| /* |
| * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. |
| * All rights reserved. |
| * |
| * This source code is licensed under the BSD-style license found in the |
| * LICENSE file in the root directory of this source tree. An additional grant |
| * of patent rights can be found in the PATENTS file in the same directory. |
| */ |
| |
| #if defined (__cplusplus) |
| extern "C" { |
| #endif |
| |
| #ifndef ZSTD_H_235446 |
| #define ZSTD_H_235446 |
| |
| /* ====== Dependency ======*/ |
| #include <stddef.h> /* size_t */ |
| |
| |
| /* ===== ZSTDLIB_API : control library symbols visibility ===== */ |
| #if defined(__GNUC__) && (__GNUC__ >= 4) |
| # define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default"))) |
| #else |
| # define ZSTDLIB_VISIBILITY |
| #endif |
| #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1) |
| # define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBILITY |
| #elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1) |
| # define ZSTDLIB_API __declspec(dllimport) ZSTDLIB_VISIBILITY /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/ |
| #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 memory management) |
| - unbounded multiple steps (described as Streaming compression) |
| The compression ratio achievable on small data can be highly improved using compression with a dictionary in: |
| - a single step (described as Simple dictionary API) |
| - a single step, reusing a dictionary (described as Fast dictionary API) |
| |
| Advanced experimental functions can be accessed using #define ZSTD_STATIC_LINKING_ONLY before including zstd.h. |
| These 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 0 |
| |
| #define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) |
| ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< to be used when checking 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); |
| |
| |
| /*************************************** |
| * Simple API |
| ***************************************/ |
| /*! ZSTD_compress() : |
| * Compresses `src` content as a single zstd compressed frame into already allocated `dst`. |
| * Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`. |
| * @return : compressed size written into `dst` (<= `dstCapacity), |
| * or an error code if it fails (which can be tested using ZSTD_isError()). */ |
| ZSTDLIB_API size_t ZSTD_compress( void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize, |
| int compressionLevel); |
| |
| /*! ZSTD_decompress() : |
| * `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames. |
| * `dstCapacity` is an upper bound of originalSize. |
| * If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data. |
| * @return : the number of bytes decompressed into `dst` (<= `dstCapacity`), |
| * or an errorCode if it fails (which can be tested using ZSTD_isError()). */ |
| ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity, |
| const void* src, size_t compressedSize); |
| |
| /*! ZSTD_getDecompressedSize() : |
| * NOTE: This function is planned to be obsolete, in favor of ZSTD_getFrameContentSize(). |
| * ZSTD_getFrameContentSize() works the same way, |
| * returning the decompressed size of a single frame, |
| * but distinguishes empty frames from frames with an unknown size, or errors. |
| * |
| * 'src' is the start of a zstd compressed frame. |
| * @return : content size to be decompressed, as a 64-bits value _if known_, 0 otherwise. |
| * note 1 : decompressed size is an optional field, it may not be present, typically in streaming mode. |
| * When `return==0`, data to decompress could be any size. |
| * In which case, it's necessary to use streaming mode to decompress data. |
| * Optionally, application can use ZSTD_decompress() while relying on implied limits. |
| * (For example, data may be necessarily cut into blocks <= 16 KB). |
| * note 2 : decompressed size is always present when compression is done with ZSTD_compress() |
| * note 3 : 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 4 : If source is untrusted, decompressed size could be wrong or intentionally modified. |
| * Always ensure result fits within application's authorized limits. |
| * Each application can set its own limits. |
| * note 5 : when `return==0`, if precise failure cause is needed, use ZSTD_getFrameParams() to know more. */ |
| ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize); |
| |
| |
| /*====== Helper functions ======*/ |
| ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */ |
| ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case scenario */ |
| ZSTDLIB_API unsigned ZSTD_isError(size_t code); /*!< tells if a `size_t` function result is an error code */ |
| ZSTDLIB_API const char* ZSTD_getErrorName(size_t code); /*!< provides readable string from an error code */ |
| |
| |
| /*************************************** |
| * Explicit memory management |
| ***************************************/ |
| /*= 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. */ |
| typedef struct ZSTD_CCtx_s ZSTD_CCtx; |
| ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void); |
| ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx); |
| |
| /*! ZSTD_compressCCtx() : |
| * Same as ZSTD_compress(), requires an allocated ZSTD_CCtx (see ZSTD_createCCtx()). */ |
| ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* ctx, |
| void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize, |
| int compressionLevel); |
| |
| /*= 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. */ |
| typedef struct ZSTD_DCtx_s ZSTD_DCtx; |
| ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx(void); |
| ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx); |
| |
| /*! ZSTD_decompressDCtx() : |
| * Same as ZSTD_decompress(), requires an allocated ZSTD_DCtx (see ZSTD_createDCtx()) */ |
| ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* ctx, |
| void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize); |
| |
| |
| /************************** |
| * Simple dictionary API |
| ***************************/ |
| /*! ZSTD_compress_usingDict() : |
| * Compression using a predefined Dictionary (see dictBuilder/zdict.h). |
| * Note : This function loads the dictionary, resulting in significant startup delay. |
| * Note : When `dict == NULL || dictSize < 8` no dictionary is used. */ |
| ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx, |
| void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize, |
| const void* dict,size_t dictSize, |
| int compressionLevel); |
| |
| /*! ZSTD_decompress_usingDict() : |
| * Decompression using a predefined Dictionary (see dictBuilder/zdict.h). |
| * Dictionary must be identical to the one used during compression. |
| * Note : This function loads the dictionary, resulting in significant startup delay. |
| * Note : When `dict == NULL || dictSize < 8` no dictionary is used. */ |
| ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx, |
| void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize, |
| const void* dict,size_t dictSize); |
| |
| |
| /**************************** |
| * Fast dictionary API |
| ****************************/ |
| typedef struct ZSTD_CDict_s ZSTD_CDict; |
| |
| /*! 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 used by multiple threads concurrently, as its usage is read-only. |
| * `dictBuffer` can be released after ZSTD_CDict creation, as 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(). */ |
| ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict); |
| |
| /*! 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); |
| |
| |
| typedef struct ZSTD_DDict_s ZSTD_DDict; |
| |
| /*! ZSTD_createDDict() : |
| * Create 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 */ |
| ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize); |
| |
| /*! ZSTD_freeDDict() : |
| * Function frees memory allocated with ZSTD_createDDict() */ |
| ZSTDLIB_API size_t ZSTD_freeDDict(ZSTD_DDict* ddict); |
| |
| /*! ZSTD_decompress_usingDDict() : |
| * Decompression using a digested Dictionary. |
| * Faster startup than ZSTD_decompress_usingDict(), recommended when same dictionary is used multiple times. */ |
| ZSTDLIB_API size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx, |
| void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize, |
| const ZSTD_DDict* ddict); |
| |
| |
| /**************************** |
| * Streaming |
| ****************************/ |
| |
| typedef struct ZSTD_inBuffer_s { |
| const void* src; /**< start of input buffer */ |
| size_t size; /**< size of input buffer */ |
| size_t pos; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */ |
| } ZSTD_inBuffer; |
| |
| typedef struct ZSTD_outBuffer_s { |
| void* dst; /**< start of output buffer */ |
| size_t size; /**< size of output buffer */ |
| size_t pos; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */ |
| } ZSTD_outBuffer; |
| |
| |
| |
| /*-*********************************************************************** |
| * Streaming compression - HowTo |
| * |
| * A ZSTD_CStream object is required to track streaming operation. |
| * Use ZSTD_createCStream() and ZSTD_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. |
| * |
| * 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 effectively same object */ |
| /* Continue due distinghish 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 =====*/ |
| ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel); |
| ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input); |
| ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); |
| ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); |
| |
| ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */ |
| ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances. */ |
| |
| |
| |
| /*-*************************************************************************** |
| * Streaming decompression - HowTo |
| * |
| * A ZSTD_DStream object is required to track streaming operations. |
| * Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources. |
| * ZSTD_DStream objects can be re-used multiple times. |
| * |
| * Use ZSTD_initDStream() to start a new decompression operation, |
| * or ZSTD_initDStream_usingDict() if decompression requires a dictionary. |
| * @return : recommended first input size |
| * |
| * 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. |
| * If `output.pos < output.size`, decoder has flushed everything it could. |
| * @return : 0 when a frame is completely decoded and fully flushed, |
| * an error code, which can be tested using ZSTD_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 (a hint to improve latency) that will never load more than the current frame. |
| * *******************************************************************************/ |
| |
| typedef struct ZSTD_DStream_s ZSTD_DStream; |
| /*===== ZSTD_DStream management functions =====*/ |
| ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void); |
| ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds); |
| |
| /*===== Streaming decompression functions =====*/ |
| ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds); |
| ZSTDLIB_API size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input); |
| |
| ZSTDLIB_API size_t ZSTD_DStreamInSize(void); /*!< recommended size for input buffer */ |
| ZSTDLIB_API size_t ZSTD_DStreamOutSize(void); /*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */ |
| |
| #endif /* ZSTD_H_235446 */ |
| |
| |
| #if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY) |
| #define ZSTD_H_ZSTD_STATIC_LINKING_ONLY |
| |
| /**************************************************************************************** |
| * START OF ADVANCED AND EXPERIMENTAL FUNCTIONS |
| * The definitions in this section are considered experimental. |
| * They should never be used with a dynamic library, as they may change in the future. |
| * They are provided for advanced usages. |
| * Use them only in association with static linking. |
| * ***************************************************************************************/ |
| |
| /* --- Constants ---*/ |
| #define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */ |
| #define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U |
| |
| #define ZSTD_WINDOWLOG_MAX_32 27 |
| #define ZSTD_WINDOWLOG_MAX_64 27 |
| #define ZSTD_WINDOWLOG_MAX ((unsigned)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64)) |
| #define ZSTD_WINDOWLOG_MIN 10 |
| #define ZSTD_HASHLOG_MAX ZSTD_WINDOWLOG_MAX |
| #define ZSTD_HASHLOG_MIN 6 |
| #define ZSTD_CHAINLOG_MAX (ZSTD_WINDOWLOG_MAX+1) |
| #define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN |
| #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 4 |
| #define ZSTD_TARGETLENGTH_MAX 999 |
| |
| #define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */ |
| #define ZSTD_FRAMEHEADERSIZE_MIN 6 |
| static const size_t ZSTD_frameHeaderSize_prefix = 5; |
| 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 */ |
| unsigned chainLog; /**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */ |
| unsigned hashLog; /**< dispatch table : larger == faster, more memory */ |
| unsigned searchLog; /**< nb of searches : larger == more compression, slower */ |
| unsigned searchLength; /**< match length searched : larger == faster decompression, sometimes less compression */ |
| unsigned targetLength; /**< acceptable match size for optimal parser (only) : larger == more compression, slower */ |
| ZSTD_strategy strategy; |
| } ZSTD_compressionParameters; |
| |
| typedef struct { |
| unsigned contentSizeFlag; /**< 1: content size will be in frame header (when known) */ |
| unsigned checksumFlag; /**< 1: generate a 32-bits checksum at end of frame, for error detection */ |
| unsigned noDictIDFlag; /**< 1: no dictID will be saved into frame header (if dictionary compression) */ |
| } ZSTD_frameParameters; |
| |
| typedef struct { |
| ZSTD_compressionParameters cParams; |
| ZSTD_frameParameters fParams; |
| } ZSTD_parameters; |
| |
| typedef struct { |
| unsigned long long frameContentSize; |
| unsigned windowSize; |
| unsigned dictID; |
| unsigned checksumFlag; |
| } ZSTD_frameHeader; |
| |
| /*= Custom memory allocation functions */ |
| typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size); |
| typedef void (*ZSTD_freeFunction) (void* opaque, void* address); |
| typedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem; |
| |
| /*************************************** |
| * Frame size functions |
| ***************************************/ |
| |
| /*! ZSTD_findFrameCompressedSize() : |
| * `src` should point to the start of a ZSTD encoded frame or skippable frame |
| * `srcSize` must be at least as large as the frame |
| * @return : the compressed size of the frame pointed to by `src`, |
| * suitable to pass to `ZSTD_decompress` or similar, |
| * or an error code if given invalid input. */ |
| ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize); |
| |
| /*! ZSTD_getFrameContentSize() : |
| * `src` should point to the start of a ZSTD encoded frame. |
| * `srcSize` must be at least as large as the frame header. |
| * A value >= `ZSTD_frameHeaderSize_max` is guaranteed to be large enough. |
| * @return : - decompressed size of the frame pointed to be `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) */ |
| #define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1) |
| #define ZSTD_CONTENTSIZE_ERROR (0ULL - 2) |
| ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize); |
| |
| /*! ZSTD_findDecompressedSize() : |
| * `src` should point the start of a series of ZSTD encoded and/or skippable frames |
| * `srcSize` must be the _exact_ size of this series |
| * (i.e. there should be a frame boundary exactly `srcSize` bytes after `src`) |
| * @return : - decompressed size of all data in all successive frames |
| * - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN |
| * - if an error occurred: ZSTD_CONTENTSIZE_ERROR |
| * |
| * note 1 : decompressed size is an optional field, that may not be present, especially 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 still use ZSTD_decompress() while relying on implied limits. |
| * (For example, data may be necessarily cut into blocks <= 16 KB). |
| * note 2 : decompressed size is always present when compression is done with ZSTD_compress() |
| * note 3 : 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 4 : If source is untrusted, decompressed size could be wrong or intentionally modified. |
| * Always ensure result fits within application's authorized limits. |
| * Each application can set its own limits. |
| * note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to |
| * read each contained frame header. This is efficient 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); |
| |
| |
| /*************************************** |
| * Context memory usage |
| ***************************************/ |
| |
| /*! ZSTD_sizeof_*() : |
| * These functions give the current memory usage of selected object. |
| * Object memory usage can evolve if it's re-used multiple times. */ |
| ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); |
| ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx); |
| ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs); |
| ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds); |
| ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict); |
| ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); |
| |
| /*! ZSTD_estimate*() : |
| * These functions make it possible to estimate memory usage |
| * of a future target object, before its allocation, |
| * given a set of parameters, which vary depending on target object. |
| * The objective is to guide decision before allocation. */ |
| ZSTDLIB_API size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams); |
| ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); |
| |
| /*! ZSTD_estimate?StreamSize() : |
| * Note : if streaming is init with function ZSTD_init?Stream_usingDict(), |
| * an internal ?Dict will be created, which size is not estimated. |
| * In this case, get additional size by using ZSTD_estimate?DictSize */ |
| ZSTDLIB_API size_t ZSTD_estimateCStreamSize(ZSTD_compressionParameters cParams); |
| ZSTDLIB_API size_t ZSTD_estimateDStreamSize(ZSTD_frameHeader fHeader); |
| |
| /*! ZSTD_estimate?DictSize() : |
| * Note : if dictionary is created "byReference", reduce estimation by dictSize */ |
| ZSTDLIB_API size_t ZSTD_estimateCDictSize(ZSTD_compressionParameters cParams, size_t dictSize); |
| ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize); |
| |
| |
| /*************************************** |
| * Advanced compression functions |
| ***************************************/ |
| /*! ZSTD_createCCtx_advanced() : |
| * Create a ZSTD compression context using external alloc and free functions */ |
| ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem); |
| |
| |
| /* !!! Soon to be deprecated !!! */ |
| typedef enum { |
| ZSTD_p_forceWindow, /* Force back-references to remain < windowSize, even when referencing Dictionary content (default:0) */ |
| ZSTD_p_forceRawDict /* Force loading dictionary in "content-only" mode (no header analysis) */ |
| } ZSTD_CCtxParameter; |
| /*! ZSTD_setCCtxParameter() : |
| * Set advanced parameters, selected through enum ZSTD_CCtxParameter |
| * @result : 0, or an error code (which can be tested with ZSTD_isError()) */ |
| ZSTDLIB_API size_t ZSTD_setCCtxParameter(ZSTD_CCtx* cctx, ZSTD_CCtxParameter param, unsigned value); |
| |
| /*! ZSTD_createCDict_byReference() : |
| * Create a digested dictionary for compression |
| * Dictionary content is simply referenced, and therefore stays in dictBuffer. |
| * It is important that dictBuffer outlives CDict, it must remain read accessible throughout the lifetime of CDict */ |
| ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel); |
| |
| /*! ZSTD_createCDict_advanced() : |
| * Create a ZSTD_CDict using external alloc and free, and customized compression parameters */ |
| ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, unsigned byReference, |
| ZSTD_compressionParameters cParams, ZSTD_customMem customMem); |
| |
| /*! ZSTD_getCParams() : |
| * @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize. |
| * `estimatedSrcSize` value is optional, select 0 if not known */ |
| ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); |
| |
| /*! ZSTD_getParams() : |
| * same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of sub-component `ZSTD_compressionParameters`. |
| * All fields of `ZSTD_frameParameters` are set to default (0) */ |
| ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); |
| |
| /*! ZSTD_checkCParams() : |
| * Ensure param values remain within authorized range */ |
| ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params); |
| |
| /*! ZSTD_adjustCParams() : |
| * optimize params for a given `srcSize` and `dictSize`. |
| * both values are optional, select `0` if unknown. */ |
| ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize); |
| |
| /*! ZSTD_compress_advanced() : |
| * Same as ZSTD_compress_usingDict(), with fine-tune control over each compression parameter */ |
| ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* cctx, |
| void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize, |
| const void* dict,size_t dictSize, |
| ZSTD_parameters params); |
| |
| /*! ZSTD_compress_usingCDict_advanced() : |
| * Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters */ |
| ZSTDLIB_API size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx, |
| void* dst, size_t dstCapacity, |
| const void* src, size_t srcSize, |
| const ZSTD_CDict* cdict, ZSTD_frameParameters fParams); |
| |
| |
| /*=== New experimental advanced parameters API ===*/ |
| |
| /* notes on API design : |
| * In this proposal, parameters are pushed one by one into an existing CCtx, |
| * and then applied on all following compression jobs. |
| * When no parameter is ever provided, CCtx is created with compression level 3. |
| * |
| * Another approach could be to load parameters into an intermediate _opaque_ object. |
| * The object would then be loaded into CCtx (like ZSTD_compress_advanced()) |
| * This approach would be compatible with ZSTD_createCDict_advanced(). |
| * But it's more cumbersome for CCtx, as it requires to manage an additional object. |
| * |
| * Below proposal push parameters directly into CCtx. |
| * It's a bit more complex for CDict, as advanced version now requires 3 steps. |
| * (basic CDict API remains the same). |
| * See API details below |
| */ |
| |
| /* notes on naming convention : |
| * Initially, the API favored names like ZSTD_setCCtxParameter() . |
| * In this proposal, convention is changed towards ZSTD_CCtx_setParameter() . |
| * The main idea is that it identifies more clearly the target object type. |
| * It feels clearer when considering other potential variants : |
| * ZSTD_CDict_setParameter() (rather than ZSTD_setCDictParameter()) |
| * ZSTD_DCtx_setParameter() (rather than ZSTD_setDCtxParameter() ) |
| * The left variant looks clearer. |
| */ |
| |
| typedef enum { |
| /* compression parameters */ |
| ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table |
| * Default level is 3. |
| * Special: value 0 means "do not change cLevel". */ |
| ZSTD_p_windowLog, /* Maximum allowed back-reference distance, expressed as power of 2. |
| * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX. |
| * default value : set through compressionLevel. |
| * Special: value 0 means "do not change windowLog". */ |
| 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 "do not change 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 "do not change 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 "do not change searchLog". */ |
| ZSTD_p_minMatch, /* Minimum size of searched matches (note : repCode matches can be smaller). |
| * Larger values make faster compression and decompression, but decrease ratio. |
| * Must be clamped between ZSTD_SEARCHLENGTH_MIN and ZSTD_SEARCHLENGTH_MAX. |
| * Note that currently, for all strategies < btopt, effective minimum is 4. |
| * Note that currently, for all strategies > fast, effective maximum is 6. |
| * Special: value 0 means "do not change minMatchLength". */ |
| ZSTD_p_targetLength, /* Only useful for strategies >= btopt. |
| * Length of Match considered "good enough" to stop search. |
| * Larger values make compression stronger and slower. |
| * Special: value 0 means "do not change targetLength". */ |
| ZSTD_p_compressionStrategy, /* See ZSTD_strategy enum definition. |
| * Cast selected strategy as unsigned for ZSTD_CCtx_setParameter() compatibility. |
| * The higher the value of selected strategy, the more complex it is, |
| * resulting in stronger and slower compression. |
| * Special: value 0 means "do not change strategy". */ |
| #if 0 |
| ZSTD_p_windowSize, /* Maximum allowed back-reference distance. |
| * Can be set to a more precise value than windowLog. |
| * Will be transparently reduced to closest possible inferior value |
| * (see Zstandard compression format) */ |
| /* Not ready yet ! */ |
| #endif |
| |
| /* frame parameters */ |
| ZSTD_p_contentSizeFlag=200, /* Content size is written into frame header _whenever known_ (default:1) */ |
| ZSTD_p_checksumFlag, /* A 32-bits checksum of content is written at end of frame (default:0) */ |
| ZSTD_p_dictIDFlag, /* When applicable, dictID of dictionary is provided in frame header (default:1) */ |
| |
| /* dictionary parameters */ |
| ZSTD_p_refDictContent=300, /* Content of dictionary content will be referenced, instead of copied (default:0). |
| * This avoids duplicating dictionary content. |
| * But it also requires that dictionary buffer outlives its user (CDict) */ |
| /* Not ready yet ! */ |
| ZSTD_p_rawContentDict, /* load dictionary in "content-only" mode (no header analysis) (default:0) */ |
| /* question : should there be an option to load dictionary only in zstd format, rejecting others with an error code ? */ |
| |
| #if 0 |
| /* multi-threading parameters (not ready yet !) */ |
| ZSTD_p_nbThreads=400, /* Select how many threads a compression job can spawn (default:1) |
| * More threads improve speed, but increases also memory usage */ |
| ZSTDMT_p_jobSize, /* Size of a compression job. Each job is compressed in parallel. |
| * 0 means default, which is dynamically determined based on compression parameters. |
| * Job size must be a minimum of overlapSize, or 1 KB, whichever is largest |
| * The minimum size is automatically and transparently enforced */ |
| ZSTDMT_p_overlapSizeLog, /* Size of previous input reloaded at the beginning of each job. |
| * 0 => no overlap, 6(default) => use 1/8th of windowSize, >=9 => use full windowSize */ |
| #endif |
| |
| /* advanced parameters - may not remain available after API update */ |
| ZSTD_p_forceMaxWindow=1100, /* Force back-references to remain < windowSize, |
| * even when referencing into Dictionary content |
| * default : 0 when using a CDict, 1 when using a Prefix */ |
| } ZSTD_cParameter; |
| |
| |
| /*! ZSTD_CCtx_setParameter() : |
| * Set one compression parameter, selected by enum ZSTD_cParameter. |
| * 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_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value); |
| |
| /*! ZSTD_CCtx_setPledgedSrcSize() : |
| * Total input data size to be compressed into 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 1 : 0 means zero, empty. |
| * In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN. |
| * Note that ZSTD_CONTENTSIZE_UNKNOWN is default value for all new compression jobs. |
| * Note 2 : If all data is provided and consumed in a single round, |
| * this value is overriden by srcSize instead. */ |
| ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize); |
| |
| /*! ZSTD_CCtx_loadDictionary() : |
| * Create an internal CDict from dict buffer. |
| * Decompression will have to use same buffer. |
| * @result : 0, or an error code (which can be tested with ZSTD_isError()). |
| * Special : Adding a NULL (or 0-size) dictionary invalidates any previous prefix, |
| * meaning "return to no-dictionary mode". |
| * Note 1 : Dictionary content will be copied internally, |
| * except if ZSTD_p_refDictContent is set. |
| * Note 2 : Loading a dictionary involves building tables, which are dependent on compression parameters. |
| * For this reason, compression parameters cannot be changed anymore after loading a prefix. |
| * It's also a CPU-heavy operation, with non-negligible impact on latency. |
| * Note 3 : Dictionary will be used for all future compression jobs. |
| * To return to "no-dictionary" situation, load a NULL dictionary */ |
| ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); /* Not ready yet ! */ |
| |
| /*! ZSTD_CCtx_refPrefix() : |
| * Reference a prefix (content-only dictionary) to bootstrap next compression job. |
| * Decompression will have to use same prefix. |
| * @result : 0, or an error code (which can be tested with ZSTD_isError()). |
| * Special : Adding a NULL (or 0-size) dictionary invalidates any previous prefix, meaning "return to no-dictionary mode". |
| * Note 1 : Prefix buffer is referenced. It must outlive compression job. |
| * Note 3 : Prefix is only used once. Tables are discarded at end of compression job. |
| * If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_CDict. |
| * Note 2 : Referencing a prefix involves building tables, which are dependent on compression parameters. |
| * For this reason, compression parameters cannot be changed anymore after loading a prefix. |
| * It's also a CPU-heavy operation, with non-negligible impact on latency. */ |
| ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize); /* Not ready yet ! */ |
| |
| |
| /*! ZSTD_CDict_createEmpty() : |
| * Create a CDict object which is still mutable after creation. |
| * It's the only one case allowing usage of ZSTD_CDict_setParameter(). |
| * Once all compression parameters are selected, |
| * it's possible to load the target dictionary, using ZSTD_CDict_loadDictionary(). |
| * Dictionary content will be copied internally (except if ZSTD_p_refDictContent is set). |
| * After loading the dictionary, no more change is possible. |
| * The only remaining operation is to free CDict object. |
| * Note : An unfinished CDict behaves the same as a NULL CDict if referenced into a CCtx. |
| */ |
| ZSTDLIB_API ZSTD_CDict* ZSTD_CDict_createEmpty(void); /* Not ready yet ! */ |
| ZSTDLIB_API size_t ZSTD_CDict_setParameter(ZSTD_CDict* cdict, ZSTD_cParameter param, unsigned value); /* Not ready yet ! */ |
| ZSTDLIB_API size_t ZSTD_CDict_loadDictionary(ZSTD_CDict* cdict, const void* dict, size_t dictSize); /* Not ready yet ! */ |
| |
| /*! ZSTD_CCtx_refCDict() : |
| * Add a prepared dictionary to cctx, to be used for next compression jobs. |
| * Note that compression parameters will be enforced from within CDict. |
| * Currently, they supercede any compression parameter previously set within CCtx. |
| * The dictionary will remain valid for future compression jobs using same cctx. |
| * @result : 0, or an error code (which can be tested with ZSTD_isError()). |
| * Special : adding a NULL CDict means "return to no-dictionary mode". |
| * Note 1 : Currently, only one dictionary can be managed. |
| * Adding a new dictionary effectively "discards" any previous one. |
| * 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); /* Not ready yet ! */ |
| |
| |
| |
| typedef enum { |
| ZSTD_e_continue=0, /* collect more data, encoder transparently decides when to output result, for optimal conditions */ |
| ZSTD_e_flush, /* flush any data provided so far - frame will continue, future data can still reference previous data for better compression */ |
| ZSTD_e_end /* flush any remaining data and ends current frame. Any future compression starts a new frame. */ |
| } ZSTD_EndDirective; |
| |
| /*! ZSTD_compressStream_generic() : |
| * Behave about the same as ZSTD_compressStream. To note : |
| * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_setCCtxParameter() |
| * - Compression parameters cannot be changed once compression is started. |
| * - *dstPos must be <= dstCapacity, *srcPos must be <= srcSize |
| * - *dspPos and *srcPos will be updated. They are guaranteed to remain below their respective limit. |
| * - @return provides the amount of data ready to flush within internal buffers |
| * or an error code, which can be tested using ZSTD_isError(). |
| * if @return != 0, flush is not fully completed, and must be called again to empty internal buffers. |
| * - after a ZSTD_e_end directive, if internal buffer is not fully flushed, |
| * only ZSTD_e_end and ZSTD_e_flush operations are allowed. |
| * It is necessary to fully flush internal buffers |
| * before changing compression parameters or start a new compression job. |
| */ |
| ZSTDLIB_API size_t ZSTD_compress_generic (ZSTD_CCtx* cctx, |
| ZSTD_outBuffer* output, |
| ZSTD_inBuffer* input, |
| ZSTD_EndDirective endOp); |
| |
| /*! 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. |
| * It's possible to modify compression parameters after a reset. |
| * Any internal data not yet flushed is cancelled. |
| */ |
| ZSTDLIB_API size_t ZSTD_CCtx_reset(ZSTD_CCtx* cctx); /* Not ready yet ! */ |
| |
| |
| |
| /*--- Advanced decompression functions ---*/ |
| |
| /*! ZSTD_isFrame() : |
| * Tells if the content of `buffer` starts with a valid Frame Identifier. |
| * Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0. |
| * Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled. |
| * Note 3 : Skippable Frame Identifiers are considered valid. */ |
| ZSTDLIB_API unsigned ZSTD_isFrame(const void* buffer, size_t size); |
| |
| /*! ZSTD_createDCtx_advanced() : |
| * Create a ZSTD decompression context using external alloc and free functions */ |
| ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem); |
| |
| /*! ZSTD_createDDict_byReference() : |
| * Create a digested dictionary, ready to start decompression operation without startup delay. |
| * Dictionary content is simply referenced, and therefore stays in dictBuffer. |
| * It is important that dictBuffer outlives DDict, it must remain read accessible throughout the lifetime of DDict */ |
| ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize); |
| |
| /*! ZSTD_createDDict_advanced() : |
| * Create a ZSTD_DDict using external alloc and free, optionally by reference */ |
| ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, |
| unsigned byReference, ZSTD_customMem customMem); |
| |
| /*! ZSTD_getDictID_fromDict() : |
| * Provides the dictID stored within dictionary. |
| * if @return == 0, the dictionary is not conformant with Zstandard specification. |
| * It can still be loaded, but as a content-only dictionary. */ |
| ZSTDLIB_API unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize); |
| |
| /*! ZSTD_getDictID_fromDDict() : |
| * Provides the dictID of the dictionary loaded into `ddict`. |
| * If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. |
| * Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */ |
| ZSTDLIB_API unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict); |
| |
| /*! ZSTD_getDictID_fromFrame() : |
| * Provides the dictID required to decompressed the frame stored within `src`. |
| * If @return == 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 < ZSTD_FRAMEHEADERSIZE_MAX`). |
| * - This is not a Zstandard frame. |
| * When identifying the exact failure cause, it's possible to use ZSTD_getFrameParams(), which will provide a more precise error code. */ |
| ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize); |
| |
| |
| /******************************************************************** |
| * Advanced streaming functions |
| ********************************************************************/ |
| |
| /*===== Advanced Streaming compression functions =====*/ |
| ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem); |
| ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct, a size of 0 means unknown. for a frame size of 0 use initCStream_advanced */ |
| ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); /**< note: a dict will not be used if dict == NULL or dictSize < 8. This result in the creation of an internal CDict */ |
| ZSTDLIB_API size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize, |
| ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize is optional and can be 0 (meaning unknown). note: if the contentSizeFlag is set, pledgedSrcSize == 0 means the source size is actually 0 */ |
| 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, unsigned long long pledgedSrcSize, ZSTD_frameParameters fParams); /**< same as ZSTD_initCStream_usingCDict(), with control over frame parameters */ |
| |
| /*! 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(). |
| * pledgedSrcSize==0 means "srcSize unknown". |
| * If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end. |
| * @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); |
| |
| |
| /*===== Advanced Streaming decompression functions =====*/ |
| typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e; |
| ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem); |
| ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue); |
| ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); /**< note: a dict will not be used if dict == NULL or dictSize < 8 */ |
| ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); /**< note : ddict will just be referenced, and must outlive decompression session */ |
| ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); /**< re-use decompression parameters from previous init; saves dictionary loading */ |
| |
| |
| /********************************************************************* |
| * Buffer-less and synchronous inner streaming functions |
| * |
| * This is an advanced API, giving full control over buffer management, for users which need direct control over memory. |
| * But it's also a complex one, with many restrictions (documented below). |
| * Prefer using normal streaming API for an easier experience |
| ********************************************************************* */ |
| |
| /** |
| Buffer-less streaming compression (synchronous mode) |
| |
| A ZSTD_CCtx object is required to track streaming operations. |
| Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource. |
| ZSTD_CCtx object can be re-used multiple times within successive compression operations. |
| |
| Start by initializing a context. |
| Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression, |
| or ZSTD_compressBegin_advanced(), for finer parameter control. |
| It's also possible to duplicate a reference context which has already been initialized, using ZSTD_copyCCtx() |
| |
| Then, consume your input using ZSTD_compressContinue(). |
| There are some important considerations to keep in mind when using this advanced function : |
| - ZSTD_compressContinue() has no internal buffer. It uses externally provided buffer only. |
| - Interface is synchronous : input is consumed entirely and produce 1+ (or more) compressed blocks. |
| - Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario. |
| Worst case evaluation is provided by ZSTD_compressBound(). |
| ZSTD_compressContinue() doesn't guarantee recover after a failed compression. |
| - ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog). |
| It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks) |
| - ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps. |
| In which case, it will "discard" the relevant memory section from its history. |
| |
| Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum. |
| It's possible to use srcSize==0, in which case, it will write a final empty block to end the frame. |
| Without last block mark, frames will be considered unfinished (corrupted) by decoders. |
| |
| `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress some new frame. |
| */ |
| |
| /*===== Buffer-less streaming compression functions =====*/ |
| ZSTDLIB_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel); |
| ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel); |
| ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize is optional and can be 0 (meaning unknown). note: if the contentSizeFlag is set, pledgedSrcSize == 0 means the source size is actually 0 */ |
| ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); /**< note: fails if cdict==NULL */ |
| ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict_advanced(ZSTD_CCtx* const cctx, const ZSTD_CDict* const cdict, ZSTD_frameParameters const fParams, unsigned long long const pledgedSrcSize); /* compression parameters are already set within cdict. pledgedSrcSize=0 means null-size */ |
| ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); /**< note: if pledgedSrcSize can be 0, indicating unknown size. if it is non-zero, it must be accurate. for 0 size frames, use compressBegin_advanced */ |
| |
| ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); |
| ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); |
| |
| |
| |
| /*- |
| Buffer-less streaming decompression (synchronous mode) |
| |
| A ZSTD_DCtx object is required to track streaming operations. |
| Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it. |
| A ZSTD_DCtx object can be re-used multiple times. |
| |
| First typical operation is to retrieve frame parameters, using ZSTD_getFrameParams(). |
| It fills a ZSTD_frameParams structure which provide important information to correctly decode the frame, |
| such as the minimum rolling buffer size to allocate to decompress data (`windowSize`), |
| and the dictionary ID used. |
| (Note : content size is optional, it may not be present. 0 means : content size unknown). |
| Note that these values could be wrong, either because of data malformation, or because an attacker is spoofing deliberate false information. |
| As a consequence, check that values remain within valid application range, especially `windowSize`, before allocation. |
| Each application can set its own limit, depending on local restrictions. For extended interoperability, it is recommended to support at least 8 MB. |
| Frame parameters are extracted from the beginning of the compressed frame. |
| Data fragment must be large enough to ensure successful decoding, typically `ZSTD_frameHeaderSize_max` bytes. |
| @result : 0 : successful decoding, the `ZSTD_frameParams` structure is correctly filled. |
| >0 : `srcSize` is too small, please provide at least @result bytes on next attempt. |
| errorCode, which can be tested using ZSTD_isError(). |
| |
| Start decompression, with ZSTD_decompressBegin(). |
| If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict(). |
| Alternatively, you can copy a prepared context, using ZSTD_copyDCtx(). |
| |
| Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively. |
| ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue(). |
| ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail. |
| |
| @result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity). |
| It can be zero, which is not an error; it just means ZSTD_decompressContinue() has decoded some metadata item. |
| It can also be an error code, which can be tested with ZSTD_isError(). |
| |
| ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize`. |
| They should preferably be located contiguously, prior to current block. |
| Alternatively, a round buffer of sufficient size is also possible. Sufficient size is determined by frame parameters. |
| ZSTD_decompressContinue() is very sensitive to contiguity, |
| if 2 blocks don't follow each other, make sure that either the compressor breaks contiguity at the same place, |
| or that previous contiguous segment is large enough to properly handle maximum back-reference. |
| |
| A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero. |
| Context can then be reset to start a new decompression. |
| |
| Note : it's possible to know if next input to present is a header or a block, using ZSTD_nextInputType(). |
| This information is not required to properly decode a frame. |
| |
| == Special case : skippable frames == |
| |
| Skippable frames allow integration of user-defined data into a flow of concatenated frames. |
| Skippable frames will be ignored (skipped) by a decompressor. The format of skippable frames is as follows : |
| a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F |
| b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits |
| c) Frame Content - any content (User Data) of length equal to Frame Size |
| For skippable frames ZSTD_decompressContinue() always returns 0. |
| For skippable frames ZSTD_getFrameParams() returns fparamsPtr->windowLog==0 what means that a frame is skippable. |
| Note : If fparamsPtr->frameContentSize==0, it is ambiguous: the frame might actually be a Zstd encoded frame with no content. |
| For purposes of decompression, it is valid in both cases to skip the frame using |
| ZSTD_findFrameCompressedSize to find its size in bytes. |
| It also returns Frame Size as fparamsPtr->frameContentSize. |
| */ |
| |
| /*===== Buffer-less streaming decompression functions =====*/ |
| ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input, see details below */ |
| 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); |
| ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); |
| ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx); |
| |
| ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx); |
| ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); |
| typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e; |
| ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); |
| |
| /** |
| Block functions |
| |
| Block functions produce and decode raw zstd blocks, without frame metadata. |
| Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes). |
| User will have to take in charge required information to regenerate data, such as compressed and content sizes. |
| |
| A few rules to respect : |
| - Compressing and decompressing require a context structure |
| + Use ZSTD_createCCtx() and ZSTD_createDCtx() |
| - It is necessary to init context before starting |
| + compression : any ZSTD_compressBegin*() variant, including with dictionary |
| + decompression : any ZSTD_decompressBegin*() variant, including with dictionary |
| + copyCCtx() and copyDCtx() can be used too |
| - Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX |
| + If input is larger than a block size, it's necessary to split input data into multiple blocks |
| + For inputs larger than a single block size, consider using the regular ZSTD_compress() instead. |
| Frame metadata is not that costly, and quickly becomes negligible as source size grows larger. |
| - When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero. |
| In which case, nothing is produced into `dst`. |
| + User must test for such outcome and deal directly with uncompressed data |
| + ZSTD_decompressBlock() doesn't accept uncompressed data as input !!! |
| + In case of multiple successive blocks, should some of them be uncompressed, |
| 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 block into `dctx` history. Useful for uncompressed blocks */ |
| |
| |
| #endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */ |
| |
| #if defined (__cplusplus) |
| } |
| #endif |
