lz4/lz4.c

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/*
LZ4 - Fast LZ compression algorithm
Copyright (C) 2011, Yann Collet.
BSD License
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.
*/
//**************************************
// Includes
//**************************************
#include <stdlib.h> // for malloc
#include <string.h> // for memset
#include "lz4.h"
//**************************************
// Performance parameter
//**************************************
// Lowering this value reduce memory usage
// It may also improve speed, especially if you reach L1 cache size (32KB for Intel, 64KB for AMD)
// Expanding memory usage typically improves compression ratio
// Memory usage formula for 32 bits systems : N->2^(N+2) Bytes (examples : 17 -> 512KB ; 12 -> 16KB)
#define HASH_LOG 12
//**************************************
// Basic Types
//**************************************
#if defined(_MSC_VER)
#define BYTE unsigned __int8
#define U16 unsigned __int16
#define U32 unsigned __int32
#define S32 __int32
#else
#include <stdint.h>
#define BYTE uint8_t
#define U16 uint16_t
#define U32 uint32_t
#define S32 int32_t
#endif
//**************************************
// Constants
//**************************************
#define MINMATCH 4
#define MINLENGTH 6
#define SKIPSTRENGTH 6
#define STACKLIMIT 13
#define HEAPMODE (HASH_LOG>STACKLIMIT) // Defines if memory is allocated into the stack (local variable), or into the heap (malloc()).
#define MAXD_LOG 16
#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
#define HASHTABLESIZE (1 << HASH_LOG)
#define HASH_MASK (HASHTABLESIZE - 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)
//**************************************
// Local structures
//**************************************
struct refTables
{
const BYTE* hashTable[HASHTABLESIZE];
};
//**************************************
// Macros
//**************************************
#define HASH_FUNCTION(i) (((i) * 2654435761U) >> ((MINMATCH*8)-HASH_LOG))
#define HASH_VALUE(p) HASH_FUNCTION(*(U32*)(p))
//****************************
// Compression CODE
//****************************
int LZ4_compressCtx(void** ctx,
char* source,
char* dest,
int isize)
{
#if HEAPMODE
struct refTables *srt = (struct refTables *) (*ctx);
const BYTE** HashTable;
#else
const BYTE* HashTable[HASHTABLESIZE] = {0};
#endif
const BYTE* ip = (BYTE*) source;
const BYTE* anchor = ip;
const BYTE* const iend = ip + isize;
const BYTE* const ilm = iend - 1;
const BYTE* const ilimit = iend - MINMATCH - 1;
BYTE* op = (BYTE*) dest;
BYTE* token;
BYTE* l_end;
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 = srt->hashTable;
memset((void*)HashTable, 0, sizeof(srt->hashTable));
#else
(void) ctx;
#endif
// First Byte
HashTable[HASH_VALUE(ip)] = ip;
ip++; forwardH = HASH_VALUE(ip);
// Main Loop
for ( ; ; )
{
int findMatchAttempts = (1U << skipStrength) + 3;
const BYTE* forwardIp = ip;
const BYTE* ref;
// Find a match
do {
U32 h = forwardH;
int step = findMatchAttempts++ >> skipStrength;
ip = forwardIp;
forwardIp = ip + step;
if (forwardIp > ilimit) { goto _last_literals; }
forwardH = HASH_VALUE(forwardIp);
ref = HashTable[h];
HashTable[h] = ip;
} while ((ref < ip - MAX_DISTANCE) || (*(U32*)ref != *(U32*)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
l_end = op + length;
do { *(U32*)op = *(U32*)anchor; op+=4; anchor+=4; } while (op<l_end) ;
op = l_end;
_next_match:
// Encode Offset
*(U16*)op = (ip-ref); op+=2;
// Start Counting
ip+=MINMATCH; ref+=MINMATCH; // MinMatch verified
anchor = ip;
while (ip<(iend-4))
{
if (*(U32*)ref == *(U32*)ip) { ip+=4; ref+=4; continue; }
if (*(U16*)ref == *(U16*)ip) { ip+=2; ref+=2; }
if (*ref == *ip) ip++;
goto _endCount;
}
if ((ip<(iend-2)) && (*(U16*)ref == *(U16*)ip)) { ip+=2; ref+=2; }
if ((ip<iend-1) && (*ref == *ip)) ip++;
_endCount:
len = (ip - anchor);
// Encode MatchLength
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 > ilimit-1) { anchor = ip; break; }
// Test next position
ref = HashTable[HASH_VALUE(ip)];
HashTable[HASH_VALUE(ip)] = ip;
if ((ref > ip - (MAX_DISTANCE + 1)) && (*(U32*)ref == *(U32*)ip)) { token = op++; *token=0; goto _next_match; }
// Prepare next loop
anchor = ip++;
forwardH = HASH_VALUE(ip);
}
_last_literals:
// Encode Last Literals
{
int lastLitRun = iend - anchor;
if (lastLitRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastLitRun-=RUN_MASK; for(; lastLitRun > 254 ; lastLitRun-=255) *op++ = 255; *op++ = (BYTE) lastLitRun; }
else *op++ = (lastLitRun<<ML_BITS);
while (anchor < iend - 3) { *(U32*)op = *(U32*)anchor; op+=4; anchor+=4; }
while (anchor < iend ) *op++ = *anchor++;
}
// End
return (int) (((char*)op)-dest);
}
int LZ4_compress(char* source,
char* dest,
int isize)
{
#if HEAPMODE
void* ctx = malloc(sizeof(struct refTables));
int result = LZ4_compressCtx(&ctx, source, dest, isize);
free(ctx);
return result;
#else
return LZ4_compressCtx(NULL, source, dest, isize);
#endif
}
//****************************
// Decompression CODE
//****************************
// Note : The decoding functions LZ4_uncompress() and LZ4_uncompress_unknownOutputSize()
// are safe against "buffer overflow" attack type
// since they will *never* write outside of the provided output buffer :
// they both check this condition *before* writing anything.
// A corrupted packet however can make them *read* within the first 64K before the output buffer.
int LZ4_uncompress(char* source,
char* dest,
int osize)
{
// Local Variables
const BYTE* ip = (const BYTE*) source;
BYTE* ref;
BYTE* op = (BYTE*) dest;
BYTE* const olimit = op + osize - 4;
BYTE* cpy;
BYTE token;
U32 dec[4]={0, 3, 2, 3};
int length;
// Main Loop
while (1)
{
// get runlength
token = *ip++;
if ((length=(token>>ML_BITS)) == RUN_MASK) { for (;*ip==255;length+=255) {ip++;} length += *ip++; }
// copy literals
ref = op+length;
if (ref > olimit)
{
if (ref > olimit+4) goto _output_error;
while(op <= olimit) { *(U32*)op=*(U32*)ip; op+=4; ip+=4; }
while(op < ref) *op++=*ip++;
break; // Necessarily EOF
}
do { *(U32*)op = *(U32*)ip; op+=4; ip+=4; } while (op<ref) ;
ip -= (op-ref); op = ref; // correction
// get offset
ref -= *(U16*)ip; ip+=2;
// get matchlength
if ((length=(token&ML_MASK)) == ML_MASK) { for (;*ip==255;length+=255) {ip++;} length += *ip++; }
length += MINMATCH;
// copy repeated sequence
cpy = op + length;
if (op-ref<4)
{
*op++ = *ref++;
*op++ = *ref++;
*op++ = *ref++;
*op++ = *ref++;
ref -= dec[op-ref];
} else { *(U32*)op=*(U32*)ref; op+=4; ref+=4; }
if (cpy > olimit)
{
if (cpy > olimit+4) goto _output_error;
while(op < cpy-3) { *(U32*)op=*(U32*)ref; op+=4; ref+=4; }
while(op < cpy) *op++=*ref++;
if (op >= olimit+4) break; // Check EOF
continue;
}
do { *(U32*)op = *(U32*)ref; op+=4; ref+=4; } while (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(
char* source,
char* dest,
int isize,
int maxOutputSize)
{
// Local Variables
const BYTE* ip = (const BYTE*) source;
const BYTE* const iend = ip + isize;
BYTE* ref;
BYTE* op = (BYTE*) dest;
BYTE* const oend = op + maxOutputSize;
BYTE* cpy;
BYTE token;
U32 dec[4]={0, 3, 2, 3};
int len, length;
// Main Loop
while (ip<iend)
{
// get runlength
token = *ip++;
if ((length=(token>>ML_BITS)) == RUN_MASK) { for (;(len=*ip++)==255;length+=255){} length += len; }
// copy literals
ref = op+length;
if (ref>oend-4)
{
if (ref > oend) goto _output_error;
while(op<oend-3) { *(U32*)op=*(U32*)ip; op+=4; ip+=4; }
while(op<ref) *op++=*ip++;
break; // Necessarily EOF
}
do { *(U32*)op = *(U32*)ip; op+=4; ip+=4; } while (op<ref) ;
ip-=(op-ref); op=ref; // correction
if (ip>=iend) break; // check EOF
// get offset
ref -= *(U16*)ip; ip+=2;
// get matchlength
if ((length=(token&ML_MASK)) == ML_MASK) { for (;(len=*ip++)==255;length+=255){} length += len; }
length += MINMATCH;
// copy repeated sequence
cpy = op + length;
if (op-ref<4)
{
*op++ = *ref++;
*op++ = *ref++;
*op++ = *ref++;
*op++ = *ref++;
ref -= dec[op-ref];
} else { *(U32*)op=*(U32*)ref; op+=4; ref+=4; }
if (cpy>oend-4)
{
if (cpy > oend) goto _output_error;
while(op<cpy-3) { *(U32*)op=*(U32*)ref; op+=4; ref+=4; }
while(op<cpy) *op++=*ref++;
if (op>=oend) break; // Check EOF
continue;
}
do { *(U32*)op = *(U32*)ref; op+=4; ref+=4; } while (op<cpy) ;
op=cpy; // correction
}
// end of decoding
return (int) (((char*)op)-dest);
// write overflow error detected
_output_error:
return (int) (-(((char*)ip)-source));
}