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40ae7043df
lz4/lz4_encoder.h
yann.collet.73@gmail.com 40ae7043df - New naming : LZ4_decompress_safe() and LZ4_decompress_fast() 
- New function : LZ4_decompress_safe_partial(), to decompress just enough data within a compressed block, saving CPU cycles
- New source files : lz4_decoder.h, lz4_encoder.h, lz4hc_encoder.h
- Improved speed of LZ4_decompress_fast()
- Improved speed for compression of small blocks < 64KB
- Improved speed for HC compression

git-svn-id: https://lz4.googlecode.com/svn/trunk@94 650e7d94-2a16-8b24-b05c-7c0b3f6821cd
2013-04-26 14:37:46 +00:00

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/*
LZ4 Encoder - Part of LZ4 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/
*/
/* lz4_encoder.h must be included into lz4.c
The objective of this file is to create a single LZ4 compression function source
which will be instanciated multiple times with minor variations
depending on a set of #define.
*/
//****************************
// Check required defines
//****************************
#ifndef FUNCTION_NAME
# error "FUNTION_NAME is not defined"
#endif
//****************************
// Local definitions
//****************************
#ifdef COMPRESS_64K
# define HASHLOG (MEMORY_USAGE-1)
# define CURRENT_H_TYPE U16
# define CURRENTBASE(base) const BYTE* const base = ip
#else
# define HASHLOG (MEMORY_USAGE-2)
# define CURRENT_H_TYPE HTYPE
# define CURRENTBASE(base) INITBASE(base)
#endif
#define HASHTABLE_NBCELLS (1U<<HASHLOG)
#define LZ4_HASH(i) (((i) * 2654435761U) >> ((MINMATCH*8)-HASHLOG))
#define LZ4_HASHVALUE(p) LZ4_HASH(A32(p))
//****************************
// Function code
//****************************
int FUNCTION_NAME(
#ifdef USE_HEAPMEMORY
void* ctx,
#endif
const char* source,
char* dest,
int inputSize
#ifdef LIMITED_OUTPUT
,int maxOutputSize
#endif
)
{
#ifdef USE_HEAPMEMORY
CURRENT_H_TYPE* HashTable = (CURRENT_H_TYPE*)ctx;
#else
CURRENT_H_TYPE HashTable[HASHTABLE_NBCELLS] = {0};
#endif
const BYTE* ip = (BYTE*) source;
CURRENTBASE(base);
const BYTE* anchor = ip;
const BYTE* const iend = ip + inputSize;
const BYTE* const mflimit = iend - MFLIMIT;
#define matchlimit (iend - LASTLITERALS)
BYTE* op = (BYTE*) dest;
#ifdef LIMITED_OUTPUT
BYTE* const oend = op + maxOutputSize;
#endif
int length;
const int skipStrength = SKIPSTRENGTH;
U32 forwardH;
// Init
if (inputSize<MINLENGTH) goto _last_literals;
#ifdef COMPRESS_64K
if (inputSize>LZ4_64KLIMIT) return 0; // Size too large (not within 64K limit)
#endif
#ifdef USE_HEAPMEMORY
memset((void*)HashTable, 0, HASHTABLESIZE);
#endif
// First Byte
HashTable[LZ4_HASHVALUE(ip)] = (CURRENT_H_TYPE)(ip - base);
ip++; forwardH = LZ4_HASHVALUE(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_HASHVALUE(forwardIp);
ref = base + HashTable[h];
HashTable[h] = (CURRENT_H_TYPE)(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++;
#ifdef LIMITED_OUTPUT
if unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) > oend) return 0; // Check output limit
#endif
#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 = (BYTE)(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);
#ifdef LIMITED_OUTPUT
if unlikely(op + (1 + LASTLITERALS) + (length>>8) > oend) return 0; // Check output limit
#endif
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 += (BYTE)length;
// Test end of chunk
if (ip > mflimit) { anchor = ip; break; }
// Fill table
HashTable[LZ4_HASHVALUE(ip-2)] = (CURRENT_H_TYPE)(ip - 2 - base);
// Test next position
ref = base + HashTable[LZ4_HASHVALUE(ip)];
HashTable[LZ4_HASHVALUE(ip)] = (CURRENT_H_TYPE)(ip - base);
if ((ref >= ip - MAX_DISTANCE) && (A32(ref) == A32(ip))) { token = op++; *token=0; goto _next_match; }
// Prepare next loop
anchor = ip++;
forwardH = LZ4_HASHVALUE(ip);
}
_last_literals:
// Encode Last Literals
{
int lastRun = (int)(iend - anchor);
#ifdef LIMITED_OUTPUT
if (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize) return 0; // Check output limit
#endif
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++ = (BYTE)(lastRun<<ML_BITS);
memcpy(op, anchor, iend - anchor);
op += iend-anchor;
}
// End
return (int) (((char*)op)-dest);
}
//****************************
// Clean defines
//****************************
// Required defines
#undef FUNCTION_NAME
// Locally Generated
#undef HASHLOG
#undef HASHTABLE_NBCELLS
#undef LZ4_HASH
#undef LZ4_HASHVALUE
#undef CURRENT_H_TYPE
#undef CURRENTBASE
// Optional defines
#ifdef LIMITED_OUTPUT
#undef LIMITED_OUTPUT
#endif
#ifdef USE_HEAPMEMORY
#undef USE_HEAPMEMORY
#endif
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