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| -rw-r--r-- | src/zstd/lib/zstd.h | 1386 |
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diff --git a/src/zstd/lib/zstd.h b/src/zstd/lib/zstd.h new file mode 100644 index 00000000..2194a3b2 --- /dev/null +++ b/src/zstd/lib/zstd.h @@ -0,0 +1,1386 @@ +/* + * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. + * All rights reserved. + * + * This source code is licensed under both the BSD-style license (found in the + * LICENSE file in the root directory of this source tree) and the GPLv2 (found + * in the COPYING file in the root directory of this source tree). + * You may select, at your option, one of the above-listed licenses. + */ +#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 ===== */ +#ifndef ZSTDLIB_VISIBILITY +# if defined(__GNUC__) && (__GNUC__ >= 4) +# define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default"))) +# else +# define ZSTDLIB_VISIBILITY +# endif +#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 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. + Advanced experimental APIs shall never be used with a dynamic library. + They are not "stable", their definition may change in the future. Only static linking is allowed. +*********************************************************************************************************/ + +/*------ Version ------*/ +#define ZSTD_VERSION_MAJOR 1 +#define ZSTD_VERSION_MINOR 3 +#define ZSTD_VERSION_RELEASE 2 + +#define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) +ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< useful to check dll version */ + +#define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE +#define ZSTD_QUOTE(str) #str +#define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str) +#define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION) +ZSTDLIB_API const char* ZSTD_versionString(void); /* v1.3.0 */ + + +/*************************************** +* 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 to regenerate. + * 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_getFrameContentSize() : v1.3.0 + * `src` should point to the start of a ZSTD encoded frame. + * `srcSize` must be at least as large as the frame header. + * hint : any size >= `ZSTD_frameHeaderSize_max` is large enough. + * @return : - decompressed size of the frame in `src`, if known + * - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined + * - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small) + * note 1 : a 0 return value means the frame is valid but "empty". + * note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode. + * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. + * In which case, it's necessary to use streaming mode to decompress data. + * Optionally, application can rely on some implicit limit, + * as ZSTD_decompress() only needs an upper bound of decompressed size. + * (For example, data could be necessarily cut into blocks <= 16 KB). + * note 3 : decompressed size is always present when compression is done with ZSTD_compress() + * note 4 : decompressed size can be very large (64-bits value), + * potentially larger than what local system can handle as a single memory segment. + * In which case, it's necessary to use streaming mode to decompress data. + * note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified. + * Always ensure return value fits within application's authorized limits. + * Each application can set its own limits. + * note 6 : This function replaces ZSTD_getDecompressedSize() */ +#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_getDecompressedSize() : + * NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize(). + * Both functions work the same way, + * but ZSTD_getDecompressedSize() blends + * "empty", "unknown" and "error" results in the same return value (0), + * while ZSTD_getFrameContentSize() distinguishes them. + * + * 'src' is the start of a zstd compressed frame. + * @return : content size to be decompressed, as a 64-bits value _if known and not empty_, 0 otherwise. */ +ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize); + + +/*====== Helper functions ======*/ +#define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < 128 KB) ? ((128 KB - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0)) /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB */ +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 */ +ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */ + + +/*************************************** +* 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); + + +/********************************** + * Bulk processing 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 shared by multiple threads concurrently, since its usage is read-only. + * `dictBuffer` can be released after ZSTD_CDict creation, since its content is copied within CDict */ +ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize, + int compressionLevel); + +/*! ZSTD_freeCDict() : + * Function frees memory allocated by ZSTD_createCDict(). */ +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 now effectively same object (>= v1.3.0) */ + /* Continue to distinguish them for compatibility with versions <= v1.2.0 */ +/*===== ZSTD_CStream management functions =====*/ +ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void); +ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs); + +/*===== Streaming compression functions =====*/ +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 ZSTD_DCtx ZSTD_DStream; /**< DCtx and DStream are now effectively same object (>= v1.3.0) */ + /* Continue to distinguish them for compatibility with versions <= v1.2.0 */ +/*===== 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 */ + + + +/**************************************************************************************** + * START OF ADVANCED AND EXPERIMENTAL FUNCTIONS + * The definitions in this section are considered experimental. + * They should never be used with a dynamic library, as prototypes may change in the future. + * They are provided for advanced scenarios. + * Use them only in association with static linking. + * ***************************************************************************************/ + +#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY) +#define ZSTD_H_ZSTD_STATIC_LINKING_ONLY + +/* --- Constants ---*/ +#define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */ +#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U +#define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* v0.7+ */ + +#define ZSTD_WINDOWLOG_MAX_32 30 +#define ZSTD_WINDOWLOG_MAX_64 31 +#define ZSTD_WINDOWLOG_MAX ((unsigned)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64)) +#define ZSTD_WINDOWLOG_MIN 10 +#define ZSTD_HASHLOG_MAX MIN(ZSTD_WINDOWLOG_MAX, 30) +#define ZSTD_HASHLOG_MIN 6 +#define ZSTD_CHAINLOG_MAX MIN(ZSTD_WINDOWLOG_MAX+1, 30) +#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 /* only useful for btopt */ +#define ZSTD_TARGETLENGTH_MAX 999 /* only useful for btopt */ +#define ZSTD_LDM_MINMATCH_MIN 4 +#define ZSTD_LDM_MINMATCH_MAX 4096 +#define ZSTD_LDM_BUCKETSIZELOG_MAX 8 + +#define ZSTD_FRAMEHEADERSIZE_PREFIX 5 /* minimum input size to know frame header size */ +#define ZSTD_FRAMEHEADERSIZE_MIN 6 +#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */ +static const size_t ZSTD_frameHeaderSize_prefix = ZSTD_FRAMEHEADERSIZE_PREFIX; +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 ZSTD_CCtx_params_s ZSTD_CCtx_params; + +/*= 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; +/* use this constant to defer to stdlib's functions */ +static const ZSTD_customMem ZSTD_defaultCMem = { NULL, NULL, NULL }; + + +/*************************************** +* 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 first frame starting at `src`, + * suitable to pass to `ZSTD_decompress` or similar, + * or an error code if input is invalid */ +ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(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 at `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. + * 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 fast as most of the data is skipped, + * however it does mean that all frame data must be present and valid. */ +ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize); + +/*! ZSTD_frameHeaderSize() : +* `src` should point to the start of a ZSTD frame +* `srcSize` must be >= ZSTD_frameHeaderSize_prefix. +* @return : size of the Frame Header */ +ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize); + + +/*************************************** +* Context memory usage +***************************************/ + +/*! ZSTD_sizeof_*() : + * These functions give the current memory usage of selected object. + * Object memory usage can evolve when 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 {D,C}Ctx, before its creation. + * ZSTD_estimateCCtxSize() will provide a budget large enough for any compression level up to selected one. + * It will also consider src size to be arbitrarily "large", which is worst case. + * If srcSize is known to always be small, ZSTD_estimateCCtxSize_usingCParams() can provide a tighter estimation. + * ZSTD_estimateCCtxSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. + * ZSTD_estimateCCtxSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbThreads is > 1. + * Note : CCtx estimation is only correct for single-threaded compression */ +ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel); +ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams); +ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params); +ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); + +/*! ZSTD_estimateCStreamSize() : + * ZSTD_estimateCStreamSize() will provide a budget large enough for any compression level up to selected one. + * It will also consider src size to be arbitrarily "large", which is worst case. + * If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation. + * ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. + * ZSTD_estimateCStreamSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbThreads is set to a value > 1. + * Note : CStream estimation is only correct for single-threaded compression. + * ZSTD_DStream memory budget depends on window Size. + * This information can be passed manually, using ZSTD_estimateDStreamSize, + * or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame(); + * Note : if streaming is init with function ZSTD_init?Stream_usingDict(), + * an internal ?Dict will be created, which additional size is not estimated here. + * In this case, get total size by adding ZSTD_estimate?DictSize */ +ZSTDLIB_API size_t ZSTD_estimateCStreamSize(int compressionLevel); +ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams); +ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params); +ZSTDLIB_API size_t ZSTD_estimateDStreamSize(size_t windowSize); +ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize); + +typedef enum { + ZSTD_dlm_byCopy = 0, /**< Copy dictionary content internally */ + ZSTD_dlm_byRef, /**< Reference dictionary content -- the dictionary buffer must outlive its users. */ +} ZSTD_dictLoadMethod_e; + +/*! ZSTD_estimate?DictSize() : + * ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict(). + * ZSTD_estimateCStreamSize_advanced_usingCParams() makes it possible to control precisely compression parameters, like ZSTD_createCDict_advanced(). + * Note : dictionary created by reference using ZSTD_dlm_byRef are smaller + */ +ZSTDLIB_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel); +ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod); +ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod); + + +/*************************************** +* 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); + +/*! ZSTD_initStaticCCtx() : initialize a fixed-size zstd compression context + * workspace: The memory area to emplace the context into. + * Provided pointer must 8-bytes aligned. + * It must outlive context usage. + * workspaceSize: Use ZSTD_estimateCCtxSize() or ZSTD_estimateCStreamSize() + * to determine how large workspace must be to support scenario. + * @return : pointer to ZSTD_CCtx*, or NULL if error (size too small) + * Note : zstd will never resize nor malloc() when using a static cctx. + * If it needs more memory than available, it will simply error out. + * Note 2 : there is no corresponding "free" function. + * Since workspace was allocated externally, it must be freed externally too. + * Limitation 1 : currently not compatible with internal CDict creation, such as + * ZSTD_CCtx_loadDictionary() or ZSTD_initCStream_usingDict(). + * Limitation 2 : currently not compatible with multi-threading + */ +ZSTDLIB_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize); + + +/*! 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); + +typedef enum { ZSTD_dm_auto=0, /* dictionary is "full" if it starts with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */ + ZSTD_dm_rawContent, /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */ + ZSTD_dm_fullDict /* refuses to load a dictionary if it does not respect Zstandard's specification */ +} ZSTD_dictMode_e; +/*! 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_dictLoadMethod_e dictLoadMethod, + ZSTD_dictMode_e dictMode, + ZSTD_compressionParameters cParams, + ZSTD_customMem customMem); + +/*! ZSTD_initStaticCDict_advanced() : + * Generate a digested dictionary in provided memory area. + * workspace: The memory area to emplace the dictionary into. + * Provided pointer must 8-bytes aligned. + * It must outlive dictionary usage. + * workspaceSize: Use ZSTD_estimateCDictSize() + * to determine how large workspace must be. + * cParams : use ZSTD_getCParams() to transform a compression level + * into its relevants cParams. + * @return : pointer to ZSTD_CDict*, or NULL if error (size too small) + * Note : there is no corresponding "free" function. + * Since workspace was allocated externally, it must be freed externally. + */ +ZSTDLIB_API ZSTD_CDict* ZSTD_initStaticCDict( + void* workspace, size_t workspaceSize, + const void* dict, size_t dictSize, + ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictMode_e dictMode, + ZSTD_compressionParameters cParams); + +/*! 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); + + +/*--- 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_initStaticDCtx() : initialize a fixed-size zstd decompression context + * workspace: The memory area to emplace the context into. + * Provided pointer must 8-bytes aligned. + * It must outlive context usage. + * workspaceSize: Use ZSTD_estimateDCtxSize() or ZSTD_estimateDStreamSize() + * to determine how large workspace must be to support scenario. + * @return : pointer to ZSTD_DCtx*, or NULL if error (size too small) + * Note : zstd will never resize nor malloc() when using a static dctx. + * If it needs more memory than available, it will simply error out. + * Note 2 : static dctx is incompatible with legacy support + * Note 3 : there is no corresponding "free" function. + * Since workspace was allocated externally, it must be freed externally. + * Limitation : currently not compatible with internal DDict creation, + * such as ZSTD_initDStream_usingDict(). + */ +ZSTDLIB_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize); + +/*! ZSTD_createDDict_byReference() : + * Create a digested dictionary, ready to start decompression operation without startup delay. + * Dictionary content is 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, + ZSTD_dictLoadMethod_e dictLoadMethod, + ZSTD_customMem customMem); + +/*! ZSTD_initStaticDDict() : + * Generate a digested dictionary in provided memory area. + * workspace: The memory area to emplace the dictionary into. + * Provided pointer must 8-bytes aligned. + * It must outlive dictionary usage. + * workspaceSize: Use ZSTD_estimateDDictSize() + * to determine how large workspace must be. + * @return : pointer to ZSTD_DDict*, or NULL if error (size too small) + * Note : there is no corresponding "free" function. + * Since workspace was allocated externally, it must be freed externally. + */ +ZSTDLIB_API ZSTD_DDict* ZSTD_initStaticDDict(void* workspace, size_t workspaceSize, + const void* dict, size_t dictSize, + ZSTD_dictLoadMethod_e dictLoadMethod); + +/*! 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_getFrameHeader(), 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 ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */ +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); /**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. Note: dict is loaded with ZSTD_dm_auto (treated as a full zstd dictionary if it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.*/ +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. dict is loaded with ZSTD_dm_auto and ZSTD_dlm_byCopy. */ +ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); /**< note : cdict will just be referenced, and must outlive compression session */ +ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize); /**< same as ZSTD_initCStream_usingCDict(), with control over frame parameters */ + +/*! 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 =====*/ +ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem); +ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */ +typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e; +ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue); /* obsolete : this API will be removed in a future version */ +ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); /**< note: no dictionary will be used if dict == NULL or dictSize < 8 */ +ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); /**< note : ddict is referenced, it 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 several restrictions, documented below. +* Prefer 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 buffers only. + - Interface is synchronous : input is consumed entirely and produces 1+ 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 are considered unfinished (hence corrupted) by compliant decoders. + + `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress again. +*/ + +/*===== 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_getFrameHeader(). + Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough. + Data fragment must be large enough to ensure successful decoding. + `ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough. + @result : 0 : successful decoding, the `ZSTD_frameHeader` 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(). + + It fills a ZSTD_frameHeader structure with important information to correctly decode the frame, + such as the dictionary ID, content size, or maximum back-reference distance (`windowSize`). + Note that these values could be wrong, either because of data corruption, or because a 3rd party deliberately spoofs false information. + As a consequence, check that values remain within valid application range. + For example, do not allocate memory blindly, check that `windowSize` is within expectation. + Each application can set its own limits, depending on local restrictions. + For extended interoperability, it is recommended to support `windowSize` of at least 8 MB. + + ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize` bytes. + 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 distance. + There are multiple ways to guarantee this condition. + + The most memory efficient way is to use a round buffer of sufficient size. + Sufficient size is determined by invoking ZSTD_decodingBufferSize_min(), + which can @return an error code if required value is too large for current system (in 32-bits mode). + In a round buffer methodology, ZSTD_decompressContinue() decompresses each block next to previous one, + up to the moment there is not enough room left in the buffer to guarantee decoding another full block, + which maximum size is provided in `ZSTD_frameHeader` structure, field `blockSizeMax`. + At which point, decoding can resume from the beginning of the buffer. + Note that already decoded data stored in the buffer should be flushed before being overwritten. + + There are alternatives possible, for example using two or more buffers of size `windowSize` each, though they consume more memory. + + Finally, if you control the compression process, you can also ignore all buffer size rules, + as long as the encoder and decoder progress in "lock-step", + aka use exactly the same buffer sizes, break contiguity at the same place, etc. + + Once buffers are setup, start decompression, with ZSTD_decompressBegin(). + If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict(). + + 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 : it just means ZSTD_decompressContinue() has decoded some metadata item. + It can also be an error code, which can be tested with ZSTD_isError(). + + 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 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_getFrameHeader() returns zfhPtr->frameType==ZSTD_skippableFrame. + For skippable frames ZSTD_decompressContinue() always returns 0 : it only skips the content. +*/ + +/*===== Buffer-less streaming decompression functions =====*/ +typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_frameType_e; +typedef struct { + unsigned long long frameContentSize; /* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */ + unsigned long long windowSize; /* can be very large, up to <= frameContentSize */ + unsigned blockSizeMax; + ZSTD_frameType_e frameType; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */ + unsigned headerSize; + unsigned dictID; + unsigned checksumFlag; +} ZSTD_frameHeader; +ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */ +ZSTDLIB_API size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); /**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */ + +ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx); +ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); +ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); + +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); + +/* misc */ +ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx); +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); + + + +/* ============================================ */ +/** New advanced API (experimental) */ +/* ============================================ */ + +/* notes on API design : + * In this proposal, parameters are pushed one by one into an existing context, + * and then applied on all subsequent compression jobs. + * When no parameter is ever provided, CCtx is created with compression level ZSTD_CLEVEL_DEFAULT. + * + * This API is intended to replace all others experimental API. + * It can basically do all other use cases, and even new ones. + * In constrast with _advanced() variants, it stands a reasonable chance to become "stable", + * after a good testing period. + */ + +/* note on naming convention : + * Initially, the API favored names like ZSTD_setCCtxParameter() . + * In this proposal, convention is changed towards ZSTD_CCtx_setParameter() . + * The main driver is that it identifies more clearly the target object type. + * It feels clearer when considering multiple targets : + * ZSTD_CDict_setParameter() (rather than ZSTD_setCDictParameter()) + * ZSTD_CCtxParams_setParameter() (rather than ZSTD_setCCtxParamsParameter() ) + * etc... + */ + +/* note on enum design : + * All enum will be pinned to explicit values before reaching "stable API" status */ + +typedef enum { + /* Question : should we have a format ZSTD_f_auto ? + * For the time being, it would mean exactly the same as ZSTD_f_zstd1. + * But, in the future, should several formats be supported, + * on the compression side, it would mean "default format". + * On the decompression side, it would mean "multi format", + * and ZSTD_f_zstd1 could be reserved to mean "accept *only* zstd frames". + * Since meaning is a little different, another option could be to define different enums for compression and decompression. + * This question could be kept for later, when there are actually multiple formats to support, + * but there is also the question of pinning enum values, and pinning value `0` is especially important */ + ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */ + ZSTD_f_zstd1_magicless, /* Variant of zstd frame format, without initial 4-bytes magic number. + * Useful to save 4 bytes per generated frame. + * Decoder cannot recognise automatically this format, requiring instructions. */ +} ZSTD_format_e; + +typedef enum { + /* compression format */ + ZSTD_p_format = 10, /* See ZSTD_format_e enum definition. + * Cast selected format as unsigned for ZSTD_CCtx_setParameter() compatibility. */ + + /* compression parameters */ + ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table + * Default level is ZSTD_CLEVEL_DEFAULT==3. + * Special: value 0 means "do not change cLevel". */ + ZSTD_p_windowLog, /* Maximum allowed back-reference distance, expressed as power of 2. + * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX. + * Special: value 0 means "do not change windowLog". + * Note: Using a window size greater than ZSTD_MAXWINDOWSIZE_DEFAULT (default: 2^27) + * requires setting the maximum window size at least as large during decompression. */ + 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". */ + + /* frame parameters */ + ZSTD_p_contentSizeFlag=200, /* Content size is written into frame header _whenever known_ (default:1) + * note that content size must be known at the beginning, + * it is sent using ZSTD_CCtx_setPledgedSrcSize() */ + 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) */ + + /* multi-threading parameters */ + ZSTD_p_nbThreads=400, /* Select how many threads a compression job can spawn (default:1) + * More threads improve speed, but also increase memory usage. + * Can only receive a value > 1 if ZSTD_MULTITHREAD is enabled. + * Special: value 0 means "do not change nbThreads" */ + ZSTD_p_jobSize, /* Size of a compression job. Each compression job is completed 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 */ + ZSTD_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 */ + + /* advanced parameters - may not remain available after API update */ + ZSTD_p_forceMaxWindow=1100, /* Force back-reference distances to remain < windowSize, + * even when referencing into Dictionary content (default:0) */ + ZSTD_p_enableLongDistanceMatching=1200, /* Enable long distance matching. + * This parameter is designed to improve the compression + * ratio for large inputs with long distance matches. + * This increases the memory usage as well as window size. + * Note: setting this parameter sets all the LDM parameters + * as well as ZSTD_p_windowLog. It should be set after + * ZSTD_p_compressionLevel and before ZSTD_p_windowLog and + * other LDM parameters. Setting the compression level + * after this parameter overrides the window log, though LDM + * will remain enabled until explicitly disabled. */ + ZSTD_p_ldmHashLog, /* Size of the table for long distance matching, as a power of 2. + * Larger values increase memory usage and compression ratio, but decrease + * compression speed. + * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX + * (default: windowlog - 7). */ + ZSTD_p_ldmMinMatch, /* Minimum size of searched matches for long distance matcher. + * Larger/too small values usually decrease compression ratio. + * Must be clamped between ZSTD_LDM_MINMATCH_MIN + * and ZSTD_LDM_MINMATCH_MAX (default: 64). */ + ZSTD_p_ldmBucketSizeLog, /* Log size of each bucket in the LDM hash table for collision resolution. + * Larger values usually improve collision resolution but may decrease + * compression speed. + * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX (default: 3). */ + ZSTD_p_ldmHashEveryLog, /* Frequency of inserting/looking up entries in the LDM hash table. + * The default is MAX(0, (windowLog - ldmHashLog)) to + * optimize hash table usage. + * Larger values improve compression speed. Deviating far from the + * default value will likely result in a decrease in compression ratio. + * Must be clamped between 0 and ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN. */ + +} 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 as a single frame. + * This value will be controlled at the end, and result in error if not respected. + * @result : 0, or an error code (which can be tested with ZSTD_isError()). + * Note 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 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 dictionary, + * meaning "return to no-dictionary mode". + * Note 1 : `dict` content will be copied internally. Use + * ZSTD_CCtx_loadDictionary_byReference() to reference dictionary + * content instead. The dictionary buffer must then outlive its + * users. + * 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 dictionary. + * 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 + * Note 5 : Use ZSTD_CCtx_loadDictionary_advanced() to select how dictionary + * content will be interpreted. + */ +ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); +ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); +ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictMode_e dictMode); + + +/*! ZSTD_CCtx_refCDict() : + * Reference a prepared dictionary, to be used for all next compression jobs. + * Note that compression parameters are enforced from within CDict, + * and supercede any compression parameter previously set within CCtx. + * The dictionary will remain valid for future 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); + +/*! ZSTD_CCtx_refPrefix() : + * Reference a prefix (single-usage dictionary) for next compression job. + * Decompression need same prefix to properly regenerate data. + * Prefix is **only used once**. Tables are discarded at end of compression job. + * Subsequent compression jobs will be done without prefix (if none is explicitly referenced). + * If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_CDict instead. + * @result : 0, or an error code (which can be tested with ZSTD_isError()). + * Special : Adding any prefix (including NULL) invalidates any previous prefix or dictionary + * Note 1 : Prefix buffer is referenced. It must outlive compression job. + * Note 2 : Referencing a prefix involves building tables, which are dependent on compression parameters. + * It's a CPU-heavy operation, with non-negligible impact on latency. + * Note 3 : By default, the prefix is treated as raw content + * (ZSTD_dm_rawContent). Use ZSTD_CCtx_refPrefix_advanced() to alter + * dictMode. */ +ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize); +ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictMode_e dictMode); + + + +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 close current frame. Any additional data starts a new frame. */ +} ZSTD_EndDirective; + +/*! ZSTD_compress_generic() : + * Behave about the same as ZSTD_compressStream. To note : + * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_setParameter() + * - Compression parameters cannot be changed once compression is started. + * - outpot->pos must be <= dstCapacity, input->pos must be <= srcSize + * - outpot->pos and input->pos will be updated. They are guaranteed to remain below their respective limit. + * - @return provides the minimum amount of data still to flush from internal buffers + * or an error code, which can be tested using ZSTD_isError(). + * if @return != 0, flush is not fully completed, there is some data left within internal buffers. + * - after a ZSTD_e_end directive, if internal buffer is not fully flushed, + * only ZSTD_e_end or ZSTD_e_flush operations are allowed. + * It is necessary to fully flush internal buffers + * before starting a new compression job, or changing compression parameters. + */ +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. + * Any internal data not yet flushed is cancelled. + * Dictionary (if any) is dropped. + * All parameters are back to default values. + * It's possible to modify compression parameters after a reset. + */ +ZSTDLIB_API void ZSTD_CCtx_reset(ZSTD_CCtx* cctx); /* Not ready yet ! */ + + +/*! ZSTD_compress_generic_simpleArgs() : + * Same as ZSTD_compress_generic(), + * but using only integral types as arguments. + * Argument list is larger than ZSTD_{in,out}Buffer, + * but can be helpful for binders from dynamic languages + * which have troubles handling structures containing memory pointers. + */ +ZSTDLIB_API size_t ZSTD_compress_generic_simpleArgs ( + ZSTD_CCtx* cctx, + void* dst, size_t dstCapacity, size_t* dstPos, + const void* src, size_t srcSize, size_t* srcPos, + ZSTD_EndDirective endOp); + + +/*! ZSTD_CCtx_params : + * Quick howto : + * - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure + * - ZSTD_CCtxParam_setParameter() : Push parameters one by one into + * an existing ZSTD_CCtx_params structure. + * This is similar to + * ZSTD_CCtx_setParameter(). + * - ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to + * an existing CCtx. + * These parameters will be applied to + * all subsequent compression jobs. + * - ZSTD_compress_generic() : Do compression using the CCtx. + * - ZSTD_freeCCtxParams() : Free the memory. + * + * This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams() + * for static allocation for single-threaded compression. + */ +ZSTDLIB_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void); + +/*! ZSTD_resetCCtxParams() : + * Reset params to default, with the default compression level. + */ +ZSTDLIB_API size_t ZSTD_resetCCtxParams(ZSTD_CCtx_params* params); + +/*! ZSTD_initCCtxParams() : + * Initializes the compression parameters of cctxParams according to + * compression level. All other parameters are reset to their default values. + */ +ZSTDLIB_API size_t ZSTD_initCCtxParams(ZSTD_CCtx_params* cctxParams, int compressionLevel); + +/*! ZSTD_initCCtxParams_advanced() : + * Initializes the compression and frame parameters of cctxParams according to + * params. All other parameters are reset to their default values. + */ +ZSTDLIB_API size_t ZSTD_initCCtxParams_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params); + +ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params); + +/*! ZSTD_CCtxParam_setParameter() : + * Similar to ZSTD_CCtx_setParameter. + * Set one compression parameter, selected by enum ZSTD_cParameter. + * Parameters must be applied to a ZSTD_CCtx using ZSTD_CCtx_setParametersUsingCCtxParams(). + * Note : when `value` is an enum, cast it to unsigned for proper type checking. + * @result : 0, or an error code (which can be tested with ZSTD_isError()). + */ +ZSTDLIB_API size_t ZSTD_CCtxParam_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned value); + +/*! ZSTD_CCtx_setParametersUsingCCtxParams() : + * Apply a set of ZSTD_CCtx_params to the compression context. + * This must be done before the dictionary is loaded. + * The pledgedSrcSize is treated as unknown. + * Multithreading parameters are applied only if nbThreads > 1. + */ +ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams( + ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params); + + +/*=== Advanced parameters for decompression API ===*/ + +/* The following parameters must be set after creating a ZSTD_DCtx* (or ZSTD_DStream*) object, + * but before starting decompression of a frame. + */ + +/*! ZSTD_DCtx_loadDictionary() : + * Create an internal DDict from dict buffer, + * to be used to decompress next frames. + * @result : 0, or an error code (which can be tested with ZSTD_isError()). + * Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary, + * meaning "return to no-dictionary mode". + * Note 1 : `dict` content will be copied internally. + * Use ZSTD_DCtx_loadDictionary_byReference() + * to reference dictionary content instead. + * In which case, the dictionary buffer must outlive its users. + * Note 2 : Loading a dictionary involves building tables, + * which has a non-negligible impact on CPU usage and latency. + * Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to select + * how dictionary content will be interpreted and loaded. + */ +ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); /* not implemented */ +ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); /* not implemented */ +ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictMode_e dictMode); /* not implemented */ + + +/*! ZSTD_DCtx_refDDict() : + * Reference a prepared dictionary, to be used to decompress next frames. + * The dictionary remains active for decompression of future frames using same DCtx. + * @result : 0, or an error code (which can be tested with ZSTD_isError()). + * Note 1 : Currently, only one dictionary can be managed. + * Referencing a new dictionary effectively "discards" any previous one. + * Special : adding a NULL DDict means "return to no-dictionary mode". + * Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx. + */ +ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); /* not implemented */ + + +/*! ZSTD_DCtx_refPrefix() : + * Reference a prefix (single-usage dictionary) for next compression job. + * Prefix is **only used once**. It must be explicitly referenced before each frame. + * If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_DDict instead. + * @result : 0, or an error code (which can be tested with ZSTD_isError()). + * Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary + * Note 2 : Prefix buffer is referenced. It must outlive compression job. + * Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent). + * Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode. + * Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost. + */ +ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize); /* not implemented */ +ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictMode_e dictMode); /* not implemented */ + + +/*! ZSTD_DCtx_setMaxWindowSize() : + * Refuses allocating internal buffers for frames requiring a window size larger than provided limit. + * This is useful to prevent a decoder context from reserving too much memory for itself (potential attack scenario). + * This parameter is only useful in streaming mode, since no internal buffer is allocated in direct mode. + * By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_MAX) + * @return : 0, or an error code (which can be tested using ZSTD_isError()). + */ +ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize); + + +/*! ZSTD_DCtx_setFormat() : + * Instruct the decoder context about what kind of data to decode next. + * This instruction is mandatory to decode data without a fully-formed header, + * such ZSTD_f_zstd1_magicless for example. + * @return : 0, or an error code (which can be tested using ZSTD_isError()). + */ +ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format); + + +/*! ZSTD_decompress_generic() : + * Behave the same as ZSTD_decompressStream. + * Decompression parameters cannot be changed once decompression is started. + * @return : an error code, which can be tested using ZSTD_isError() + * if >0, a hint, nb of expected input bytes for next invocation. + * `0` means : a frame has just been fully decoded and flushed. + */ +ZSTDLIB_API size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx, + ZSTD_outBuffer* output, + ZSTD_inBuffer* input); + + +/*! ZSTD_decompress_generic_simpleArgs() : + * Same as ZSTD_decompress_generic(), + * but using only integral types as arguments. + * Argument list is larger than ZSTD_{in,out}Buffer, + * but can be helpful for binders from dynamic languages + * which have troubles handling structures containing memory pointers. + */ +ZSTDLIB_API size_t ZSTD_decompress_generic_simpleArgs ( + ZSTD_DCtx* dctx, + void* dst, size_t dstCapacity, size_t* dstPos, + const void* src, size_t srcSize, size_t* srcPos); + + +/*! ZSTD_DCtx_reset() : + * Return a DCtx to clean state. + * If a decompression was ongoing, any internal data not yet flushed is cancelled. + * All parameters are back to default values, including sticky ones. + * Dictionary (if any) is dropped. + * Parameters can be modified again after a reset. + */ +ZSTDLIB_API void ZSTD_DCtx_reset(ZSTD_DCtx* dctx); + + + +/* ============================ */ +/** Block level API */ +/* ============================ */ + +/*! + 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 == 128 KB + + 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 uncompressed block into `dctx` history. Useful for multi-blocks decompression */ + + +#endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */ + +#if defined (__cplusplus) +} +#endif |