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Diffstat (limited to 'contrib/zstd/zstd.h')
| -rw-r--r-- | contrib/zstd/zstd.h | 629 |
1 files changed, 421 insertions, 208 deletions
diff --git a/contrib/zstd/zstd.h b/contrib/zstd/zstd.h index bd5d68b27..eef2b0b5e 100644 --- a/contrib/zstd/zstd.h +++ b/contrib/zstd/zstd.h @@ -1,4 +1,4 @@ -/** +/* * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. * All rights reserved. * @@ -7,32 +7,55 @@ * of patent rights can be found in the PATENTS file in the same directory. */ -#ifndef ZSTD_H_235446 -#define ZSTD_H_235446 - #if defined (__cplusplus) extern "C" { #endif -/*====== Dependency ======*/ +#ifndef ZSTD_H_235446 +#define ZSTD_H_235446 +#define ZSTD_STATIC_LINKING_ONLY +/* ====== Dependency ======*/ #include <stddef.h> /* size_t */ -/*====== Export for Windows ======*/ -/*! -* ZSTD_DLL_EXPORT : -* Enable exporting of functions when building a Windows DLL -*/ -#if defined(_WIN32) && defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1) -# define ZSTDLIB_API __declspec(dllexport) +/* ===== ZSTDLIB_API : control library symbols visibility ===== */ +#if defined(__GNUC__) && (__GNUC__ >= 4) +# define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default"))) #else -# define ZSTDLIB_API +# 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 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) -/*======= Version =======*/ + 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 0 +#define ZSTD_VERSION_MINOR 3 #define ZSTD_VERSION_RELEASE 0 #define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE @@ -41,47 +64,57 @@ extern "C" { #define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION) #define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) -ZSTDLIB_API unsigned ZSTD_versionNumber (void); +ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< library version number; to be used when checking dll version */ -/* ************************************* +/*************************************** * Simple API ***************************************/ /*! ZSTD_compress() : - Compresses `src` buffer into already allocated `dst`. - Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`. - @return : the number of bytes written into `dst` (<= `dstCapacity), - or an error code if it fails (which can be tested using ZSTD_isError()) */ + * 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_getDecompressedSize() : -* @return : decompressed size as a 64-bits value _if known_, 0 otherwise. -* note 1 : 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 2 : decompressed size is an optional field, that may not be present. -* When `return==0`, data to decompress can have any size. -* In which case, it's necessary to use streaming mode to decompress data. -* Optionally, application may rely on its own implied limits. -* (For example, application data could be necessarily cut into blocks <= 16 KB). -* note 3 : 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 4 : 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); - /*! ZSTD_decompress() : - `compressedSize` : must be the _exact_ size of compressed input, otherwise decompression will fail. - `dstCapacity` must be equal or larger than originalSize (see ZSTD_getDecompressedSize() ). - If originalSize is unknown, and if there is no implied application-specific limitations, - it's preferable 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()) */ + * `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 favour of ZSTD_getFrameContentSize. + * ZSTD_getFrameContentSize functions the same way, returning the decompressed size of a single + * frame, but distinguishes empty frames from frames with an unknown size, or errors. + * + * Additionally, ZSTD_findDecompressedSize can be used instead. It can handle multiple + * concatenated frames in one buffer, and so is more general. + * As a result however, it requires more computation and entire frames to be passed to it, + * as opposed to ZSTD_getFrameContentSize which requires only a single frame's header. + * + * '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, that may not be present, especially 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 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 : 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 */ @@ -90,34 +123,43 @@ ZSTDLIB_API unsigned ZSTD_isError(size_t code); /*!< tells if a `siz ZSTDLIB_API const char* ZSTD_getErrorName(size_t code); /*!< provides readable string from an error code */ -/*-************************************* +/*************************************** * Explicit memory management ***************************************/ -/** Compression context */ +/*= 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()) */ +/*! 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 */ +/*= Decompression context + * When decompressing 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_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()) */ +/*! 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 load the dictionary, resulting in significant startup delay. */ +* 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, @@ -127,41 +169,54 @@ ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx, /*! 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 load the dictionary, resulting in significant startup delay */ +* 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 +/**************************** +* Fast dictionary API ****************************/ -/*! ZSTD_createCDict() : -* Create a digested dictionary, ready to start compression operation without startup delay. -* `dict` can be released after ZSTD_CDict creation */ typedef struct ZSTD_CDict_s ZSTD_CDict; -ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dict, size_t dictSize, int compressionLevel); + +/*! 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 */ + * 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. -* `dict` can be released after creation */ -typedef struct ZSTD_DDict_s ZSTD_DDict; -ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize); +* 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 +* 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, @@ -169,7 +224,7 @@ ZSTDLIB_API size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); -/*-************************** +/**************************** * Streaming ****************************/ @@ -186,31 +241,33 @@ typedef struct ZSTD_outBuffer_s { } ZSTD_outBuffer; -/*====== streaming compression ======*/ /*-*********************************************************************** -* Streaming compression - howto +* 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 by initializing ZSTD_CStream. +* Start a new compression by initializing ZSTD_CStream. * Use ZSTD_initCStream() to start a new compression operation. -* Use ZSTD_initCStream_usingDict() for a compression which requires a dictionary. +* 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`. +* 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 -* (it's just a hint, to help latency a little, any other value will work fine) -* (note : the size hint is guaranteed to be <= ZSTD_CStreamInSize() ) * 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 buffer, using ZSTD_flushStream(). +* At any moment, it's possible to flush whatever data remains within internal buffer, using ZSTD_flushStream(). * `output->pos` will be updated. -* Note some content might still be left within internal buffer if `output->size` is too small. +* 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(). * @@ -219,29 +276,30 @@ typedef struct ZSTD_outBuffer_s { * The epilogue is required for decoders to consider a frame completed. * Similar to ZSTD_flushStream(), it may not be able to flush the full content if `output->size` is too small. * In which case, call again ZSTD_endStream() to complete the flush. -* @return : nb of bytes still present within internal buffer (0 if it's empty) +* @return : nb of bytes still present within internal buffer (0 if it's empty, hence compression completed) * or an error code, which can be tested using ZSTD_isError(). * * *******************************************************************/ -typedef struct ZSTD_CStream_s ZSTD_CStream; +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); -ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */ -ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer */ - +/*===== Streaming compression functions =====*/ ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel); -ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, 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. */ + -/*====== decompression ======*/ /*-*************************************************************************** -* Streaming decompression howto +* Streaming decompression - HowTo * * A ZSTD_DStream object is required to track streaming operations. * Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources. @@ -249,68 +307,75 @@ ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); * * 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`. -* Note that it may not consume the entire input (pos < size), -* in which case it's up to the caller to present remaining input again. +* 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, -* 1 when there is still some data left within internal buffer to flush, -* >1 when more data is expected, with value being a suggested next input size (it's just a hint, which helps latency, any size is accepted), -* or an error code, which can be tested using ZSTD_isError(). -* +* 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); -ZSTDLIB_API size_t ZSTD_DStreamInSize(void); /*!< recommended size for input buffer */ -ZSTDLIB_API size_t ZSTD_DStreamOutSize(void); /*!< recommended size for output buffer */ - +/*===== 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_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); +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 */ -#ifdef ZSTD_STATIC_LINKING_ONLY +#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 */ +/* --- Constants ---*/ +#define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */ #define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U -#define ZSTD_WINDOWLOG_MAX_32 25 +#define ZSTD_WINDOWLOG_MAX_32 27 #define ZSTD_WINDOWLOG_MAX_64 27 -#define ZSTD_WINDOWLOG_MAX ((U32)(MEM_32bits() ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64)) -#define ZSTD_WINDOWLOG_MIN 18 -#define ZSTD_CHAINLOG_MAX (ZSTD_WINDOWLOG_MAX+1) -#define ZSTD_CHAINLOG_MIN 4 +#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 12 +#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 -#define ZSTD_SEARCHLENGTH_MIN 3 +#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 */ -static const size_t ZSTD_frameHeaderSize_min = 5; +#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 */ -/*--- Types ---*/ -typedef enum { ZSTD_fast, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2, ZSTD_btlazy2, ZSTD_btopt } ZSTD_strategy; /* from faster to stronger */ +/*--- Advanced types ---*/ +typedef enum { ZSTD_fast, 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 */ @@ -323,9 +388,9 @@ typedef struct { } ZSTD_compressionParameters; typedef struct { - unsigned contentSizeFlag; /**< 1: content size will be in frame header (if known). */ - unsigned checksumFlag; /**< 1: will generate a 22-bits checksum at end of frame, to be used for error detection by decompressor */ - unsigned noDictIDFlag; /**< 1: no dict ID will be saved into frame header (if dictionary compression) */ + 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 { @@ -333,42 +398,138 @@ typedef struct { ZSTD_frameParameters fParams; } ZSTD_parameters; -/* custom memory allocation functions */ +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 +***************************************/ -/*-************************************* -* Advanced compression 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_estimateCCtxSize() : - * Gives the amount of memory allocated for a ZSTD_CCtx given a set of compression parameters. - * `frameContentSize` is an optional parameter, provide `0` if unknown */ + +/*! 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); +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, - ZSTD_parameters params, ZSTD_customMem customMem); +ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, unsigned byReference, + ZSTD_compressionParameters cParams, ZSTD_customMem customMem); -/*! ZSTD_sizeofCCtx() : - * Gives the amount of memory used by a given ZSTD_CCtx */ -ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); +/*! 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 a `ZSTD_compressionParameters`. +* 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 srcSize, size_t dictSize); - -/*! ZSTD_getCParams() : -* @return ZSTD_compressionParameters structure for a selected compression level and srcSize. -* `srcSize` value is optional, select 0 if not known */ -ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long srcSize, size_t dictSize); +ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); /*! ZSTD_checkCParams() : * Ensure param values remain within authorized range */ @@ -380,67 +541,113 @@ ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params); 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 of each compression parameter */ -ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* ctx, - void* dst, size_t dstCapacity, - const void* src, size_t srcSize, - const void* dict,size_t dictSize, - ZSTD_parameters params); +* 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); -/*--- Advanced Decompression functions ---*/ -/*! ZSTD_estimateDCtxSize() : - * Gives the potential amount of memory allocated to create a ZSTD_DCtx */ -ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); +/*--- 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_sizeofDCtx() : - * Gives the amount of memory used by a given ZSTD_DCtx */ -ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx); - - -/* ****************************************************************** -* Advanced Streaming functions +/*! 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 ********************************************************************/ -/*====== compression ======*/ - +/*===== 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); -ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs); - - -/*====== decompression ======*/ - -typedef enum { ZSTDdsp_maxWindowSize } ZSTD_DStreamParameter_e; - + 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_sizeof_DStream(const ZSTD_DStream* zds); +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. +* +* 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 */ +* Prefer using normal streaming API for an easier experience +********************************************************************* */ -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); -ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx); - -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 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. @@ -463,32 +670,26 @@ ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapaci 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 a NULL,0 src content, in which case, it will write a final empty block to end the frame, - Without last block mark, frames will be considered unfinished (broken) by decoders. + 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. - You can then reuse `ZSTD_CCtx` (ZSTD_compressBegin()) to compress some new frame. + `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress some new frame. */ -typedef struct { - unsigned long long frameContentSize; - unsigned windowSize; - unsigned dictID; - unsigned checksumFlag; -} ZSTD_frameParams; +/*===== 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_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t srcSize); /**< doesn't consume input, see details below */ +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); -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 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); - -/* +/*- Buffer-less streaming decompression (synchronous mode) A ZSTD_DCtx object is required to track streaming operations. @@ -542,14 +743,26 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); 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 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. +/** + 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. @@ -557,32 +770,32 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); - Compressing and decompressing require a context structure + Use ZSTD_createCCtx() and ZSTD_createDCtx() - It is necessary to init context before starting - + compression : ZSTD_compressBegin() - + decompression : ZSTD_decompressBegin() - + variants _usingDict() are also allowed - + copyCCtx() and copyDCtx() work too - - Block size is limited, it must be <= ZSTD_getBlockSizeMax() - + If you need to compress more, cut data into multiple blocks - + Consider using the regular ZSTD_compress() instead, as frame metadata costs become negligible when source size is large. + + 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_getBlockSizeMax() <= ZSTD_BLOCKSIZE_ABSOLUTEMAX + + 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, decoder must be informed of uncompressed block existence to follow proper history. - Use ZSTD_insertBlock() in such a case. + + 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_BLOCKSIZE_ABSOLUTEMAX (128 * 1024) /* define, for static allocation */ +/*===== Raw zstd block functions =====*/ ZSTDLIB_API size_t ZSTD_getBlockSizeMax(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_STATIC_LINKING_ONLY */ +#endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */ #if defined (__cplusplus) } #endif - -#endif /* ZSTD_H_235446 */ |