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update documentation on deprecated functions 

mostly : note that these functions will soon generate deprecation warnings
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Yann Collet 2019-10-22 13:51:18 -07:00
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doc/zstd_manual.html
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@ -27,10 +27,16 @@
<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>
<li><a href="#Chapter20">! ZSTD_initCStream_usingDict() :</a></li>
<li><a href="#Chapter21">! ZSTD_initCStream_advanced() :</a></li>
<li><a href="#Chapter22">! ZSTD_initCStream_usingCDict() :</a></li>
<li><a href="#Chapter23">! ZSTD_initCStream_usingCDict_advanced() :</a></li>
<li><a href="#Chapter24">This function is deprecated, and is equivalent to:</a></li>
<li><a href="#Chapter25">This function is deprecated, and is equivalent to:</a></li>
<li><a href="#Chapter26">Buffer-less and synchronous inner streaming functions</a></li>
<li><a href="#Chapter27">Buffer-less streaming compression (synchronous mode)</a></li>
<li><a href="#Chapter28">Buffer-less streaming decompression (synchronous mode)</a></li>
<li><a href="#Chapter29">Block level API</a></li>
</ol>
<hr>
<a name="Chapter1"></a><h2>Introduction</h2><pre>
@ -157,9 +163,13 @@ size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx);
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
int compressionLevel);
</b><p> Same as ZSTD_compress(), using an explicit ZSTD_CCtx
The function will compress at requested compression level,
ignoring any other parameter
</b><p> Same as ZSTD_compress(), using an explicit ZSTD_CCtx.
Important : in order to behave similarly to `ZSTD_compress()`,
this function compresses at requested compression level,
__ignoring any other parameter__ .
If any advanced parameter was set using the advanced API,
they will all be reset. Only `compressionLevel` remains.
</p></pre><BR>
<h3>Decompression context</h3><pre> When decompressing many times,
@ -199,18 +209,26 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
</b>/* compression parameters<b>
* Note: When compressing with a ZSTD_CDict these parameters are superseded
* by the parameters used to construct the ZSTD_CDict. See ZSTD_CCtx_refCDict()
* for more info (superseded-by-cdict). */
ZSTD_c_compressionLevel=100, </b>/* Update all compression parameters according to pre-defined cLevel table<b>
* by the parameters used to construct the ZSTD_CDict.
* See ZSTD_CCtx_refCDict() for more info (superseded-by-cdict). */
ZSTD_c_compressionLevel=100, </b>/* Set compression parameters according to pre-defined cLevel table.<b>
* Note that exact compression parameters are dynamically determined,
* depending on both compression level and srcSize (when known).
* Default level is ZSTD_CLEVEL_DEFAULT==3.
* Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT.
* Note 1 : it's possible to pass a negative compression level.
* Note 2 : setting a level sets all default values of other compression parameters */
* Note 2 : setting a level resets all other compression parameters to default */
</b>/* Advanced compression parameters :<b>
* It's possible to pin down compression parameters to some specific values.
* In which case, these values are no longer dynamically selected by the compressor */
ZSTD_c_windowLog=101, </b>/* Maximum allowed back-reference distance, expressed as power of 2.<b>
* This will set a memory budget for streaming decompression,
* with larger values requiring more memory
* and typically compressing more.
* Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
* Special: value 0 means "use default windowLog".
* Note: Using a windowLog greater than ZSTD_WINDOWLOG_LIMIT_DEFAULT
* requires explicitly allowing such window size at decompression stage if using streaming. */
* requires explicitly allowing such size at streaming decompression stage. */
ZSTD_c_hashLog=102, </b>/* Size of the initial probe table, as a power of 2.<b>
* Resulting memory usage is (1 << (hashLog+2)).
* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX.
@ -221,13 +239,13 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
* Resulting memory usage is (1 << (chainLog+2)).
* Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX.
* Larger tables result in better and slower compression.
* This parameter is useless when using "fast" strategy.
* This parameter is useless for "fast" strategy.
* It's still useful when using "dfast" strategy,
* in which case it defines a secondary probe table.
* Special: value 0 means "use default chainLog". */
ZSTD_c_searchLog=104, </b>/* Number of search attempts, as a power of 2.<b>
* More attempts result in better and slower compression.
* This parameter is useless when using "fast" and "dFast" strategies.
* This parameter is useless for "fast" and "dFast" strategies.
* Special: value 0 means "use default searchLog". */
ZSTD_c_minMatch=105, </b>/* Minimum size of searched matches.<b>
* Note that Zstandard can still find matches of smaller size,
@ -282,7 +300,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
ZSTD_c_contentSizeFlag=200, </b>/* Content size will be written into frame header _whenever known_ (default:1)<b>
* Content size must be known at the beginning of compression.
* This is automatically the case when using ZSTD_compress2(),
* For streaming variants, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */
* For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */
ZSTD_c_checksumFlag=201, </b>/* A 32-bits checksum of content is written at end of frame (default:0) */<b>
ZSTD_c_dictIDFlag=202, </b>/* When applicable, dictionary's ID is written into frame header (default:1) */<b>
@ -301,7 +319,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
* Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads.
* 0 means default, which is dynamically determined based on compression parameters.
* Job size must be a minimum of overlap size, or 1 MB, whichever is largest.
* The minimum size is automatically and transparently enforced */
* The minimum size is automatically and transparently enforced. */
ZSTD_c_overlapLog=402, </b>/* Control the overlap size, as a fraction of window size.<b>
* The overlap size is an amount of data reloaded from previous job at the beginning of a new job.
* It helps preserve compression ratio, while each job is compressed in parallel.
@ -335,7 +353,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
ZSTD_c_experimentalParam4=1001,
ZSTD_c_experimentalParam5=1002,
ZSTD_c_experimentalParam6=1003,
ZSTD_c_experimentalParam7=1004,
ZSTD_c_experimentalParam7=1004
} ZSTD_cParameter;
</b></pre><BR>
<pre><b>typedef struct {
@ -913,21 +931,12 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
</b></pre><BR>
<pre><b>typedef enum {
ZSTD_dlm_byCopy = 0, </b>/**< Copy dictionary content internally */<b>
ZSTD_dlm_byRef = 1, </b>/**< Reference dictionary content -- the dictionary buffer must outlive its users. */<b>
ZSTD_dlm_byRef = 1 </b>/**< Reference dictionary content -- the dictionary buffer must outlive its users. */<b>
} ZSTD_dictLoadMethod_e;
</b></pre><BR>
<pre><b>typedef enum {
</b>/* Opened question : should we have a format ZSTD_f_auto ?<b>
* Today, it would mean exactly the same as ZSTD_f_zstd1.
* But, in the future, should several formats become supported,
* on the compression side, it would mean "default format".
* On the decompression side, it would mean "automatic format detection",
* so that ZSTD_f_zstd1 would mean "accept *only* zstd frames".
* Since meaning is a little different, another option could be to define different enums for compression and decompression.
* This question could be kept for later, when there are actually multiple formats to support,
* but there is also the question of pinning enum values, and pinning value `0` is especially important */
ZSTD_f_zstd1 = 0, </b>/* zstd frame format, specified in zstd_compression_format.md (default) */<b>
ZSTD_f_zstd1_magicless = 1, </b>/* Variant of zstd frame format, without initial 4-bytes magic number.<b>
ZSTD_f_zstd1_magicless = 1 </b>/* Variant of zstd frame format, without initial 4-bytes magic number.<b>
* Useful to save 4 bytes per generated frame.
* Decoder cannot recognise automatically this format, requiring this instruction. */
} ZSTD_format_e;
@ -961,7 +970,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
*/
ZSTD_dictDefaultAttach = 0, </b>/* Use the default heuristic. */<b>
ZSTD_dictForceAttach = 1, </b>/* Never copy the dictionary. */<b>
ZSTD_dictForceCopy = 2, </b>/* Always copy the dictionary. */<b>
ZSTD_dictForceCopy = 2 </b>/* Always copy the dictionary. */<b>
} ZSTD_dictAttachPref_e;
</b></pre><BR>
<pre><b>typedef enum {
@ -970,7 +979,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
* levels will be compressed. */
ZSTD_lcm_huffman = 1, </b>/**< Always attempt Huffman compression. Uncompressed literals will still be<b>
* emitted if Huffman compression is not profitable. */
ZSTD_lcm_uncompressed = 2, </b>/**< Always emit uncompressed literals. */<b>
ZSTD_lcm_uncompressed = 2 </b>/**< Always emit uncompressed literals. */<b>
} ZSTD_literalCompressionMode_e;
</b></pre><BR>
<a name="Chapter15"></a><h2>Frame size functions</h2><pre></pre>
@ -1124,6 +1133,7 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
Dictionary content is just referenced, not duplicated.
As a consequence, `dictBuffer` **must** outlive CDict,
and its content must remain unmodified throughout the lifetime of CDict.
note: equivalent to ZSTD_createCDict_advanced(), with dictLoadMethod==ZSTD_dlm_byRef
</p></pre><BR>
<pre><b>ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize);
@ -1154,7 +1164,9 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
const void* src, size_t srcSize,
const void* dict,size_t dictSize,
ZSTD_parameters params);
</b><p> Same as ZSTD_compress_usingDict(), with fine-tune control over compression parameters (by structure)
</b><p> Note : this function is now DEPRECATED.
It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_setParameter() and other parameter setters.
This prototype will be marked as deprecated and generate compilation warning on reaching v1.5.x
</p></pre><BR>
<pre><b>size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx,
@ -1162,7 +1174,9 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
const void* src, size_t srcSize,
const ZSTD_CDict* cdict,
ZSTD_frameParameters fParams);
</b><p> Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters
</b><p> Note : this function is now REDUNDANT.
It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_loadDictionary() and other parameter setters.
This prototype will be marked as deprecated and generate compilation warning in some future version
</p></pre><BR>
<pre><b>size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
@ -1339,59 +1353,67 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
* pledgedSrcSize must be correct. If it is not known at init time, use
* ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs,
* "0" also disables frame content size field. It may be enabled in the future.
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize);
</b>/**! ZSTD_initCStream_usingDict() :<b>
* This function is deprecated, and is equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
* ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
* ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
*
* Creates of an internal CDict (incompatible with static CCtx), except if
* dict == NULL or dictSize < 8, in which case no dict is used.
* Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if
* it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.
*/
size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel);
</b>/**! ZSTD_initCStream_advanced() :<b>
* This function is deprecated, and is approximately equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
* // Pseudocode: Set each zstd parameter and leave the rest as-is.
* for ((param, value) : params) {
* ZSTD_CCtx_setParameter(zcs, param, value);
* }
* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
* ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
*
* pledgedSrcSize must be correct. If srcSize is not known at init time, use
* value ZSTD_CONTENTSIZE_UNKNOWN. dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy.
*/
size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize,
ZSTD_parameters params, unsigned long long pledgedSrcSize);
</b>/**! ZSTD_initCStream_usingCDict() :<b>
* This function is deprecated, and equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
* ZSTD_CCtx_refCDict(zcs, cdict);
*
* note : cdict will just be referenced, and must outlive compression session
*/
size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict);
</b>/**! ZSTD_initCStream_usingCDict_advanced() :<b>
* This function is deprecated, and is approximately equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
* // Pseudocode: Set each zstd frame parameter and leave the rest as-is.
* for ((fParam, value) : fParams) {
* ZSTD_CCtx_setParameter(zcs, fParam, value);
* }
* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
* ZSTD_CCtx_refCDict(zcs, cdict);
*
* same as ZSTD_initCStream_usingCDict(), with control over frame parameters.
* pledgedSrcSize must be correct. If srcSize is not known at init time, use
* value ZSTD_CONTENTSIZE_UNKNOWN.
*/
size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize);
size_t
ZSTD_initCStream_srcSize(ZSTD_CStream* zcs,
int compressionLevel,
unsigned long long pledgedSrcSize);
</pre></b><BR>
<a name="Chapter20"></a><h2>! ZSTD_initCStream_usingDict() :</h2><pre> This function is deprecated, and is equivalent to:
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
Creates of an internal CDict (incompatible with static CCtx), except if
dict == NULL or dictSize < 8, in which case no dict is used.
Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if
it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.
Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
<BR></pre>
<a name="Chapter21"></a><h2>! ZSTD_initCStream_advanced() :</h2><pre> This function is deprecated, and is approximately equivalent to:
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
// Pseudocode: Set each zstd parameter and leave the rest as-is.
for ((param, value) : params) {
ZSTD_CCtx_setParameter(zcs, param, value);
}
ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy.
pledgedSrcSize must be correct.
If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN.
Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
<BR></pre>
<a name="Chapter22"></a><h2>! ZSTD_initCStream_usingCDict() :</h2><pre> This function is deprecated, and equivalent to:
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
ZSTD_CCtx_refCDict(zcs, cdict);
note : cdict will just be referenced, and must outlive compression session
Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
<BR></pre>
<a name="Chapter23"></a><h2>! ZSTD_initCStream_usingCDict_advanced() :</h2><pre> This function is DEPRECATED, and is approximately equivalent to:
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
// Pseudocode: Set each zstd frame parameter and leave the rest as-is.
for ((fParam, value) : fParams) {
ZSTD_CCtx_setParameter(zcs, fParam, value);
}
ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
ZSTD_CCtx_refCDict(zcs, cdict);
same as ZSTD_initCStream_usingCDict(), with control over frame parameters.
pledgedSrcSize must be correct. If srcSize is not known at init time, use
value ZSTD_CONTENTSIZE_UNKNOWN.
Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
<BR></pre>
<pre><b>size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);
</b><p> This function is deprecated, and is equivalent to:
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
@ -1405,6 +1427,7 @@ size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict*
For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs,
but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead.
@return : 0, or an error code (which can be tested using ZSTD_isError())
Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
</p></pre><BR>
@ -1439,34 +1462,35 @@ size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict*
* ZSTD_DCtx_loadDictionary(zds, dict, dictSize);
*
* note: no dictionary will be used if dict == NULL or dictSize < 8
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize);
</b>/**<b>
* This function is deprecated, and is equivalent to:
*
* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
* ZSTD_DCtx_refDDict(zds, ddict);
*
* note : ddict is referenced, it must outlive decompression session
*/
size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict);
</b>/**<b>
* This function is deprecated, and is equivalent to:
*
* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
*
* re-use decompression parameters from previous init; saves dictionary loading
*/
size_t ZSTD_resetDStream(ZSTD_DStream* zds);
</pre></b><BR>
<a name="Chapter20"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
<a name="Chapter24"></a><h2>This function is deprecated, and is equivalent to:</h2><pre>
ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
ZSTD_DCtx_refDDict(zds, ddict);
note : ddict is referenced, it must outlive decompression session
Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
<BR></pre>
<a name="Chapter25"></a><h2>This function is deprecated, and is equivalent to:</h2><pre>
ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
re-use decompression parameters from previous init; saves dictionary loading
Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
<BR></pre>
<a name="Chapter26"></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="Chapter21"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
<a name="Chapter27"></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.
@ -1502,7 +1526,7 @@ 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="Chapter22"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
<a name="Chapter28"></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.
@ -1598,9 +1622,9 @@ size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long
<pre><b>typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
</b></pre><BR>
<a name="Chapter23"></a><h2>Block level API</h2><pre></pre>
<a name="Chapter29"></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).
<pre><b></b><p> Frame metadata cost is typically ~12 bytes, which can be non-negligible for very small blocks (< 100 bytes).
But users will have to take in charge needed metadata to regenerate data, such as compressed and content sizes.
A few rules to respect :

105
lib/zstd.h
View File

@ -197,9 +197,13 @@ ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void);
ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx);
/*! ZSTD_compressCCtx() :
* Same as ZSTD_compress(), using an explicit ZSTD_CCtx
* The function will compress at requested compression level,
* ignoring any other parameter */
* Same as ZSTD_compress(), using an explicit ZSTD_CCtx.
* Important : in order to behave similarly to `ZSTD_compress()`,
* this function compresses at requested compression level,
* __ignoring any other parameter__ .
* If any advanced parameter was set using the advanced API,
* they will all be reset. Only `compressionLevel` remains.
*/
ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
@ -234,7 +238,7 @@ ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx,
* using ZSTD_CCtx_set*() functions.
* Pushed parameters are sticky : they are valid for next compressed frame, and any subsequent frame.
* "sticky" parameters are applicable to `ZSTD_compress2()` and `ZSTD_compressStream*()` !
* They do not apply to "simple" one-shot variants such as ZSTD_compressCCtx()
* __They do not apply to "simple" one-shot variants such as ZSTD_compressCCtx()__ .
*
* It's possible to reset all parameters to "default" using ZSTD_CCtx_reset().
*
@ -262,18 +266,26 @@ typedef enum {
/* compression parameters
* Note: When compressing with a ZSTD_CDict these parameters are superseded
* by the parameters used to construct the ZSTD_CDict. See ZSTD_CCtx_refCDict()
* for more info (superseded-by-cdict). */
ZSTD_c_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table
* by the parameters used to construct the ZSTD_CDict.
* See ZSTD_CCtx_refCDict() for more info (superseded-by-cdict). */
ZSTD_c_compressionLevel=100, /* Set compression parameters according to pre-defined cLevel table.
* Note that exact compression parameters are dynamically determined,
* depending on both compression level and srcSize (when known).
* Default level is ZSTD_CLEVEL_DEFAULT==3.
* Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT.
* Note 1 : it's possible to pass a negative compression level.
* Note 2 : setting a level sets all default values of other compression parameters */
* Note 2 : setting a level resets all other compression parameters to default */
/* Advanced compression parameters :
* It's possible to pin down compression parameters to some specific values.
* In which case, these values are no longer dynamically selected by the compressor */
ZSTD_c_windowLog=101, /* Maximum allowed back-reference distance, expressed as power of 2.
* This will set a memory budget for streaming decompression,
* with larger values requiring more memory
* and typically compressing more.
* Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
* Special: value 0 means "use default windowLog".
* Note: Using a windowLog greater than ZSTD_WINDOWLOG_LIMIT_DEFAULT
* requires explicitly allowing such window size at decompression stage if using streaming. */
* requires explicitly allowing such size at streaming decompression stage. */
ZSTD_c_hashLog=102, /* Size of the initial probe table, as a power of 2.
* Resulting memory usage is (1 << (hashLog+2)).
* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX.
@ -284,13 +296,13 @@ typedef enum {
* Resulting memory usage is (1 << (chainLog+2)).
* Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX.
* Larger tables result in better and slower compression.
* This parameter is useless when using "fast" strategy.
* This parameter is useless for "fast" strategy.
* It's still useful when using "dfast" strategy,
* in which case it defines a secondary probe table.
* Special: value 0 means "use default chainLog". */
ZSTD_c_searchLog=104, /* Number of search attempts, as a power of 2.
* More attempts result in better and slower compression.
* This parameter is useless when using "fast" and "dFast" strategies.
* This parameter is useless for "fast" and "dFast" strategies.
* Special: value 0 means "use default searchLog". */
ZSTD_c_minMatch=105, /* Minimum size of searched matches.
* Note that Zstandard can still find matches of smaller size,
@ -345,7 +357,7 @@ typedef enum {
ZSTD_c_contentSizeFlag=200, /* Content size will be written into frame header _whenever known_ (default:1)
* Content size must be known at the beginning of compression.
* This is automatically the case when using ZSTD_compress2(),
* For streaming variants, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */
* For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */
ZSTD_c_checksumFlag=201, /* A 32-bits checksum of content is written at end of frame (default:0) */
ZSTD_c_dictIDFlag=202, /* When applicable, dictionary's ID is written into frame header (default:1) */
@ -364,7 +376,7 @@ typedef enum {
* Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads.
* 0 means default, which is dynamically determined based on compression parameters.
* Job size must be a minimum of overlap size, or 1 MB, whichever is largest.
* The minimum size is automatically and transparently enforced */
* The minimum size is automatically and transparently enforced. */
ZSTD_c_overlapLog=402, /* Control the overlap size, as a fraction of window size.
* The overlap size is an amount of data reloaded from previous job at the beginning of a new job.
* It helps preserve compression ratio, while each job is compressed in parallel.
@ -1128,15 +1140,6 @@ typedef enum {
} ZSTD_dictLoadMethod_e;
typedef enum {
/* Opened question : should we have a format ZSTD_f_auto ?
* Today, it would mean exactly the same as ZSTD_f_zstd1.
* But, in the future, should several formats become supported,
* on the compression side, it would mean "default format".
* On the decompression side, it would mean "automatic format detection",
* so that ZSTD_f_zstd1 would mean "accept *only* zstd frames".
* Since meaning is a little different, another option could be to define different enums for compression and decompression.
* This question could be kept for later, when there are actually multiple formats to support,
* but there is also the question of pinning enum values, and pinning value `0` is especially important */
ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */
ZSTD_f_zstd1_magicless = 1 /* Variant of zstd frame format, without initial 4-bytes magic number.
* Useful to save 4 bytes per generated frame.
@ -1375,7 +1378,8 @@ ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictS
* Create a digested dictionary for compression
* Dictionary content is just referenced, not duplicated.
* As a consequence, `dictBuffer` **must** outlive CDict,
* and its content must remain unmodified throughout the lifetime of CDict. */
* and its content must remain unmodified throughout the lifetime of CDict.
* note: equivalent to ZSTD_createCDict_advanced(), with dictLoadMethod==ZSTD_dlm_byRef */
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
/*! ZSTD_getCParams() :
@ -1402,7 +1406,9 @@ ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params);
ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize);
/*! ZSTD_compress_advanced() :
* Same as ZSTD_compress_usingDict(), with fine-tune control over compression parameters (by structure) */
* Note : this function is now DEPRECATED.
* It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_setParameter() and other parameter setters.
* This prototype will be marked as deprecated and generate compilation warning on reaching v1.5.x */
ZSTDLIB_API size_t ZSTD_compress_advanced(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
@ -1410,7 +1416,9 @@ ZSTDLIB_API size_t ZSTD_compress_advanced(ZSTD_CCtx* cctx,
ZSTD_parameters params);
/*! ZSTD_compress_usingCDict_advanced() :
* Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters */
* Note : this function is now REDUNDANT.
* It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_loadDictionary() and other parameter setters.
* This prototype will be marked as deprecated and generate compilation warning in some future version */
ZSTDLIB_API size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
@ -1660,8 +1668,13 @@ ZSTDLIB_API size_t ZSTD_decompressStream_simpleArgs (
* pledgedSrcSize must be correct. If it is not known at init time, use
* ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs,
* "0" also disables frame content size field. It may be enabled in the future.
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize);
ZSTDLIB_API size_t
ZSTD_initCStream_srcSize(ZSTD_CStream* zcs,
int compressionLevel,
unsigned long long pledgedSrcSize);
/**! ZSTD_initCStream_usingDict() :
* This function is deprecated, and is equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
@ -1672,8 +1685,13 @@ ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLe
* dict == NULL or dictSize < 8, in which case no dict is used.
* Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if
* it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel);
ZSTDLIB_API size_t
ZSTD_initCStream_usingDict(ZSTD_CStream* zcs,
const void* dict, size_t dictSize,
int compressionLevel);
/**! ZSTD_initCStream_advanced() :
* This function is deprecated, and is approximately equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
@ -1684,21 +1702,29 @@ ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dic
* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
* ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
*
* pledgedSrcSize must be correct. If srcSize is not known at init time, use
* value ZSTD_CONTENTSIZE_UNKNOWN. dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy.
* dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy.
* pledgedSrcSize must be correct.
* If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN.
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize,
ZSTD_parameters params, unsigned long long pledgedSrcSize);
ZSTDLIB_API size_t
ZSTD_initCStream_advanced(ZSTD_CStream* zcs,
const void* dict, size_t dictSize,
ZSTD_parameters params,
unsigned long long pledgedSrcSize);
/**! ZSTD_initCStream_usingCDict() :
* This function is deprecated, and equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
* ZSTD_CCtx_refCDict(zcs, cdict);
*
* note : cdict will just be referenced, and must outlive compression session
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict);
/**! ZSTD_initCStream_usingCDict_advanced() :
* This function is deprecated, and is approximately equivalent to:
* This function is DEPRECATED, and is approximately equivalent to:
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
* // Pseudocode: Set each zstd frame parameter and leave the rest as-is.
* for ((fParam, value) : fParams) {
@ -1710,8 +1736,13 @@ ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDi
* same as ZSTD_initCStream_usingCDict(), with control over frame parameters.
* pledgedSrcSize must be correct. If srcSize is not known at init time, use
* value ZSTD_CONTENTSIZE_UNKNOWN.
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize);
ZSTDLIB_API size_t
ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs,
const ZSTD_CDict* cdict,
ZSTD_frameParameters fParams,
unsigned long long pledgedSrcSize);
/*! ZSTD_resetCStream() :
* This function is deprecated, and is equivalent to:
@ -1726,6 +1757,7 @@ ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const
* For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs,
* but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead.
* @return : 0, or an error code (which can be tested using ZSTD_isError())
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);
@ -1771,8 +1803,10 @@ ZSTDLIB_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx);
* ZSTD_DCtx_loadDictionary(zds, dict, dictSize);
*
* note: no dictionary will be used if dict == NULL or dictSize < 8
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize);
/**
* This function is deprecated, and is equivalent to:
*
@ -1780,14 +1814,17 @@ ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dic
* ZSTD_DCtx_refDDict(zds, ddict);
*
* note : ddict is referenced, it must outlive decompression session
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict);
/**
* This function is deprecated, and is equivalent to:
*
* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
*
* re-use decompression parameters from previous init; saves dictionary loading
* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
*/
ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds);
@ -1961,7 +1998,7 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx);
/*!
Block functions produce and decode raw zstd blocks, without frame metadata.
Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes).
Frame metadata cost is typically ~12 bytes, which can be non-negligible for very small blocks (< 100 bytes).
But users will have to take in charge needed metadata to regenerate data, such as compressed and content sizes.
A few rules to respect :