Added : function LZ4_compress_limitedOutput()
Removed : functions with explicit *ctx management (LZ4_compressCtx & LZ4_compress64kCtx). Functions are still present in the .c Changed : LZ4_compressBound() now a macro git-svn-id: https://lz4.googlecode.com/svn/trunk@71 650e7d94-2a16-8b24-b05c-7c0b3f6821cd
This commit is contained in:
yann.collet.73@gmail.com
parent
cfbace25d7
commit
84004b9015
69
lz4.c
69
lz4.c
@ -41,20 +41,13 @@
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// Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
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#define MEMORY_USAGE 14
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// NOTCOMPRESSIBLE_CONFIRMATION :
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// NOTCOMPRESSIBLE_DETECTIONLEVEL :
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// Decreasing this value will make the algorithm skip faster data segments considered "incompressible"
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// This may decrease compression ratio dramatically, but will be faster on incompressible data
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// Increasing this value will make the algorithm search more before declaring a segment "incompressible"
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// This could improve compression a bit, but will be slower on incompressible data
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// The default value (6) is recommended
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#define NOTCOMPRESSIBLE_CONFIRMATION 6
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// LZ4_COMPRESSMIN :
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// Compression function will *fail* if it is not successful at compressing input by at least LZ4_COMPRESSMIN bytes
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// Since the compression function stops working prematurely, it results in a speed gain
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// The output however is unusable. Compression function result will be zero.
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// Default : 0 = disabled
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#define LZ4_COMPRESSMIN 0
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#define NOTCOMPRESSIBLE_DETECTIONLEVEL 6
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// BIG_ENDIAN_NATIVE_BUT_INCOMPATIBLE :
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// This will provide a small boost to performance for big endian cpu, but the resulting compressed stream will be incompatible with little-endian CPU.
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@ -185,7 +178,7 @@ typedef struct _U64_S { U64 v; } U64_S;
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#define HASHTABLESIZE (1 << HASH_LOG)
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#define HASH_MASK (HASHTABLESIZE - 1)
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#define SKIPSTRENGTH (NOTCOMPRESSIBLE_CONFIRMATION>2?NOTCOMPRESSIBLE_CONFIRMATION:2)
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#define SKIPSTRENGTH (NOTCOMPRESSIBLE_DETECTIONLEVEL>2?NOTCOMPRESSIBLE_DETECTIONLEVEL:2)
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#define STACKLIMIT 13
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#define HEAPMODE (HASH_LOG>STACKLIMIT) // Defines if memory is allocated into the stack (local variable), or into the heap (malloc()).
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#define COPYLENGTH 8
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@ -257,7 +250,7 @@ struct refTables
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//****************************
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#if LZ4_ARCH64
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inline static int LZ4_NbCommonBytes (register U64 val)
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inline int LZ4_NbCommonBytes (register U64 val)
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{
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#if defined(LZ4_BIG_ENDIAN)
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#if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)
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@ -289,7 +282,7 @@ inline static int LZ4_NbCommonBytes (register U64 val)
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#else
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inline static int LZ4_NbCommonBytes (register U32 val)
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inline int LZ4_NbCommonBytes (register U32 val)
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{
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#if defined(LZ4_BIG_ENDIAN)
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#if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)
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@ -321,25 +314,16 @@ inline static int LZ4_NbCommonBytes (register U32 val)
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#endif
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//****************************
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// Public functions
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//****************************
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int LZ4_compressBound(int isize)
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{
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return (isize + (isize/255) + 16);
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}
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//******************************
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// Compression functions
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//******************************
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int LZ4_compressCtx(void** ctx,
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inline int LZ4_compressCtx(void** ctx,
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const char* source,
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char* dest,
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int isize)
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int isize,
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int maxOutputSize)
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{
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#if HEAPMODE
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struct refTables *srt = (struct refTables *) (*ctx);
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@ -356,6 +340,7 @@ int LZ4_compressCtx(void** ctx,
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#define matchlimit (iend - LASTLITERALS)
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BYTE* op = (BYTE*) dest;
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BYTE* const oend = op + maxOutputSize;
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int len, length;
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const int skipStrength = SKIPSTRENGTH;
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@ -410,6 +395,7 @@ int LZ4_compressCtx(void** ctx,
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// Encode Literal length
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length = ip - anchor;
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token = op++;
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if unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) >= oend) return 0; // Check output limit
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if (length>=(int)RUN_MASK) { *token=(RUN_MASK<<ML_BITS); len = length-RUN_MASK; for(; len > 254 ; len-=255) *op++ = 255; *op++ = (BYTE)len; }
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else *token = (length<<ML_BITS);
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@ -460,7 +446,7 @@ _last_literals:
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// Encode Last Literals
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{
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int lastRun = iend - anchor;
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if ((LZ4_COMPRESSMIN>0) && (((op - (BYTE*)dest) + lastRun + 1 + ((lastRun-15)/255)) > isize - LZ4_COMPRESSMIN)) return 0;
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if (op + lastRun + 1 + ((lastRun-15)/255) >= oend) return 0;
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if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; }
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else *op++ = (lastRun<<ML_BITS);
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memcpy(op, anchor, iend - anchor);
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@ -479,10 +465,11 @@ _last_literals:
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#define HASH64KTABLESIZE (1U<<HASHLOG64K)
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#define LZ4_HASH64K_FUNCTION(i) (((i) * 2654435761U) >> ((MINMATCH*8)-HASHLOG64K))
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#define LZ4_HASH64K_VALUE(p) LZ4_HASH64K_FUNCTION(A32(p))
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int LZ4_compress64kCtx(void** ctx,
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inline int LZ4_compress64kCtx(void** ctx,
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const char* source,
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char* dest,
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int isize)
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int isize,
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int maxOutputSize)
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{
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#if HEAPMODE
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struct refTables *srt = (struct refTables *) (*ctx);
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@ -499,6 +486,7 @@ int LZ4_compress64kCtx(void** ctx,
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#define matchlimit (iend - LASTLITERALS)
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BYTE* op = (BYTE*) dest;
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BYTE* const oend = op + maxOutputSize;
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int len, length;
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const int skipStrength = SKIPSTRENGTH;
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@ -552,6 +540,7 @@ int LZ4_compress64kCtx(void** ctx,
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// Encode Literal length
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length = ip - anchor;
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token = op++;
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if unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) >= oend) return 0; // Check output limit
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if (length>=(int)RUN_MASK) { *token=(RUN_MASK<<ML_BITS); len = length-RUN_MASK; for(; len > 254 ; len-=255) *op++ = 255; *op++ = (BYTE)len; }
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else *token = (length<<ML_BITS);
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@ -602,7 +591,7 @@ _last_literals:
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// Encode Last Literals
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{
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int lastRun = iend - anchor;
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if ((LZ4_COMPRESSMIN>0) && (((op - (BYTE*)dest) + lastRun + 1 + ((lastRun-15)/255)) > isize - LZ4_COMPRESSMIN)) return 0;
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if (op + lastRun + 1 + ((lastRun-15)/255) >= oend) return 0;
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if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; }
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else *op++ = (lastRun<<ML_BITS);
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memcpy(op, anchor, iend - anchor);
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@ -614,26 +603,34 @@ _last_literals:
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}
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int LZ4_compress(const char* source,
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char* dest,
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int isize)
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int LZ4_compress_limitedOutput(const char* source,
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char* dest,
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int isize,
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int maxOutputSize)
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{
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#if HEAPMODE
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void* ctx = malloc(sizeof(struct refTables));
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int result;
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if (isize < LZ4_64KLIMIT)
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result = LZ4_compress64kCtx(&ctx, source, dest, isize);
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else result = LZ4_compressCtx(&ctx, source, dest, isize);
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result = LZ4_compress64kCtx(&ctx, source, dest, isize, maxOutputSize);
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else result = LZ4_compressCtx(&ctx, source, dest, isize, maxOutputSize);
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free(ctx);
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return result;
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#else
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if (isize < (int)LZ4_64KLIMIT) return LZ4_compress64kCtx(NULL, source, dest, isize);
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return LZ4_compressCtx(NULL, source, dest, isize);
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if (isize < (int)LZ4_64KLIMIT) return LZ4_compress64kCtx(NULL, source, dest, isize, maxOutputSize);
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return LZ4_compressCtx(NULL, source, dest, isize, maxOutputSize);
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#endif
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}
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int LZ4_compress(const char* source,
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char* dest,
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int isize)
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{
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return LZ4_compress_limitedOutput(source, dest, isize, LZ4_compressBound(isize));
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}
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//****************************
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51
lz4.h
51
lz4.h
@ -47,19 +47,22 @@ int LZ4_uncompress (const char* source, char* dest, int osize);
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/*
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LZ4_compress() :
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Compresses 'isize' bytes from 'source' into 'dest'.
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Destination buffer must be already allocated,
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and must be sized to handle worst cases situations (input data not compressible)
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Worst case size evaluation is provided by macro LZ4_compressBound()
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isize : is the input size. Max supported value is ~1.9GB
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return : the number of bytes written in buffer dest
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or 0 if the compression fails (if LZ4_COMPRESSMIN is set)
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note : destination buffer must be already allocated.
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destination buffer must be sized to handle worst cases situations (input data not compressible)
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worst case size evaluation is provided by function LZ4_compressBound()
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LZ4_uncompress() :
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osize : is the output size, therefore the original size
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return : the number of bytes read in the source buffer
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If the source stream is malformed, the function will stop decoding and return a negative result, indicating the byte position of the faulty instruction
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This function never writes beyond dest + osize, and is therefore protected against malicious data packets
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note : destination buffer must be already allocated
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note : destination buffer must be already allocated.
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its size must be a minimum of 'osize' bytes.
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*/
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@ -67,7 +70,7 @@ LZ4_uncompress() :
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// Advanced Functions
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//****************************
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int LZ4_compressBound(int isize);
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#define LZ4_compressBound(isize) (isize + (isize/255) + 16)
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/*
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LZ4_compressBound() :
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@ -80,6 +83,21 @@ LZ4_compressBound() :
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*/
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int LZ4_compress_limitedOutput (const char* source, char* dest, int isize, int maxOutputSize);
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/*
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LZ4_compress_limitedOutput() :
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Compress 'isize' bytes from 'source' into an output buffer 'dest' of maximum size 'maxOutputSize'.
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If it cannot achieve it, compression will stop, and result of the function will be zero.
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This function never writes outside of provided output buffer.
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isize : is the input size. Max supported value is ~1.9GB
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maxOutputSize : is the size of the destination buffer (which must be already allocated)
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return : the number of bytes written in buffer dest
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or 0 if the compression fails
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*/
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int LZ4_uncompress_unknownOutputSize (const char* source, char* dest, int isize, int maxOutputSize);
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/*
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@ -94,27 +112,6 @@ LZ4_uncompress_unknownOutputSize() :
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*/
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int LZ4_compressCtx(void** ctx, const char* source, char* dest, int isize);
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int LZ4_compress64kCtx(void** ctx, const char* source, char* dest, int isize);
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/*
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LZ4_compressCtx() :
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This function explicitly handles the CTX memory structure.
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It avoids allocating/deallocating memory between each call, improving performance when malloc is heavily invoked.
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This function is only useful when memory is allocated into the heap (HASH_LOG value beyond STACK_LIMIT)
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Performance difference will be noticeable only when repetitively calling the compression function over many small segments.
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Note : by default, memory is allocated into the stack, therefore "malloc" is not invoked.
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LZ4_compress64kCtx() :
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Same as LZ4_compressCtx(), but specific to small inputs (<64KB).
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isize *Must* be <64KB, otherwise the output will be corrupted.
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On first call : provide a *ctx=NULL; It will be automatically allocated.
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On next calls : reuse the same ctx pointer.
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Use different pointers for different threads when doing multi-threading.
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*/
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#if defined (__cplusplus)
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}
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#endif
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