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Added comments on I/O buffer sizes for streaming
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Yann Collet 2019-06-04 12:38:43 -07:00 committed by GitHub
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doc/zstd_manual.html
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@ -10,37 +10,27 @@
<ol>
<li><a href="#Chapter1">Introduction</a></li>
<li><a href="#Chapter2">Version</a></li>
<li><a href="#Chapter3">Default constant</a></li>
<li><a href="#Chapter4">Constants</a></li>
<li><a href="#Chapter5">Simple API</a></li>
<li><a href="#Chapter6">Explicit context</a></li>
<li><a href="#Chapter7">Advanced compression API</a></li>
<li><a href="#Chapter8">Advanced decompression API</a></li>
<li><a href="#Chapter9">Streaming</a></li>
<li><a href="#Chapter10">Streaming compression - HowTo</a></li>
<li><a href="#Chapter11">This is a legacy streaming API, and can be replaced by ZSTD_CCtx_reset() and</a></li>
<li><a href="#Chapter12">Equivalent to:</a></li>
<li><a href="#Chapter13">Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue).</a></li>
<li><a href="#Chapter14">Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush).</a></li>
<li><a href="#Chapter15">Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end).</a></li>
<li><a href="#Chapter16">Streaming decompression - HowTo</a></li>
<li><a href="#Chapter17">Simple dictionary API</a></li>
<li><a href="#Chapter18">Bulk processing dictionary API</a></li>
<li><a href="#Chapter19">Dictionary helper functions</a></li>
<li><a href="#Chapter20">Advanced dictionary and prefix API</a></li>
<li><a href="#Chapter21">ADVANCED AND EXPERIMENTAL FUNCTIONS</a></li>
<li><a href="#Chapter22">experimental API (static linking only)</a></li>
<li><a href="#Chapter23">Frame size functions</a></li>
<li><a href="#Chapter24">ZSTD_decompressBound() :</a></li>
<li><a href="#Chapter25">Memory management</a></li>
<li><a href="#Chapter26">Advanced compression functions</a></li>
<li><a href="#Chapter27">Advanced decompression functions</a></li>
<li><a href="#Chapter28">Advanced streaming functions</a></li>
<li><a href="#Chapter29">Buffer-less and synchronous inner streaming functions</a></li>
<li><a href="#Chapter30">Buffer-less streaming compression (synchronous mode)</a></li>
<li><a href="#Chapter31">Buffer-less streaming decompression (synchronous mode)</a></li>
<li><a href="#Chapter32">ZSTD_getFrameHeader() :</a></li>
<li><a href="#Chapter33">Block level API</a></li>
<li><a href="#Chapter3">Simple API</a></li>
<li><a href="#Chapter4">Explicit context</a></li>
<li><a href="#Chapter5">Advanced compression API</a></li>
<li><a href="#Chapter6">Advanced decompression API</a></li>
<li><a href="#Chapter7">Streaming</a></li>
<li><a href="#Chapter8">Streaming compression - HowTo</a></li>
<li><a href="#Chapter9">Streaming decompression - HowTo</a></li>
<li><a href="#Chapter10">Simple dictionary API</a></li>
<li><a href="#Chapter11">Bulk processing dictionary API</a></li>
<li><a href="#Chapter12">Dictionary helper functions</a></li>
<li><a href="#Chapter13">Advanced dictionary and prefix API</a></li>
<li><a href="#Chapter14">experimental API (static linking only)</a></li>
<li><a href="#Chapter15">Frame size functions</a></li>
<li><a href="#Chapter16">Memory management</a></li>
<li><a href="#Chapter17">Advanced compression functions</a></li>
<li><a href="#Chapter18">Advanced decompression functions</a></li>
<li><a href="#Chapter19">Advanced streaming functions</a></li>
<li><a href="#Chapter20">Buffer-less and synchronous inner streaming functions</a></li>
<li><a href="#Chapter21">Buffer-less streaming compression (synchronous mode)</a></li>
<li><a href="#Chapter22">Buffer-less streaming decompression (synchronous mode)</a></li>
<li><a href="#Chapter23">Block level API</a></li>
</ol>
<hr>
<a name="Chapter1"></a><h2>Introduction</h2><pre>
@ -78,11 +68,7 @@
<pre><b>unsigned ZSTD_versionNumber(void); </b>/**< to check runtime library version */<b>
</b></pre><BR>
<a name="Chapter3"></a><h2>Default constant</h2><pre></pre>
<a name="Chapter4"></a><h2>Constants</h2><pre></pre>
<a name="Chapter5"></a><h2>Simple API</h2><pre></pre>
<a name="Chapter3"></a><h2>Simple API</h2><pre></pre>
<pre><b>size_t ZSTD_compress( void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
@ -152,7 +138,7 @@ const char* ZSTD_getErrorName(size_t code); </b>/*!< provides readable strin
int ZSTD_minCLevel(void); </b>/*!< minimum negative compression level allowed */<b>
int ZSTD_maxCLevel(void); </b>/*!< maximum compression level available */<b>
</pre></b><BR>
<a name="Chapter6"></a><h2>Explicit context</h2><pre></pre>
<a name="Chapter4"></a><h2>Explicit context</h2><pre></pre>
<h3>Compression context</h3><pre> When compressing many times,
it is recommended to allocate a context just once, and re-use it for each successive compression operation.
@ -189,7 +175,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
</p></pre><BR>
<a name="Chapter7"></a><h2>Advanced compression API</h2><pre></pre>
<a name="Chapter5"></a><h2>Advanced compression API</h2><pre></pre>
<pre><b>typedef enum { ZSTD_fast=1,
ZSTD_dfast=2,
@ -424,7 +410,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
</p></pre><BR>
<a name="Chapter8"></a><h2>Advanced decompression API</h2><pre></pre>
<a name="Chapter6"></a><h2>Advanced decompression API</h2><pre></pre>
<pre><b>typedef enum {
@ -472,7 +458,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
</p></pre><BR>
<a name="Chapter9"></a><h2>Streaming</h2><pre></pre>
<a name="Chapter7"></a><h2>Streaming</h2><pre></pre>
<pre><b>typedef struct ZSTD_inBuffer_s {
const void* src; </b>/**< start of input buffer */<b>
@ -486,7 +472,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
size_t pos; </b>/**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */<b>
} ZSTD_outBuffer;
</b></pre><BR>
<a name="Chapter10"></a><h2>Streaming compression - HowTo</h2><pre>
<a name="Chapter8"></a><h2>Streaming compression - HowTo</h2><pre>
A ZSTD_CStream object is required to track streaming operation.
Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources.
ZSTD_CStream objects can be reused multiple times on consecutive compression operations.
@ -592,31 +578,28 @@ size_t ZSTD_freeCStream(ZSTD_CStream* zcs);
<pre><b>size_t ZSTD_CStreamInSize(void); </b>/**< recommended size for input buffer */<b>
</b></pre><BR>
<pre><b>size_t ZSTD_CStreamOutSize(void); </b>/**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances. */<b>
<pre><b>size_t ZSTD_CStreamOutSize(void); </b>/**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */<b>
</b></pre><BR>
<a name="Chapter11"></a><h2>This is a legacy streaming API, and can be replaced by ZSTD_CCtx_reset() and</h2><pre> ZSTD_compressStream2(). It is redundant, but is still fully supported.
Advanced parameters and dictionary compression can only be used through the
new API.
<BR></pre>
<a name="Chapter12"></a><h2>Equivalent to:</h2><pre>
<pre><b>size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel);
</b>/*!<b>
* Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue).
* NOTE: The return value is different. ZSTD_compressStream() returns a hint for
* the next read size (if non-zero and not an error). ZSTD_compressStream2()
* returns the minimum nb of bytes left to flush (if non-zero and not an error).
*/
size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
</b>/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */<b>
size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
</b>/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */<b>
size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
</b><p>
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any)
ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
<BR></pre>
</p></pre><BR>
<a name="Chapter13"></a><h2>Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue).</h2><pre> NOTE: The return value is different. ZSTD_compressStream() returns a hint for
the next read size (if non-zero and not an error). ZSTD_compressStream2()
returns the number of bytes left to flush (if non-zero and not an error).
<BR></pre>
<a name="Chapter14"></a><h2>Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush).</h2><pre></pre>
<a name="Chapter15"></a><h2>Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end).</h2><pre></pre>
<a name="Chapter16"></a><h2>Streaming decompression - HowTo</h2><pre>
<a name="Chapter9"></a><h2>Streaming decompression - HowTo</h2><pre>
A ZSTD_DStream object is required to track streaming operations.
Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources.
ZSTD_DStream objects can be re-used multiple times.
@ -652,7 +635,7 @@ size_t ZSTD_freeDStream(ZSTD_DStream* zds);
</b></pre><BR>
<pre><b>size_t ZSTD_DStreamOutSize(void); </b>/*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */<b>
</b></pre><BR>
<a name="Chapter17"></a><h2>Simple dictionary API</h2><pre></pre>
<a name="Chapter10"></a><h2>Simple dictionary API</h2><pre></pre>
<pre><b>size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx,
void* dst, size_t dstCapacity,
@ -678,7 +661,7 @@ size_t ZSTD_freeDStream(ZSTD_DStream* zds);
Note : When `dict == NULL || dictSize < 8` no dictionary is used.
</p></pre><BR>
<a name="Chapter18"></a><h2>Bulk processing dictionary API</h2><pre></pre>
<a name="Chapter11"></a><h2>Bulk processing dictionary API</h2><pre></pre>
<pre><b>ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
int compressionLevel);
@ -721,7 +704,7 @@ size_t ZSTD_freeDStream(ZSTD_DStream* zds);
Recommended when same dictionary is used multiple times.
</p></pre><BR>
<a name="Chapter19"></a><h2>Dictionary helper functions</h2><pre></pre>
<a name="Chapter12"></a><h2>Dictionary helper functions</h2><pre></pre>
<pre><b>unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize);
</b><p> Provides the dictID stored within dictionary.
@ -747,7 +730,7 @@ size_t ZSTD_freeDStream(ZSTD_DStream* zds);
When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code.
</p></pre><BR>
<a name="Chapter20"></a><h2>Advanced dictionary and prefix API</h2><pre>
<a name="Chapter13"></a><h2>Advanced dictionary and prefix API</h2><pre>
This API allows dictionaries to be used with ZSTD_compress2(),
ZSTD_compressStream2(), and ZSTD_decompress(). Dictionaries are sticky, and
only reset with the context is reset with ZSTD_reset_parameters or
@ -865,15 +848,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
Note that object memory usage can evolve (increase or decrease) over time.
</p></pre><BR>
<a name="Chapter21"></a><h2>ADVANCED AND EXPERIMENTAL FUNCTIONS</h2><pre>
The definitions in the following section are considered experimental.
They are provided for advanced scenarios.
They should never be used with a dynamic library, as prototypes may change in the future.
Use them only in association with static linking.
<BR></pre>
<a name="Chapter22"></a><h2>experimental API (static linking only)</h2><pre>
<a name="Chapter14"></a><h2>experimental API (static linking only)</h2><pre>
The following symbols and constants
are not planned to join "stable API" status in the near future.
They can still change in future versions.
@ -971,7 +946,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
ZSTD_lcm_uncompressed = 2, </b>/**< Always emit uncompressed literals. */<b>
} ZSTD_literalCompressionMode_e;
</b></pre><BR>
<a name="Chapter23"></a><h2>Frame size functions</h2><pre></pre>
<a name="Chapter15"></a><h2>Frame size functions</h2><pre></pre>
<pre><b>unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);
</b><p> `src` should point to the start of a series of ZSTD encoded and/or skippable frames
@ -996,7 +971,8 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
however it does mean that all frame data must be present and valid.
</p></pre><BR>
<a name="Chapter24"></a><h2>ZSTD_decompressBound() :</h2><pre> `src` should point to the start of a series of ZSTD encoded and/or skippable frames
<pre><b>unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize);
</b><p> `src` should point to the start of a series of ZSTD encoded and/or skippable frames
`srcSize` must be the _exact_ size of this series
(i.e. there should be a frame boundary at `src + srcSize`)
@return : - upper-bound for the decompressed size of all data in all successive frames
@ -1008,7 +984,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
note 3 : when the decompressed size field isn't available, the upper-bound for that frame is calculated by:
upper-bound = # blocks * min(128 KB, Window_Size)
<BR></pre>
</p></pre><BR>
<pre><b>size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
</b><p> srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX.
@ -1016,7 +992,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
or an error code (if srcSize is too small)
</p></pre><BR>
<a name="Chapter25"></a><h2>Memory management</h2><pre></pre>
<a name="Chapter16"></a><h2>Memory management</h2><pre></pre>
<pre><b>size_t ZSTD_estimateCCtxSize(int compressionLevel);
size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams);
@ -1096,7 +1072,7 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
</p></pre><BR>
<a name="Chapter26"></a><h2>Advanced compression functions</h2><pre></pre>
<a name="Chapter17"></a><h2>Advanced compression functions</h2><pre></pre>
<pre><b>ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
</b><p> Create a digested dictionary for compression
@ -1241,7 +1217,7 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
</p></pre><BR>
<a name="Chapter27"></a><h2>Advanced decompression functions</h2><pre></pre>
<a name="Chapter18"></a><h2>Advanced decompression functions</h2><pre></pre>
<pre><b>unsigned ZSTD_isFrame(const void* buffer, size_t size);
</b><p> Tells if the content of `buffer` starts with a valid Frame Identifier.
@ -1303,7 +1279,7 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
</p></pre><BR>
<a name="Chapter28"></a><h2>Advanced streaming functions</h2><pre> Warning : most of these functions are now redundant with the Advanced API.
<a name="Chapter19"></a><h2>Advanced streaming functions</h2><pre> Warning : most of these functions are now redundant with the Advanced API.
Once Advanced API reaches "stable" status,
redundant functions will be deprecated, and then at some point removed.
<BR></pre>
@ -1432,14 +1408,14 @@ size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict);
*/
size_t ZSTD_resetDStream(ZSTD_DStream* zds);
</pre></b><BR>
<a name="Chapter29"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
<a name="Chapter20"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
This is an advanced API, giving full control over buffer management, for users which need direct control over memory.
But it's also a complex one, with several restrictions, documented below.
Prefer normal streaming API for an easier experience.
<BR></pre>
<a name="Chapter30"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
<a name="Chapter21"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
A ZSTD_CCtx object is required to track streaming operations.
Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource.
ZSTD_CCtx object can be re-used multiple times within successive compression operations.
@ -1475,7 +1451,7 @@ size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
size_t ZSTD_compressBegin_usingCDict_advanced(ZSTD_CCtx* const cctx, const ZSTD_CDict* const cdict, ZSTD_frameParameters const fParams, unsigned long long const pledgedSrcSize); </b>/* compression parameters are already set within cdict. pledgedSrcSize must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */<b>
size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); </b>/**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */<b>
</pre></b><BR>
<a name="Chapter31"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
<a name="Chapter22"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
A ZSTD_DCtx object is required to track streaming operations.
Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it.
A ZSTD_DCtx object can be re-used multiple times.
@ -1557,23 +1533,21 @@ typedef struct {
unsigned checksumFlag;
} ZSTD_frameHeader;
</pre></b><BR>
<a name="Chapter32"></a><h2>ZSTD_getFrameHeader() :</h2><pre> decode Frame Header, or requires larger `srcSize`.
<pre><b>size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); </b>/**< doesn't consume input */<b>
</b>/*! ZSTD_getFrameHeader_advanced() :<b>
* same as ZSTD_getFrameHeader(),
* with added capability to select a format (like ZSTD_f_zstd1_magicless) */
size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format);
size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); </b>/**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */<b>
</b><p> decode Frame Header, or requires larger `srcSize`.
@return : 0, `zfhPtr` is correctly filled,
>0, `srcSize` is too small, value is wanted `srcSize` amount,
or an error code, which can be tested using ZSTD_isError()
<BR></pre>
<pre><b>size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); </b>/**< doesn't consume input */<b>
</b></pre><BR>
<pre><b>size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format);
size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); </b>/**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */<b>
</b><p> same as ZSTD_getFrameHeader(),
with added capability to select a format (like ZSTD_f_zstd1_magicless)
</p></pre><BR>
<pre><b>typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
</b></pre><BR>
<a name="Chapter33"></a><h2>Block level API</h2><pre></pre>
<a name="Chapter23"></a><h2>Block level API</h2><pre></pre>
<pre><b></b><p> Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes).
User will have to take in charge required information to regenerate data, such as compressed and content sizes.

54
lib/zstd.h
View File

@ -82,16 +82,16 @@ ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< to check runtime library v
#define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION)
ZSTDLIB_API const char* ZSTD_versionString(void); /* requires v1.3.0+ */
/***************************************
* Default constant
***************************************/
/* *************************************
* Default constant
***************************************/
#ifndef ZSTD_CLEVEL_DEFAULT
# define ZSTD_CLEVEL_DEFAULT 3
#endif
/***************************************
* Constants
***************************************/
/* *************************************
* Constants
***************************************/
/* All magic numbers are supposed read/written to/from files/memory using little-endian convention */
#define ZSTD_MAGICNUMBER 0xFD2FB528 /* valid since v0.8.0 */
@ -657,17 +657,33 @@ ZSTDLIB_API size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
ZSTD_inBuffer* input,
ZSTD_EndDirective endOp);
ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */
ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances. */
/*******************************************************************************
* This is a legacy streaming API, and can be replaced by ZSTD_CCtx_reset() and
* ZSTD_compressStream2(). It is redundant, but is still fully supported.
/* These buffer sizes are softly recommended.
* They are not required : ZSTD_compressStream*() happily accepts any buffer size, for both input and output.
* Respecting the recommended size just makes it a bit easier for ZSTD_compressStream*(),
* reducing the amount of memory shuffling and buffering, resulting in minor performance savings.
*
* However, note that these recommendations are from the perspective of a C caller program.
* If the streaming interface is invoked from some other language,
* especially managed ones such as Java or Go, through a foreign function interface such as jni or cgo,
* a major performance rule is to reduce crossing such interface to an absolute minimum.
* It's not rare that performance ends being spent more into the interface, rather than compression itself.
* In which cases, prefer using large buffers, as large as practical,
* for both input and output, to reduce the nb of roundtrips.
*/
ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */
ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */
/* *****************************************************************************
* This following is a legacy streaming API.
* It can be replaced by ZSTD_CCtx_reset() and ZSTD_compressStream2().
* It is redundant, but remains fully supported.
* Advanced parameters and dictionary compression can only be used through the
* new API.
******************************************************************************/
/**
/*!
* Equivalent to:
*
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
@ -675,16 +691,16 @@ ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output
* ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
*/
ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel);
/**
/*!
* Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue).
* NOTE: The return value is different. ZSTD_compressStream() returns a hint for
* the next read size (if non-zero and not an error). ZSTD_compressStream2()
* returns the number of bytes left to flush (if non-zero and not an error).
* returns the minimum nb of bytes left to flush (if non-zero and not an error).
*/
ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
/** Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */
/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */
ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
/** Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */
/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */
ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
@ -969,7 +985,7 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
#endif /* ZSTD_H_235446 */
/****************************************************************************************
/* **************************************************************************************
* ADVANCED AND EXPERIMENTAL FUNCTIONS
****************************************************************************************
* The definitions in the following section are considered experimental.
@ -1162,7 +1178,7 @@ typedef enum {
* however it does mean that all frame data must be present and valid. */
ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);
/** ZSTD_decompressBound() :
/*! ZSTD_decompressBound() :
* `src` should point to the start of a series of ZSTD encoded and/or skippable frames
* `srcSize` must be the _exact_ size of this series
* (i.e. there should be a frame boundary at `src + srcSize`)
@ -1843,7 +1859,7 @@ typedef struct {
unsigned checksumFlag;
} ZSTD_frameHeader;
/** ZSTD_getFrameHeader() :
/*! ZSTD_getFrameHeader() :
* decode Frame Header, or requires larger `srcSize`.
* @return : 0, `zfhPtr` is correctly filled,
* >0, `srcSize` is too small, value is wanted `srcSize` amount,