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fparamsPtr->windowLog==0 means that a frame is skippable

dev
inikep 2016-06-01 18:47:04 +02:00
parent 13f42d9085
commit 9242816b56
3 changed files with 12 additions and 1 deletions
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9
lib/common/zstd_static.h
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@ -246,6 +246,15 @@ ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t ds
A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero.
Context can then be reset to start a new decompression.
Skippable frames allow the integration of user-defined data into a flow of concatenated frames.
Skippable frames will be ignored (skipped) by a decompressor. The format of skippable frame is following:
a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F
b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits
c) Frame Content - any content (User Data) of length equal to Frame Size
For skippable frames ZSTD_decompressContinue() always returns 0.
For skippable frames ZSTD_getFrameParams() returns fparamsPtr->windowLog==0 what means that a frame is skippable.
It also returns Frame Size as fparamsPtr->frameContentSize.
*/

2
lib/decompress/zbuff_decompress.c
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@ -192,6 +192,8 @@ size_t ZBUFF_decompressContinue(ZBUFF_DCtx* zbd,
if (ZSTD_isError(h2Result)) return h2Result;
} }
if (zbd->fParams.windowLog < ZSTD_WINDOWLOG_ABSOLUTEMIN) zbd->fParams.windowLog = ZSTD_WINDOWLOG_ABSOLUTEMIN; /* required for buffer allocation */
/* Frame header instruct buffer sizes */
{ size_t const blockSize = MIN(1 << zbd->fParams.windowLog, ZSTD_BLOCKSIZE_MAX);
zbd->blockSize = blockSize;

2
lib/decompress/zstd_decompress.c
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@ -335,7 +335,7 @@ size_t ZSTD_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t
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->windowLog = ZSTD_WINDOWLOG_ABSOLUTEMIN;
fparamsPtr->windowLog = 0; /* windowLog==0 means a frame is skippable */
return 0;
}
return ERROR(prefix_unknown);