ddidderr/zstd-rs
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added ZSTD_estimateDStreamSize()

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This commit is contained in:
Yann Collet
2017-05-09 16:18:17 -07:00
parent 542c9dfcf8
commit f16f4497ca
4 changed files with 50 additions and 25 deletions
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lib/decompress/zstd_decompress.c
+20 -10
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@@ -221,20 +221,21 @@ static size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize)
/** ZSTD_getFrameHeader() :
* decode Frame Header, or require larger `srcSize`.
* @return : 0, `fparamsPtr` is correctly filled,
* @return : 0, `fhiPtr` is correctly filled,
* >0, `srcSize` is too small, result is expected `srcSize`,
* or an error code, which can be tested using ZSTD_isError() */
size_t ZSTD_getFrameHeader(ZSTD_frameHeader* fparamsPtr, const void* src, size_t srcSize)
size_t ZSTD_getFrameHeader(ZSTD_frameHeader* fhiPtr, const void* src, size_t srcSize)
{
const BYTE* ip = (const BYTE*)src;
if (srcSize < ZSTD_frameHeaderSize_prefix) return ZSTD_frameHeaderSize_prefix;
if (MEM_readLE32(src) != ZSTD_MAGICNUMBER) {
if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
/* skippable frame */
if (srcSize < ZSTD_skippableHeaderSize) return ZSTD_skippableHeaderSize; /* magic number + skippable frame length */
memset(fparamsPtr, 0, sizeof(*fparamsPtr));
fparamsPtr->frameContentSize = MEM_readLE32((const char *)src + 4);
fparamsPtr->windowSize = 0; /* windowSize==0 means a frame is skippable */
memset(fhiPtr, 0, sizeof(*fhiPtr));
fhiPtr->frameContentSize = MEM_readLE32((const char *)src + 4);
fhiPtr->windowSize = 0; /* windowSize==0 means a frame is skippable */
return 0;
}
return ERROR(prefix_unknown);
@@ -281,10 +282,10 @@ size_t ZSTD_getFrameHeader(ZSTD_frameHeader* fparamsPtr, const void* src, size_t
}
if (!windowSize) windowSize = (U32)frameContentSize;
if (windowSize > windowSizeMax) return ERROR(frameParameter_windowTooLarge);
fparamsPtr->frameContentSize = frameContentSize;
fparamsPtr->windowSize = windowSize;
fparamsPtr->dictID = dictID;
fparamsPtr->checksumFlag = checksumFlag;
fhiPtr->frameContentSize = frameContentSize;
fhiPtr->windowSize = windowSize;
fhiPtr->dictID = dictID;
fhiPtr->checksumFlag = checksumFlag;
}
return 0;
}
@@ -2182,6 +2183,15 @@ size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds)
+ zds->inBuffSize + zds->outBuffSize;
}
size_t ZSTD_estimateDStreamSize(ZSTD_frameHeader fHeader)
{
size_t const windowSize = fHeader.windowSize;
size_t const blockSize = MIN(windowSize, ZSTD_BLOCKSIZE_ABSOLUTEMAX);
size_t const inBuffSize = blockSize; /* no block can be larger */
size_t const outBuffSize = windowSize + blockSize + (WILDCOPY_OVERLENGTH * 2);
return sizeof(ZSTD_DStream) + ZSTD_estimateDCtxSize() + inBuffSize + outBuffSize;
}
/* ***** Decompression ***** */