/*

 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.

 * All rights reserved.

 *

 * This source code is licensed under the BSD-style license found in the

 * LICENSE file in the root directory of this source tree. An additional grant

 * of patent rights can be found in the PATENTS file in the same directory.

 */

#if defined (__cplusplus)

extern "C" {

#endif

/* ======   Dependency   ======*/

#include <stddef.h>   /* size_t */

#  define ZSTDLIB_API __declspec(dllexport)

#else

#  define ZSTDLIB_API

#endif

/*******************************************************************************************************

  Introduction

  zstd, short for Zstandard, is a fast lossless compression algorithm, targeting real-time compression scenarios

  at zlib-level and better compression ratios. The zstd compression library provides in-memory compression and

  decompression functions. The library supports compression levels from 1 up to ZSTD_maxCLevel() which is 22.

  Levels >= 20, labelled `--ultra`, should be used with caution, as they require more memory.

  Compression can be done in:

    - a single step (described as Simple API)

    - a single step, reusing a context (described as Explicit memory management)

    - unbounded multiple steps (described as Streaming compression)

  The compression ratio achievable on small data can be highly improved using compression with a dictionary in:

    - a single step (described as Simple dictionary API)

    - a single step, reusing a dictionary (described as Fast dictionary API)

  Advanced experimental functions can be accessed using #define ZSTD_STATIC_LINKING_ONLY before including zstd.h.

  These APIs shall never be used with a dynamic library.

  They are not "stable", their definition may change in the future. Only static linking is allowed.

*********************************************************************************************************/

/*------   Version   ------*/

#define ZSTD_VERSION_MAJOR    1

#define ZSTD_VERSION_MINOR    1

#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)

/***************************************

*  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),

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 a single compressed frame.

    `dstCapacity` is an upper bound of originalSize.

    If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data.

    @return : the number of bytes decompressed into `dst` (<= `dstCapacity`),

ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity,

                              const void* src, size_t compressedSize);

/*! ZSTD_getDecompressedSize() :

*   'src' is the start of a zstd compressed frame.

*   @return : content size to be decompressed, as a 64-bits value _if known_, 0 otherwise.

*    note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode.

*             When `return==0`, data to decompress could be any size.

*             In which case, it's necessary to use streaming mode to decompress data.

*             Optionally, application can still use ZSTD_decompress() while relying on implied limits.

*             (For example, data may be necessarily cut into blocks <= 16 KB).

*    note 2 : decompressed size is always present when compression is done with ZSTD_compress()

*    note 3 : decompressed size can be very large (64-bits value),

*             potentially larger than what local system can handle as a single memory segment.

*             In which case, it's necessary to use streaming mode to decompress data.

*    note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified.

*             Always ensure result fits within application's authorized limits.

*             Each application can set its own limits.

*    note 5 : when `return==0`, if precise failure cause is needed, use ZSTD_getFrameParams() to know more. */

ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);

/*======  Helper functions  ======*/

ZSTDLIB_API int         ZSTD_maxCLevel(void);               /*!< maximum compression level available */

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

*   it is recommended to allocate a context just once, and re-use it for each successive compression operation.

*   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() :

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() :

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).

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.

ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,

                                             void* dst, size_t dstCapacity,

                                       const void* src, size_t srcSize,

                                       const void* dict,size_t dictSize);

/****************************

*  Fast dictionary API

****************************/

typedef struct ZSTD_CDict_s ZSTD_CDict;

/*! ZSTD_createCDict() :

*   When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.

*   ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.

*   ZSTD_CDict can be created once and used by multiple threads concurrently, as its usage is read-only.

ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dict, size_t dictSize, int compressionLevel);

/*! ZSTD_freeCDict() :

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.

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.

ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize);

/*! ZSTD_freeDDict() :

*   Function frees memory allocated with ZSTD_createDDict() */

ZSTDLIB_API size_t      ZSTD_freeDDict(ZSTD_DDict* ddict);

/*! ZSTD_decompress_usingDDict() :

*   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_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().

*

*  `output->pos` will be updated.

*  @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.

*            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_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(),

* *******************************************************************************/

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_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. */

/****************************************************************************************

 * START OF ADVANCED AND EXPERIMENTAL FUNCTIONS

 * The definitions in this section are considered experimental.

 * They should never be used with a dynamic library, as they may change in the future.

 * They are provided for advanced usages.

 * Use them only in association with static linking.

 * ***************************************************************************************/

/* --- Constants ---*/

#define ZSTD_MAGICNUMBER            0xFD2FB528   /* v0.8 */

#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     10

#define ZSTD_HASHLOG_MAX       ZSTD_WINDOWLOG_MAX

#define ZSTD_HASHLOG_MIN        6

#define ZSTD_CHAINLOG_MAX     (ZSTD_WINDOWLOG_MAX+1)

#define ZSTD_CHAINLOG_MIN      ZSTD_HASHLOG_MIN

#define ZSTD_HASHLOG3_MAX      17

#define ZSTD_SEARCHLOG_MAX    (ZSTD_WINDOWLOG_MAX-1)

#define ZSTD_SEARCHLOG_MIN      1

#define ZSTD_SEARCHLENGTH_MAX   7   /* only for ZSTD_fast, other strategies are limited to 6 */

#define ZSTD_SEARCHLENGTH_MIN   3   /* only for ZSTD_btopt, other strategies are limited to 4 */

#define ZSTD_TARGETLENGTH_MIN   4

#define ZSTD_TARGETLENGTH_MAX 999

#define ZSTD_FRAMEHEADERSIZE_MAX 18    /* for static allocation */

static const size_t ZSTD_frameHeaderSize_prefix = 5;

static const size_t ZSTD_frameHeaderSize_min = 6;

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, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2, ZSTD_btlazy2, ZSTD_btopt, ZSTD_btopt2 } 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_sizeofCCtx() :

 *  Gives the amount of memory used by a given ZSTD_CCtx */

ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);

/*! 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_sizeof_CDict() :

 *  Gives the amount of memory used by a given ZSTD_sizeof_CDict */

ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict);

/*! 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_sizeof_DCtx() :

 *  Gives the amount of memory used by a given ZSTD_DCtx */

ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);

/*! ZSTD_sizeof_DDict() :

 *  Gives the amount of memory used by a given ZSTD_DDict */

ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);

/********************************************************************

*  Advanced streaming functions

********************************************************************/

/*=====   Advanced Streaming compression functions  =====*/

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);  /**< pledgedSrcSize is optional and can be zero == unknown */

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_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);  /**< re-use compression parameters from previous init; skip dictionary loading stage; zcs must be init at least once before */

ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs);

/*=====   Advanced Streaming decompression functions  =====*/

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_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict);  /**< note : ddict will just be referenced, and must outlive decompression session */

ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds);  /**< re-use decompression parameters from previous init; saves dictionary loading */

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

********************************************************************* */