gecko/mfbt/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/
*/

/*
Note : this source file requires "lz4_encoder.h"
*/

//**************************************
// 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 function will allocate memory for its hash table,
// in memory stack (0:default, fastest), or in memory heap (1:requires memory allocation (malloc)).
// Default allocation strategy is to use stack (HEAPMODE 0)
// Note : explicit functions *_stack* and *_heap* are unaffected by this setting
#define HEAPMODE 0

// BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE :
// This will provide a small 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 remain 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(_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, 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 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 defined (__STDC_VERSION__) && __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
#  include <intrin.h>   // For Visual 2005
#  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
#  pragma warning(disable : 4127)        // disable: C4127: conditional expression is constant
#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 (__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

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

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

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

#if !defined(LZ4_FORCE_UNALIGNED_ACCESS) && !defined(__GNUC__)
#  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 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
//**************************************
#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


//**************************************
// Macros
//**************************************
#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

static 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 & -val) * 0x0218A392CDABBD3F)) >> 58];
    #endif
#endif
}

#else

static 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
//******************************

/*
int LZ4_compress_stack(
                 const char* source,
                 char* dest,
                 int inputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest'.
Destination buffer must be already allocated, and sized at a minimum of LZ4_compressBound(inputSize).
return : the number of bytes written in buffer 'dest'
*/
#define FUNCTION_NAME LZ4_compress_stack
#include "lz4_encoder.h"


/*
int LZ4_compress_stack_limitedOutput(
                 const char* source,
                 char* dest,
                 int inputSize,
                 int maxOutputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest' of maximum size 'maxOutputSize'.
If it cannot achieve it, compression will stop, and result of the function will be zero.
return : the number of bytes written in buffer 'dest', or 0 if the compression fails
*/
#define FUNCTION_NAME LZ4_compress_stack_limitedOutput
#define LIMITED_OUTPUT
#include "lz4_encoder.h"


/*
int LZ4_compress64k_stack(
                 const char* source,
                 char* dest,
                 int inputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest'.
This function compresses better than LZ4_compress_stack(), on the condition that
'inputSize' must be < to LZ4_64KLIMIT, or the function will fail.
Destination buffer must be already allocated, and sized at a minimum of LZ4_compressBound(inputSize).
return : the number of bytes written in buffer 'dest', or 0 if compression fails
*/
#define FUNCTION_NAME LZ4_compress64k_stack
#define COMPRESS_64K
#include "lz4_encoder.h"


/*
int LZ4_compress64k_stack_limitedOutput(
                 const char* source,
                 char* dest,
                 int inputSize,
                 int maxOutputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest' of maximum size 'maxOutputSize'.
This function compresses better than LZ4_compress_stack_limitedOutput(), on the condition that
'inputSize' must be < to LZ4_64KLIMIT, or the function will fail.
If it cannot achieve it, compression will stop, and result of the function will be zero.
return : the number of bytes written in buffer 'dest', or 0 if the compression fails
*/
#define FUNCTION_NAME LZ4_compress64k_stack_limitedOutput
#define COMPRESS_64K
#define LIMITED_OUTPUT
#include "lz4_encoder.h"


/*
void* LZ4_createHeapMemory();
int LZ4_freeHeapMemory(void* ctx);

Used to allocate and free hashTable memory 
to be used by the LZ4_compress_heap* family of functions.
LZ4_createHeapMemory() returns NULL is memory allocation fails.
*/
void* LZ4_create() { return malloc(HASHTABLESIZE); }
int   LZ4_free(void* ctx) { free(ctx); return 0; }


/*
int LZ4_compress_heap(
                 void* ctx,
                 const char* source,
                 char* dest,
                 int inputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest'.
The memory used for compression must be created by LZ4_createHeapMemory() and provided by pointer 'ctx'.
Destination buffer must be already allocated, and sized at a minimum of LZ4_compressBound(inputSize).
return : the number of bytes written in buffer 'dest'
*/
#define FUNCTION_NAME LZ4_compress_heap
#define USE_HEAPMEMORY
#include "lz4_encoder.h"


/*
int LZ4_compress_heap_limitedOutput(
                 void* ctx,
                 const char* source,
                 char* dest,
                 int inputSize,
                 int maxOutputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest' of maximum size 'maxOutputSize'.
If it cannot achieve it, compression will stop, and result of the function will be zero.
The memory used for compression must be created by LZ4_createHeapMemory() and provided by pointer 'ctx'.
return : the number of bytes written in buffer 'dest', or 0 if the compression fails
*/
#define FUNCTION_NAME LZ4_compress_heap_limitedOutput
#define LIMITED_OUTPUT
#define USE_HEAPMEMORY
#include "lz4_encoder.h"


/*
int LZ4_compress64k_heap(
                 void* ctx,
                 const char* source,
                 char* dest,
                 int inputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest'.
The memory used for compression must be created by LZ4_createHeapMemory() and provided by pointer 'ctx'.
'inputSize' must be < to LZ4_64KLIMIT, or the function will fail.
Destination buffer must be already allocated, and sized at a minimum of LZ4_compressBound(inputSize).
return : the number of bytes written in buffer 'dest'
*/
#define FUNCTION_NAME LZ4_compress64k_heap
#define COMPRESS_64K
#define USE_HEAPMEMORY
#include "lz4_encoder.h"


/*
int LZ4_compress64k_heap_limitedOutput(
                 void* ctx,
                 const char* source,
                 char* dest,
                 int inputSize,
                 int maxOutputSize)

Compress 'inputSize' bytes from 'source' into an output buffer 'dest' of maximum size 'maxOutputSize'.
If it cannot achieve it, compression will stop, and result of the function will be zero.
The memory used for compression must be created by LZ4_createHeapMemory() and provided by pointer 'ctx'.
'inputSize' must be < to LZ4_64KLIMIT, or the function will fail.
return : the number of bytes written in buffer 'dest', or 0 if the compression fails
*/
#define FUNCTION_NAME LZ4_compress64k_heap_limitedOutput
#define COMPRESS_64K
#define LIMITED_OUTPUT
#define USE_HEAPMEMORY
#include "lz4_encoder.h"


int LZ4_compress(const char* source, char* dest, int inputSize)
{
#if HEAPMODE
    void* ctx = LZ4_create();
    int result;
    if (ctx == NULL) return 0;    // Failed allocation => compression not done
    if (inputSize < LZ4_64KLIMIT)
        result = LZ4_compress64k_heap(ctx, source, dest, inputSize);
    else result = LZ4_compress_heap(ctx, source, dest, inputSize);
    LZ4_free(ctx);
    return result;
#else
    if (inputSize < (int)LZ4_64KLIMIT) return LZ4_compress64k_stack(source, dest, inputSize);
    return LZ4_compress_stack(source, dest, inputSize);
#endif
}


int LZ4_compress_limitedOutput(const char* source, char* dest, int inputSize, int maxOutputSize)
{
#if HEAPMODE
    void* ctx = LZ4_create();
    int result;
    if (ctx == NULL) return 0;    // Failed allocation => compression not done
    if (inputSize < LZ4_64KLIMIT)
        result = LZ4_compress64k_heap_limitedOutput(ctx, source, dest, inputSize, maxOutputSize);
    else result = LZ4_compress_heap_limitedOutput(ctx, source, dest, inputSize, maxOutputSize);
    LZ4_free(ctx);
    return result;
#else
    if (inputSize < (int)LZ4_64KLIMIT) return LZ4_compress64k_stack_limitedOutput(source, dest, inputSize, maxOutputSize);
    return LZ4_compress_stack_limitedOutput(source, dest, inputSize, maxOutputSize);
#endif
}


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

typedef enum { noPrefix = 0, withPrefix = 1 } prefix64k_directive;
typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } end_directive;
typedef enum { full = 0, partial = 1 } exit_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.
static 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
    const BYTE* restrict ip = (const BYTE*) source;
    const BYTE* ref;
    const BYTE* 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 case
    if ((partialDecoding) && (oexit> oend-MFLIMIT)) oexit = oend-MFLIMIT;   // targetOutputSize too large, better decode everything
    if unlikely(outputSize==0) goto _output_error;                          // Empty output buffer


    // 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, due to parsing restrictions
                if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) goto _output_error;   // Error : not enough place for another match (min 4) + 5 literals
            }
            memcpy(op, ip, length);
            ip += length;
            op += length;
            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 ((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) : 1)    // A minimum nb of input bytes must remain for LASTLITERALS + token
            { 
                unsigned s = *ip++; 
                length += s; 
                if (s==255) continue; 
                break; 
            } 
        }

        // copy repeated sequence
        if unlikely((op-ref)<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(ref,op); }
        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(ref, op, (oend-COPYLENGTH));
            while(op<cpy) *op++=*ref++;
            op=cpy;
            continue;
        }
        LZ4_WILDCOPY(ref, op, 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_fast(const char* source, char* dest, int outputSize)
{
    return LZ4_decompress_generic(source, dest, 0, outputSize, endOnOutputSize, 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_fast_withPrefix64k(const char* source, char* dest, int outputSize)
{
    return LZ4_decompress_generic(source, dest, 0, outputSize, endOnOutputSize, 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);
}