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 *  @return : - decompressed size of `src` frame content, 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 completed using single-pass functions,
 *            such as ZSTD_compress(), ZSTD_compressCCtx() ZSTD_compress_usingDict() or ZSTD_compress_usingCDict().
 *   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 to the same return value (0),
 *  while ZSTD_getFrameContentSize() gives them separate return values.
 * @return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise. */
ZSTD_DEPRECATED("Replaced by ZSTD_getFrameContentSize")
ZSTDLIB_API
unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);

/*! ZSTD_findFrameCompressedSize() : Requires v1.4.0+
 * `src` should point to the start of a ZSTD frame or skippable frame.
 * `srcSize` must be >= first frame size
 * @return : the compressed size of the first frame starting at `src`,
 *           suitable to pass as `srcSize` 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);


/*======  Helper functions  ======*/
/* ZSTD_compressBound() :
 * maximum compressed size in worst case single-pass scenario.
 * When invoking `ZSTD_compress()` or any other one-pass compression function,
 * it's recommended to provide @dstCapacity >= ZSTD_compressBound(srcSize)
 * as it eliminates one potential failure scenario,
 * aka not enough room in dst buffer to write the compressed frame.
 * Note : ZSTD_compressBound() itself can fail, if @srcSize > ZSTD_MAX_INPUT_SIZE .
 *        In which case, ZSTD_compressBound() will return an error code
 *        which can be tested using ZSTD_isError().
 *
 * ZSTD_COMPRESSBOUND() :
 * same as ZSTD_compressBound(), but as a macro.
 * It can be used to produce constants, which can be useful for static allocation,
 * for example to size a static array on stack.
 * Will produce constant value 0 if srcSize too large.
 */
#define ZSTD_MAX_INPUT_SIZE ((sizeof(size_t)==8) ? 0xFF00FF00FF00FF00LLU : 0xFF00FF00U)
#define ZSTD_COMPRESSBOUND(srcSize)   (((size_t)(srcSize) >= ZSTD_MAX_INPUT_SIZE) ? 0 : (srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0))  /* this formula ensures that bound(A) + ...
ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case single-pass scenario */
/* ZSTD_isError() :
 * Most ZSTD_* functions returning a size_t value can be tested for error,
 * using ZSTD_isError().
 * @return 1 if error, 0 otherwise
 */
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_minCLevel(void);               /*!< minimum negative compression level allowed, requires v1.4.0+ */
ZSTDLIB_API int         ZSTD_maxCLevel(void);               /*!< maximum compression level available */
ZSTDLIB_API int         ZSTD_defaultCLevel(void);           /*!< default compression level, specified by ZSTD_CLEVEL_DEFAULT, requires v1.5.0+ */


/***************************************
*  Explicit context
***************************************/
/*= Compression context
 *  When compressing many times,
 *  it is recommended to allocate a context just once,
 *  and re-use it for each successive compression operation.
 *  This will make workload friendlier for system's memory.
 *  Note : re-using context is just a speed / resource optimization.
 *         It doesn't change the compression ratio, which remains identical.
 *  Note 2 : In multi-threaded environments,
 *         use one different context per thread for parallel execution.
 */
typedef struct ZSTD_CCtx_s ZSTD_CCtx;
ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void);
ZSTDLIB_API size_t     ZSTD_freeCCtx(ZSTD_CCtx* cctx);  /* accept NULL pointer */

/*! ZSTD_compressCCtx() :
 *  Same as ZSTD_compress(), using an explicit ZSTD_CCtx.
 *  Important : in order to behave similarly to `ZSTD_compress()`,
 *  this function compresses at requested compression level,
 *  __ignoring any other parameter__ .
 *  If any advanced parameter was set using the advanced API,
 *  they will all be reset. Only `compressionLevel` remains.
 */
ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* cctx,
                                     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);  /* accept NULL pointer */

/*! ZSTD_decompressDCtx() :
 *  Same as ZSTD_decompress(),
 *  requires an allocated ZSTD_DCtx.
 *  Compatible with sticky parameters.
 */
ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx,
                                       void* dst, size_t dstCapacity,