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author | Vsevolod Stakhov <vsevolod@highsecure.ru> | 2016-09-08 16:59:45 +0100 |
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committer | Vsevolod Stakhov <vsevolod@highsecure.ru> | 2016-09-08 17:00:14 +0100 |
commit | bd10330aa73c9f6eab293b38cf1c86e03fe46fa1 (patch) | |
tree | d82e7505b0903a9155f35202e486455066826b1e /contrib/zstd/zstd.h | |
parent | e3c5642da397104ed4d5c0171353e997f4ceba77 (diff) | |
download | rspamd-bd10330aa73c9f6eab293b38cf1c86e03fe46fa1.tar.gz rspamd-bd10330aa73c9f6eab293b38cf1c86e03fe46fa1.zip |
[Feature] Add zstd compression library
Diffstat (limited to 'contrib/zstd/zstd.h')
-rw-r--r-- | contrib/zstd/zstd.h | 587 |
1 files changed, 587 insertions, 0 deletions
diff --git a/contrib/zstd/zstd.h b/contrib/zstd/zstd.h new file mode 100644 index 000000000..d768ded35 --- /dev/null +++ b/contrib/zstd/zstd.h @@ -0,0 +1,587 @@ +/** + * 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. + */ + +#ifndef ZSTD_H_235446 +#define ZSTD_H_235446 + +#if defined (__cplusplus) +extern "C" { +#endif + +/*====== 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) +#else +# define ZSTDLIB_API +#endif + + +/*======= Version =======*/ +#define ZSTD_VERSION_MAJOR 1 +#define ZSTD_VERSION_MINOR 0 +#define ZSTD_VERSION_RELEASE 0 + +#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) + +#define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) +ZSTDLIB_API unsigned ZSTD_versionNumber (void); + + +/* ************************************* +* 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()) */ +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()) */ +ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity, + const void* src, size_t compressedSize); + + +/*====== 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 */ +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 */ +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 load the dictionary, resulting in significant startup delay. */ +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 load the dictionary, resulting in significant startup delay */ +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 +****************************/ +/*! 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); +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 */ +ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx, + void* dst, size_t dstCapacity, + const void* src, size_t srcSize, + const ZSTD_CDict* cdict); + +/*! ZSTD_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); +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 ======*/ + +/*-*********************************************************************** +* 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. +* +* Start 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_compressStream() repetitively to consume input stream. +* The function will automatically update both `pos`. +* 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(). +* +* At any moment, it's possible to flush whatever data remains within 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. +* @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. +* 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) +* or an error code, which can be tested using ZSTD_isError(). +* +* *******************************************************************/ + +typedef struct ZSTD_CStream_s ZSTD_CStream; +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 */ + +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); + + +/*====== decompression ======*/ + +/*-*************************************************************************** +* 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. +* +* 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. +* @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(). +* +* *******************************************************************************/ + +typedef struct ZSTD_DStream_s ZSTD_DStream; +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 */ + +ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds); +ZSTDLIB_API size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input); + + + +#ifdef ZSTD_STATIC_LINKING_ONLY + +/* ==================================================================================== + * 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 */ +#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U + +#define ZSTD_WINDOWLOG_MAX_32 25 +#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_HASHLOG_MAX ZSTD_WINDOWLOG_MAX +#define ZSTD_HASHLOG_MIN 12 +#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_TARGETLENGTH_MIN 4 +#define ZSTD_TARGETLENGTH_MAX 999 + +#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */ +static const size_t ZSTD_frameHeaderSize_min = 5; +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 */ + +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 (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) */ +} ZSTD_frameParameters; + +typedef struct { + ZSTD_compressionParameters cParams; + ZSTD_frameParameters fParams; +} ZSTD_parameters; + +/* 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; + + +/*-************************************* +* Advanced compression functions +***************************************/ +/*! 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 */ +ZSTDLIB_API size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams); + +/*! ZSTD_createCCtx_advanced() : + * Create a ZSTD compression context using external alloc and free functions */ +ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem); + +/*! 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); + +/*! 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_getParams() : +* same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of a `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); + +/*! 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 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); + + +/*--- Advanced Decompression functions ---*/ + +/*! ZSTD_estimateDCtxSize() : + * Gives the potential amount of memory allocated to create a ZSTD_DCtx */ +ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); + +/*! 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 +********************************************************************/ + +/*====== compression ======*/ + +ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem); +ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); +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; + +ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem); +ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); +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); + + +/* ****************************************************************** +* 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 */ + +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); + +/* + 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 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. + + You can then reuse `ZSTD_CCtx` (ZSTD_compressBegin()) to compress some new frame. +*/ + +typedef struct { + unsigned long long frameContentSize; + unsigned windowSize; + unsigned dictID; + unsigned checksumFlag; +} ZSTD_frameParams; + +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_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. + 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() or ZSTD_decompressBegin_usingDict(). + 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. + It also returns Frame Size as fparamsPtr->frameContentSize. +*/ + + +/* ************************************** +* 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 : 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. + - 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. +*/ + +#define ZSTD_BLOCKSIZE_ABSOLUTEMAX (128 * 1024) /* define, for static allocation */ +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 */ + +#if defined (__cplusplus) +} +#endif + +#endif /* ZSTD_H_235446 */ |