comparison contrib/python-zstandard/zstd/zstd.h @ 40121:73fef626dae3

zstandard: vendor python-zstandard 0.10.1

This was just released.

The upstream source distribution from PyPI was extracted. Unwanted
files were removed.

The clang-format ignore list was updated to reflect the new source
of files.

setup.py was updated to pass a new argument to python-zstandard's
function for returning an Extension instance. Upstream had to change
to use relative paths because Python 3.7's packaging doesn't
seem to like absolute paths when defining sources, includes, etc.
The default relative path calculation is relative to setup_zstd.py
which is different from the directory of Mercurial's setup.py.

The project contains a vendored copy of zstandard 1.3.6. The old
version was 1.3.4.

The API should be backwards compatible and nothing in core should
need adjusted. However, there is a new "chunker" API that we
may find useful in places where we want to emit compressed chunks
of a fixed size.

There are a pair of bug fixes in 0.10.0 with regards to
compressobj() and decompressobj() when block flushing is used. I
actually found these bugs when introducing these APIs in Mercurial!
But existing Mercurial code is not affected because we don't
perform block flushing.

# no-check-commit because 3rd party code has different style guidelines

Differential Revision: https://phab.mercurial-scm.org/D4911

40120:89742f1fa6cb

#else
#  define ZSTDLIB_API ZSTDLIB_VISIBILITY
#endif


/*******************************************************************************************************
  Introduction

  zstd, short for Zstandard, is a fast lossless compression algorithm,
  targeting real-time compression scenarios at zlib-level and better compression ratios.
  The zstd compression library provides in-memory compression and decompression functions.
  The library supports compression levels from 1 up to ZSTD_maxCLevel() which is currently 22.
  Levels >= 20, labeled `--ultra`, should be used with caution, as they require more memory.
  Compression can be done in:
    - a single step (described as Simple API)
    - a single step, reusing a context (described as Explicit context)
    - unbounded multiple steps (described as Streaming compression)
  The compression ratio achievable on small data can be highly improved using a dictionary in:
    - a single step (described as Simple dictionary API)
    - a single step, reusing a dictionary (described as Bulk-processing dictionary API)

  Advanced experimental functions can be accessed using #define ZSTD_STATIC_LINKING_ONLY before including zstd.h.
  Advanced experimental APIs shall never be used with a dynamic library.
  They are not "stable", their definition may change in the future. Only static linking is allowed.
*********************************************************************************************************/

/*------   Version   ------*/
#define ZSTD_VERSION_MAJOR    1
#define ZSTD_VERSION_MINOR    3
#define ZSTD_VERSION_RELEASE  4

#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_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE
#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 */


/***************************************
*  Simple API
***************************************/
/*! ZSTD_compress() :

/*! ZSTD_getFrameContentSize() : added in v1.3.0
 *  `src` should point to the start of a ZSTD encoded frame.
 *  `srcSize` must be at least as large as the frame header.
 *            hint : any size >= `ZSTD_frameHeaderSize_max` is large enough.
 *  @return : - decompressed size of the frame in `src`, if known
 *            - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined
 *            - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small)
 *   note 1 : a 0 return value means the frame is valid but "empty".
 *   note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode.
 *            When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size.
 *            In which case, it's necessary to use streaming mode to decompress data.
 *            Optionally, application can rely on some implicit limit,
 *            as ZSTD_decompress() only needs an upper bound of decompressed size.
 *            (For example, data could be necessarily cut into blocks <= 16 KB).
 *   note 3 : decompressed size is always present when compression is done with ZSTD_compress()
 *   note 4 : decompressed size can be very large (64-bits value),
 *            potentially larger than what local system can handle as a single memory segment.
 *            In which case, it's necessary to use streaming mode to decompress data.
 *   note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified.
 *            Always ensure return value fits within application's authorized limits.

/*! ZSTD_getDecompressedSize() :
 *  NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize().
 *  Both functions work the same way, but ZSTD_getDecompressedSize() blends
 *  "empty", "unknown" and "error" results to the same return value (0),
 *  while ZSTD_getFrameContentSize() gives them separate return values.
 * `src` is the start of a zstd compressed frame.
 * @return : content size to be decompressed, as a 64-bits value _if known and not empty_, 0 otherwise. */
ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);


/*======  Helper functions  ======*/
#define ZSTD_COMPRESSBOUND(srcSize)   ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0))  /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB */

/*! ZSTD_createCDict() :
 *  When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
 *  ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
 *  ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
 *  `dictBuffer` can be released after ZSTD_CDict creation, since its content is copied within CDict */
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
                                         int compressionLevel);

/*! ZSTD_freeCDict() :
 *  Function frees memory allocated by ZSTD_createCDict(). */

/*! ZSTD_compress_usingCDict() :
 *  Compression using a digested Dictionary.
 *  Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times.
 *  Note that compression level is decided during dictionary creation.
 *  Frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no) */
ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
                                            void* dst, size_t dstCapacity,
                                      const void* src, size_t srcSize,
                                      const ZSTD_CDict* cdict);

*  ZSTD_CStream objects can be reused multiple times on consecutive compression operations.
*  It is recommended to re-use ZSTD_CStream in situations where many streaming operations will be achieved consecutively,
*  since it will play nicer with system's memory, by re-using already allocated memory.
*  Use one separate ZSTD_CStream per thread for parallel execution.
*
*  Start a new compression by initializing ZSTD_CStream.
*  Use ZSTD_initCStream() to start a new compression operation.
*  Use ZSTD_initCStream_usingDict() or ZSTD_initCStream_usingCDict() for a compression which requires a dictionary (experimental section)
*
*  Use ZSTD_compressStream() repetitively to consume input stream.
*  The function will automatically update both `pos` fields.
*  Note that it may not consume the entire input, in which case `pos < size`,
*  and it's up to the caller to present again remaining data.
*  @return : a size hint, preferred nb of bytes to use as input for next function call
*            or an error code, which can be tested using ZSTD_isError().
*            Note 1 : it's just a hint, to help latency a little, any other value will work fine.
*            Note 2 : size hint is guaranteed to be <= ZSTD_CStreamInSize()
*
*  At any moment, it's possible to flush whatever data remains within internal buffer, using ZSTD_flushStream().
*  `output->pos` will be updated.
*  Note that some content might still be left within internal buffer if `output->size` is too small.
*  @return : nb of bytes still present within internal buffer (0 if it's empty)
*            or an error code, which can be tested using ZSTD_isError().
*
*  ZSTD_endStream() instructs to finish a frame.
*  It will perform a flush and write frame epilogue.
*  The epilogue is required for decoders to consider a frame completed.
*  ZSTD_endStream() may not be able to flush full data if `output->size` is too small.
*  In which case, call again ZSTD_endStream() to complete the flush.
*  @return : 0 if frame fully completed and fully flushed,
             or >0 if some data is still present within internal buffer
                  (value is minimum size estimation for remaining data to flush, but it could be more)
*            or an error code, which can be tested using ZSTD_isError().
*
* *******************************************************************/

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 */
/*===== ZSTD_CStream management functions =====*/
ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void);
ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs);

/*===== Streaming compression functions =====*/

#endif  /* ZSTD_H_235446 */



/****************************************************************************************
 * START OF 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

/* --- Constants ---*/
#define ZSTD_MAGICNUMBER            0xFD2FB528   /* >= v0.8.0 */
#define ZSTD_MAGIC_SKIPPABLE_START  0x184D2A50U
#define ZSTD_MAGIC_DICTIONARY       0xEC30A437   /* >= v0.7.0 */

#define ZSTD_WINDOWLOG_MAX_32   30
#define ZSTD_WINDOWLOG_MAX_64   31
#define ZSTD_WINDOWLOG_MAX    ((unsigned)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64))
#define ZSTD_WINDOWLOG_MIN      10

#define ZSTD_HASHLOG3_MAX       17
#define ZSTD_SEARCHLOG_MAX     (ZSTD_WINDOWLOG_MAX-1)
#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_TARGETLENGTH_MIN    1   /* only used by btopt, btultra and btfast */
#define ZSTD_LDM_MINMATCH_MIN    4
#define ZSTD_LDM_MINMATCH_MAX 4096
#define ZSTD_LDM_BUCKETSIZELOG_MAX 8

#define ZSTD_FRAMEHEADERSIZE_PREFIX 5   /* minimum input size to know frame header size */
#define ZSTD_FRAMEHEADERSIZE_MIN    6
#define ZSTD_FRAMEHEADERSIZE_MAX   18   /* for static allocation */

static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN;
static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
static const size_t ZSTD_skippableHeaderSize = 8;  /* magic number + skippable frame length */


/*--- 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 */

typedef struct {
    unsigned windowLog;      /**< largest match distance : larger == more compression, more memory needed during decompression */

 *            read each contained frame header.  This is fast as most of the data is skipped,
 *            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() :
*   `src` should point to the start of a ZSTD frame
*   `srcSize` must be >= ZSTD_frameHeaderSize_prefix.
*   @return : size of the Frame Header */
ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);


/***************************************
*  Memory management

ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict);  /**< note : cdict will just be referenced, and must outlive compression session */
ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize);  /**< 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. */

/*! ZSTD_resetCStream() :
 *  start a new compression job, using same parameters from previous job.
 *  This is typically useful to skip dictionary loading stage, since it will re-use it in-place..
 *  Note that zcs must be init at least once before using ZSTD_resetCStream().
 *  If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN.
 *  If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end.
 *  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()) */
ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);


typedef struct {
    unsigned long long ingested;
    unsigned long long consumed;
    unsigned long long produced;
} ZSTD_frameProgression;

/* ZSTD_getFrameProgression():
 * tells how much data has been ingested (read from input)
 * consumed (input actually compressed) and produced (output) for current frame.
 * Therefore, (ingested - consumed) is amount of input data buffered internally, not yet compressed.
 * Can report progression inside worker threads (multi-threading and non-blocking mode).
 */
ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx);



/*=====   Advanced Streaming decompression functions  =====*/
typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e;

    ZSTD_frameType_e frameType;          /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */
    unsigned headerSize;
    unsigned dictID;
    unsigned checksumFlag;
} ZSTD_frameHeader;
ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize);   /**< doesn't consume input */
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);
ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);

/* ============================================ */
/**       New advanced API (experimental)       */
/* ============================================ */

/* notes on API design :
 *   In this proposal, parameters are pushed one by one into an existing context,
 *   and then applied on all subsequent compression jobs.
 *   When no parameter is ever provided, CCtx is created with compression level ZSTD_CLEVEL_DEFAULT.
 *
 *   This API is intended to replace all others advanced / experimental API entry points.
 *   But it stands a reasonable chance to become "stable", after a reasonable testing period.
 */

/* note on naming convention :
 *   Initially, the API favored names like ZSTD_setCCtxParameter() .
 *   In this proposal, convention is changed towards ZSTD_CCtx_setParameter() .
 *   The main driver is that it identifies more clearly the target object type.
 *   It feels clearer when considering multiple targets :
 *   ZSTD_CDict_setParameter() (rather than ZSTD_setCDictParameter())
 *   ZSTD_CCtxParams_setParameter()  (rather than ZSTD_setCCtxParamsParameter() )
 *   etc...
 */

/* note on enum design :
 * All enum will be pinned to explicit values before reaching "stable API" status */

                              * Cast selected format as unsigned for ZSTD_CCtx_setParameter() compatibility. */

    /* compression parameters */
    ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table
                              * Default level is ZSTD_CLEVEL_DEFAULT==3.
                              * Special: value 0 means "do not change cLevel".
                              * Note 1 : it's possible to pass a negative compression level by casting it to unsigned type.
                              * Note 2 : setting a level sets all default values of other compression parameters.
                              * Note 3 : setting compressionLevel automatically updates ZSTD_p_compressLiterals. */
    ZSTD_p_windowLog,        /* Maximum allowed back-reference distance, expressed as power of 2.
                              * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
                              * Special: value 0 means "use default windowLog".
                              * Note: Using a window size greater than ZSTD_MAXWINDOWSIZE_DEFAULT (default: 2^27)
                              *       requires explicitly allowing such window size during decompression stage. */
    ZSTD_p_hashLog,          /* Size of the probe table, as a power of 2.
                              * Resulting table size is (1 << (hashLog+2)).
                              * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX.
                              * Larger tables improve compression ratio of strategies <= dFast,
                              * and improve speed of strategies > dFast.
                              * Special: value 0 means "use default hashLog". */
    ZSTD_p_chainLog,         /* Size of the full-search table, as a power of 2.
                              * Resulting table size is (1 << (chainLog+2)).
                              * Larger tables result in better and slower compression.
                              * This parameter is useless when using "fast" strategy.
                              * Special: value 0 means "use default chainLog". */
    ZSTD_p_searchLog,        /* 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.
                              * Special: value 0 means "use default searchLog". */

    /* =================================================================== */
    /* experimental parameters - no stability guaranteed                   */
    /* =================================================================== */

    ZSTD_p_compressLiterals=1000, /* control huffman compression of literals (enabled) by default.
                              * disabling it improves speed and decreases compression ratio by a large amount.
                              * note : this setting is automatically updated when changing compression level.
                              *        positive compression levels set ZSTD_p_compressLiterals to 1.
                              *        negative compression levels set ZSTD_p_compressLiterals to 0. */

    ZSTD_p_forceMaxWindow=1100, /* Force back-reference distances to remain < windowSize,
                              * even when referencing into Dictionary content (default:0) */

} ZSTD_cParameter;


/*! ZSTD_CCtx_setParameter() :
 *  Set one compression parameter, selected by enum ZSTD_cParameter.
 *  Setting a parameter is generally only possible during frame initialization (before starting compression),
 *  except for a few exceptions which can be updated during compression: compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy.
 *  Note : when `value` is an enum, cast it to unsigned for proper type checking.
 *  @result : informational value (typically, value being set clamped correctly),
 *            or an error code (which can be tested with ZSTD_isError()). */
ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value);

/*! ZSTD_CCtx_setPledgedSrcSize() :
 *  Total input data size to be compressed as a single frame.
 *  This value will be controlled at the end, and result in error if not respected.
 * @result : 0, or an error code (which can be tested with ZSTD_isError()).

 *  Note 2 : CDict is just referenced, its lifetime must outlive CCtx. */
ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);

/*! ZSTD_CCtx_refPrefix() :
 *  Reference a prefix (single-usage dictionary) for next compression job.
 *  Decompression need same prefix to properly regenerate data.
 *  Prefix is **only used once**. Tables are discarded at end of compression job.
 *  Subsequent compression jobs will be done without prefix (if none is explicitly referenced).
 *  If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_CDict instead.
 * @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.
 *  Note 2 : Referencing a prefix involves building tables, which are dependent on compression parameters.
 *           It's a CPU consuming operation, with non-negligible impact on latency.
 *  Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
 *           Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode. */
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize);
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);

/*! ZSTD_CCtx_reset() :
 *  Return a CCtx to clean state.
 *  Useful after an error, or to interrupt an ongoing compression job and start a new one.
 *  Any internal data not yet flushed is cancelled.
 *  Dictionary (if any) is dropped.
 *  All parameters are back to default values.
 *  It's possible to modify compression parameters after a reset.
 */
ZSTDLIB_API void ZSTD_CCtx_reset(ZSTD_CCtx* cctx);



typedef enum {
    ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal conditions */

 *  Note : when `value` is an enum, cast it to unsigned for proper type checking.
 * @result : 0, or an error code (which can be tested with ZSTD_isError()).
 */
ZSTDLIB_API size_t ZSTD_CCtxParam_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned value);

/*! ZSTD_CCtx_setParametersUsingCCtxParams() :
 *  Apply a set of ZSTD_CCtx_params to the compression context.
 *  This can be done even after compression is started,
 *    if nbWorkers==0, this will have no impact until a new compression is started.
 *    if nbWorkers>=1, new parameters will be picked up at next job,

 */
ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams(
        ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params);


/*===   Advanced parameters for decompression API  ===*/

/* The following parameters must be set after creating a ZSTD_DCtx* (or ZSTD_DStream*) object,
 * but before starting decompression of a frame.
 */

/*! ZSTD_DCtx_loadDictionary() :
 *  Create an internal DDict from dict buffer,
 *  to be used to decompress next frames.

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.
 *  Prefix is **only used once**. It must be explicitly referenced before each frame.
 *  If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_DDict instead.
 * @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 compression job.
 *  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.
 */
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 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_decompress_generic() :
 *  Behave the same as ZSTD_decompressStream.
 *  Decompression parameters cannot be changed once decompression is started.

      + In case of multiple successive blocks, should some of them be uncompressed,
        decoder must be informed of their existence in order to follow proper history.
        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);
ZSTDLIB_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZSTD_insertBlock    (ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize);  /**< insert uncompressed block into `dctx` history. Useful for multi-blocks decompression. */

40121:73fef626dae3

#else
#  define ZSTDLIB_API ZSTDLIB_VISIBILITY
#endif


/*******************************************************************************
  Introduction

  zstd, short for Zstandard, is a fast lossless compression algorithm, targeting
  real-time compression scenarios at zlib-level and better compression ratios.
  The zstd compression library provides in-memory compression and decompression
  functions.

  The library supports regular compression levels from 1 up to ZSTD_maxCLevel(),
  which is currently 22. Levels >= 20, labeled `--ultra`, should be used with
  caution, as they require more memory. The library also offers negative
  compression levels, which extend the range of speed vs. ratio preferences.
  The lower the level, the faster the speed (at the cost of compression).

  Compression can be done in:
    - a single step (described as Simple API)
    - a single step, reusing a context (described as Explicit context)
    - unbounded multiple steps (described as Streaming compression)

  The compression ratio achievable on small data can be highly improved using
  a dictionary. Dictionary compression can be performed in:
    - a single step (described as Simple dictionary API)
    - a single step, reusing a dictionary (described as Bulk-processing
      dictionary API)

  Advanced experimental functions can be accessed using
  `#define ZSTD_STATIC_LINKING_ONLY` before including zstd.h.

  Advanced experimental APIs should never be used with a dynamically-linked
  library. They are not "stable"; their definitions or signatures may change in
  the future. Only static linking is allowed.
*******************************************************************************/

/*------   Version   ------*/
#define ZSTD_VERSION_MAJOR    1
#define ZSTD_VERSION_MINOR    3
#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_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE
#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);   /* v1.3.0+ */

/***************************************
*  Default constant
***************************************/
#ifndef ZSTD_CLEVEL_DEFAULT
#  define ZSTD_CLEVEL_DEFAULT 3
#endif

/***************************************
*  Simple API
***************************************/
/*! ZSTD_compress() :

/*! ZSTD_getFrameContentSize() : added in v1.3.0
 *  `src` should point to the start of a ZSTD encoded frame.
 *  `srcSize` must be at least as large as the frame header.
 *            hint : any size >= `ZSTD_frameHeaderSize_max` is large enough.
 *  @return : - decompressed size of `src` frame content, if known
 *            - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined
 *            - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small)
 *   note 1 : a 0 return value means the frame is valid but "empty".
 *   note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode.
 *            When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size.
 *            In which case, it's necessary to use streaming mode to decompress data.
 *            Optionally, application can rely on some implicit limit,
 *            as ZSTD_decompress() only needs an upper bound of decompressed size.
 *            (For example, data could be necessarily cut into blocks <= 16 KB).
 *   note 3 : decompressed size is always present when compression is completed using single-pass functions,
 *            such as ZSTD_compress(), ZSTD_compressCCtx() ZSTD_compress_usingDict() or ZSTD_compress_usingCDict().
 *   note 4 : decompressed size can be very large (64-bits value),
 *            potentially larger than what local system can handle as a single memory segment.
 *            In which case, it's necessary to use streaming mode to decompress data.
 *   note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified.
 *            Always ensure return value fits within application's authorized limits.

/*! ZSTD_getDecompressedSize() :
 *  NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize().
 *  Both functions work the same way, but ZSTD_getDecompressedSize() blends
 *  "empty", "unknown" and "error" results to the same return value (0),
 *  while ZSTD_getFrameContentSize() gives them separate return values.
 * @return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise. */
ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);


/*======  Helper functions  ======*/
#define ZSTD_COMPRESSBOUND(srcSize)   ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0))  /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB */

/*! ZSTD_createCDict() :
 *  When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
 *  ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
 *  ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
 *  `dictBuffer` can be released after ZSTD_CDict creation, since its content is copied within CDict
 *  Note : A ZSTD_CDict can be created with an empty dictionary, but it is inefficient for small data. */
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
                                         int compressionLevel);

/*! ZSTD_freeCDict() :
 *  Function frees memory allocated by ZSTD_createCDict(). */

/*! ZSTD_compress_usingCDict() :
 *  Compression using a digested Dictionary.
 *  Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times.
 *  Note that compression level is decided during dictionary creation.
 *  Frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no)
 *  Note : ZSTD_compress_usingCDict() can be used with a ZSTD_CDict created from an empty dictionary.
 *         But it is inefficient for small data, and it is recommended to use ZSTD_compressCCtx(). */
ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
                                            void* dst, size_t dstCapacity,
                                      const void* src, size_t srcSize,
                                      const ZSTD_CDict* cdict);

*  ZSTD_CStream objects can be reused multiple times on consecutive compression operations.
*  It is recommended to re-use ZSTD_CStream in situations where many streaming operations will be achieved consecutively,
*  since it will play nicer with system's memory, by re-using already allocated memory.
*  Use one separate ZSTD_CStream per thread for parallel execution.
*
*  Start a new compression by initializing ZSTD_CStream context.
*  Use ZSTD_initCStream() to start a new compression operation.
*  Use variants ZSTD_initCStream_usingDict() or ZSTD_initCStream_usingCDict() for streaming with dictionary (experimental section)
*
*  Use ZSTD_compressStream() as many times as necessary to consume input stream.
*  The function will automatically update both `pos` fields within `input` and `output`.
*  Note that the function may not consume the entire input,
*  for example, because the output buffer is already full,
*  in which case `input.pos < input.size`.
*  The caller must check if input has been entirely consumed.
*  If not, the caller must make some room to receive more compressed data,
*  typically by emptying output buffer, or allocating a new output buffer,
*  and then present again remaining input data.
*  @return : a size hint, preferred nb of bytes to use as input for next function call
*            or an error code, which can be tested using ZSTD_isError().
*            Note 1 : it's just a hint, to help latency a little, any other value will work fine.
*            Note 2 : size hint is guaranteed to be <= ZSTD_CStreamInSize()
*
*  At any moment, it's possible to flush whatever data might remain stuck within internal buffer,
*  using ZSTD_flushStream(). `output->pos` will be updated.
*  Note that, if `output->size` is too small, a single invocation of ZSTD_flushStream() might not be enough (return code > 0).
*  In which case, make some room to receive more compressed data, and call again ZSTD_flushStream().
*  @return : 0 if internal buffers are entirely flushed,
*            >0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
*            or an error code, which can be tested using ZSTD_isError().
*
*  ZSTD_endStream() instructs to finish a frame.
*  It will perform a flush and write frame epilogue.
*  The epilogue is required for decoders to consider a frame completed.
*  flush() operation is the same, and follows same rules as ZSTD_flushStream().
*  @return : 0 if frame fully completed and fully flushed,
*            >0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
*            or an error code, which can be tested using ZSTD_isError().
*
* *******************************************************************/

typedef ZSTD_CCtx ZSTD_CStream;  /**< CCtx and CStream are now effectively same object (>= v1.3.0) */
                                 /* 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);

/*===== Streaming compression functions =====*/

#endif  /* ZSTD_H_235446 */




#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
#define ZSTD_H_ZSTD_STATIC_LINKING_ONLY

/****************************************************************************************
 *   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.
 * ***************************************************************************************/

ZSTDLIB_API int ZSTD_minCLevel(void);  /*!< minimum negative compression level allowed */

/* ---  Constants  ---*/
#define ZSTD_MAGICNUMBER            0xFD2FB528   /* v0.8+ */
#define ZSTD_MAGIC_DICTIONARY       0xEC30A437   /* v0.7+ */
#define ZSTD_MAGIC_SKIPPABLE_START  0x184D2A50U

#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_WINDOWLOG_MAX    ((unsigned)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64))
#define ZSTD_WINDOWLOG_MIN      10

#define ZSTD_HASHLOG3_MAX       17
#define ZSTD_SEARCHLOG_MAX     (ZSTD_WINDOWLOG_MAX-1)
#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_TARGETLENGTH_MAX  ZSTD_BLOCKSIZE_MAX
#define ZSTD_TARGETLENGTH_MIN    0   /* note : comparing this constant to an unsigned results in a tautological test */
#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 */
#define ZSTD_FRAMEHEADERSIZE_MIN    6
#define ZSTD_FRAMEHEADERSIZE_MAX   18   /* for static allocation */

static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN;
static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
static const size_t ZSTD_skippableHeaderSize = 8;  /* magic number + skippable frame length */



/* ---  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 */

typedef struct {
    unsigned windowLog;      /**< largest match distance : larger == more compression, more memory needed during decompression */

 *            read each contained frame header.  This is fast as most of the data is skipped,
 *            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() :
 *  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);


/***************************************
*  Memory management

ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict);  /**< note : cdict will just be referenced, and must outlive compression session */
ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize);  /**< 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. */

/*! ZSTD_resetCStream() :
 *  start a new compression job, using same parameters from previous job.
 *  This is typically useful to skip dictionary loading stage, since it will re-use it in-place.
 *  Note that zcs must be init at least once before using ZSTD_resetCStream().
 *  If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN.
 *  If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end.
 *  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())
 */
ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);


typedef struct {
    unsigned long long ingested;   /* nb input bytes read and buffered */
    unsigned long long consumed;   /* nb input bytes actually compressed */
    unsigned long long produced;   /* nb of compressed bytes generated and buffered */
    unsigned long long flushed;    /* nb of compressed bytes flushed : not provided; can be tracked from caller side */
    unsigned currentJobID;         /* MT only : latest started job nb */
    unsigned nbActiveWorkers;      /* MT only : nb of workers actively compressing at probe time */
} ZSTD_frameProgression;

/* ZSTD_getFrameProgression() :
 * tells how much data has been ingested (read from input)
 * consumed (input actually compressed) and produced (output) for current frame.
 * Note : (ingested - consumed) is amount of input data buffered internally, not yet compressed.
 * Aggregates progression inside active worker threads.
 */
ZSTDLIB_API ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx);

/*! ZSTD_toFlushNow() :
 *  Tell how many bytes are ready to be flushed immediately.
 *  Useful for multithreading scenarios (nbWorkers >= 1).
 *  Probe the oldest active job, defined as oldest job not yet entirely flushed,
 *  and check its output buffer.
 * @return : amount of data stored in oldest job and ready to be flushed immediately.
 *  if @return == 0, it means either :
 *  + there is no active job (could be checked with ZSTD_frameProgression()), or
 *  + oldest job is still actively compressing data,
 *    but everything it has produced has also been flushed so far,
 *    therefore flushing speed is currently limited by production speed of oldest job
 *    irrespective of the speed of concurrent newer jobs.
 */
ZSTDLIB_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx);



/*=====   Advanced Streaming decompression functions  =====*/
typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e;

    ZSTD_frameType_e frameType;          /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */
    unsigned headerSize;
    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 */
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);
ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);

/* ============================================ */
/**       New advanced API (experimental)       */
/* ============================================ */

/* API design :
 *   In this advanced API, parameters are pushed one by one into an existing context,
 *   using ZSTD_CCtx_set*() functions.
 *   Pushed parameters are sticky : they are applied to next job, and any subsequent job.
 *   It's possible to reset parameters to "default" using ZSTD_CCtx_reset().
 *   Important : "sticky" parameters only work with `ZSTD_compress_generic()` !
 *               For any other entry point, "sticky" parameters are ignored !
 *
 *   This API is intended to replace all others advanced / experimental API entry points.
 */

/* note on enum design :
 * All enum will be pinned to explicit values before reaching "stable API" status */

                              * Cast selected format as unsigned for ZSTD_CCtx_setParameter() compatibility. */

    /* compression parameters */
    ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table
                              * 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 by casting it to unsigned type.
                              * Note 2 : setting a level sets all default values of other compression parameters.
                              * Note 3 : setting compressionLevel automatically updates ZSTD_p_compressLiterals. */
    ZSTD_p_windowLog,        /* Maximum allowed back-reference distance, expressed as power of 2.
                              * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
                              * Special: value 0 means "use default windowLog".
                              * Note: Using a window size greater than ZSTD_MAXWINDOWSIZE_DEFAULT (default: 2^27)
                              *       requires explicitly allowing such window size during decompression stage. */
    ZSTD_p_hashLog,          /* Size of the initial probe table, as a power of 2.
                              * Resulting table size is (1 << (hashLog+2)).
                              * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX.
                              * Larger tables improve compression ratio of strategies <= dFast,
                              * and improve speed of strategies > dFast.
                              * Special: value 0 means "use default hashLog". */
    ZSTD_p_chainLog,         /* Size of the multi-probe search table, as a power of 2.
                              * Resulting table size 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.
                              * Note 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_p_searchLog,        /* 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.
                              * Special: value 0 means "use default searchLog". */

    /* =================================================================== */
    /* experimental parameters - no stability guaranteed                   */
    /* =================================================================== */

    ZSTD_p_forceMaxWindow=1100, /* Force back-reference distances to remain < windowSize,
                              * even when referencing into Dictionary content (default:0) */
    ZSTD_p_forceAttachDict,  /* ZSTD supports usage of a CDict in-place
                              * (avoiding having to copy the compression tables
                              * from the CDict into the working context). Using
                              * a CDict in this way saves an initial setup step,
                              * but comes at the cost of more work per byte of
                              * input. ZSTD has a simple internal heuristic that
                              * guesses which strategy will be faster. You can
                              * use this flag to override that guess.
                              *
                              * Note that the by-reference, in-place strategy is
                              * only used when reusing a compression context
                              * with compatible compression parameters. (If
                              * incompatible / uninitialized, the working
                              * context needs to be cleared anyways, which is
                              * about as expensive as overwriting it with the
                              * dictionary context, so there's no savings in
                              * using the CDict by-ref.)
                              *
                              * Values greater than 0 force attaching the dict.
                              * Values less than 0 force copying the dict.
                              * 0 selects the default heuristic-guided behavior.
                              */

} ZSTD_cParameter;


/*! ZSTD_CCtx_setParameter() :
 *  Set one compression parameter, selected by enum ZSTD_cParameter.
 *  Setting a parameter is generally only possible during frame initialization (before starting compression).
 *  Exception : when using multi-threading mode (nbThreads >= 1),
 *              following parameters can be updated _during_ compression (within same frame):
 *              => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy.
 *              new parameters will be active on next job, or after a flush().
 *  Note : when `value` type is not unsigned (int, or enum), cast it to unsigned for proper type checking.
 *  @result : informational value (typically, value being set, correctly clamped),
 *            or an error code (which can be tested with ZSTD_isError()). */
ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value);

/*! ZSTD_CCtx_getParameter() :
 * Get the requested value of one compression parameter, selected by enum ZSTD_cParameter.
 * @result : 0, or an error code (which can be tested with ZSTD_isError()).
 */
ZSTDLIB_API size_t ZSTD_CCtx_getParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned* value);

/*! ZSTD_CCtx_setPledgedSrcSize() :
 *  Total input data size to be compressed as a single frame.
 *  This value will be controlled at the end, and result in error if not respected.
 * @result : 0, or an error code (which can be tested with ZSTD_isError()).

 *  Note 2 : CDict is just referenced, its lifetime must outlive CCtx. */
ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);

/*! ZSTD_CCtx_refPrefix() :
 *  Reference a prefix (single-usage dictionary) for next compression job.
 *  Decompression will need same prefix to properly regenerate data.
 *  Compressing with a prefix is similar in outcome as performing a diff and compressing it,
 *  but performs much faster, especially during decompression (compression speed is tunable with compression level).
 *  Note that prefix is **only used once**. Tables are discarded at end of compression job (ZSTD_e_end).
 * @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).
 *  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.
 *  Note 4 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent).
 *           Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode. */
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx,
                                       const void* prefix, size_t prefixSize);
ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx,
                                       const void* prefix, size_t prefixSize,
                                       ZSTD_dictContentType_e dictContentType);

/*! ZSTD_CCtx_reset() :
 *  Return a CCtx to clean state.
 *  Useful after an error, or to interrupt an ongoing compression job and start a new one.
 *  Any internal data not yet flushed is cancelled.
 *  The parameters and dictionary are kept unchanged, to reset them use ZSTD_CCtx_resetParameters().
 */
ZSTDLIB_API void ZSTD_CCtx_reset(ZSTD_CCtx* cctx);

/*! ZSTD_CCtx_resetParameters() :
 *  All parameters are back to default values (compression level is ZSTD_CLEVEL_DEFAULT).
 *  Dictionary (if any) is dropped.
 *  Resetting parameters is only possible during frame initialization (before starting compression).
 *  To reset the context use ZSTD_CCtx_reset().
 *  @return 0 or an error code (which can be checked with ZSTD_isError()).
 */
ZSTDLIB_API size_t ZSTD_CCtx_resetParameters(ZSTD_CCtx* cctx);



typedef enum {
    ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal conditions */

 *  Note : when `value` is an enum, cast it to unsigned for proper type checking.
 * @result : 0, or an error code (which can be tested with ZSTD_isError()).
 */
ZSTDLIB_API size_t ZSTD_CCtxParam_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned value);

/*! ZSTD_CCtxParam_getParameter() :
 * Similar to ZSTD_CCtx_getParameter.
 * Get the requested value of one compression parameter, selected by enum ZSTD_cParameter.
 * @result : 0, or an error code (which can be tested with ZSTD_isError()).
 */
ZSTDLIB_API size_t ZSTD_CCtxParam_getParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned* value);

/*! ZSTD_CCtx_setParametersUsingCCtxParams() :
 *  Apply a set of ZSTD_CCtx_params to the compression context.
 *  This can be done even after compression is started,
 *    if nbWorkers==0, this will have no impact until a new compression is started.
 *    if nbWorkers>=1, new parameters will be picked up at next job,

 */
ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams(
        ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params);


/* ==================================== */
/*===   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.

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 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.

      + In case of multiple successive blocks, should some of them be uncompressed,
        decoder must be informed of their existence in order to follow proper history.
        Use ZSTD_insertBlock() for such a case.
*/

/*=====   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);
ZSTDLIB_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZSTD_insertBlock    (ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize);  /**< insert uncompressed block into `dctx` history. Useful for multi-blocks decompression. */