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fileio.c does no longer need ZSTD_LEGACY_SUPPORT, and does no longer depend on zstd_legacy.h

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Added : ZSTD_isFrame() in experimental section
This commit is contained in:
Yann Collet
2016-11-02 17:30:49 -07:00
parent f3f13211ae
commit 179b19776f
3 changed files with 37 additions and 31 deletions
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lib/decompress/zstd_decompress.c
+18 -1
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@@ -193,7 +193,24 @@ static void ZSTD_refDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx)
* Decompression section
***************************************************************/
/* See compression format details in : doc/zstd_compression_format.md */
/*! ZSTD_isFrame() :
* Tells if the content of `buffer` starts with a valid Frame Identifier.
* Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0.
* Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled.
* Note 3 : Skippable Frame Identifiers are considered valid. */
unsigned ZSTD_isFrame(const void* buffer, size_t size)
{
if (size < 4) return 0;
{ U32 const magic = MEM_readLE32(buffer);
if (magic == ZSTD_MAGICNUMBER) return 1;
if ((magic & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) return 1;
}
#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
if (ZSTD_isLegacy(buffer, size)) return 1;
#endif
return 0;
}
/** ZSTD_frameHeaderSize() :
* srcSize must be >= ZSTD_frameHeaderSize_prefix.