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ZeroTierOne/ext/lz4/lz4.c

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New git repository for release - version 0.2.0 tagged
2013-07-04 20:56:19 +00:00
/*
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
//**************************************
// 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
// 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(__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 ?
// 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(__ppc__) || defined(_POWER) || defined(__powerpc__) || defined(_ARCH_PPC) || defined(__PPC__) || defined(__PPC) || defined(PPC) || defined(__powerpc__) || defined(__powerpc) || defined(powerpc) \
|| 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 __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
#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 (MEMORY_USAGE-2)
#define HASHTABLESIZE (1 << HASH_LOG)
#define HASH_MASK (HASHTABLESIZE - 1)
// NOTCOMPRESSIBLE_DETECTIONLEVEL :
// 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_DETECTIONLEVEL 6
#define SKIPSTRENGTH (NOTCOMPRESSIBLE_DETECTIONLEVEL>2?NOTCOMPRESSIBLE_DETECTIONLEVEL: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
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
//******************************
// LZ4_compressCtx :
// -----------------
// Compress 'isize' 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
static inline int LZ4_compressCtx(void** ctx,
const char* source,
char* dest,
int isize,
int maxOutputSize)
{
#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;
BYTE* const oend = op + maxOutputSize;
int 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 = (int)(ip - anchor);
token = op++;
if unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) > oend) return 0; // Check output limit
#ifdef _MSC_VER
if (length>=(int)RUN_MASK)
{
int len = length-RUN_MASK;
*token=(RUN_MASK<<ML_BITS);
if (len>254)
{
do { *op++ = 255; len -= 255; } while (len>254);
*op++ = (BYTE)len;
memcpy(op, anchor, length);
op += length;
goto _next_match;
}
else
*op++ = (BYTE)len;
}
else *token = (length<<ML_BITS);
#else
if (length>=(int)RUN_MASK)
{
int len;
*token=(RUN_MASK<<ML_BITS);
len = length-RUN_MASK;
for(; len > 254 ; len-=255) *op++ = 255;
*op++ = (BYTE)len;
}
else *token = (length<<ML_BITS);
#endif
// Copy Literals
LZ4_BLINDCOPY(anchor, op, length);
_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))
{
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
length = (int)(ip - anchor);
if 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 > 254) { length-=255; *op++ = 255; }
*op++ = (BYTE)length;
}
else *token += length;
// 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 = (int)(iend - anchor);
if (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize) 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))
static inline int LZ4_compress64kCtx(void** ctx,
const char* source,
char* dest,
int isize,
int maxOutputSize)
{
#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;
BYTE* const oend = op + maxOutputSize;
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] = (U16)(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 = (int)(ip - anchor);
token = op++;
if unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) > oend) return 0; // Check output limit
#ifdef _MSC_VER
if (length>=(int)RUN_MASK)
{
int len = length-RUN_MASK;
*token=(RUN_MASK<<ML_BITS);
if (len>254)
{
do { *op++ = 255; len -= 255; } while (len>254);
*op++ = (BYTE)len;
memcpy(op, anchor, length);
op += length;
goto _next_match;
}
else
*op++ = (BYTE)len;
}
else *token = (length<<ML_BITS);
#else
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);
#endif
// Copy Literals
LZ4_BLINDCOPY(anchor, op, length);
_next_match:
// Encode Offset
LZ4_WRITE_LITTLEENDIAN_16(op,(U16)(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 = (int)(ip - anchor);
if unlikely(op + (1 + LASTLITERALS) + (len>>8) > oend) return 0; // Check output limit
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)] = (U16)(ip - 2 - base);
// Test next position
ref = base + HashTable[LZ4_HASH64K_VALUE(ip)];
HashTable[LZ4_HASH64K_VALUE(ip)] = (U16)(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 = (int)(iend - anchor);
if (op + lastRun + 1 + (lastRun-RUN_MASK+255)/255 > oend) 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_limitedOutput(const char* source,
char* dest,
int isize,
int maxOutputSize)
{
#if HEAPMODE
void* ctx = malloc(sizeof(struct refTables));
int result;
if (isize < LZ4_64KLIMIT)
result = LZ4_compress64kCtx(&ctx, source, dest, isize, maxOutputSize);
else result = LZ4_compressCtx(&ctx, source, dest, isize, maxOutputSize);
free(ctx);
return result;
#else
if (isize < (int)LZ4_64KLIMIT) return LZ4_compress64kCtx(NULL, source, dest, isize, maxOutputSize);
return LZ4_compressCtx(NULL, source, dest, isize, maxOutputSize);
#endif
}
int LZ4_compress(const char* source,
char* dest,
int isize)
{
return LZ4_compress_limitedOutput(source, dest, isize, LZ4_compressBound(isize));
}
//****************************
// 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* ref;
BYTE* op = (BYTE*) dest;
BYTE* const oend = op + osize;
BYTE* cpy;
unsigned token;
size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
#if LZ4_ARCH64
size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
#endif
// Main Loop
while (1)
{
size_t length;
// get runlength
token = *ip++;
if ((length=(token>>ML_BITS)) == RUN_MASK) { size_t len; for (;(len=*ip++)==255;length+=255){} length += len; }
// copy literals
cpy = op+length;
if (cpy>oend-COPYLENGTH)
{
if (cpy != oend) goto _output_error; // Error : not enough place for another match (min 4) + 5 literals
memcpy(op, ip, length);
ip += length;
break; // EOF
}
LZ4_WILDCOPY(ip, op, cpy); ip -= (op-cpy); op = cpy;
// get offset
LZ4_READ_LITTLEENDIAN_16(ref,cpy,ip); ip+=2;
if unlikely(ref < (BYTE* const)dest) goto _output_error; // Error : offset 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 dec64 = dec64table[op-ref];
#else
const int 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
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* ref;
BYTE* op = (BYTE*) dest;
BYTE* const oend = op + maxOutputSize;
BYTE* cpy;
size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};
#if LZ4_ARCH64
size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
#endif
// Special case
if unlikely(ip==iend) goto _output_error; // A correctly formed null-compressed LZ4 must have at least one byte (token=0)
// Main Loop
while (1)
{
unsigned token;
size_t length;
// get runlength
token = *ip++;
if ((length=(token>>ML_BITS)) == RUN_MASK)
{
int s=255;
while (likely(ip<iend) && (s==255)) { s=*ip++; length += s; }
}
// copy literals
cpy = op+length;
if ((cpy>oend-MFLIMIT) || (ip+length>iend-(2+1+LASTLITERALS)))
{
if (cpy > oend) goto _output_error; // Error : writes beyond output buffer
if (ip+length != iend) goto _output_error; // Error : LZ4 format requires to consume all input at this stage (no match within the last 11 bytes, and at least 8 remaining input bytes for another match+literals)
memcpy(op, 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 unlikely(ref < (BYTE* const)dest) goto _output_error; // Error : offset outside of destination buffer
// get matchlength
if ((length=(token&ML_MASK)) == ML_MASK)
{
while likely(ip<iend-(LASTLITERALS+1)) // Error : a minimum input bytes must remain for LASTLITERALS + token
{
int 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 int 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
return (int) (((char*)op)-dest);
// write overflow error detected
_output_error:
return (int) (-(((char*)ip)-source));
}
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