
{
    // Local Variables
    Ptr restrict ip = (Ptr) source;
    Ptr ref;
    Ptr const iend = ip + inputSize;

    BYTE* op = (BYTE*) dest;
    BYTE* const oend = op + outputSize;
    BYTE* cpy;
    BYTE* oexit = op + targetOutputSize;

    size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
#if LZ4_ARCH64
    size_t dec64table[] = {0, 0, 0, (size_t)-1, 0, 1, 2, 3};
#endif


    // Special cases
    if ((partialDecoding) && (oexit> oend-MFLIMIT)) oexit = oend-MFLIMIT;                        // targetOutputSize too high => decode everything
    if ((endOnInput) && unlikely(outputSize==0)) return ((inputSize==1) && (*ip==0)) ? 0 : -1;   // Empty output buffer
    if ((!endOnInput) && unlikely(outputSize==0)) return (*ip==0?1:-1);


    // Main Loop
    while (1)
    {
        unsigned token;
        size_t length;

        // get runlength
        token = *ip++;
        if ((length=(token>>ML_BITS)) == RUN_MASK)
        { 
            unsigned s=255; 
            while (((endOnInput)?ip<iend:1) && (s==255))
            { 
                s = *ip++; 
                length += s; 
            } 
        }

        // copy literals
        cpy = op+length;
        if (((endOnInput) && ((cpy>(partialDecoding?oexit:oend-MFLIMIT)) || (ip+length>iend-(2+1+LASTLITERALS))) )
            || ((!endOnInput) && (cpy>oend-COPYLENGTH)))
        {
            if (partialDecoding)
            {
                if (cpy > oend) goto _output_error;                           // Error : write attempt beyond end of output buffer
                if ((endOnInput) && (ip+length > iend)) goto _output_error;   // Error : read attempt beyond end of input buffer
            }
            else
            {
                if ((!endOnInput) && (cpy != oend)) goto _output_error;       // Error : block decoding must stop exactly there
                if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) goto _output_error;   // Error : input must be consumed
            }
            memcpy(op, ip, length);
            ip += length;
            op += length;
            break;                                       // Necessarily EOF, due to parsing restrictions
        }
        LZ4_WILDCOPY(op, ip, cpy); ip -= (op-cpy); op = cpy;

        // get offset
        LZ4_READ_LITTLEENDIAN_16(ref,cpy,ip); ip+=2;
        if ((prefix64k==noPrefix) && unlikely(ref < (BYTE* const)dest)) goto _output_error;   // Error : offset outside destination buffer

        // get matchlength
        if ((length=(token&ML_MASK)) == ML_MASK) 
        { 
            while ((!endOnInput) || (ip<iend-(LASTLITERALS+1)))   // Ensure enough bytes remain for LASTLITERALS + token
            {
                unsigned s = *ip++; 
                length += s; 
                if (s==255) continue; 
                break; 
            }
        }

        // copy repeated sequence
        if unlikely((op-ref)<(int)STEPSIZE)
        {
#if LZ4_ARCH64
            size_t dec64 = dec64table[op-ref];
#else
            const size_t dec64 = 0;
#endif
            op[0] = ref[0];
            op[1] = ref[1];
            op[2] = ref[2];
            op[3] = ref[3];
            op += 4, ref += 4; ref -= dec32table[op-ref];
            A32(op) = A32(ref); 
            op += STEPSIZE-4; ref -= dec64;
        } else { LZ4_COPYSTEP(op,ref); }
        cpy = op + length - (STEPSIZE-4);

        if unlikely(cpy>oend-COPYLENGTH-(STEPSIZE-4))
        {
            if (cpy > oend-LASTLITERALS) goto _output_error;    // Error : last 5 bytes must be literals
            LZ4_SECURECOPY(op, ref, (oend-COPYLENGTH));
            while(op<cpy) *op++=*ref++;
            op=cpy;
            continue;
        }
        LZ4_WILDCOPY(op, ref, cpy);
        op=cpy;   // correction
    }

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

    // Overflow error detected
_output_error:
    return (int) (-(((char*)ip)-source))-1;
}


int LZ4_decompress_safe(const char* source, char* dest, int inputSize, int maxOutputSize)
{
    return LZ4_decompress_generic(source, dest, inputSize, maxOutputSize, endOnInputSize, noPrefix, full, 0);
}

int LZ4_decompress_safe_withPrefix64k(const char* source, char* dest, int inputSize, int maxOutputSize)
{
    return LZ4_decompress_generic(source, dest, inputSize, maxOutputSize, endOnInputSize, withPrefix, full, 0);
}

int LZ4_decompress_safe_partial(const char* source, char* dest, int inputSize, int targetOutputSize, int maxOutputSize)
{
    return LZ4_decompress_generic(source, dest, inputSize, maxOutputSize, endOnInputSize, noPrefix, partial, targetOutputSize);
}

int LZ4_decompress_fast(const char* source, char* dest, int outputSize)
{
#ifdef _MSC_VER   // This version is faster with Visual
    return LZ4_decompress_generic(source, dest, 0, outputSize, endOnOutputSize, noPrefix, full, 0);
#else
    return LZ4_decompress_generic(source, dest, 0, outputSize, endOnOutputSize, withPrefix, full, 0);
#endif
}

int LZ4_decompress_fast_withPrefix64k(const char* source, char* dest, int outputSize)
{
    return LZ4_decompress_generic(source, dest, 0, outputSize, endOnOutputSize, withPrefix, full, 0);
}