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Code Issues Releases 1 Activity

introduced FSE_decompress_wksp(), to use less stack space

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This commit is contained in:
Yann Collet 2016-11-30 12:36:45 -08:00
parent 95eb43be09
commit 766431909f
3 changed files with 24 additions and 20 deletions
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3
lib/common/entropy_common.c
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@ -187,8 +187,9 @@ size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
huffWeight[n+1] = ip[n/2] & 15;
} } }
else { /* header compressed with FSE (normal case) */
FSE_DTable fseWorkspace[FSE_DTABLE_SIZE_U32(5)]; /* 5 is max possible tableLog for HUF header */
if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
oSize = FSE_decompress(huffWeight, hwSize-1, ip+1, iSize); /* max (hwSize-1) values decoded, as last one is implied */
oSize = FSE_decompress_wksp(huffWeight, hwSize-1, ip+1, iSize, fseWorkspace, 5); /* max (hwSize-1) values decoded, as last one is implied */
if (FSE_isError(oSize)) return oSize;
}

5
lib/common/fse.h
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@ -286,7 +286,7 @@ If there is an error, the function will return an error code, which can be teste
#define FSE_BLOCKBOUND(size) (size + (size>>7))
#define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size)) /* Macro version, useful for static allocation */
/* It is possible to statically allocate FSE CTable/DTable as a table of unsigned using below macros */
/* It is possible to statically allocate FSE CTable/DTable as a table of FSE_CTable/FSE_DTable using below macros */
#define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) (1 + (1<<(maxTableLog-1)) + ((maxSymbolValue+1)*2))
#define FSE_DTABLE_SIZE_U32(maxTableLog) (1 + (1<<maxTableLog))
@ -312,6 +312,9 @@ size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits);
size_t FSE_buildDTable_rle (FSE_DTable* dt, unsigned char symbolValue);
/**< build a fake FSE_DTable, designed to always generate the same symbolValue */
size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, FSE_DTable* workSpace, unsigned maxLog);
/**< same as FSE_decompress(), using an externally allocated `workSpace` produced with `FSE_DTABLE_SIZE_U32(maxLog)` */
/* *****************************************
* FSE symbol compression API

36
lib/common/fse_decompress.c
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@ -75,12 +75,6 @@
#define CHECK_F(f) { size_t const e = f; if (FSE_isError(e)) return e; }
/* **************************************************************
* Complex types
****************************************************************/
typedef U32 DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];
/* **************************************************************
* Templates
****************************************************************/
@ -300,28 +294,34 @@ size_t FSE_decompress_usingDTable(void* dst, size_t originalSize,
}
size_t FSE_decompress(void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize)
size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, FSE_DTable* workSpace, unsigned maxLog)
{
const BYTE* const istart = (const BYTE*)cSrc;
const BYTE* ip = istart;
short counting[FSE_MAX_SYMBOL_VALUE+1];
DTable_max_t dt; /* Static analyzer seems unable to understand this table will be properly initialized later */
unsigned tableLog;
unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
if (cSrcSize<2) return ERROR(srcSize_wrong); /* too small input size */
/* normal FSE decoding mode */
{ size_t const NCountLength = FSE_readNCount (counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
if (FSE_isError(NCountLength)) return NCountLength;
if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong); /* too small input size */
ip += NCountLength;
cSrcSize -= NCountLength;
}
size_t const NCountLength = FSE_readNCount (counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
if (FSE_isError(NCountLength)) return NCountLength;
//if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong); /* too small input size; supposed to be already checked in NCountLength, only remaining case : NCountLength==cSrcSize */
if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
ip += NCountLength;
cSrcSize -= NCountLength;
CHECK_F( FSE_buildDTable (dt, counting, maxSymbolValue, tableLog) );
CHECK_F( FSE_buildDTable (workSpace, counting, maxSymbolValue, tableLog) );
return FSE_decompress_usingDTable (dst, maxDstSize, ip, cSrcSize, dt); /* always return, even if it is an error code */
return FSE_decompress_usingDTable (dst, dstCapacity, ip, cSrcSize, workSpace); /* always return, even if it is an error code */
}
typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];
size_t FSE_decompress(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize)
{
DTable_max_t dt; /* Static analyzer seems unable to understand this table will be properly initialized later */
return FSE_decompress_wksp(dst, dstCapacity, cSrc, cSrcSize, dt, FSE_MAX_TABLELOG);
}