<li><a href="#Chapter21">Buffer-less and synchronous inner streaming functions</a></li>
<li><a href="#Chapter22">Buffer-less streaming compression (synchronous mode)</a></li>
<li><a href="#Chapter23">Buffer-less streaming decompression (synchronous mode)</a></li>
-<li><a href="#Chapter24">Block level API</a></li>
+<li><a href="#Chapter24">ZSTD_getFrameHeader() :</a></li>
+<li><a href="#Chapter25">Block level API</a></li>
</ol>
<hr>
<a name="Chapter1"></a><h2>Introduction</h2><pre>
@result : 0, or an error code (which can be tested with ZSTD_isError()).
Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary
Note 1 : Prefix buffer is referenced. It **must** outlive compression job.
- Its contain must remain unmodified up to end of compression (ZSTD_e_end).
+ Its content must remain unmodified during compression.
Note 2 : If the intention is to diff some large src data blob with some prior version of itself,
ensure that the window size is large enough to contain the entire source.
See ZSTD_p_windowLog.
Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters.
It's a CPU consuming operation, with non-negligible impact on latency.
- If there is a need to use same prefix multiple times, consider loadDictionary instead.
+ If there is a need to use the same prefix multiple times, consider loadDictionary instead.
Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dm_rawContent).
- Use ZSTD_CCtx_refPrefix_advanced() to alter dictionary intepretation.
+ Use ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation.
</p></pre><BR>
<pre><b>typedef enum {
ZSTD_inBuffer* input,
ZSTD_EndDirective endOp);
</b><p> Behave about the same as ZSTD_compressStream. To note :
- - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_setParameter()
- - Compression parameters cannot be changed once compression is started.
+ - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
+ - Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode)
- outpot->pos must be <= dstCapacity, input->pos must be <= srcSize
- outpot->pos and input->pos will be updated. They are guaranteed to remain below their respective limit.
- - In single-thread mode (default), function is blocking : it completed its job before returning to caller.
+ - In single-thread mode (default), function is blocking : it completes its job before returning to caller.
- In multi-thread mode, function is non-blocking : it just acquires a copy of input, and distribute job to internal worker threads,
and then immediately returns, just indicating that there is some data remaining to be flushed.
The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte.
ZSTD_EndDirective endOp);
</b><p> Same as ZSTD_compress_generic(),
but using only integral types as arguments.
- This variant might be be helpful for binders from dynamic languages
+ This variant might be helpful for binders from dynamic languages
+ which have troubles handling structures containing memory pointers.
+
+</p></pre><BR>
+
+<pre><b> ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
+</b><p> Refuses allocating internal buffers for frames requiring a window size larger than provided limit.
+ This protects a decoder context from reserving too much memory for itself (potential attack scenario).
+ This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode.
+ By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT)
+ @return : 0, or an error code (which can be tested using ZSTD_isError()).
+
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
+</b><p> Create an internal DDict from dict buffer,
+ to be used to decompress next frames.
+ The dictionary remains valid for all future frames, until explicitly invalidated.
+ @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary,
+ meaning "return to no-dictionary mode".
+ Note 1 : Loading a dictionary involves building tables,
+ which has a non-negligible impact on CPU usage and latency.
+ It's recommended to "load once, use many times", to amortize the cost
+ Note 2 :`dict` content will be copied internally, so `dict` can be released after loading.
+ Use ZSTD_DCtx_loadDictionary_byReference() to reference dictionary content instead.
+ Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to take control of
+ how dictionary content is loaded and interpreted.
+
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
+</b><p> Reference a prepared dictionary, to be used to decompress next frames.
+ The dictionary remains active for decompression of future frames using same DCtx.
+ @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ Note 1 : Currently, only one dictionary can be managed.
+ Referencing a new dictionary effectively "discards" any previous one.
+ Special : adding a NULL DDict means "return to no-dictionary mode".
+ Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx.
+
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx,
+ const void* prefix, size_t prefixSize);
+</b><p> Reference a prefix (single-usage dictionary) for next compression job.
+ This is the reverse operation of ZSTD_CCtx_refPrefix(),
+ and must use the same prefix as the one used during compression.
+ Prefix is **only used once**. Reference is discarded at end of frame.
+ End of frame is reached when ZSTD_DCtx_decompress_generic() returns 0.
+ @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary
+ Note 2 : Prefix buffer is referenced. It **must** outlive decompression job.
+ Prefix buffer must remain unmodified up to the end of frame,
+ reached when ZSTD_DCtx_decompress_generic() returns 0.
+ Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
+ Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode.
+ Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost.
+ A fulldict prefix requires building tables, hence is more costly.
+
+</p></pre><BR>
+
+<pre><b>void ZSTD_DCtx_reset(ZSTD_DCtx* dctx); </b>/* <==== There is a discrepancy with ZSTD_CCtx_reset(): here it necessarily resets everything (context and parameters) */<b>
+</b><p> Return a DCtx to clean state.
+ If a decompression was ongoing, any internal data not yet flushed is cancelled.
+ All parameters are back to default values, including sticky ones.
+ Dictionary (if any) is dropped.
+ Parameters can be modified again after a reset.
+
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx,
+ ZSTD_outBuffer* output,
+ ZSTD_inBuffer* input);
+</b><p> Behave the same as ZSTD_decompressStream.
+ Decompression parameters cannot be changed once decompression is started.
+ @return : an error code, which can be tested using ZSTD_isError()
+ if >0, a hint, nb of expected input bytes for next invocation.
+ `0` means : a frame has just been fully decoded and flushed.
+
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_decompress_generic_simpleArgs (
+ ZSTD_DCtx* dctx,
+ void* dst, size_t dstCapacity, size_t* dstPos,
+ const void* src, size_t srcSize, size_t* srcPos);
+</b><p> Same as ZSTD_decompress_generic(),
+ but using only integral types as arguments.
+ This can be helpful for binders from dynamic languages
which have troubles handling structures containing memory pointers.
</p></pre><BR>
<a name="Chapter15"></a><h2>experimental API (static linking only)</h2><pre>
The following symbols and constants
are not planned to join "stable API" status anytime soon.
- Some will never reach "stable", and remain in the static_only section.
- Some of them might be removed in the future.
+ Some of them will never reach "stable", and are planned to remain in the static_only section indefinitely.
+ Some of them might even be removed in the future.
<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.
+</b><p> srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX.
@return : size of the Frame Header,
or an error code (if srcSize is too small)
</p></pre><BR>
<pre><b>size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
</b><p> Same as ZSTD_CCtx_refPrefix(), but gives finer control over
- and how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?)
+ how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?)
</p></pre><BR>
<pre><b>size_t ZSTD_CCtx_getParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned* value);
When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code.
</p></pre><BR>
+<pre><b>size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
+</b><p> Same as ZSTD_DCtx_loadDictionary(),
+ but references `dict` content instead of copying it into `dctx`.
+ This saves memory if `dict` remains around.,
+ However, it's imperative that `dict` remains accessible (and unmodified) while being used, so it must outlive decompression.
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
+</b><p> Same as ZSTD_DCtx_loadDictionary(),
+ but gives direct control over
+ how to load the dictionary (by copy ? by reference ?)
+ and how to interpret it (automatic ? force raw mode ? full mode only ?).
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
+</b><p> Same as ZSTD_DCtx_refPrefix(), but gives finer control over
+ how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?)
+</p></pre><BR>
+
+<pre><b>size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
+</b><p> Instruct the decoder context about what kind of data to decode next.
+ This instruction is mandatory to decode data without a fully-formed header,
+ such ZSTD_f_zstd1_magicless for example.
+ @return : 0, or an error code (which can be tested using ZSTD_isError()).
+</p></pre><BR>
+
<a name="Chapter20"></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>
unsigned dictID;
unsigned checksumFlag;
} ZSTD_frameHeader;
-</b>/** ZSTD_getFrameHeader() :<b>
- * 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() */
-size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); </b>/**< doesn't consume input */<b>
-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>
-</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>
-<h3>Advanced decompression API</h3><pre></pre><b><pre></b>/* ==================================== */<b>
</pre></b><BR>
-<pre><b>size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
-size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
-size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
-</b><p> Create an internal DDict from dict buffer,
- to be used to decompress next frames.
- @result : 0, or an error code (which can be tested with ZSTD_isError()).
- Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary,
- meaning "return to no-dictionary mode".
- Note 1 : `dict` content will be copied internally.
- Use ZSTD_DCtx_loadDictionary_byReference()
- to reference dictionary content instead.
- In which case, the dictionary buffer must outlive its users.
- Note 2 : Loading a dictionary involves building tables,
- which has a non-negligible impact on CPU usage and latency.
- Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to select
- how dictionary content will be interpreted and loaded.
-
-</p></pre><BR>
-
-<pre><b>size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
-</b><p> Reference a prepared dictionary, to be used to decompress next frames.
- The dictionary remains active for decompression of future frames using same DCtx.
- @result : 0, or an error code (which can be tested with ZSTD_isError()).
- Note 1 : Currently, only one dictionary can be managed.
- Referencing a new dictionary effectively "discards" any previous one.
- Special : adding a NULL DDict means "return to no-dictionary mode".
- Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx.
-
-</p></pre><BR>
-
-<pre><b>size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx,
- const void* prefix, size_t prefixSize);
-size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx,
- const void* prefix, size_t prefixSize,
- ZSTD_dictContentType_e dictContentType);
-</b><p> Reference a prefix (single-usage dictionary) for next compression job.
- This is the reverse operation of ZSTD_CCtx_refPrefix(),
- and must use the same prefix as the one used during compression.
- Prefix is **only used once**. Reference is discarded at end of frame.
- End of frame is reached when ZSTD_DCtx_decompress_generic() returns 0.
- @result : 0, or an error code (which can be tested with ZSTD_isError()).
- Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary
- Note 2 : Prefix buffer is referenced. It **must** outlive decompression job.
- Prefix buffer must remain unmodified up to the end of frame,
- reached when ZSTD_DCtx_decompress_generic() returns 0.
- Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
- Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode.
- Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost.
- A fulldict prefix is more costly though.
-
-</p></pre><BR>
-
-<pre><b>size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
-</b><p> Refuses allocating internal buffers for frames requiring a window size larger than provided limit.
- This is useful to prevent a decoder context from reserving too much memory for itself (potential attack scenario).
- This parameter is only useful in streaming mode, since no internal buffer is allocated in direct mode.
- By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT)
- @return : 0, or an error code (which can be tested using ZSTD_isError()).
-
-</p></pre><BR>
-
-<pre><b>size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
-</b><p> Instruct the decoder context about what kind of data to decode next.
- This instruction is mandatory to decode data without a fully-formed header,
- such ZSTD_f_zstd1_magicless for example.
- @return : 0, or an error code (which can be tested using ZSTD_isError()).
-
-</p></pre><BR>
+<a name="Chapter24"></a><h2>ZSTD_getFrameHeader() :</h2><pre> 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_advanced(ZSTD_frameHeader* zfhPtr,
- const void* src, size_t srcSize, ZSTD_format_e format);
+<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>size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx,
- ZSTD_outBuffer* output,
- ZSTD_inBuffer* input);
-</b><p> Behave the same as ZSTD_decompressStream.
- Decompression parameters cannot be changed once decompression is started.
- @return : an error code, which can be tested using ZSTD_isError()
- if >0, a hint, nb of expected input bytes for next invocation.
- `0` means : a frame has just been fully decoded and flushed.
-
-</p></pre><BR>
-
-<pre><b>size_t ZSTD_decompress_generic_simpleArgs (
- ZSTD_DCtx* dctx,
- void* dst, size_t dstCapacity, size_t* dstPos,
- const void* src, size_t srcSize, size_t* srcPos);
-</b><p> Same as ZSTD_decompress_generic(),
- but using only integral types as arguments.
- Argument list is larger than ZSTD_{in,out}Buffer,
- but can be helpful for binders from dynamic languages
- which have troubles handling structures containing memory pointers.
-
-</p></pre><BR>
-
-<pre><b>void ZSTD_DCtx_reset(ZSTD_DCtx* dctx);
-</b><p> Return a DCtx to clean state.
- If a decompression was ongoing, any internal data not yet flushed is cancelled.
- All parameters are back to default values, including sticky ones.
- Dictionary (if any) is dropped.
- Parameters can be modified again after a reset.
-
-</p></pre><BR>
-
-<a name="Chapter24"></a><h2>Block level API</h2><pre></pre>
+<pre><b>typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
+</b></pre><BR>
+<a name="Chapter25"></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.
+ copyCCtx() and copyDCtx() can be used too
- Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB
+ If input is larger than a block size, it's necessary to split input data into multiple blocks
- + For inputs larger than a single block size, consider using the regular ZSTD_compress() instead.
+ + For inputs larger than a single block, really consider using regular ZSTD_compress() instead.
Frame metadata is not that costly, and quickly becomes negligible as source size grows larger.
- When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero.
- In which case, nothing is produced into `dst`.
+ In which case, nothing is produced into `dst` !
+ User must test for such outcome and deal directly with uncompressed data
+ ZSTD_decompressBlock() doesn't accept uncompressed data as input !!!
+ In case of multiple successive blocks, should some of them be uncompressed,
* @result : 0, or an error code (which can be tested with ZSTD_isError()).
* Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary
* Note 1 : Prefix buffer is referenced. It **must** outlive compression job.
- * Its contain must remain unmodified up to end of compression (ZSTD_e_end).
+ * Its content must remain unmodified during compression.
* Note 2 : If the intention is to diff some large src data blob with some prior version of itself,
* ensure that the window size is large enough to contain the entire source.
* See ZSTD_p_windowLog.
* Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters.
* It's a CPU consuming operation, with non-negligible impact on latency.
- * If there is a need to use same prefix multiple times, consider loadDictionary instead.
+ * If there is a need to use the same prefix multiple times, consider loadDictionary instead.
* Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dm_rawContent).
- * Use ZSTD_CCtx_refPrefix_advanced() to alter dictionary intepretation. */
+ * Use ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation. */
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx,
const void* prefix, size_t prefixSize);
/*! ZSTD_compress_generic() :
* Behave about the same as ZSTD_compressStream. To note :
- * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_setParameter()
- * - Compression parameters cannot be changed once compression is started.
+ * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
+ * - Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode)
* - outpot->pos must be <= dstCapacity, input->pos must be <= srcSize
* - outpot->pos and input->pos will be updated. They are guaranteed to remain below their respective limit.
- * - In single-thread mode (default), function is blocking : it completed its job before returning to caller.
+ * - In single-thread mode (default), function is blocking : it completes its job before returning to caller.
* - In multi-thread mode, function is non-blocking : it just acquires a copy of input, and distribute job to internal worker threads,
* and then immediately returns, just indicating that there is some data remaining to be flushed.
* The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte.
/*! ZSTD_compress_generic_simpleArgs() :
* Same as ZSTD_compress_generic(),
* but using only integral types as arguments.
- * This variant might be be helpful for binders from dynamic languages
+ * This variant might be helpful for binders from dynamic languages
* which have troubles handling structures containing memory pointers.
*/
ZSTDLIB_API size_t ZSTD_compress_generic_simpleArgs (
+/* ============================== */
+/* Advanced decompression API */
+/* ============================== */
+
+/* The following API works the same way as the advanced compression API :
+ * a context is created, parameters are pushed into it one by one,
+ * then the context can be used to decompress data
+ * using ZSTD_decompress_generic(), similar to the streaming API.
+ * Note that sticky parameters only apply to ZSTD_decompress_generic() and ZSTD_decompress_generic_simpleArgs().
+ * They are not valid if a "simple" function is used on the context (like `ZSTD_decompressDCtx()`).
+ */
+
+ /*! ZSTD_DCtx_setMaxWindowSize() :
+ * Refuses allocating internal buffers for frames requiring a window size larger than provided limit.
+ * This protects a decoder context from reserving too much memory for itself (potential attack scenario).
+ * This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode.
+ * By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT)
+ * @return : 0, or an error code (which can be tested using ZSTD_isError()).
+ */
+ ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
+
+/*! ZSTD_DCtx_loadDictionary() :
+ * Create an internal DDict from dict buffer,
+ * to be used to decompress next frames.
+ * The dictionary remains valid for all future frames, until explicitly invalidated.
+ * @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ * Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary,
+ * meaning "return to no-dictionary mode".
+ * Note 1 : Loading a dictionary involves building tables,
+ * which has a non-negligible impact on CPU usage and latency.
+ * It's recommended to "load once, use many times", to amortize the cost
+ * Note 2 :`dict` content will be copied internally, so `dict` can be released after loading.
+ * Use ZSTD_DCtx_loadDictionary_byReference() to reference dictionary content instead.
+ * Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to take control of
+ * how dictionary content is loaded and interpreted.
+ */
+ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
+
+/*! ZSTD_DCtx_refDDict() :
+ * Reference a prepared dictionary, to be used to decompress next frames.
+ * The dictionary remains active for decompression of future frames using same DCtx.
+ * @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ * Note 1 : Currently, only one dictionary can be managed.
+ * Referencing a new dictionary effectively "discards" any previous one.
+ * Special : adding a NULL DDict means "return to no-dictionary mode".
+ * Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx.
+ */
+ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
+
+/*! ZSTD_DCtx_refPrefix() :
+ * Reference a prefix (single-usage dictionary) for next compression job.
+ * This is the reverse operation of ZSTD_CCtx_refPrefix(),
+ * and must use the same prefix as the one used during compression.
+ * Prefix is **only used once**. Reference is discarded at end of frame.
+ * End of frame is reached when ZSTD_DCtx_decompress_generic() returns 0.
+ * @result : 0, or an error code (which can be tested with ZSTD_isError()).
+ * Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary
+ * Note 2 : Prefix buffer is referenced. It **must** outlive decompression job.
+ * Prefix buffer must remain unmodified up to the end of frame,
+ * reached when ZSTD_DCtx_decompress_generic() returns 0.
+ * Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
+ * Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode.
+ * Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost.
+ * A fulldict prefix requires building tables, hence is more costly.
+ */
+ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx,
+ const void* prefix, size_t prefixSize);
+
+/*! ZSTD_DCtx_reset() :
+ * Return a DCtx to clean state.
+ * If a decompression was ongoing, any internal data not yet flushed is cancelled.
+ * All parameters are back to default values, including sticky ones.
+ * Dictionary (if any) is dropped.
+ * Parameters can be modified again after a reset.
+ */
+ZSTDLIB_API void ZSTD_DCtx_reset(ZSTD_DCtx* dctx); /* <==== There is a discrepancy with ZSTD_CCtx_reset(): here it necessarily resets everything (context and parameters) */
+
+
+/*! ZSTD_decompress_generic() :
+ * Behave the same as ZSTD_decompressStream.
+ * Decompression parameters cannot be changed once decompression is started.
+ * @return : an error code, which can be tested using ZSTD_isError()
+ * if >0, a hint, nb of expected input bytes for next invocation.
+ * `0` means : a frame has just been fully decoded and flushed.
+ */
+ZSTDLIB_API size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx,
+ ZSTD_outBuffer* output,
+ ZSTD_inBuffer* input);
+
+
+/*! ZSTD_decompress_generic_simpleArgs() :
+ * Same as ZSTD_decompress_generic(),
+ * but using only integral types as arguments.
+ * This can be helpful for binders from dynamic languages
+ * which have troubles handling structures containing memory pointers.
+ */
+ZSTDLIB_API size_t ZSTD_decompress_generic_simpleArgs (
+ ZSTD_DCtx* dctx,
+ void* dst, size_t dstCapacity, size_t* dstPos,
+ const void* src, size_t srcSize, size_t* srcPos);
+
+
+
+
/****************************************************************************************
****************************************************************************************
* The following symbols and constants
* are not planned to join "stable API" status anytime soon.
- * Some will never reach "stable", and remain in the static_only section.
- * Some of them might be removed in the future.
+ * Some of them will never reach "stable", and are planned to remain in the static_only section indefinitely.
+ * Some of them might even be removed in the future.
* ***************************************************************************************/
#define ZSTD_HASHLOG3_MAX 17
-#define ZSTD_FRAMEHEADERSIZE_PREFIX 5 /* minimum input size to know frame header size */
+#define ZSTD_FRAMEHEADERSIZE_PREFIX 5 /* minimum input size required to query frame header size */
#define ZSTD_FRAMEHEADERSIZE_MIN 6
-#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */
+#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* can be useful for static allocation */
#define ZSTD_SKIPPABLEHEADERSIZE 8
ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);
/*! ZSTD_frameHeaderSize() :
- * srcSize must be >= ZSTD_frameHeaderSize_prefix.
+ * 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_frameHeaderSize(const void* src, size_t srcSize);
/*! ZSTD_CCtx_refPrefix_advanced() :
* Same as ZSTD_CCtx_refPrefix(), but gives finer control over
- * and how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */
+ * how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
/*! ZSTD_CCtx_getParameter() :
ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params);
-/*--- Advanced decompression functions ---*/
+/***************************************
+* Advanced decompression functions
+***************************************/
/*! ZSTD_isFrame() :
* 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. */
ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize);
+/*! ZSTD_DCtx_loadDictionary_byReference() :
+ * Same as ZSTD_DCtx_loadDictionary(),
+ * but references `dict` content instead of copying it into `dctx`.
+ * This saves memory if `dict` remains around.,
+ * However, it's imperative that `dict` remains accessible (and unmodified) while being used, so it must outlive decompression. */
+ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
+
+/*! ZSTD_DCtx_loadDictionary_advanced() :
+ * Same as ZSTD_DCtx_loadDictionary(),
+ * but gives direct control over
+ * how to load the dictionary (by copy ? by reference ?)
+ * and how to interpret it (automatic ? force raw mode ? full mode only ?). */
+ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
+
+/*! ZSTD_DCtx_refPrefix_advanced() :
+ * Same as ZSTD_DCtx_refPrefix(), but gives finer control over
+ * how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */
+ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
+
+/*! ZSTD_DCtx_setFormat() :
+ * Instruct the decoder context about what kind of data to decode next.
+ * This instruction is mandatory to decode data without a fully-formed header,
+ * such ZSTD_f_zstd1_magicless for example.
+ * @return : 0, or an error code (which can be tested using ZSTD_isError()). */
+ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
+
+
/********************************************************************
* Advanced streaming functions
unsigned dictID;
unsigned checksumFlag;
} ZSTD_frameHeader;
+
/** 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,
* or an error code, which can be tested using ZSTD_isError() */
ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */
+/*! 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, const void* src, size_t srcSize, ZSTD_format_e format);
ZSTDLIB_API size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); /**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */
ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
-
-/* ==================================== */
-/*=== Advanced decompression API ===*/
-/* ==================================== */
-
-/* The following API works the same way as the advanced compression API :
- * a context is created, parameters are pushed into it one by one,
- * then the context can be used to decompress data using an interface similar to the straming API.
- */
-
-/*! ZSTD_DCtx_loadDictionary() :
- * Create an internal DDict from dict buffer,
- * to be used to decompress next frames.
- * @result : 0, or an error code (which can be tested with ZSTD_isError()).
- * Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary,
- * meaning "return to no-dictionary mode".
- * Note 1 : `dict` content will be copied internally.
- * Use ZSTD_DCtx_loadDictionary_byReference()
- * to reference dictionary content instead.
- * In which case, the dictionary buffer must outlive its users.
- * Note 2 : Loading a dictionary involves building tables,
- * which has a non-negligible impact on CPU usage and latency.
- * Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to select
- * how dictionary content will be interpreted and loaded.
- */
-ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
-ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
-ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
-
-
-/*! ZSTD_DCtx_refDDict() :
- * Reference a prepared dictionary, to be used to decompress next frames.
- * The dictionary remains active for decompression of future frames using same DCtx.
- * @result : 0, or an error code (which can be tested with ZSTD_isError()).
- * Note 1 : Currently, only one dictionary can be managed.
- * Referencing a new dictionary effectively "discards" any previous one.
- * Special : adding a NULL DDict means "return to no-dictionary mode".
- * Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx.
- */
-ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
-
-
-/*! ZSTD_DCtx_refPrefix() :
- * Reference a prefix (single-usage dictionary) for next compression job.
- * This is the reverse operation of ZSTD_CCtx_refPrefix(),
- * and must use the same prefix as the one used during compression.
- * Prefix is **only used once**. Reference is discarded at end of frame.
- * End of frame is reached when ZSTD_DCtx_decompress_generic() returns 0.
- * @result : 0, or an error code (which can be tested with ZSTD_isError()).
- * Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary
- * Note 2 : Prefix buffer is referenced. It **must** outlive decompression job.
- * Prefix buffer must remain unmodified up to the end of frame,
- * reached when ZSTD_DCtx_decompress_generic() returns 0.
- * Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
- * Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode.
- * Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost.
- * A fulldict prefix is more costly though.
- */
-ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx,
- const void* prefix, size_t prefixSize);
-ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx,
- const void* prefix, size_t prefixSize,
- ZSTD_dictContentType_e dictContentType);
-
-
-/*! ZSTD_DCtx_setMaxWindowSize() :
- * Refuses allocating internal buffers for frames requiring a window size larger than provided limit.
- * This is useful to prevent a decoder context from reserving too much memory for itself (potential attack scenario).
- * This parameter is only useful in streaming mode, since no internal buffer is allocated in direct mode.
- * By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT)
- * @return : 0, or an error code (which can be tested using ZSTD_isError()).
- */
-ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
-
-
-/*! ZSTD_DCtx_setFormat() :
- * Instruct the decoder context about what kind of data to decode next.
- * This instruction is mandatory to decode data without a fully-formed header,
- * such ZSTD_f_zstd1_magicless for example.
- * @return : 0, or an error code (which can be tested using ZSTD_isError()).
- */
-ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
-
-
-/*! 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,
- const void* src, size_t srcSize, ZSTD_format_e format);
-
-
-/*! ZSTD_decompress_generic() :
- * Behave the same as ZSTD_decompressStream.
- * Decompression parameters cannot be changed once decompression is started.
- * @return : an error code, which can be tested using ZSTD_isError()
- * if >0, a hint, nb of expected input bytes for next invocation.
- * `0` means : a frame has just been fully decoded and flushed.
- */
-ZSTDLIB_API size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx,
- ZSTD_outBuffer* output,
- ZSTD_inBuffer* input);
-
-
-/*! ZSTD_decompress_generic_simpleArgs() :
- * Same as ZSTD_decompress_generic(),
- * but using only integral types as arguments.
- * Argument list is larger than ZSTD_{in,out}Buffer,
- * but can be helpful for binders from dynamic languages
- * which have troubles handling structures containing memory pointers.
- */
-ZSTDLIB_API size_t ZSTD_decompress_generic_simpleArgs (
- ZSTD_DCtx* dctx,
- void* dst, size_t dstCapacity, size_t* dstPos,
- const void* src, size_t srcSize, size_t* srcPos);
-
-
-/*! ZSTD_DCtx_reset() :
- * Return a DCtx to clean state.
- * If a decompression was ongoing, any internal data not yet flushed is cancelled.
- * All parameters are back to default values, including sticky ones.
- * Dictionary (if any) is dropped.
- * Parameters can be modified again after a reset.
- */
-ZSTDLIB_API void ZSTD_DCtx_reset(ZSTD_DCtx* dctx);
-
-
-
/* ============================ */
/** Block level API */
/* ============================ */
+ copyCCtx() and copyDCtx() can be used too
- Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB
+ If input is larger than a block size, it's necessary to split input data into multiple blocks
- + For inputs larger than a single block size, consider using the regular ZSTD_compress() instead.
+ + For inputs larger than a single block, really consider using regular ZSTD_compress() instead.
Frame metadata is not that costly, and quickly becomes negligible as source size grows larger.
- When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero.
- In which case, nothing is produced into `dst`.
+ In which case, nothing is produced into `dst` !
+ User must test for such outcome and deal directly with uncompressed data
+ ZSTD_decompressBlock() doesn't accept uncompressed data as input !!!
+ In case of multiple successive blocks, should some of them be uncompressed,
projects / thirdparty / zstd.git / commitdiff
