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-<title>zstd 1.3.5 Manual</title>
+<title>zstd 1.3.6 Manual</title>
</head>
<body>
-<h1>zstd 1.3.5 Manual</h1>
+<h1>zstd 1.3.6 Manual</h1>
<hr>
<a name="Contents"></a><h2>Contents</h2>
<ol>
<li><a href="#Chapter8">Streaming</a></li>
<li><a href="#Chapter9">Streaming compression - HowTo</a></li>
<li><a href="#Chapter10">Streaming decompression - HowTo</a></li>
-<li><a href="#Chapter11">START OF ADVANCED AND EXPERIMENTAL FUNCTIONS</a></li>
-<li><a href="#Chapter12">Advanced types</a></li>
-<li><a href="#Chapter13">Frame size functions</a></li>
-<li><a href="#Chapter14">ZSTD_frameHeaderSize() :</a></li>
-<li><a href="#Chapter15">Memory management</a></li>
-<li><a href="#Chapter16">Advanced compression functions</a></li>
-<li><a href="#Chapter17">Advanced decompression functions</a></li>
-<li><a href="#Chapter18">Advanced streaming functions</a></li>
-<li><a href="#Chapter19">Buffer-less and synchronous inner streaming functions</a></li>
-<li><a href="#Chapter20">Buffer-less streaming compression (synchronous mode)</a></li>
-<li><a href="#Chapter21">Buffer-less streaming decompression (synchronous mode)</a></li>
-<li><a href="#Chapter22">New advanced API (experimental)</a></li>
-<li><a href="#Chapter23">ZSTD_getFrameHeader_advanced() :</a></li>
-<li><a href="#Chapter24">Block level API</a></li>
+<li><a href="#Chapter11">ADVANCED AND EXPERIMENTAL FUNCTIONS</a></li>
+<li><a href="#Chapter12">Frame size functions</a></li>
+<li><a href="#Chapter13">Memory management</a></li>
+<li><a href="#Chapter14">Advanced compression functions</a></li>
+<li><a href="#Chapter15">Advanced decompression functions</a></li>
+<li><a href="#Chapter16">Advanced streaming functions</a></li>
+<li><a href="#Chapter17">Buffer-less and synchronous inner streaming functions</a></li>
+<li><a href="#Chapter18">Buffer-less streaming compression (synchronous mode)</a></li>
+<li><a href="#Chapter19">Buffer-less streaming decompression (synchronous mode)</a></li>
+<li><a href="#Chapter20">New advanced API (experimental)</a></li>
+<li><a href="#Chapter21">Block level API</a></li>
</ol>
<hr>
<a name="Chapter1"></a><h2>Introduction</h2><pre>
</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="Chapter11"></a><h2>START OF ADVANCED AND EXPERIMENTAL FUNCTIONS</h2><pre> The definitions in this section are considered experimental.
+<a name="Chapter11"></a><h2>ADVANCED AND EXPERIMENTAL FUNCTIONS</h2><pre>
+ The definitions in this section are considered experimental.
They should never be used with a dynamic library, as prototypes may change in the future.
They are provided for advanced scenarios.
Use them only in association with static linking.
<BR></pre>
-<a name="Chapter12"></a><h2>Advanced types</h2><pre></pre>
-
+<pre><b>int ZSTD_minCLevel(void); </b>/*!< minimum negative compression level allowed */<b>
+</b></pre><BR>
<pre><b>typedef enum { ZSTD_fast=1, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2,
ZSTD_btlazy2, ZSTD_btopt, ZSTD_btultra } ZSTD_strategy; </b>/* from faster to stronger */<b>
</b></pre><BR>
ZSTD_dlm_byRef, </b>/**< Reference dictionary content -- the dictionary buffer must outlive its users. */<b>
} ZSTD_dictLoadMethod_e;
</b></pre><BR>
-<a name="Chapter1
3"></a><h2>Frame size functions</h2><pre></pre>
+<a name="Chapter1
2"></a><h2>Frame size functions</h2><pre></pre>
<pre><b>size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
</b><p> `src` should point to the start of a ZSTD encoded frame or skippable frame
however it does mean that all frame data must be present and valid.
</p></pre><BR>
-<a name="Chapter14"></a><h2>ZSTD_frameHeaderSize() :</h2><pre> srcSize must be >= ZSTD_frameHeaderSize_prefix.
+<pre><b>size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
+</b><p> srcSize must be >= ZSTD_frameHeaderSize_prefix.
@return : size of the Frame Header,
or an error code (if srcSize is too small)
-<BR></pre>
+</p></pre><BR>
-<a name="Chapter1
5"></a><h2>Memory management</h2><pre></pre>
+<a name="Chapter1
3"></a><h2>Memory management</h2><pre></pre>
<pre><b>size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);
</p></pre><BR>
-<a name="Chapter1
6"></a><h2>Advanced compression functions</h2><pre></pre>
+<a name="Chapter1
4"></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
</b><p> Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters
</p></pre><BR>
-<a name="Chapter1
7"></a><h2>Advanced decompression functions</h2><pre></pre>
+<a name="Chapter1
5"></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.
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="Chapter1
8"></a><h2>Advanced streaming functions</h2><pre></pre>
+<a name="Chapter1
6"></a><h2>Advanced streaming functions</h2><pre></pre>
<h3>Advanced Streaming compression functions</h3><pre></pre><b><pre>size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); </b>/**< 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. */<b>
size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); </b>/**< 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_dm_auto (treated as a full zstd dictionary if it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.*/<b>
size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); </b>/**< note : ddict is referenced, it must outlive decompression session */<b>
size_t ZSTD_resetDStream(ZSTD_DStream* zds); </b>/**< re-use decompression parameters from previous init; saves dictionary loading */<b>
</pre></b><BR>
-<a name="Chapter1
9"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
+<a name="Chapter1
7"></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="Chapter
20"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
+<a name="Chapter
18"></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.
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="Chapter
21"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
+<a name="Chapter
19"></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.
</pre></b><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="Chapter2
2"></a><h2>New advanced API (experimental)</h2><pre></pre>
+<a name="Chapter2
0"></a><h2>New advanced API (experimental)</h2><pre></pre>
<pre><b>typedef enum {
</b>/* Opened question : should we have a format ZSTD_f_auto ?<b>
</p></pre><BR>
-<a name="Chapter23"></a><h2>ZSTD_getFrameHeader_advanced() :</h2><pre> same as ZSTD_getFrameHeader(),
+<pre><b>size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr,
+ const void* src, size_t srcSize, ZSTD_format_e format);
+</b><p> same as ZSTD_getFrameHeader(),
with added capability to select a format (like ZSTD_f_zstd1_magicless)
-<BR></pre>
+</p></pre><BR>
<pre><b>size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx,
ZSTD_outBuffer* output,
</p></pre><BR>
-<a name="Chapter2
4"></a><h2>Block level API</h2><pre></pre>
+<a name="Chapter2
1"></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.
/*------ Version ------*/
#define ZSTD_VERSION_MAJOR 1
#define ZSTD_VERSION_MINOR 3
-#define ZSTD_VERSION_RELEASE 5
+#define ZSTD_VERSION_RELEASE 6
#define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< useful to check dll version */
#define ZSTD_QUOTE(str) #str
#define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str)
#define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION)
-ZSTDLIB_API const char* ZSTD_versionString(void); /* added in v1.3.0 */
+ZSTDLIB_API const char* ZSTD_versionString(void); /* v1.3.0+ */
/***************************************
* Default constant
* *******************************************************************/
typedef ZSTD_CCtx ZSTD_CStream; /**< CCtx and CStream are now effectively same object (>= v1.3.0) */
- /* Continue to distinguish them for compatibility with versions <= v1.2.0 */
+ /* Continue to distinguish them for compatibility with older versions <= v1.2.0 */
/*===== ZSTD_CStream management functions =====*/
ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void);
ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs);
+
+#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
+#define ZSTD_H_ZSTD_STATIC_LINKING_ONLY
+
/****************************************************************************************
- * START OF ADVANCED AND EXPERIMENTAL FUNCTIONS
+ * ADVANCED AND EXPERIMENTAL FUNCTIONS
+ ****************************************************************************************
* The definitions in this section are considered experimental.
* They should never be used with a dynamic library, as prototypes may change in the future.
* They are provided for advanced scenarios.
* Use them only in association with static linking.
* ***************************************************************************************/
-#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
-#define ZSTD_H_ZSTD_STATIC_LINKING_ONLY
+ZSTDLIB_API int ZSTD_minCLevel(void); /*!< minimum negative compression level allowed */
-/* --- Constants ---*/
-#define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */
+/* --- Constants ---*/
+#define ZSTD_MAGICNUMBER 0xFD2FB528 /* v0.8+ */
+#define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* v0.7+ */
#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U
-#define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* >= v0.7.0 */
+
+#define ZSTD_BLOCKSIZELOG_MAX 17
+#define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX) /* define, for static allocation */
#define ZSTD_WINDOWLOG_MAX_32 30
#define ZSTD_WINDOWLOG_MAX_64 31
#define ZSTD_SEARCHLOG_MIN 1
#define ZSTD_SEARCHLENGTH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */
#define ZSTD_SEARCHLENGTH_MIN 3 /* only for ZSTD_btopt, other strategies are limited to 4 */
-#define ZSTD_LDM_MINMATCH_MIN 4
+#define ZSTD_TARGETLENGTH_MAX ZSTD_BLOCKSIZE_MAX
+#define ZSTD_TARGETLENGTH_MIN 0
#define ZSTD_LDM_MINMATCH_MAX 4096
+#define ZSTD_LDM_MINMATCH_MIN 4
#define ZSTD_LDM_BUCKETSIZELOG_MAX 8
#define ZSTD_FRAMEHEADERSIZE_PREFIX 5 /* minimum input size to know frame header size */
static const size_t ZSTD_skippableHeaderSize = 8; /* magic number + skippable frame length */
-/*--- Advanced types ---*/
+
+/* --- Advanced types --- */
typedef enum { ZSTD_fast=1, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2,
ZSTD_btlazy2, ZSTD_btopt, ZSTD_btultra } ZSTD_strategy; /* from faster to stronger */
* 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_frameHeaderSize() :
+/*! ZSTD_frameHeaderSize() :
* srcSize must be >= ZSTD_frameHeaderSize_prefix.
* @return : size of the Frame Header,
* or an error code (if srcSize is too small) */
ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
-/** ZSTD_getFrameHeader_advanced() :
+/*! ZSTD_getFrameHeader_advanced() :
* same as ZSTD_getFrameHeader(),
* with added capability to select a format (like ZSTD_f_zstd1_magicless) */
ZSTDLIB_API size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr,
Use ZSTD_insertBlock() for such a case.
*/
-#define ZSTD_BLOCKSIZELOG_MAX 17
-#define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX) /* define, for static allocation */
/*===== Raw zstd block functions =====*/
ZSTDLIB_API size_t ZSTD_getBlockSize (const ZSTD_CCtx* cctx);
ZSTDLIB_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
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