Class Zstd


  • public class Zstd
    extends java.lang.Object
    Native bindings to Zstandard (zstd), a fast lossless compression algorithm, targeting real-time compression scenarios at zlib-level and better compression ratios.

    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 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.

    Streaming compression - HowTo

    A ZSTD_CStream object is required to track streaming operation.

    Use createCStream and freeCStream to create/release resources. ZSTD_CStream objects can be reused multiple times on consecutive compression operations. It is recommended to re-use ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory.

    For parallel execution, use one separate ZSTD_CStream.

    Since v1.3.0, ZSTD_CStream and ZSTD_CCtx are the same thing.

    Parameters are sticky: when starting a new compression on the same context, it will re-use the same sticky parameters as previous compression session. When in doubt, it's recommended to fully initialize the context before usage. Use CCtx_reset to reset the context and CCtx_setParameter, CCtx_setPledgedSrcSize, or CCtx_loadDictionary and friends to set more specific parameters, the pledged source size, or load a dictionary.

    Use compressStream2 with e_continue 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, and then present again remaining input data.

    Note: ZSTD_e_continue is guaranteed to make some forward progress when called, but doesn't guarantee maximal forward progress. This is especially relevant when compressing with multiple threads. The call won't block if it can consume some input, but if it can't it will wait for some, but not all, output to be flushed.

    At any moment, it's possible to flush whatever data might remain stuck within internal buffer, using ZSTD_compressStream2() with e_flush. output->pos will be updated. Note that, if output->size is too small, a single invocation with ZSTD_e_flush might not be enough (return code > 0). In which case, make some room to receive more compressed data, and call again ZSTD_compressStream2() with ZSTD_e_flush. You must continue calling ZSTD_compressStream2() with ZSTD_e_flush until it returns 0, at which point you can change the operation.

    Note: ZSTD_e_flush will flush as much output as possible, meaning when compressing with multiple threads, it will block until the flush is complete or the output buffer is full.

    Calling ZSTD_compressStream2() with e_end 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 calling ZSTD_compressStream2() with ZSTD_e_flush. You must continue calling ZSTD_compressStream2() with ZSTD_e_end until it returns 0, at which point you are free to start a new frame.

    Note: ZSTD_e_end will flush as much output as possible, meaning when compressing with multiple threads, it will block until the flush is complete or the output buffer is full.

    Streaming decompression - HowTo

    A ZSTD_DStream object is required to track streaming operations.

    Use createDStream and freeDStream to create/release resources. ZSTD_DStream objects can be re-used multiple times.

    Use DCtx_reset and DCtx_refDDict to start a new decompression operation. Alternatively, use advanced API to set specific properties.

    Use decompressStream repetitively to consume your input. The function will update both pos fields. If input.pos < input.size, some input has not been consumed. It's up to the caller to present again remaining data. The function tries to flush all data decoded immediately, respecting output buffer size. If output.pos < output.size, decoder has flushed everything it could. But if output.pos == output.size, there might be some data left within internal buffers. In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer.

    Note: with no additional input provided, amount of data flushed is necessarily ≤ BLOCKSIZE_MAX.

    • Field Detail

      • ZSTD_c_compressionLevel, ZSTD_c_windowLog, ZSTD_c_hashLog, ZSTD_c_chainLog, ZSTD_c_searchLog, ZSTD_c_minMatch, ZSTD_c_targetLength, ZSTD_c_strategy, ZSTD_c_enableLongDistanceMatching, ZSTD_c_ldmHashLog, ZSTD_c_ldmMinMatch, ZSTD_c_ldmBucketSizeLog, ZSTD_c_ldmHashRateLog, ZSTD_c_contentSizeFlag, ZSTD_c_checksumFlag, ZSTD_c_dictIDFlag, ZSTD_c_nbWorkers, ZSTD_c_jobSize, ZSTD_c_overlapLog, ZSTD_c_experimentalParam1, ZSTD_c_experimentalParam2, ZSTD_c_experimentalParam3, ZSTD_c_experimentalParam4, ZSTD_c_experimentalParam5, ZSTD_c_experimentalParam6

        Compression parameters. (ZSTD_cParameter)

        Note: When compressing with a ZSTD_CDict these parameters are superseded by the parameters used to construct the ZSTD_CDict. See CCtx_refCDict for more info.

        Enum values:
        • c_compressionLevel - Update all compression parameters according to pre-defined cLevel table Default level is CLEVEL_DEFAULT==3. Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT.

          Note 1: it's possible to pass a negative compression level.

          Note 2 : setting a level sets all default values of other compression parameters

        • c_windowLog - Maximum allowed back-reference distance, expressed as power of 2. Must be clamped between WINDOWLOG_MIN and WINDOWLOG_MAX. Special: value 0 means "use default windowLog".

          Note: Using a windowLog greater than WINDOWLOG_LIMIT_DEFAULT requires explicitly allowing such window size at decompression stage if using streaming.

        • c_hashLog - Size of the initial probe table, as a power of 2. Resulting memory usage is (1 << (hashLog+2)). Must be clamped between HASHLOG_MIN and HASHLOG_MAX. Larger tables improve compression ratio of strategies ≤ dFast, and improve speed of strategies > dFast. Special: value 0 means "use default hashLog".
        • c_chainLog - Size of the multi-probe search table, as a power of 2. Resulting memory usage is (1 << (chainLog+2)). Must be clamped between CHAINLOG_MIN and CHAINLOG_MAX. Larger tables result in better and slower compression. This parameter is useless when using "fast" strategy. It's still useful when using "dfast" strategy, in which case it defines a secondary probe table. Special: value 0 means "use default chainLog".
        • c_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".
        • c_minMatch - Minimum size of searched matches. Note that Zstandard can still find matches of smaller size, it just tweaks its search algorithm to look for this size and larger. Larger values increase compression and decompression speed, but decrease ratio. Must be clamped between MINMATCH_MIN and MINMATCH_MAX. Note that currently, for all strategies <btopt, effective minimum is 4. , for all strategies > fast, effective maximum is 6. Special: value 0 means "use default minMatchLength".
        • c_targetLength - Impact of this field depends on strategy. For strategies btopt, btultra & btultra2: Length of Match considered "good enough" to stop search. Larger values make compression stronger, and slower. For strategy fast: Distance between match sampling. Larger values make compression faster, and weaker. Special: value 0 means "use default targetLength".
        • c_strategy - See ZSTD_strategy enum definition. The higher the value of selected strategy, the more complex it is, resulting in stronger and slower compression. Special: value 0 means "use default strategy".
        • c_enableLongDistanceMatching - Enable long distance matching. This parameter is designed to improve compression ratio for large inputs, by finding large matches at long distance. It increases memory usage and window size. Note: enabling this parameter increases default c_windowLog to 128 MB except when expressly set to a different value.
        • c_ldmHashLog - Size of the table for long distance matching, as a power of 2. Larger values increase memory usage and compression ratio, but decrease compression speed. Must be clamped between HASHLOG_MIN and HASHLOG_MAX default: windowlog - 7. Special: value 0 means "automatically determine hashlog".
        • c_ldmMinMatch - Minimum match size for long distance matcher. Larger/too small values usually decrease compression ratio. Must be clamped between LDM_MINMATCH_MIN and LDM_MINMATCH_MAX. Special: value 0 means "use default value" (default: 64).
        • c_ldmBucketSizeLog - Log size of each bucket in the LDM hash table for collision resolution. Larger values improve collision resolution but decrease compression speed. The maximum value is LDM_BUCKETSIZELOG_MAX. Special: value 0 means "use default value" (default: 3).
        • c_ldmHashRateLog - Frequency of inserting/looking up entries into the LDM hash table. Must be clamped between 0 and (WINDOWLOG_MAX - HASHLOG_MIN). Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage. Larger values improve compression speed. Deviating far from default value will likely result in a compression ratio decrease. Special: value 0 means "automatically determine hashRateLog".
        • c_contentSizeFlag - Content size will be written into frame header _whenever known_ (default:1) Content size must be known at the beginning of compression. This is automatically the case when using compress2, For streaming variants, content size must be provided with CCtx_setPledgedSrcSize.
        • c_checksumFlag - A 32-bits checksum of content is written at end of frame (default:0)
        • c_dictIDFlag - When applicable, dictionary's ID is written into frame header (default:1)
        • c_nbWorkers - Select how many threads will be spawned to compress in parallel. When nbWorkers &ge; 1, triggers asynchronous mode when used with ZSTD_compressStream*(): ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller, while compression work is performed in parallel, within worker threads. (note: a strong exception to this rule is when first invocation of compressStream2 sets e_end: in which case, ZSTD_compressStream2() delegates to compress2, which is always a blocking call). More workers improve speed, but also increase memory usage. Default value is 0, aka "single-threaded mode": no worker is spawned, compression is performed inside Caller's thread, all invocations are blocking.
        • c_jobSize - Size of a compression job. This value is enforced only when nbWorkers &ge; 1. Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads. 0 means default, which is dynamically determined based on compression parameters. Job size must be a minimum of overlap size, or 1 MB, whichever is largest. The minimum size is automatically and transparently enforced.
        • c_overlapLog - Control the overlap size, as a fraction of window size. The overlap size is an amount of data reloaded from previous job at the beginning of a new job. It helps preserve compression ratio, while each job is compressed in parallel. This value is enforced only when nbWorkers &ge; 1. Larger values increase compression ratio, but decrease speed. Possible values range from 0 to 9:
          • 0 means "default" : value will be determined by the library, depending on strategy
          • 1 means "no overlap"
          • 9 means "full overlap", using a full window size. Each intermediate rank increases/decreases load size by a factor 2: 9: full window; 8: w/2; 7: w/4; 6: w/8; 5:w/16; 4: w/32; 3:w/64; 2:w/128; 1:no overlap; 0:default default value varies between 6 and 9, depending on strategy
        • c_experimentalParam1
        • c_experimentalParam2
        • c_experimentalParam3
        • c_experimentalParam4
        • c_experimentalParam5
        • c_experimentalParam6
      • ZSTD_d_windowLogMax, ZSTD_d_experimentalParam1

        The advanced API pushes parameters one by one into an existing DCtx context. Parameters are sticky, and remain valid for all following frames using the same DCtx context. It's possible to reset parameters to default values using DCtx_reset.

        Note: This API is compatible with existing decompressDCtx and decompressStream. Therefore, no new decompression function is necessary.

        (ZSTD_dParameter)

        Enum values:
        • d_windowLogMax - Select a size limit (in power of 2) beyond which the streaming API will refuse to allocate memory buffer in order to protect the host from unreasonable memory requirements.

          This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode. By default, a decompression context accepts window sizes ≤ (1 << WINDOWLOG_LIMIT_DEFAULT)

          Special: value 0 means "use default maximum windowLog".

        • d_experimentalParam1 - Note: additional experimental parameters are also available within the experimental section of the API. At the time of this writing, they include: c_format

          Note: never ever use experimentalParam? names directly

      • ZSTD_e_continue, ZSTD_e_flush, ZSTD_e_end

        ZSTD_EndDirective
        Enum values:
        • e_continue - collect more data, encoder decides when to output compressed result, for optimal compression ratio
        • e_flush - flush any data provided so far, it creates (at least) one new block, that can be decoded immediately on reception; frame will continue: any future data can still reference previously compressed data, improving compression.
        • e_end - flush any remaining data and close current frame. note that frame is only closed after compressed data is fully flushed (return value == 0). After that point, any additional data starts a new frame.

          Note: each frame is independent (does not reference any content from previous frame).

    • Method Detail

      • ZSTD_versionNumber

        public static int ZSTD_versionNumber()
        Returns the version number.
      • nZSTD_versionString

        public static long nZSTD_versionString()
        Unsafe version of: versionString
      • ZSTD_versionString

        public static java.lang.String ZSTD_versionString()
        Returns the version string.
      • nZSTD_compress

        public static long nZSTD_compress​(long dst,
                                          long dstCapacity,
                                          long src,
                                          long srcSize,
                                          int compressionLevel)
        Unsafe version of: compress
      • ZSTD_compress

        public static long ZSTD_compress​(java.nio.ByteBuffer dst,
                                         java.nio.ByteBuffer src,
                                         int compressionLevel)
        Compresses src content as a single zstd compressed frame into already allocated dst.

        Hint: compression runs faster if dstCapacitycompressBound(srcSize)

        Returns:
        compressed size written into dst (≤ dstCapacity), or an error code if it fails (which can be tested using isError).
      • nZSTD_decompress

        public static long nZSTD_decompress​(long dst,
                                            long dstCapacity,
                                            long src,
                                            long compressedSize)
        Unsafe version of: decompress
        Parameters:
        dstCapacity - is an upper bound of originalSize to regenerate. If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data.
        compressedSize - must be the exact size of some number of compressed and/or skippable frames
      • ZSTD_decompress

        public static long ZSTD_decompress​(java.nio.ByteBuffer dst,
                                           java.nio.ByteBuffer src)
        Returns:
        the number of bytes decompressed into dst (≤ dstCapacity), or an errorCode if it fails (which can be tested using isError).
      • nZSTD_getFrameContentSize

        public static long nZSTD_getFrameContentSize​(long src,
                                                     long srcSize)
        Unsafe version of: getFrameContentSize
        Parameters:
        srcSize - must be at least as large as the frame header. Hint: any size ≥ FRAMEHEADERSIZE_MAX is large enough.
      • ZSTD_getFrameContentSize

        public static long ZSTD_getFrameContentSize​(java.nio.ByteBuffer src)
        Notes:
        1. a 0 return value means the frame is valid but "empty"
        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 decompress only needs an upper bound of decompressed size. (For example, data could be necessarily cut into blocks ≤ 16 KB).
        3. decompressed size is always present when compression is completed using single-pass functions, such as compress, compressCCtx, compress_usingDict or compress_usingCDict.
        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.
        5. If source is untrusted, decompressed size could be wrong or intentionally modified. Always ensure return value fits within application's authorized limits. Each application can set its own limits.
        Parameters:
        src - should point to the start of a ZSTD encoded frame
        Returns:
        decompressed size of src frame content, if known
      • nZSTD_findFrameCompressedSize

        public static long nZSTD_findFrameCompressedSize​(long src,
                                                         long srcSize)
        Unsafe version of: findFrameCompressedSize
        Parameters:
        srcSize - must be ≥ first frame size
      • ZSTD_findFrameCompressedSize

        public static long ZSTD_findFrameCompressedSize​(java.nio.ByteBuffer src)
        Parameters:
        src - should point to the start of a ZSTD frame or skippable frame
        Returns:
        the compressed size of the first frame starting at src, suitable to pass as srcSize to decompress or similar, or an error code if input is invalid
      • ZSTD_compressBound

        public static long ZSTD_compressBound​(long srcSize)
        Returns the maximum compressed size in worst case single-pass scenario.
      • nZSTD_isError

        public static int nZSTD_isError​(long code)
        Unsafe version of: isError
      • ZSTD_isError

        public static boolean ZSTD_isError​(long code)
        Tells if a size_t function result is an error code.
      • nZSTD_getErrorName

        public static long nZSTD_getErrorName​(long code)
        Unsafe version of: getErrorName
      • ZSTD_getErrorName

        public static java.lang.String ZSTD_getErrorName​(long code)
        Provides readable string from an error code.
      • ZSTD_minCLevel

        public static int ZSTD_minCLevel()
        Returns the minimum compression level available.
      • ZSTD_maxCLevel

        public static int ZSTD_maxCLevel()
        Returns the maximum compression level available.
      • ZSTD_createCCtx

        public static long ZSTD_createCCtx()
        Creates a compression context.

        When compressing many times, it is recommended to allocate a context just once, and re-use it for each successive compression operation. This will make workload friendlier for system's memory. Use one context per thread for parallel execution in multi-threaded environments.

      • nZSTD_freeCCtx

        public static long nZSTD_freeCCtx​(long cctx)
        Unsafe version of: freeCCtx
      • ZSTD_freeCCtx

        public static long ZSTD_freeCCtx​(long cctx)
        Frees memory allocated by createCCtx.
      • nZSTD_compressCCtx

        public static long nZSTD_compressCCtx​(long ctx,
                                              long dst,
                                              long dstCapacity,
                                              long src,
                                              long srcSize,
                                              int compressionLevel)
        Unsafe version of: compressCCtx
      • ZSTD_compressCCtx

        public static long ZSTD_compressCCtx​(long ctx,
                                             java.nio.ByteBuffer dst,
                                             java.nio.ByteBuffer src,
                                             int compressionLevel)
        Same as compress, using an explicit ZSTD_CCtx. The function will compress at requested compression level, ignoring any other parameter.
      • ZSTD_createDCtx

        public static long ZSTD_createDCtx()
        Creates a decompression context.

        When decompressing many times, it is recommended to allocate a context only once, and re-use it for each successive compression operation. This will make workload friendlier for system's memory. Use one context per thread for parallel execution.

      • nZSTD_freeDCtx

        public static long nZSTD_freeDCtx​(long dctx)
        Unsafe version of: freeDCtx
      • ZSTD_freeDCtx

        public static long ZSTD_freeDCtx​(long dctx)
        Frees memory allocated by createDCtx.
      • nZSTD_decompressDCtx

        public static long nZSTD_decompressDCtx​(long ctx,
                                                long dst,
                                                long dstCapacity,
                                                long src,
                                                long srcSize)
        Unsafe version of: decompressDCtx
      • ZSTD_decompressDCtx

        public static long ZSTD_decompressDCtx​(long ctx,
                                               java.nio.ByteBuffer dst,
                                               java.nio.ByteBuffer src)
        Same as decompress, requires an allocated ZSTD_DCtx. Compatible with sticky parameters.
      • nZSTD_cParam_getBounds

        public static void nZSTD_cParam_getBounds​(int cParam,
                                                  long __result)
        Unsafe version of: cParam_getBounds
      • nZSTD_CCtx_setParameter

        public static long nZSTD_CCtx_setParameter​(long cctx,
                                                   int param,
                                                   int value)
        Unsafe version of: CCtx_setParameter
      • nZSTD_CCtx_setPledgedSrcSize

        public static long nZSTD_CCtx_setPledgedSrcSize​(long cctx,
                                                        long pledgedSrcSize)
        Unsafe version of: CCtx_setPledgedSrcSize
      • ZSTD_CCtx_setPledgedSrcSize

        public static long ZSTD_CCtx_setPledgedSrcSize​(long cctx,
                                                       long pledgedSrcSize)
        Total input data size to be compressed as a single frame.

        Value will be written in frame header, unless if explicitly forbidden using c_contentSizeFlag. This value will also be controlled at end of frame, and trigger an error if not respected.

        Note 1: pledgedSrcSize==0 actually means zero, aka an empty frame. In order to mean "unknown content size", pass constant CONTENTSIZE_UNKNOWN. ZSTD_CONTENTSIZE_UNKNOWN is default value for any new frame.

        Note 2: pledgedSrcSize is only valid once, for the next frame. It's discarded at the end of the frame, and replaced by ZSTD_CONTENTSIZE_UNKNOWN.

        Note 3 : Whenever all input data is provided and consumed in a single round, for example with compress2, or invoking immediately ZSTD_compressStream2(,,,ZSTD_e_end), this value is automatically overridden by srcSize instead.

        Returns:
        0, or an error code (which can be tested with isError).
      • nZSTD_CCtx_reset

        public static long nZSTD_CCtx_reset​(long cctx,
                                            int reset)
        Unsafe version of: CCtx_reset
      • ZSTD_CCtx_reset

        public static long ZSTD_CCtx_reset​(long cctx,
                                           int reset)
        There are 2 different things that can be reset, independently or jointly :
        • The session: will stop compressing current frame, and make CCtx ready to start a new one. Useful after an error, or to interrupt any ongoing compression. Any internal data not yet flushed is cancelled. Compression parameters and dictionary remain unchanged. They will be used to compress next frame. Resetting session never fails.
        • The parameters: changes all parameters back to "default". This removes any reference to any dictionary too. Parameters can only be changed between 2 sessions (i.e. no compression is currently ongoing) otherwise the reset fails, and function returns an error value (which can be tested using isError)
        • Both: similar to resetting the session, followed by resetting parameters.
        Parameters:
        reset - one of:
        reset_session_onlyreset_parametersreset_session_and_parameters
      • nZSTD_compress2

        public static long nZSTD_compress2​(long cctx,
                                           long dst,
                                           long dstCapacity,
                                           long src,
                                           long srcSize)
        Unsafe version of: compress2
      • ZSTD_compress2

        public static long ZSTD_compress2​(long cctx,
                                          java.nio.ByteBuffer dst,
                                          java.nio.ByteBuffer src)
        Behaves the same as compressCCtx, but compression parameters are set using the advanced API.

        ZSTD_compress2() always starts a new frame. Should cctx hold data from a previously unfinished frame, everything about it is forgotten.

        - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*() - The function is always blocking, returns when compression is completed. Hint: compression runs faster if dstCapacityZSTD_compressBound(srcSize).

        Returns:
        compressed size written into dst (≤ dstCapacity), or an error code if it fails (which can be tested using isError)
      • nZSTD_dParam_getBounds

        public static void nZSTD_dParam_getBounds​(int dParam,
                                                  long __result)
        Unsafe version of: dParam_getBounds
      • ZSTD_dParam_getBounds

        public static ZSTDBounds ZSTD_dParam_getBounds​(int dParam,
                                                       ZSTDBounds __result)
        All parameters must belong to an interval with lower and upper bounds, otherwise they will either trigger an error or be automatically clamped.
        Parameters:
        __result - returns a structure, ZSTD_bounds, which contains - an error status field, which must be tested using isError - both lower and upper bounds, inclusive
      • nZSTD_DCtx_setParameter

        public static long nZSTD_DCtx_setParameter​(long dctx,
                                                   int param,
                                                   int value)
        Unsafe version of: DCtx_setParameter
      • ZSTD_DCtx_setParameter

        public static long ZSTD_DCtx_setParameter​(long dctx,
                                                  int param,
                                                  int value)
        Set one compression parameter, selected by enum ZSTD_dParameter.

        All parameters have valid bounds. Bounds can be queried using dParam_getBounds. Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). Setting a parameter is only possible during frame initialization (before starting decompression).

        Parameters:
        param - one of:
        d_windowLogMaxd_experimentalParam1
        Returns:
        0, or an error code (which can be tested using isError)
      • nZSTD_DCtx_reset

        public static long nZSTD_DCtx_reset​(long dctx,
                                            int reset)
        Unsafe version of: DCtx_reset
      • ZSTD_DCtx_reset

        public static long ZSTD_DCtx_reset​(long dctx,
                                           int reset)
        Returns a DCtx to clean state.

        Session and parameters can be reset jointly or separately. Parameters can only be reset when no active frame is being decompressed.

        Parameters:
        reset - one of:
        reset_session_onlyreset_parametersreset_session_and_parameters
        Returns:
        0, or an error code, which can be tested with isError
      • ZSTD_createCStream

        public static long ZSTD_createCStream()
        A ZSTD_CStream object is required to track streaming operation.

        Use ZSTD_createCStream() and freeCStream to create/release resources.

        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.

      • nZSTD_freeCStream

        public static long nZSTD_freeCStream​(long zcs)
        Unsafe version of: freeCStream
      • ZSTD_freeCStream

        public static long ZSTD_freeCStream​(long zcs)
        Frees memory allocated by createCStream.
      • nZSTD_compressStream2

        public static long nZSTD_compressStream2​(long cctx,
                                                 long output,
                                                 long input,
                                                 int endOp)
        Unsafe version of: compressStream2
      • ZSTD_compressStream2

        public static long ZSTD_compressStream2​(long cctx,
                                                ZSTDOutBuffer output,
                                                ZSTDInBuffer input,
                                                int endOp)
        Behaves about the same as ZSTD_compressStream(), with additional control on end directive.
        • 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.
        • When nbWorkers==0 (default), function is blocking: it completes its job before returning to caller.
        • When nbWorkers&ge;1, function is non-blocking: it just acquires a copy of input, and distributes jobs to internal worker threads, flush whatever is available, 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.
        • Exception: if the first call requests a e_end directive and provides enough dstCapacity, the function delegates to compress2 which is always blocking.
        Parameters:
        endOp - one of:
        e_continuee_flushe_end
        Returns:
        provides a minimum amount of data remaining to be flushed from internal buffers or an error code, which can be tested using isError.

        If != 0, flush is not fully completed, there is still some data left within internal buffers. This is useful for e_flush, since in this case more flushes are necessary to empty all buffers. For e_end, == 0 when internal buffers are fully flushed and frame is completed.

        - after a ZSTD_e_end directive, if internal buffer is not fully flushed (!= 0), only ZSTD_e_end or ZSTD_e_flush operations are allowed. Before starting a new compression job, or changing compression parameters, it is required to fully flush internal buffers.

      • ZSTD_CStreamInSize

        public static long ZSTD_CStreamInSize()
        Returns the recommended size for input buffer.

        These buffer sizes are softly recommended. They are not required: ZSTD_compressStream*() happily accepts any buffer size, for both input and output. Respecting the recommended size just makes it a bit easier for ZSTD_compressStream*(), reducing the amount of memory shuffling and buffering, resulting in minor performance savings.

        However, note that these recommendations are from the perspective of a C caller program. If the streaming interface is invoked from some other language, especially managed ones such as Java or Go, through a foreign function interface such as jni or cgo, a major performance rule is to reduce crossing such interface to an absolute minimum. It's not rare that performance ends being spent more into the interface, rather than compression itself. In which cases, prefer using large buffers, as large as practical, for both input and output, to reduce the nb of roundtrips.

      • ZSTD_CStreamOutSize

        public static long ZSTD_CStreamOutSize()
        Returns the recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block.
      • ZSTD_createDStream

        public static long ZSTD_createDStream()
        A ZSTD_DStream object is required to track streaming operations.

        Use ZSTD_createDStream() and freeDStream to create/release resources. ZSTD_DStream objects can be re-used multiple times.

      • nZSTD_freeDStream

        public static long nZSTD_freeDStream​(long zds)
        Unsafe version of: freeDStream
      • ZSTD_freeDStream

        public static long ZSTD_freeDStream​(long zds)
        Frees memory allocated by createDStream.
      • nZSTD_decompressStream

        public static long nZSTD_decompressStream​(long zds,
                                                  long output,
                                                  long input)
        Unsafe version of: decompressStream
      • ZSTD_decompressStream

        public static long ZSTD_decompressStream​(long zds,
                                                 ZSTDOutBuffer output,
                                                 ZSTDInBuffer input)
        Use ZSTD_decompressStream() repetitively to consume your input.

        The function will update both pos fields. If input.pos < input.size, some input has not been consumed. It's up to the caller to present again remaining data. The function tries to flush all data decoded immediately, respecting output buffer size. If output.pos < output.size, decoder has flushed everything it could. But if output.pos == output.size, there might be some data left within internal buffers. In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer. With no additional input provided, amount of data flushed is necessarily ≤ BLOCKSIZE_MAX.

        Returns:
        0 when a frame is completely decoded and fully flushed, an error code, which can be tested using isError, any other value > 0, which means there is still some decoding to do to complete current frame. The return value is a suggested next input size (just a hint to improve latency) that will never request more than the remaining frame size.
      • ZSTD_DStreamInSize

        public static long ZSTD_DStreamInSize()
        Returns the recommended size for input buffer.
      • ZSTD_DStreamOutSize

        public static long ZSTD_DStreamOutSize()
        Returns the recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances.
      • nZSTD_compress_usingDict

        public static long nZSTD_compress_usingDict​(long ctx,
                                                    long dst,
                                                    long dstCapacity,
                                                    long src,
                                                    long srcSize,
                                                    long dict,
                                                    long dictSize,
                                                    int compressionLevel)
        Unsafe version of: compress_usingDict
      • ZSTD_compress_usingDict

        public static long ZSTD_compress_usingDict​(long ctx,
                                                   java.nio.ByteBuffer dst,
                                                   java.nio.ByteBuffer src,
                                                   @Nullable
                                                   java.nio.ByteBuffer dict,
                                                   int compressionLevel)
        Compression at an explicit compression level using a Dictionary.

        A dictionary can be any arbitrary data segment (also called a prefix), or a buffer with specified information (see dictBuilder/zdict.h).

        This function loads the dictionary, resulting in significant startup delay. It's intended for a dictionary used only once.

        When dict == NULL || dictSize < 8 no dictionary is used.

      • nZSTD_decompress_usingDict

        public static long nZSTD_decompress_usingDict​(long dctx,
                                                      long dst,
                                                      long dstCapacity,
                                                      long src,
                                                      long srcSize,
                                                      long dict,
                                                      long dictSize)
        Unsafe version of: decompress_usingDict
      • ZSTD_decompress_usingDict

        public static long ZSTD_decompress_usingDict​(long dctx,
                                                     java.nio.ByteBuffer dst,
                                                     java.nio.ByteBuffer src,
                                                     @Nullable
                                                     java.nio.ByteBuffer dict)
        Decompression using a known Dictionary. Dictionary must be identical to the one used during compression.

        This function loads the dictionary, resulting in significant startup delay. It's intended for a dictionary used only once.

        When dict == NULL || dictSize < 8 no dictionary is used.

      • nZSTD_createCDict

        public static long nZSTD_createCDict​(long dictBuffer,
                                             long dictSize,
                                             int compressionLevel)
        Unsafe version of: createCDict
      • ZSTD_createCDict

        public static long ZSTD_createCDict​(java.nio.ByteBuffer dictBuffer,
                                            int compressionLevel)
        When compressing multiple messages / blocks using the same dictionary, it's recommended to load it only once.

        ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup cost. 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, because its content is copied within CDict. Consider experimental function createCDict_byReference if you prefer to not duplicate dictBuffer content.

        Note: A ZSTD_CDict can be created from an empty dictBuffer, but it is inefficient when used to compress small data.

      • nZSTD_freeCDict

        public static long nZSTD_freeCDict​(long CDict)
        Unsafe version of: freeCDict
      • ZSTD_freeCDict

        public static long ZSTD_freeCDict​(long CDict)
        Frees memory allocated by createCDict.
      • nZSTD_compress_usingCDict

        public static long nZSTD_compress_usingCDict​(long cctx,
                                                     long dst,
                                                     long dstCapacity,
                                                     long src,
                                                     long srcSize,
                                                     long cdict)
        Unsafe version of: compress_usingCDict
      • ZSTD_compress_usingCDict

        public static long ZSTD_compress_usingCDict​(long cctx,
                                                    java.nio.ByteBuffer dst,
                                                    java.nio.ByteBuffer src,
                                                    long cdict)
        Compression using a digested Dictionary. Recommended when same dictionary is used multiple times.

        Compression level is decided at dictionary creation time, and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no)

      • nZSTD_createDDict

        public static long nZSTD_createDDict​(long dictBuffer,
                                             long dictSize)
        Unsafe version of: createDDict
      • ZSTD_createDDict

        public static long ZSTD_createDDict​(java.nio.ByteBuffer dictBuffer)
        Creates a digested dictionary, ready to start decompression operation without startup delay.

        dictBuffer can be released after DDict creation, as its content is copied inside DDict.

      • nZSTD_freeDDict

        public static long nZSTD_freeDDict​(long ddict)
        Unsafe version of: freeDDict
      • ZSTD_freeDDict

        public static long ZSTD_freeDDict​(long ddict)
        Frees memory allocated with createDDict.
      • nZSTD_decompress_usingDDict

        public static long nZSTD_decompress_usingDDict​(long dctx,
                                                       long dst,
                                                       long dstCapacity,
                                                       long src,
                                                       long srcSize,
                                                       long ddict)
        Unsafe version of: decompress_usingDDict
      • ZSTD_decompress_usingDDict

        public static long ZSTD_decompress_usingDDict​(long dctx,
                                                      java.nio.ByteBuffer dst,
                                                      java.nio.ByteBuffer src,
                                                      long ddict)
        Decompression using a digested Dictionary.

        Recommended when same dictionary is used multiple times.

      • nZSTD_getDictID_fromDict

        public static int nZSTD_getDictID_fromDict​(long dict,
                                                   long dictSize)
        Unsafe version of: getDictID_fromDict
      • ZSTD_getDictID_fromDict

        public static int ZSTD_getDictID_fromDict​(java.nio.ByteBuffer dict)
        Provides the dictID stored within dictionary.
        Returns:
        if == 0, the dictionary is not conformant with Zstandard specification. It can still be loaded, but as a content-only dictionary.
      • nZSTD_getDictID_fromDDict

        public static int nZSTD_getDictID_fromDDict​(long ddict)
        Unsafe version of: getDictID_fromDDict
      • ZSTD_getDictID_fromDDict

        public static int ZSTD_getDictID_fromDDict​(long ddict)
        Provides the dictID of the dictionary loaded into ddict.
        Returns:
        if == 0, the dictionary is not conformant to Zstandard specification, or empty.

        Non-conformant dictionaries can still be loaded, but as content-only dictionaries.

      • nZSTD_getDictID_fromFrame

        public static int nZSTD_getDictID_fromFrame​(long src,
                                                    long srcSize)
        Unsafe version of: getDictID_fromFrame
      • ZSTD_getDictID_fromFrame

        public static int ZSTD_getDictID_fromFrame​(java.nio.ByteBuffer src)
        Provides the dictID required to decompressed the frame stored within src.
        Returns:
        if == 0, the dictID could not be decoded. This could for one of the following reasons :
        • The frame does not require a dictionary to be decoded (most common case).
        • The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information.

          Note: this use case also happens when using a non-conformant dictionary.

        • srcSize is too small, and as a result, the frame header could not be decoded (only possible if srcSize < FRAMEHEADERSIZE_MAX).
        • This is not a Zstandard frame. When identifying the exact failure cause, it's possible to use getFrameHeader, which will provide a more precise error code.
      • nZSTD_CCtx_loadDictionary

        public static long nZSTD_CCtx_loadDictionary​(long cctx,
                                                     long dict,
                                                     long dictSize)
        Unsafe version of: CCtx_loadDictionary
      • ZSTD_CCtx_loadDictionary

        public static long ZSTD_CCtx_loadDictionary​(long cctx,
                                                    @Nullable
                                                    java.nio.ByteBuffer dict)
        Creates an internal CDict from dict buffer. Decompression will have to use same dictionary.

        Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary, meaning "return to no-dictionary mode".

        Note 1: Dictionary is sticky, it will be used for all future compressed frames. To return to "no-dictionary" situation, load a NULL dictionary (or reset parameters).

        Note 2: Loading a dictionary involves building tables. It's also a CPU consuming operation, with non-negligible impact on latency. Tables are dependent on compression parameters, and for this reason, compression parameters can no longer be changed after loading a dictionary.

        Note 3: dict content will be copied internally. Use experimental CCtx_loadDictionary_byReference to reference content instead. In such a case, dictionary buffer must outlive its users.

        Note 4: Use CCtx_loadDictionary_advanced to precisely select how dictionary content must be interpreted.

        Returns:
        0, or an error code (which can be tested with isError).
      • nZSTD_CCtx_refCDict

        public static long nZSTD_CCtx_refCDict​(long cctx,
                                               long cdict)
        Unsafe version of: CCtx_refCDict
      • ZSTD_CCtx_refCDict

        public static long ZSTD_CCtx_refCDict​(long cctx,
                                              long cdict)
        References a prepared dictionary, to be used for all next compressed frames.

        Note that compression parameters are enforced from within CDict, and supercede any compression parameter previously set within CCtx. The dictionary will remain valid for future compressed frames using same CCtx.

        Special: Referencing a NULL CDict means "return to no-dictionary mode".

        Note 1: Currently, only one dictionary can be managed. Referencing a new dictionary effectively "discards" any previous one.

        Note 2: CDict is just referenced, its lifetime must outlive its usage within CCtx.

        Returns:
        0, or an error code (which can be tested with isError).
      • nZSTD_CCtx_refPrefix

        public static long nZSTD_CCtx_refPrefix​(long cctx,
                                                long prefix,
                                                long prefixSize)
        Unsafe version of: CCtx_refPrefix
      • ZSTD_CCtx_refPrefix

        public static long ZSTD_CCtx_refPrefix​(long cctx,
                                               @Nullable
                                               java.nio.ByteBuffer prefix)
        References a prefix (single-usage dictionary) for next compressed frame.

        A prefix is only used once. Tables are discarded at end of frame (e_end). 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).

        Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary

        Note 1: Prefix buffer is referenced. It must outlive compression. 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 c_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 the same prefix multiple times, consider loadDictionary instead.

        Note 4: By default, the prefix is interpreted as raw content (dct_rawContent). Use experimental CCtx_refPrefix_advanced to alter dictionary interpretation.

        Returns:
        0, or an error code (which can be tested with isError).
      • nZSTD_DCtx_loadDictionary

        public static long nZSTD_DCtx_loadDictionary​(long dctx,
                                                     long dict,
                                                     long dictSize)
        Unsafe version of: DCtx_loadDictionary
      • ZSTD_DCtx_loadDictionary

        public static long ZSTD_DCtx_loadDictionary​(long dctx,
                                                    @Nullable
                                                    java.nio.ByteBuffer dict)
        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.

        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 DCtx_loadDictionary_byReference to reference dictionary content instead.

        Note 3: Use DCtx_loadDictionary_advanced to take control of how dictionary content is loaded and interpreted.

        Returns:
        0, or an error code (which can be tested with ZSTD_isError())
      • nZSTD_DCtx_refDDict

        public static long nZSTD_DCtx_refDDict​(long dctx,
                                               long ddict)
        Unsafe version of: DCtx_refDDict
      • ZSTD_DCtx_refDDict

        public static long ZSTD_DCtx_refDDict​(long dctx,
                                              long ddict)
        References a prepared dictionary, to be used to decompress next frames. The dictionary remains active for decompression of future frames using same DCtx.

        Note 1: Currently, only one dictionary can be managed. Referencing a new dictionary effectively "discards" any previous one. Special: referencing a NULL DDict means "return to no-dictionary mode".

        Note 2: DDict is just referenced, its lifetime must outlive its usage from DCtx.

        Returns:
        0, or an error code (which can be tested with isError)
      • nZSTD_DCtx_refPrefix

        public static long nZSTD_DCtx_refPrefix​(long dctx,
                                                long prefix,
                                                long prefixSize)
        Unsafe version of: DCtx_refPrefix
      • ZSTD_DCtx_refPrefix

        public static long ZSTD_DCtx_refPrefix​(long dctx,
                                               java.nio.ByteBuffer prefix)
        References a prefix (single-usage dictionary) to decompress next frame.

        This is the reverse operation of 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 decompressStream returns 0.

        Note 1: Adding any prefix (including NULL) invalidates any previously set prefix or dictionary.

        Note 2: Prefix buffer is referenced. It must outlive decompression. Prefix buffer must remain unmodified up to the end of frame, reached when ZSTD_decompressStream() returns 0.

        Note 3: By default, the prefix is treated as raw content (dct_rawContent). Use CCtx_refPrefix_advanced to alter dictMode.

        Note 4: Referencing a raw content prefix has almost no cpu nor memory cost. A full dictionary is more costly, as it requires building tables.

        Returns:
        0, or an error code (which can be tested with isError)
      • nZSTD_sizeof_CCtx

        public static long nZSTD_sizeof_CCtx​(long cctx)
      • ZSTD_sizeof_CCtx

        public static long ZSTD_sizeof_CCtx​(long cctx)
      • nZSTD_sizeof_DCtx

        public static long nZSTD_sizeof_DCtx​(long dctx)
      • ZSTD_sizeof_DCtx

        public static long ZSTD_sizeof_DCtx​(long dctx)
      • nZSTD_sizeof_CStream

        public static long nZSTD_sizeof_CStream​(long zcs)
      • ZSTD_sizeof_CStream

        public static long ZSTD_sizeof_CStream​(long zcs)
      • nZSTD_sizeof_DStream

        public static long nZSTD_sizeof_DStream​(long zds)
      • ZSTD_sizeof_DStream

        public static long ZSTD_sizeof_DStream​(long zds)
      • nZSTD_sizeof_CDict

        public static long nZSTD_sizeof_CDict​(long cdict)
      • ZSTD_sizeof_CDict

        public static long ZSTD_sizeof_CDict​(long cdict)
      • nZSTD_sizeof_DDict

        public static long nZSTD_sizeof_DDict​(long ddict)
      • ZSTD_sizeof_DDict

        public static long ZSTD_sizeof_DDict​(long ddict)
      • ZSTD_COMPRESSBOUND

        public static long ZSTD_COMPRESSBOUND​(long srcSize)
        Pure Java version of ZSTD_compressBound(long).