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[fse] Reduce stack usage of FSE_decompress_wksp() by 512 bytes

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* Move `counting` into the workspace
* Inrease `HUF_DECOMPRESS_WORKSPACE_SIZE` by 512 bytes
This commit is contained in:
Nick Terrell
2021-03-05 13:24:27 -08:00
parent 0f18059a4e
commit 3b1aba42cc
3 changed files with 17 additions and 10 deletions
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lib/common/fse_decompress.c
+15 -8
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@@ -318,22 +318,29 @@ FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
{
const BYTE* const istart = (const BYTE*)cSrc;
const BYTE* ip = istart;
short counting[FSE_MAX_SYMBOL_VALUE+1];
unsigned tableLog;
unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
FSE_DTable* const dtable = (FSE_DTable*)workSpace;
short* counting = (short*) workSpace;
size_t const countingSize = sizeof(short) * (FSE_MAX_SYMBOL_VALUE + 1);
FSE_DTable* const dtable = (FSE_DTable*)(void*)((BYTE*)workSpace + countingSize);
DEBUG_STATIC_ASSERT((FSE_MAX_SYMBOL_VALUE + 1) % 2 == 0);
if (wkspSize < countingSize) return ERROR(GENERIC);
/* normal FSE decoding mode */
size_t const NCountLength = FSE_readNCount_bmi2(counting, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
if (FSE_isError(NCountLength)) return NCountLength;
if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
assert(NCountLength <= cSrcSize);
ip += NCountLength;
cSrcSize -= NCountLength;
{
size_t const NCountLength = FSE_readNCount_bmi2(counting, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
if (FSE_isError(NCountLength)) return NCountLength;
if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
assert(NCountLength <= cSrcSize);
ip += NCountLength;
cSrcSize -= NCountLength;
}
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 -= countingSize;
CHECK_F( FSE_buildDTable_internal(dtable, counting, maxSymbolValue, tableLog, workSpace, wkspSize) );