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authorYann Collet <cyan@fb.com>2017-08-10 19:12:53 (GMT)
committerYann Collet <cyan@fb.com>2017-08-10 19:12:53 (GMT)
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support dictionary compression with independent blocks
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-rw-r--r--doc/lz4frame_manual.html55
1 files changed, 28 insertions, 27 deletions
diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index a1a6e96..9593181 100644
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@@ -96,8 +96,8 @@
<a name="Chapter5"></a><h2>Simple compression function</h2><pre></pre>
<pre><b>size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr);
-</b><p> Returns the maximum possible size of a frame compressed with LZ4F_compressFrame() given srcSize content and preferences.
- Note : this result is only usable with LZ4F_compressFrame(), not with multi-segments compression.
+</b><p> Returns the maximum possible size of a frame compressed with LZ4F_compressFrame() given srcSize content and preferences.
+ Note : this result is only usable with LZ4F_compressFrame(), not with multi-segments compression.
</p></pre><BR>
@@ -210,10 +210,10 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
<pre><b>size_t LZ4F_getFrameInfo(LZ4F_dctx* dctx,
LZ4F_frameInfo_t* frameInfoPtr,
const void* srcBuffer, size_t* srcSizePtr);
-</b><p> This function extracts frame parameters (such as max blockSize, frame checksum, etc.).
- Its usage is optional.
- Extracted information can typically be useful for allocation purposes.
- This function works in 2 situations :
+</b><p> This function extracts frame parameters (max blockSize, dictID, etc.).
+ Its usage is optional.
+ Extracted information is typically useful for allocation and dictionary.
+ This function works in 2 situations :
- At the beginning of a new frame, in which case
it will decode information from `srcBuffer`, starting the decoding process.
Input size must be large enough to successfully decode the entire frame header.
@@ -221,13 +221,14 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
It's allowed to provide more input data than this minimum.
- After decoding has been started.
In which case, no input is read, frame parameters are extracted from dctx.
- - If decoding has barely started, but not yet extracted information from header, LZ4F_getFrameInfo() will fail.
- The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
- Decompression must resume from (srcBuffer + *srcSizePtr).
+ - If decoding has barely started, but not yet extracted information from header,
+ LZ4F_getFrameInfo() will fail.
+ The number of bytes consumed from srcBuffer will be updated within *srcSizePtr (necessarily <= original value).
+ Decompression must resume from (srcBuffer + *srcSizePtr).
@return : an hint about how many srcSize bytes LZ4F_decompress() expects for next call,
- or an error code which can be tested using LZ4F_isError()
- note 1 : in case of error, dctx is not modified. Decoding operation can resume safely.
- note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
+ or an error code which can be tested using LZ4F_isError().
+ note 1 : in case of error, dctx is not modified. Decoding operation can resume from beginning safely.
+ note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure.
</p></pre><BR>
@@ -235,28 +236,28 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
void* dstBuffer, size_t* dstSizePtr,
const void* srcBuffer, size_t* srcSizePtr,
const LZ4F_decompressOptions_t* dOptPtr);
-</b><p> Call this function repetitively to regenerate compressed data from `srcBuffer`.
- The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
+</b><p> Call this function repetitively to regenerate compressed data from `srcBuffer`.
+ The function will attempt to decode up to *srcSizePtr bytes from srcBuffer, into dstBuffer of capacity *dstSizePtr.
- The number of bytes regenerated into dstBuffer is provided within *dstSizePtr (necessarily <= original value).
+ The number of bytes regenerated into dstBuffer is provided within *dstSizePtr (necessarily <= original value).
- The number of bytes consumed from srcBuffer is provided within *srcSizePtr (necessarily <= original value).
- Number of bytes consumed can be < number of bytes provided.
- It typically happens when dstBuffer is not large enough to contain all decoded data.
- Unconsumed source data must be presented again in subsequent invocations.
+ The number of bytes consumed from srcBuffer is provided within *srcSizePtr (necessarily <= original value).
+ Number of bytes consumed can be < number of bytes provided.
+ It typically happens when dstBuffer is not large enough to contain all decoded data.
+ Unconsumed source data must be presented again in subsequent invocations.
`dstBuffer` content is expected to be flushed between each invocation, as its content will be overwritten.
`dstBuffer` itself can be changed at will between each consecutive function invocation.
- @return is an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call.
- Schematically, it's the size of the current (or remaining) compressed block + header of next block.
- Respecting the hint provides some small speed benefit, because it skips intermediate buffers.
- This is just a hint though, it's always possible to provide any srcSize.
- When a frame is fully decoded, @return will be 0 (no more data expected).
- If decompression failed, @return is an error code, which can be tested using LZ4F_isError().
+ @return : an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call.
+ Schematically, it's the size of the current (or remaining) compressed block + header of next block.
+ Respecting the hint provides some small speed benefit, because it skips intermediate buffers.
+ This is just a hint though, it's always possible to provide any srcSize.
+ When a frame is fully decoded, @return will be 0 (no more data expected).
+ If decompression failed, @return is an error code, which can be tested using LZ4F_isError().
- After a frame is fully decoded, dctx can be used again to decompress another frame.
- After a decompression error, use LZ4F_resetDecompressionContext() before re-using dctx, to return to clean state.
+ After a frame is fully decoded, dctx can be used again to decompress another frame.
+ After a decompression error, use LZ4F_resetDecompressionContext() before re-using dctx, to return to clean state.
</p></pre><BR>