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[FSE] Clean up workspace using dynamically sized struct

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This commit is contained in:
Nick Terrell 2021-03-19 16:04:59 -07:00
parent 756bd59322
commit 634bfd339f
2 changed files with 13 additions and 14 deletions
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2
lib/common/fse.h
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@ -352,7 +352,7 @@ 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 */
#define FSE_DECOMPRESS_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) (FSE_DTABLE_SIZE_U32(maxTableLog) + FSE_BUILD_DTABLE_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) + (FSE_MAX_SYMBOL_VALUE + 1) / 2)
#define FSE_DECOMPRESS_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) (FSE_DTABLE_SIZE_U32(maxTableLog) + FSE_BUILD_DTABLE_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) + (FSE_MAX_SYMBOL_VALUE + 1) / 2 + 1)
#define FSE_DECOMPRESS_WKSP_SIZE(maxTableLog, maxSymbolValue) (FSE_DECOMPRESS_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) * sizeof(unsigned))
size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize);
/**< same as FSE_decompress(), using an externally allocated `workSpace` produced with `FSE_DECOMPRESS_WKSP_SIZE_U32(maxLog, maxSymbolValue)` */

25
lib/common/fse_decompress.c
View File

@ -311,8 +311,9 @@ size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size
}
typedef struct {
short count[FSE_MAX_SYMBOL_VALUE + 1];
} FSE_NormalizedCount;
short ncount[FSE_MAX_SYMBOL_VALUE + 1];
FSE_DTable dtable[1]; /* Dynamically sized */
} FSE_DecompressWksp;
FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
@ -325,15 +326,14 @@ FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
const BYTE* ip = istart;
unsigned tableLog;
unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
FSE_NormalizedCount* const ncount = (FSE_NormalizedCount*)workSpace;
FSE_DTable* const dtable = (FSE_DTable*)(void*)((BYTE*)workSpace + sizeof(*ncount));
FSE_DecompressWksp* const wksp = (FSE_DecompressWksp*)workSpace;
DEBUG_STATIC_ASSERT((FSE_MAX_SYMBOL_VALUE + 1) % 2 == 0);
if (wkspSize < sizeof(*ncount)) return ERROR(GENERIC);
if (wkspSize < sizeof(*wksp)) return ERROR(GENERIC);
/* normal FSE decoding mode */
{
size_t const NCountLength = FSE_readNCount_bmi2(ncount->count, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
size_t const NCountLength = FSE_readNCount_bmi2(wksp->ncount, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
if (FSE_isError(NCountLength)) return NCountLength;
if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
assert(NCountLength <= cSrcSize);
@ -342,20 +342,19 @@ FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
}
if (FSE_DECOMPRESS_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(tableLog_tooLarge);
workSpace = dtable + FSE_DTABLE_SIZE_U32(tableLog);
wkspSize -= FSE_DTABLE_SIZE(tableLog);
wkspSize -= sizeof(*ncount);
workSpace = wksp->dtable + FSE_DTABLE_SIZE_U32(tableLog);
wkspSize -= sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog);
CHECK_F( FSE_buildDTable_internal(dtable, ncount->count, maxSymbolValue, tableLog, workSpace, wkspSize) );
CHECK_F( FSE_buildDTable_internal(wksp->dtable, wksp->ncount, maxSymbolValue, tableLog, workSpace, wkspSize) );
{
const void* ptr = dtable;
const void* ptr = wksp->dtable;
const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
const U32 fastMode = DTableH->fastMode;
/* select fast mode (static) */
if (fastMode) return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, dtable, 1);
return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, dtable, 0);
if (fastMode) return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 1);
return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 0);
}
}