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removed ZSTD_decompressBegin() from ZSTD_initDCtx_internal()

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It does not feel "right" from a dependency perspective.
ZSTD_initDCtx_internal() is triggered once, on DCtx creation,
while ZSTD_decompressBegin() is invoked at the beginning of each new frame,
and is also a user-facing prototype.

Downside : a DCtx must be init before first usage !
This was always the intention by the way, and is documented as such.
This stage is automatically done within ZSTD_decompress() and variants,
and also within ZSTD_decompressStream().
Only ZSTD_decompressContinue() is impacted,
it must be preceded by a ZSTD_decompressBegin(), as detailed in doc.

A test has been fixed, to no longer rely on undocumented assumption that ZSTD_decompressBegin() is invoked during init.
This commit is contained in:
Yann Collet 2017-09-27 13:51:05 -07:00
parent c994932788
commit ea1f50bf73
2 changed files with 26 additions and 25 deletions
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50
lib/decompress/zstd_decompress.c
View File

@ -162,33 +162,9 @@ static size_t ZSTD_startingInputLength(ZSTD_format_e format)
return startingInputLength;
}
/* Note : this function cannot fail */
size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx)
{
assert(dctx != NULL);
dctx->expected = ZSTD_startingInputLength(dctx->format);
dctx->stage = ZSTDds_getFrameHeaderSize;
dctx->decodedSize = 0;
dctx->previousDstEnd = NULL;
dctx->base = NULL;
dctx->vBase = NULL;
dctx->dictEnd = NULL;
dctx->entropy.hufTable[0] = (HUF_DTable)((HufLog)*0x1000001); /* cover both little and big endian */
dctx->litEntropy = dctx->fseEntropy = 0;
dctx->dictID = 0;
ZSTD_STATIC_ASSERT(sizeof(dctx->entropy.rep) == sizeof(repStartValue));
memcpy(dctx->entropy.rep, repStartValue, sizeof(repStartValue)); /* initial repcodes */
dctx->LLTptr = dctx->entropy.LLTable;
dctx->MLTptr = dctx->entropy.MLTable;
dctx->OFTptr = dctx->entropy.OFTable;
dctx->HUFptr = dctx->entropy.hufTable;
return 0;
}
static void ZSTD_initDCtx_internal(ZSTD_DCtx* dctx)
{
dctx->format = ZSTD_f_zstd1; /* ZSTD_decompressBegin() invokes ZSTD_startingInputLength() with argument dctx->format */
ZSTD_decompressBegin(dctx); /* cannot fail */
dctx->staticSize = 0;
dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
dctx->ddict = NULL;
@ -542,7 +518,8 @@ static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity,
}
/*! ZSTD_decodeLiteralsBlock() :
* @return : nb of bytes read from src (< srcSize ) */
* @return : nb of bytes read from src (< srcSize )
* note : symbol not declared but exposed for fullbench */
size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
const void* src, size_t srcSize) /* note : srcSize < BLOCKSIZE */
{
@ -2003,6 +1980,29 @@ static size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict
return ZSTD_refDictContent(dctx, dict, dictSize);
}
/* Note : this function cannot fail */
size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx)
{
assert(dctx != NULL);
dctx->expected = ZSTD_startingInputLength(dctx->format); /* dctx->format must be properly set */
dctx->stage = ZSTDds_getFrameHeaderSize;
dctx->decodedSize = 0;
dctx->previousDstEnd = NULL;
dctx->base = NULL;
dctx->vBase = NULL;
dctx->dictEnd = NULL;
dctx->entropy.hufTable[0] = (HUF_DTable)((HufLog)*0x1000001); /* cover both little and big endian */
dctx->litEntropy = dctx->fseEntropy = 0;
dctx->dictID = 0;
ZSTD_STATIC_ASSERT(sizeof(dctx->entropy.rep) == sizeof(repStartValue));
memcpy(dctx->entropy.rep, repStartValue, sizeof(repStartValue)); /* initial repcodes */
dctx->LLTptr = dctx->entropy.LLTable;
dctx->MLTptr = dctx->entropy.MLTable;
dctx->OFTptr = dctx->entropy.OFTable;
dctx->HUFptr = dctx->entropy.hufTable;
return 0;
}
size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
{
CHECK_F( ZSTD_decompressBegin(dctx) );

1
tests/fullbench.c
View File

@ -376,6 +376,7 @@ static size_t benchMem(const void* src, size_t srcSize, U32 benchNb)
skippedSize = frameHeaderSize + ZSTD_blockHeaderSize;
memcpy(buff2, dstBuff+skippedSize, g_cSize-skippedSize);
srcSize = srcSize > 128 KB ? 128 KB : srcSize; /* speed relative to block */
ZSTD_decompressBegin(g_zdc);
break;
}
case 32: /* ZSTD_decodeSeqHeaders */