1	/*
2	* Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
3	* All rights reserved.
4	*
5	* This source code is licensed under both the BSD-style license (found in the
6	* LICENSE file in the root directory of this source tree) and the GPLv2 (found
7	* in the COPYING file in the root directory of this source tree).
8	* You may select, at your option, one of the above-listed licenses.
9	*/
10	#if defined (__cplusplus)
11	extern "C" {
12	#endif
13
14	#ifndef ZSTD_H_235446
15	#define ZSTD_H_235446
16
17	/* ====== Dependency ======*/
18	#include <limits.h> /* INT_MAX */
19	#include <stddef.h> /* size_t */
20
21
22	/* ===== ZSTDLIB_API : control library symbols visibility ===== */
23	#ifndef ZSTDLIB_VISIBILITY
24	# if defined(__GNUC__) && (__GNUC__ >= 4)
25	# define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default")))
26	# else
27	# define ZSTDLIB_VISIBILITY
28	# endif
29	#endif
30	#if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
31	# define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBILITY
32	#elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1)
33	# 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.*/
34	#else
35	# define ZSTDLIB_API ZSTDLIB_VISIBILITY
36	#endif
37
38
39	/*******************************************************************************
40	Introduction
41
42	zstd, short for Zstandard, is a fast lossless compression algorithm, targeting
43	real-time compression scenarios at zlib-level and better compression ratios.
44	The zstd compression library provides in-memory compression and decompression
45	functions.
46
47	The library supports regular compression levels from 1 up to ZSTD_maxCLevel(),
48	which is currently 22. Levels >= 20, labeled `--ultra`, should be used with
49	caution, as they require more memory. The library also offers negative
50	compression levels, which extend the range of speed vs. ratio preferences.
51	The lower the level, the faster the speed (at the cost of compression).
52
53	Compression can be done in:
54	- a single step (described as Simple API)
55	- a single step, reusing a context (described as Explicit context)
56	- unbounded multiple steps (described as Streaming compression)
57
58	The compression ratio achievable on small data can be highly improved using
59	a dictionary. Dictionary compression can be performed in:
60	- a single step (described as Simple dictionary API)
61	- a single step, reusing a dictionary (described as Bulk-processing
62	dictionary API)
63
64	Advanced experimental functions can be accessed using
65	`#define ZSTD_STATIC_LINKING_ONLY` before including zstd.h.
66
67	Advanced experimental APIs should never be used with a dynamically-linked
68	library. They are not "stable"; their definitions or signatures may change in
69	the future. Only static linking is allowed.
70	*******************************************************************************/
71
72	/*------ Version ------*/
73	#define ZSTD_VERSION_MAJOR 1
74	#define ZSTD_VERSION_MINOR 4
75	#define ZSTD_VERSION_RELEASE 8
76	#define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE)
77
78	/*! ZSTD_versionNumber() :
79	* Return runtime library version, the value is (MAJOR*100*100 + MINOR*100 + RELEASE). */
80	ZSTDLIB_API unsigned ZSTD_versionNumber(void);
81
82	#define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE
83	#define ZSTD_QUOTE(str) #str
84	#define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str)
85	#define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION)
86
87	/*! ZSTD_versionString() :
88	* Return runtime library version, like "1.4.5". Requires v1.3.0+. */
89	ZSTDLIB_API const char* ZSTD_versionString(void);
90
91	/* *************************************
92	* Default constant
93	***************************************/
94	#ifndef ZSTD_CLEVEL_DEFAULT
95	# define ZSTD_CLEVEL_DEFAULT 3
96	#endif
97
98	/* *************************************
99	* Constants
100	***************************************/
101
102	/* All magic numbers are supposed read/written to/from files/memory using little-endian convention */
103	#define ZSTD_MAGICNUMBER 0xFD2FB528 /* valid since v0.8.0 */
104	#define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* valid since v0.7.0 */
105	#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50 /* all 16 values, from 0x184D2A50 to 0x184D2A5F, signal the beginning of a skippable frame */
106	#define ZSTD_MAGIC_SKIPPABLE_MASK 0xFFFFFFF0
107
108	#define ZSTD_BLOCKSIZELOG_MAX 17
109	#define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX)
110
111
112
113	/***************************************
114	* Simple API
115	***************************************/
116	/*! ZSTD_compress() :
117	* Compresses `src` content as a single zstd compressed frame into already allocated `dst`.
118	* Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
119	* @return : compressed size written into `dst` (<= `dstCapacity),
120	* or an error code if it fails (which can be tested using ZSTD_isError()). */
121	ZSTDLIB_API size_t ZSTD_compress( void* dst, size_t dstCapacity,
122	const void* src, size_t srcSize,
123	int compressionLevel);
124
125	/*! ZSTD_decompress() :
126	* `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames.
127	* `dstCapacity` is an upper bound of originalSize to regenerate.
128	* If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data.
129	* @return : the number of bytes decompressed into `dst` (<= `dstCapacity`),
130	* or an errorCode if it fails (which can be tested using ZSTD_isError()). */
131	ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity,
132	const void* src, size_t compressedSize);
133
134	/*! ZSTD_getFrameContentSize() : requires v1.3.0+
135	* `src` should point to the start of a ZSTD encoded frame.
136	* `srcSize` must be at least as large as the frame header.
137	* hint : any size >= `ZSTD_frameHeaderSize_max` is large enough.
138	* @return : - decompressed size of `src` frame content, if known
139	* - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined
140	* - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small)
141	* note 1 : a 0 return value means the frame is valid but "empty".
142	* note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode.
143	* When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size.
144	* In which case, it's necessary to use streaming mode to decompress data.
145	* Optionally, application can rely on some implicit limit,
146	* as ZSTD_decompress() only needs an upper bound of decompressed size.
147	* (For example, data could be necessarily cut into blocks <= 16 KB).
148	* note 3 : decompressed size is always present when compression is completed using single-pass functions,
149	* such as ZSTD_compress(), ZSTD_compressCCtx() ZSTD_compress_usingDict() or ZSTD_compress_usingCDict().
150	* note 4 : decompressed size can be very large (64-bits value),
151	* potentially larger than what local system can handle as a single memory segment.
152	* In which case, it's necessary to use streaming mode to decompress data.
153	* note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified.
154	* Always ensure return value fits within application's authorized limits.
155	* Each application can set its own limits.
156	* note 6 : This function replaces ZSTD_getDecompressedSize() */
157	#define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1)
158	#define ZSTD_CONTENTSIZE_ERROR (0ULL - 2)
159	ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize);
160
161	/*! ZSTD_getDecompressedSize() :
162	* NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize().
163	* Both functions work the same way, but ZSTD_getDecompressedSize() blends
164	* "empty", "unknown" and "error" results to the same return value (0),
165	* while ZSTD_getFrameContentSize() gives them separate return values.
166	* @return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise. */
167	ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);
168
169	/*! ZSTD_findFrameCompressedSize() :
170	* `src` should point to the start of a ZSTD frame or skippable frame.
171	* `srcSize` must be >= first frame size
172	* @return : the compressed size of the first frame starting at `src`,
173	* suitable to pass as `srcSize` to `ZSTD_decompress` or similar,
174	* or an error code if input is invalid */
175	ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
176
177
178	/*====== Helper functions ======*/
179	#define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (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 */
180	ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case single-pass scenario */
181	ZSTDLIB_API unsigned ZSTD_isError(size_t code); /*!< tells if a `size_t` function result is an error code */
182	ZSTDLIB_API const char* ZSTD_getErrorName(size_t code); /*!< provides readable string from an error code */
183	ZSTDLIB_API int ZSTD_minCLevel(void); /*!< minimum negative compression level allowed */
184	ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */
185
186
187	/***************************************
188	* Explicit context
189	***************************************/
190	/*= Compression context
191	* When compressing many times,
192	* it is recommended to allocate a context just once,
193	* and re-use it for each successive compression operation.
194	* This will make workload friendlier for system's memory.
195	* Note : re-using context is just a speed / resource optimization.
196	* It doesn't change the compression ratio, which remains identical.
197	* Note 2 : In multi-threaded environments,
198	* use one different context per thread for parallel execution.
199	*/
200	typedef struct ZSTD_CCtx_s ZSTD_CCtx;
201	ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void);
202	ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx);
203
204	/*! ZSTD_compressCCtx() :
205	* Same as ZSTD_compress(), using an explicit ZSTD_CCtx.
206	* Important : in order to behave similarly to `ZSTD_compress()`,
207	* this function compresses at requested compression level,
208	* __ignoring any other parameter__ .
209	* If any advanced parameter was set using the advanced API,
210	* they will all be reset. Only `compressionLevel` remains.
211	*/
212	ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* cctx,
213	void* dst, size_t dstCapacity,
214	const void* src, size_t srcSize,
215	int compressionLevel);
216
217	/*= Decompression context
218	* When decompressing many times,
219	* it is recommended to allocate a context only once,
220	* and re-use it for each successive compression operation.
221	* This will make workload friendlier for system's memory.
222	* Use one context per thread for parallel execution. */
223	typedef struct ZSTD_DCtx_s ZSTD_DCtx;
224	ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx(void);
225	ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
226
227	/*! ZSTD_decompressDCtx() :
228	* Same as ZSTD_decompress(),
229	* requires an allocated ZSTD_DCtx.
230	* Compatible with sticky parameters.
231	*/
232	ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx,
233	void* dst, size_t dstCapacity,
234	const void* src, size_t srcSize);
235
236
237	/***************************************
238	* Advanced compression API
239	***************************************/
240
241	/* API design :
242	* Parameters are pushed one by one into an existing context,
243	* using ZSTD_CCtx_set*() functions.
244	* Pushed parameters are sticky : they are valid for next compressed frame, and any subsequent frame.
245	* "sticky" parameters are applicable to `ZSTD_compress2()` and `ZSTD_compressStream*()` !
246	* __They do not apply to "simple" one-shot variants such as ZSTD_compressCCtx()__ .
247	*
248	* It's possible to reset all parameters to "default" using ZSTD_CCtx_reset().
249	*
250	* This API supercedes all other "advanced" API entry points in the experimental section.
251	* In the future, we expect to remove from experimental API entry points which are redundant with this API.
252	*/
253
254
255	/* Compression strategies, listed from fastest to strongest */
256	typedef enum { ZSTD_fast=1,
257	ZSTD_dfast=2,
258	ZSTD_greedy=3,
259	ZSTD_lazy=4,
260	ZSTD_lazy2=5,
261	ZSTD_btlazy2=6,
262	ZSTD_btopt=7,
263	ZSTD_btultra=8,
264	ZSTD_btultra2=9
265	/* note : new strategies _might_ be added in the future.
266	Only the order (from fast to strong) is guaranteed */
267	} ZSTD_strategy;
268
269
270	typedef enum {
271
272	/* compression parameters
273	* Note: When compressing with a ZSTD_CDict these parameters are superseded
274	* by the parameters used to construct the ZSTD_CDict.
275	* See ZSTD_CCtx_refCDict() for more info (superseded-by-cdict). */
276	ZSTD_c_compressionLevel=100, /* Set compression parameters according to pre-defined cLevel table.
277	* Note that exact compression parameters are dynamically determined,
278	* depending on both compression level and srcSize (when known).
279	* Default level is ZSTD_CLEVEL_DEFAULT==3.
280	* Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT.
281	* Note 1 : it's possible to pass a negative compression level.
282	* Note 2 : setting a level does not automatically set all other compression parameters
283	* to default. Setting this will however eventually dynamically impact the compression
284	* parameters which have not been manually set. The manually set
285	* ones will 'stick'. */
286	/* Advanced compression parameters :
287	* It's possible to pin down compression parameters to some specific values.
288	* In which case, these values are no longer dynamically selected by the compressor */
289	ZSTD_c_windowLog=101, /* Maximum allowed back-reference distance, expressed as power of 2.
290	* This will set a memory budget for streaming decompression,
291	* with larger values requiring more memory
292	* and typically compressing more.
293	* Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
294	* Special: value 0 means "use default windowLog".
295	* Note: Using a windowLog greater than ZSTD_WINDOWLOG_LIMIT_DEFAULT
296	* requires explicitly allowing such size at streaming decompression stage. */
297	ZSTD_c_hashLog=102, /* Size of the initial probe table, as a power of 2.
298	* Resulting memory usage is (1 << (hashLog+2)).
299	* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX.
300	* Larger tables improve compression ratio of strategies <= dFast,
301	* and improve speed of strategies > dFast.
302	* Special: value 0 means "use default hashLog". */
303	ZSTD_c_chainLog=103, /* Size of the multi-probe search table, as a power of 2.
304	* Resulting memory usage is (1 << (chainLog+2)).
305	* Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX.
306	* Larger tables result in better and slower compression.
307	* This parameter is useless for "fast" strategy.
308	* It's still useful when using "dfast" strategy,
309	* in which case it defines a secondary probe table.
310	* Special: value 0 means "use default chainLog". */
311	ZSTD_c_searchLog=104, /* Number of search attempts, as a power of 2.
312	* More attempts result in better and slower compression.
313	* This parameter is useless for "fast" and "dFast" strategies.
314	* Special: value 0 means "use default searchLog". */
315	ZSTD_c_minMatch=105, /* Minimum size of searched matches.
316	* Note that Zstandard can still find matches of smaller size,
317	* it just tweaks its search algorithm to look for this size and larger.
318	* Larger values increase compression and decompression speed, but decrease ratio.
319	* Must be clamped between ZSTD_MINMATCH_MIN and ZSTD_MINMATCH_MAX.
320	* Note that currently, for all strategies < btopt, effective minimum is 4.
321	* , for all strategies > fast, effective maximum is 6.
322	* Special: value 0 means "use default minMatchLength". */
323	ZSTD_c_targetLength=106, /* Impact of this field depends on strategy.
324	* For strategies btopt, btultra & btultra2:
325	* Length of Match considered "good enough" to stop search.
326	* Larger values make compression stronger, and slower.
327	* For strategy fast:
328	* Distance between match sampling.
329	* Larger values make compression faster, and weaker.
330	* Special: value 0 means "use default targetLength". */
331	ZSTD_c_strategy=107, /* See ZSTD_strategy enum definition.
332	* The higher the value of selected strategy, the more complex it is,
333	* resulting in stronger and slower compression.
334	* Special: value 0 means "use default strategy". */
335
336	/* LDM mode parameters */
337	ZSTD_c_enableLongDistanceMatching=160, /* Enable long distance matching.
338	* This parameter is designed to improve compression ratio
339	* for large inputs, by finding large matches at long distance.
340	* It increases memory usage and window size.
341	* Note: enabling this parameter increases default ZSTD_c_windowLog to 128 MB
342	* except when expressly set to a different value.
343	* Note: will be enabled by default if ZSTD_c_windowLog >= 128 MB and
344	* compression strategy >= ZSTD_btopt (== compression level 16+) */
345	ZSTD_c_ldmHashLog=161, /* Size of the table for long distance matching, as a power of 2.
346	* Larger values increase memory usage and compression ratio,
347	* but decrease compression speed.
348	* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX
349	* default: windowlog - 7.
350	* Special: value 0 means "automatically determine hashlog". */
351	ZSTD_c_ldmMinMatch=162, /* Minimum match size for long distance matcher.
352	* Larger/too small values usually decrease compression ratio.
353	* Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX.
354	* Special: value 0 means "use default value" (default: 64). */
355	ZSTD_c_ldmBucketSizeLog=163, /* Log size of each bucket in the LDM hash table for collision resolution.
356	* Larger values improve collision resolution but decrease compression speed.
357	* The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX.
358	* Special: value 0 means "use default value" (default: 3). */
359	ZSTD_c_ldmHashRateLog=164, /* Frequency of inserting/looking up entries into the LDM hash table.
360	* Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN).
361	* Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage.
362	* Larger values improve compression speed.
363	* Deviating far from default value will likely result in a compression ratio decrease.
364	* Special: value 0 means "automatically determine hashRateLog". */
365
366	/* frame parameters */
367	ZSTD_c_contentSizeFlag=200, /* Content size will be written into frame header _whenever known_ (default:1)
368	* Content size must be known at the beginning of compression.
369	* This is automatically the case when using ZSTD_compress2(),
370	* For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */
371	ZSTD_c_checksumFlag=201, /* A 32-bits checksum of content is written at end of frame (default:0) */
372	ZSTD_c_dictIDFlag=202, /* When applicable, dictionary's ID is written into frame header (default:1) */
373
374	/* multi-threading parameters */
375	/* These parameters are only active if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD).
376	* Otherwise, trying to set any other value than default (0) will be a no-op and return an error.
377	* In a situation where it's unknown if the linked library supports multi-threading or not,
378	* setting ZSTD_c_nbWorkers to any value >= 1 and consulting the return value provides a quick way to check this property.
379	*/
380	ZSTD_c_nbWorkers=400, /* Select how many threads will be spawned to compress in parallel.
381	* When nbWorkers >= 1, triggers asynchronous mode when invoking ZSTD_compressStream*() :
382	* ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller,
383	* while compression is performed in parallel, within worker thread(s).
384	* (note : a strong exception to this rule is when first invocation of ZSTD_compressStream2() sets ZSTD_e_end :
385	* in which case, ZSTD_compressStream2() delegates to ZSTD_compress2(), which is always a blocking call).
386	* More workers improve speed, but also increase memory usage.
387	* Default value is `0`, aka "single-threaded mode" : no worker is spawned,
388	* compression is performed inside Caller's thread, and all invocations are blocking */
389	ZSTD_c_jobSize=401, /* Size of a compression job. This value is enforced only when nbWorkers >= 1.
390	* Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads.
391	* 0 means default, which is dynamically determined based on compression parameters.
392	* Job size must be a minimum of overlap size, or 1 MB, whichever is largest.
393	* The minimum size is automatically and transparently enforced. */
394	ZSTD_c_overlapLog=402, /* Control the overlap size, as a fraction of window size.
395	* The overlap size is an amount of data reloaded from previous job at the beginning of a new job.
396	* It helps preserve compression ratio, while each job is compressed in parallel.
397	* This value is enforced only when nbWorkers >= 1.
398	* Larger values increase compression ratio, but decrease speed.
399	* Possible values range from 0 to 9 :
400	* - 0 means "default" : value will be determined by the library, depending on strategy
401	* - 1 means "no overlap"
402	* - 9 means "full overlap", using a full window size.
403	* Each intermediate rank increases/decreases load size by a factor 2 :
404	* 9: full window; 8: w/2; 7: w/4; 6: w/8; 5:w/16; 4: w/32; 3:w/64; 2:w/128; 1:no overlap; 0:default
405	* default value varies between 6 and 9, depending on strategy */
406
407	/* note : additional experimental parameters are also available
408	* within the experimental section of the API.
409	* At the time of this writing, they include :
410	* ZSTD_c_rsyncable
411	* ZSTD_c_format
412	* ZSTD_c_forceMaxWindow
413	* ZSTD_c_forceAttachDict
414	* ZSTD_c_literalCompressionMode
415	* ZSTD_c_targetCBlockSize
416	* ZSTD_c_srcSizeHint
417	* ZSTD_c_enableDedicatedDictSearch
418	* ZSTD_c_stableInBuffer
419	* ZSTD_c_stableOutBuffer
420	* ZSTD_c_blockDelimiters
421	* ZSTD_c_validateSequences
422	* Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them.
423	* note : never ever use experimentalParam? names directly;
424	* also, the enums values themselves are unstable and can still change.
425	*/
426	ZSTD_c_experimentalParam1=500,
427	ZSTD_c_experimentalParam2=10,
428	ZSTD_c_experimentalParam3=1000,
429	ZSTD_c_experimentalParam4=1001,
430	ZSTD_c_experimentalParam5=1002,
431	ZSTD_c_experimentalParam6=1003,
432	ZSTD_c_experimentalParam7=1004,
433	ZSTD_c_experimentalParam8=1005,
434	ZSTD_c_experimentalParam9=1006,
435	ZSTD_c_experimentalParam10=1007,
436	ZSTD_c_experimentalParam11=1008,
437	ZSTD_c_experimentalParam12=1009
438	} ZSTD_cParameter;
439
440	typedef struct {
441	size_t error;
442	int lowerBound;
443	int upperBound;
444	} ZSTD_bounds;
445
446	/*! ZSTD_cParam_getBounds() :
447	* All parameters must belong to an interval with lower and upper bounds,
448	* otherwise they will either trigger an error or be automatically clamped.
449	* @return : a structure, ZSTD_bounds, which contains
450	* - an error status field, which must be tested using ZSTD_isError()
451	* - lower and upper bounds, both inclusive
452	*/
453	ZSTDLIB_API ZSTD_bounds ZSTD_cParam_getBounds(ZSTD_cParameter cParam);
454
455	/*! ZSTD_CCtx_setParameter() :
456	* Set one compression parameter, selected by enum ZSTD_cParameter.
457	* All parameters have valid bounds. Bounds can be queried using ZSTD_cParam_getBounds().
458	* Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter).
459	* Setting a parameter is generally only possible during frame initialization (before starting compression).
460	* Exception : when using multi-threading mode (nbWorkers >= 1),
461	* the following parameters can be updated _during_ compression (within same frame):
462	* => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy.
463	* new parameters will be active for next job only (after a flush()).
464	* @return : an error code (which can be tested using ZSTD_isError()).
465	*/
466	ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value);
467
468	/*! ZSTD_CCtx_setPledgedSrcSize() :
469	* Total input data size to be compressed as a single frame.
470	* Value will be written in frame header, unless if explicitly forbidden using ZSTD_c_contentSizeFlag.
471	* This value will also be controlled at end of frame, and trigger an error if not respected.
472	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
473	* Note 1 : pledgedSrcSize==0 actually means zero, aka an empty frame.
474	* In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN.
475	* ZSTD_CONTENTSIZE_UNKNOWN is default value for any new frame.
476	* Note 2 : pledgedSrcSize is only valid once, for the next frame.
477	* It's discarded at the end of the frame, and replaced by ZSTD_CONTENTSIZE_UNKNOWN.
478	* Note 3 : Whenever all input data is provided and consumed in a single round,
479	* for example with ZSTD_compress2(),
480	* or invoking immediately ZSTD_compressStream2(,,,ZSTD_e_end),
481	* this value is automatically overridden by srcSize instead.
482	*/
483	ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize);
484
485	typedef enum {
486	ZSTD_reset_session_only = 1,
487	ZSTD_reset_parameters = 2,
488	ZSTD_reset_session_and_parameters = 3
489	} ZSTD_ResetDirective;
490
491	/*! ZSTD_CCtx_reset() :
492	* There are 2 different things that can be reset, independently or jointly :
493	* - The session : will stop compressing current frame, and make CCtx ready to start a new one.
494	* Useful after an error, or to interrupt any ongoing compression.
495	* Any internal data not yet flushed is cancelled.
496	* Compression parameters and dictionary remain unchanged.
497	* They will be used to compress next frame.
498	* Resetting session never fails.
499	* - The parameters : changes all parameters back to "default".
500	* This removes any reference to any dictionary too.
501	* Parameters can only be changed between 2 sessions (i.e. no compression is currently ongoing)
502	* otherwise the reset fails, and function returns an error value (which can be tested using ZSTD_isError())
503	* - Both : similar to resetting the session, followed by resetting parameters.
504	*/
505	ZSTDLIB_API size_t ZSTD_CCtx_reset(ZSTD_CCtx* cctx, ZSTD_ResetDirective reset);
506
507	/*! ZSTD_compress2() :
508	* Behave the same as ZSTD_compressCCtx(), but compression parameters are set using the advanced API.
509	* ZSTD_compress2() always starts a new frame.
510	* Should cctx hold data from a previously unfinished frame, everything about it is forgotten.
511	* - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
512	* - The function is always blocking, returns when compression is completed.
513	* Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
514	* @return : compressed size written into `dst` (<= `dstCapacity),
515	* or an error code if it fails (which can be tested using ZSTD_isError()).
516	*/
517	ZSTDLIB_API size_t ZSTD_compress2( ZSTD_CCtx* cctx,
518	void* dst, size_t dstCapacity,
519	const void* src, size_t srcSize);
520
521
522	/***************************************
523	* Advanced decompression API
524	***************************************/
525
526	/* The advanced API pushes parameters one by one into an existing DCtx context.
527	* Parameters are sticky, and remain valid for all following frames
528	* using the same DCtx context.
529	* It's possible to reset parameters to default values using ZSTD_DCtx_reset().
530	* Note : This API is compatible with existing ZSTD_decompressDCtx() and ZSTD_decompressStream().
531	* Therefore, no new decompression function is necessary.
532	*/
533
534	typedef enum {
535
536	ZSTD_d_windowLogMax=100, /* Select a size limit (in power of 2) beyond which
537	* the streaming API will refuse to allocate memory buffer
538	* in order to protect the host from unreasonable memory requirements.
539	* This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode.
540	* By default, a decompression context accepts window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT).
541	* Special: value 0 means "use default maximum windowLog". */
542
543	/* note : additional experimental parameters are also available
544	* within the experimental section of the API.
545	* At the time of this writing, they include :
546	* ZSTD_d_format
547	* ZSTD_d_stableOutBuffer
548	* ZSTD_d_forceIgnoreChecksum
549	* Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them.
550	* note : never ever use experimentalParam? names directly
551	*/
552	ZSTD_d_experimentalParam1=1000,
553	ZSTD_d_experimentalParam2=1001,
554	ZSTD_d_experimentalParam3=1002
555
556	} ZSTD_dParameter;
557
558	/*! ZSTD_dParam_getBounds() :
559	* All parameters must belong to an interval with lower and upper bounds,
560	* otherwise they will either trigger an error or be automatically clamped.
561	* @return : a structure, ZSTD_bounds, which contains
562	* - an error status field, which must be tested using ZSTD_isError()
563	* - both lower and upper bounds, inclusive
564	*/
565	ZSTDLIB_API ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam);
566
567	/*! ZSTD_DCtx_setParameter() :
568	* Set one compression parameter, selected by enum ZSTD_dParameter.
569	* All parameters have valid bounds. Bounds can be queried using ZSTD_dParam_getBounds().
570	* Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter).
571	* Setting a parameter is only possible during frame initialization (before starting decompression).
572	* @return : 0, or an error code (which can be tested using ZSTD_isError()).
573	*/
574	ZSTDLIB_API size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int value);
575
576	/*! ZSTD_DCtx_reset() :
577	* Return a DCtx to clean state.
578	* Session and parameters can be reset jointly or separately.
579	* Parameters can only be reset when no active frame is being decompressed.
580	* @return : 0, or an error code, which can be tested with ZSTD_isError()
581	*/
582	ZSTDLIB_API size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset);
583
584
585	/****************************
586	* Streaming
587	****************************/
588
589	typedef struct ZSTD_inBuffer_s {
590	const void* src; /**< start of input buffer */
591	size_t size; /**< size of input buffer */
592	size_t pos; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */
593	} ZSTD_inBuffer;
594
595	typedef struct ZSTD_outBuffer_s {
596	void* dst; /**< start of output buffer */
597	size_t size; /**< size of output buffer */
598	size_t pos; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */
599	} ZSTD_outBuffer;
600
601
602
603	/*-***********************************************************************
604	* Streaming compression - HowTo
605	*
606	* A ZSTD_CStream object is required to track streaming operation.
607	* Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources.
608	* ZSTD_CStream objects can be reused multiple times on consecutive compression operations.
609	* It is recommended to re-use ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory.
610	*
611	* For parallel execution, use one separate ZSTD_CStream per thread.
612	*
613	* note : since v1.3.0, ZSTD_CStream and ZSTD_CCtx are the same thing.
614	*
615	* Parameters are sticky : when starting a new compression on the same context,
616	* it will re-use the same sticky parameters as previous compression session.
617	* When in doubt, it's recommended to fully initialize the context before usage.
618	* Use ZSTD_CCtx_reset() to reset the context and ZSTD_CCtx_setParameter(),
619	* ZSTD_CCtx_setPledgedSrcSize(), or ZSTD_CCtx_loadDictionary() and friends to
620	* set more specific parameters, the pledged source size, or load a dictionary.
621	*
622	* Use ZSTD_compressStream2() with ZSTD_e_continue as many times as necessary to
623	* consume input stream. The function will automatically update both `pos`
624	* fields within `input` and `output`.
625	* Note that the function may not consume the entire input, for example, because
626	* the output buffer is already full, in which case `input.pos < input.size`.
627	* The caller must check if input has been entirely consumed.
628	* If not, the caller must make some room to receive more compressed data,
629	* and then present again remaining input data.
630	* note: ZSTD_e_continue is guaranteed to make some forward progress when called,
631	* but doesn't guarantee maximal forward progress. This is especially relevant
632	* when compressing with multiple threads. The call won't block if it can
633	* consume some input, but if it can't it will wait for some, but not all,
634	* output to be flushed.
635	* @return : provides a minimum amount of data remaining to be flushed from internal buffers
636	* or an error code, which can be tested using ZSTD_isError().
637	*
638	* At any moment, it's possible to flush whatever data might remain stuck within internal buffer,
639	* using ZSTD_compressStream2() with ZSTD_e_flush. `output->pos` will be updated.
640	* Note that, if `output->size` is too small, a single invocation with ZSTD_e_flush might not be enough (return code > 0).
641	* In which case, make some room to receive more compressed data, and call again ZSTD_compressStream2() with ZSTD_e_flush.
642	* You must continue calling ZSTD_compressStream2() with ZSTD_e_flush until it returns 0, at which point you can change the
643	* operation.
644	* note: ZSTD_e_flush will flush as much output as possible, meaning when compressing with multiple threads, it will
645	* block until the flush is complete or the output buffer is full.
646	* @return : 0 if internal buffers are entirely flushed,
647	* >0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
648	* or an error code, which can be tested using ZSTD_isError().
649	*
650	* Calling ZSTD_compressStream2() with ZSTD_e_end instructs to finish a frame.
651	* It will perform a flush and write frame epilogue.
652	* The epilogue is required for decoders to consider a frame completed.
653	* flush operation is the same, and follows same rules as calling ZSTD_compressStream2() with ZSTD_e_flush.
654	* You must continue calling ZSTD_compressStream2() with ZSTD_e_end until it returns 0, at which point you are free to
655	* start a new frame.
656	* note: ZSTD_e_end will flush as much output as possible, meaning when compressing with multiple threads, it will
657	* block until the flush is complete or the output buffer is full.
658	* @return : 0 if frame fully completed and fully flushed,
659	* >0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
660	* or an error code, which can be tested using ZSTD_isError().
661	*
662	* *******************************************************************/
663
664	typedef ZSTD_CCtx ZSTD_CStream; /**< CCtx and CStream are now effectively same object (>= v1.3.0) */
665	/* Continue to distinguish them for compatibility with older versions <= v1.2.0 */
666	/*===== ZSTD_CStream management functions =====*/
667	ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void);
668	ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs);
669
670	/*===== Streaming compression functions =====*/
671	typedef enum {
672	ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal compression ratio */
673	ZSTD_e_flush=1, /* flush any data provided so far,
674	* it creates (at least) one new block, that can be decoded immediately on reception;
675	* frame will continue: any future data can still reference previously compressed data, improving compression.
676	* note : multithreaded compression will block to flush as much output as possible. */
677	ZSTD_e_end=2 /* flush any remaining data _and_ close current frame.
678	* note that frame is only closed after compressed data is fully flushed (return value == 0).
679	* After that point, any additional data starts a new frame.
680	* note : each frame is independent (does not reference any content from previous frame).
681	: note : multithreaded compression will block to flush as much output as possible. */
682	} ZSTD_EndDirective;
683
684	/*! ZSTD_compressStream2() :
685	* Behaves about the same as ZSTD_compressStream, with additional control on end directive.
686	* - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
687	* - Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode)
688	* - output->pos must be <= dstCapacity, input->pos must be <= srcSize
689	* - output->pos and input->pos will be updated. They are guaranteed to remain below their respective limit.
690	* - endOp must be a valid directive
691	* - When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller.
692	* - When nbWorkers>=1, function is non-blocking : it copies a portion of input, distributes jobs to internal worker threads, flush to output whatever is available,
693	* and then immediately returns, just indicating that there is some data remaining to be flushed.
694	* The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte.
695	* - Exception : if the first call requests a ZSTD_e_end directive and provides enough dstCapacity, the function delegates to ZSTD_compress2() which is always blocking.
696	* - @return provides a minimum amount of data remaining to be flushed from internal buffers
697	* or an error code, which can be tested using ZSTD_isError().
698	* if @return != 0, flush is not fully completed, there is still some data left within internal buffers.
699	* This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers.
700	* For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed.
701	* - after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0),
702	* only ZSTD_e_end or ZSTD_e_flush operations are allowed.
703	* Before starting a new compression job, or changing compression parameters,
704	* it is required to fully flush internal buffers.
705	*/
706	ZSTDLIB_API size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
707	ZSTD_outBuffer* output,
708	ZSTD_inBuffer* input,
709	ZSTD_EndDirective endOp);
710
711
712	/* These buffer sizes are softly recommended.
713	* They are not required : ZSTD_compressStream*() happily accepts any buffer size, for both input and output.
714	* Respecting the recommended size just makes it a bit easier for ZSTD_compressStream*(),
715	* reducing the amount of memory shuffling and buffering, resulting in minor performance savings.
716	*
717	* However, note that these recommendations are from the perspective of a C caller program.
718	* If the streaming interface is invoked from some other language,
719	* especially managed ones such as Java or Go, through a foreign function interface such as jni or cgo,
720	* a major performance rule is to reduce crossing such interface to an absolute minimum.
721	* It's not rare that performance ends being spent more into the interface, rather than compression itself.
722	* In which cases, prefer using large buffers, as large as practical,
723	* for both input and output, to reduce the nb of roundtrips.
724	*/
725	ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */
726	ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */
727
728
729	/* *****************************************************************************
730	* This following is a legacy streaming API.
731	* It can be replaced by ZSTD_CCtx_reset() and ZSTD_compressStream2().
732	* It is redundant, but remains fully supported.
733	* Advanced parameters and dictionary compression can only be used through the
734	* new API.
735	******************************************************************************/
736
737	/*!
738	* Equivalent to:
739	*
740	* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
741	* ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any)
742	* ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
743	*/
744	ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel);
745	/*!
746	* Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue).
747	* NOTE: The return value is different. ZSTD_compressStream() returns a hint for
748	* the next read size (if non-zero and not an error). ZSTD_compressStream2()
749	* returns the minimum nb of bytes left to flush (if non-zero and not an error).
750	*/
751	ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
752	/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */
753	ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
754	/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */
755	ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
756
757
758	/*-***************************************************************************
759	* Streaming decompression - HowTo
760	*
761	* A ZSTD_DStream object is required to track streaming operations.
762	* Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources.
763	* ZSTD_DStream objects can be re-used multiple times.
764	*
765	* Use ZSTD_initDStream() to start a new decompression operation.
766	* @return : recommended first input size
767	* Alternatively, use advanced API to set specific properties.
768	*
769	* Use ZSTD_decompressStream() repetitively to consume your input.
770	* The function will update both `pos` fields.
771	* If `input.pos < input.size`, some input has not been consumed.
772	* It's up to the caller to present again remaining data.
773	* The function tries to flush all data decoded immediately, respecting output buffer size.
774	* If `output.pos < output.size`, decoder has flushed everything it could.
775	* But if `output.pos == output.size`, there might be some data left within internal buffers.,
776	* In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer.
777	* Note : with no additional input provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX.
778	* @return : 0 when a frame is completely decoded and fully flushed,
779	* or an error code, which can be tested using ZSTD_isError(),
780	* or any other value > 0, which means there is still some decoding or flushing to do to complete current frame :
781	* the return value is a suggested next input size (just a hint for better latency)
782	* that will never request more than the remaining frame size.
783	* *******************************************************************************/
784
785	typedef ZSTD_DCtx ZSTD_DStream; /**< DCtx and DStream are now effectively same object (>= v1.3.0) */
786	/* For compatibility with versions <= v1.2.0, prefer differentiating them. */
787	/*===== ZSTD_DStream management functions =====*/
788	ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void);
789	ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds);
790
791	/*===== Streaming decompression functions =====*/
792
793	/* This function is redundant with the advanced API and equivalent to:
794	*
795	* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
796	* ZSTD_DCtx_refDDict(zds, NULL);
797	*/
798	ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds);
799
800	ZSTDLIB_API size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
801
802	ZSTDLIB_API size_t ZSTD_DStreamInSize(void); /*!< recommended size for input buffer */
803	ZSTDLIB_API size_t ZSTD_DStreamOutSize(void); /*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */
804
805
806	/**************************
807	* Simple dictionary API
808	***************************/
809	/*! ZSTD_compress_usingDict() :
810	* Compression at an explicit compression level using a Dictionary.
811	* A dictionary can be any arbitrary data segment (also called a prefix),
812	* or a buffer with specified information (see dictBuilder/zdict.h).
813	* Note : This function loads the dictionary, resulting in significant startup delay.
814	* It's intended for a dictionary used only once.
815	* Note 2 : When `dict == NULL || dictSize < 8` no dictionary is used. */
816	ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx,
817	void* dst, size_t dstCapacity,
818	const void* src, size_t srcSize,
819	const void* dict,size_t dictSize,
820	int compressionLevel);
821
822	/*! ZSTD_decompress_usingDict() :
823	* Decompression using a known Dictionary.
824	* Dictionary must be identical to the one used during compression.
825	* Note : This function loads the dictionary, resulting in significant startup delay.
826	* It's intended for a dictionary used only once.
827	* Note : When `dict == NULL || dictSize < 8` no dictionary is used. */
828	ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
829	void* dst, size_t dstCapacity,
830	const void* src, size_t srcSize,
831	const void* dict,size_t dictSize);
832
833
834	/***********************************
835	* Bulk processing dictionary API
836	**********************************/
837	typedef struct ZSTD_CDict_s ZSTD_CDict;
838
839	/*! ZSTD_createCDict() :
840	* When compressing multiple messages or blocks using the same dictionary,
841	* it's recommended to digest the dictionary only once, since it's a costly operation.
842	* ZSTD_createCDict() will create a state from digesting a dictionary.
843	* The resulting state can be used for future compression operations with very limited startup cost.
844	* ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
845	* @dictBuffer can be released after ZSTD_CDict creation, because its content is copied within CDict.
846	* Note 1 : Consider experimental function `ZSTD_createCDict_byReference()` if you prefer to not duplicate @dictBuffer content.
847	* Note 2 : A ZSTD_CDict can be created from an empty @dictBuffer,
848	* in which case the only thing that it transports is the @compressionLevel.
849	* This can be useful in a pipeline featuring ZSTD_compress_usingCDict() exclusively,
850	* expecting a ZSTD_CDict parameter with any data, including those without a known dictionary. */
851	ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
852	int compressionLevel);
853
854	/*! ZSTD_freeCDict() :
855	* Function frees memory allocated by ZSTD_createCDict(). */
856	ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict);
857
858	/*! ZSTD_compress_usingCDict() :
859	* Compression using a digested Dictionary.
860	* Recommended when same dictionary is used multiple times.
861	* Note : compression level is _decided at dictionary creation time_,
862	* and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no) */
863	ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
864	void* dst, size_t dstCapacity,
865	const void* src, size_t srcSize,
866	const ZSTD_CDict* cdict);
867
868
869	typedef struct ZSTD_DDict_s ZSTD_DDict;
870
871	/*! ZSTD_createDDict() :
872	* Create a digested dictionary, ready to start decompression operation without startup delay.
873	* dictBuffer can be released after DDict creation, as its content is copied inside DDict. */
874	ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize);
875
876	/*! ZSTD_freeDDict() :
877	* Function frees memory allocated with ZSTD_createDDict() */
878	ZSTDLIB_API size_t ZSTD_freeDDict(ZSTD_DDict* ddict);
879
880	/*! ZSTD_decompress_usingDDict() :
881	* Decompression using a digested Dictionary.
882	* Recommended when same dictionary is used multiple times. */
883	ZSTDLIB_API size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx,
884	void* dst, size_t dstCapacity,
885	const void* src, size_t srcSize,
886	const ZSTD_DDict* ddict);
887
888
889	/********************************
890	* Dictionary helper functions
891	*******************************/
892
893	/*! ZSTD_getDictID_fromDict() :
894	* Provides the dictID stored within dictionary.
895	* if @return == 0, the dictionary is not conformant with Zstandard specification.
896	* It can still be loaded, but as a content-only dictionary. */
897	ZSTDLIB_API unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize);
898
899	/*! ZSTD_getDictID_fromDDict() :
900	* Provides the dictID of the dictionary loaded into `ddict`.
901	* If @return == 0, the dictionary is not conformant to Zstandard specification, or empty.
902	* Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */
903	ZSTDLIB_API unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict);
904
905	/*! ZSTD_getDictID_fromFrame() :
906	* Provides the dictID required to decompressed the frame stored within `src`.
907	* If @return == 0, the dictID could not be decoded.
908	* This could for one of the following reasons :
909	* - The frame does not require a dictionary to be decoded (most common case).
910	* - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information.
911	* Note : this use case also happens when using a non-conformant dictionary.
912	* - `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`).
913	* - This is not a Zstandard frame.
914	* When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code. */
915	ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize);
916
917
918	/*******************************************************************************
919	* Advanced dictionary and prefix API
920	*
921	* This API allows dictionaries to be used with ZSTD_compress2(),
922	* ZSTD_compressStream2(), and ZSTD_decompress(). Dictionaries are sticky, and
923	* only reset with the context is reset with ZSTD_reset_parameters or
924	* ZSTD_reset_session_and_parameters. Prefixes are single-use.
925	******************************************************************************/
926
927
928	/*! ZSTD_CCtx_loadDictionary() :
929	* Create an internal CDict from `dict` buffer.
930	* Decompression will have to use same dictionary.
931	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
932	* Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary,
933	* meaning "return to no-dictionary mode".
934	* Note 1 : Dictionary is sticky, it will be used for all future compressed frames.
935	* To return to "no-dictionary" situation, load a NULL dictionary (or reset parameters).
936	* Note 2 : Loading a dictionary involves building tables.
937	* It's also a CPU consuming operation, with non-negligible impact on latency.
938	* Tables are dependent on compression parameters, and for this reason,
939	* compression parameters can no longer be changed after loading a dictionary.
940	* Note 3 :`dict` content will be copied internally.
941	* Use experimental ZSTD_CCtx_loadDictionary_byReference() to reference content instead.
942	* In such a case, dictionary buffer must outlive its users.
943	* Note 4 : Use ZSTD_CCtx_loadDictionary_advanced()
944	* to precisely select how dictionary content must be interpreted. */
945	ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
946
947	/*! ZSTD_CCtx_refCDict() :
948	* Reference a prepared dictionary, to be used for all next compressed frames.
949	* Note that compression parameters are enforced from within CDict,
950	* and supersede any compression parameter previously set within CCtx.
951	* The parameters ignored are labled as "superseded-by-cdict" in the ZSTD_cParameter enum docs.
952	* The ignored parameters will be used again if the CCtx is returned to no-dictionary mode.
953	* The dictionary will remain valid for future compressed frames using same CCtx.
954	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
955	* Special : Referencing a NULL CDict means "return to no-dictionary mode".
956	* Note 1 : Currently, only one dictionary can be managed.
957	* Referencing a new dictionary effectively "discards" any previous one.
958	* Note 2 : CDict is just referenced, its lifetime must outlive its usage within CCtx. */
959	ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
960
961	/*! ZSTD_CCtx_refPrefix() :
962	* Reference a prefix (single-usage dictionary) for next compressed frame.
963	* A prefix is **only used once**. Tables are discarded at end of frame (ZSTD_e_end).
964	* Decompression will need same prefix to properly regenerate data.
965	* Compressing with a prefix is similar in outcome as performing a diff and compressing it,
966	* but performs much faster, especially during decompression (compression speed is tunable with compression level).
967	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
968	* Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary
969	* Note 1 : Prefix buffer is referenced. It **must** outlive compression.
970	* Its content must remain unmodified during compression.
971	* Note 2 : If the intention is to diff some large src data blob with some prior version of itself,
972	* ensure that the window size is large enough to contain the entire source.
973	* See ZSTD_c_windowLog.
974	* Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters.
975	* It's a CPU consuming operation, with non-negligible impact on latency.
976	* If there is a need to use the same prefix multiple times, consider loadDictionary instead.
977	* Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dct_rawContent).
978	* Use experimental ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation. */
979	ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx,
980	const void* prefix, size_t prefixSize);
981
982	/*! ZSTD_DCtx_loadDictionary() :
983	* Create an internal DDict from dict buffer,
984	* to be used to decompress next frames.
985	* The dictionary remains valid for all future frames, until explicitly invalidated.
986	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
987	* Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary,
988	* meaning "return to no-dictionary mode".
989	* Note 1 : Loading a dictionary involves building tables,
990	* which has a non-negligible impact on CPU usage and latency.
991	* It's recommended to "load once, use many times", to amortize the cost
992	* Note 2 :`dict` content will be copied internally, so `dict` can be released after loading.
993	* Use ZSTD_DCtx_loadDictionary_byReference() to reference dictionary content instead.
994	* Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to take control of
995	* how dictionary content is loaded and interpreted.
996	*/
997	ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
998
999	/*! ZSTD_DCtx_refDDict() :
1000	* Reference a prepared dictionary, to be used to decompress next frames.
1001	* The dictionary remains active for decompression of future frames using same DCtx.
1002	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
1003	* Note 1 : Currently, only one dictionary can be managed.
1004	* Referencing a new dictionary effectively "discards" any previous one.
1005	* Special: referencing a NULL DDict means "return to no-dictionary mode".
1006	* Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx.
1007	*/
1008	ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
1009
1010	/*! ZSTD_DCtx_refPrefix() :
1011	* Reference a prefix (single-usage dictionary) to decompress next frame.
1012	* This is the reverse operation of ZSTD_CCtx_refPrefix(),
1013	* and must use the same prefix as the one used during compression.
1014	* Prefix is **only used once**. Reference is discarded at end of frame.
1015	* End of frame is reached when ZSTD_decompressStream() returns 0.
1016	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
1017	* Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary
1018	* Note 2 : Prefix buffer is referenced. It **must** outlive decompression.
1019	* Prefix buffer must remain unmodified up to the end of frame,
1020	* reached when ZSTD_decompressStream() returns 0.
1021	* Note 3 : By default, the prefix is treated as raw content (ZSTD_dct_rawContent).
1022	* Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode (Experimental section)
1023	* Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost.
1024	* A full dictionary is more costly, as it requires building tables.
1025	*/
1026	ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx,
1027	const void* prefix, size_t prefixSize);
1028
1029	/* === Memory management === */
1030
1031	/*! ZSTD_sizeof_*() :
1032	* These functions give the _current_ memory usage of selected object.
1033	* Note that object memory usage can evolve (increase or decrease) over time. */
1034	ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
1035	ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);
1036	ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs);
1037	ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds);
1038	ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict);
1039	ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
1040
1041	#endif /* ZSTD_H_235446 */
1042
1043
1044	/* **************************************************************************************
1045	* ADVANCED AND EXPERIMENTAL FUNCTIONS
1046	****************************************************************************************
1047	* The definitions in the following section are considered experimental.
1048	* They are provided for advanced scenarios.
1049	* They should never be used with a dynamic library, as prototypes may change in the future.
1050	* Use them only in association with static linking.
1051	* ***************************************************************************************/
1052
1053	#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
1054	#define ZSTD_H_ZSTD_STATIC_LINKING_ONLY
1055
1056	/****************************************************************************************
1057	* experimental API (static linking only)
1058	****************************************************************************************
1059	* The following symbols and constants
1060	* are not planned to join "stable API" status in the near future.
1061	* They can still change in future versions.
1062	* Some of them are planned to remain in the static_only section indefinitely.
1063	* Some of them might be removed in the future (especially when redundant with existing stable functions)
1064	* ***************************************************************************************/
1065
1066	#define ZSTD_FRAMEHEADERSIZE_PREFIX(format) ((format) == ZSTD_f_zstd1 ? 5 : 1) /* minimum input size required to query frame header size */
1067	#define ZSTD_FRAMEHEADERSIZE_MIN(format) ((format) == ZSTD_f_zstd1 ? 6 : 2)
1068	#define ZSTD_FRAMEHEADERSIZE_MAX 18 /* can be useful for static allocation */
1069	#define ZSTD_SKIPPABLEHEADERSIZE 8
1070
1071	/* compression parameter bounds */
1072	#define ZSTD_WINDOWLOG_MAX_32 30
1073	#define ZSTD_WINDOWLOG_MAX_64 31
1074	#define ZSTD_WINDOWLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64))
1075	#define ZSTD_WINDOWLOG_MIN 10
1076	#define ZSTD_HASHLOG_MAX ((ZSTD_WINDOWLOG_MAX < 30) ? ZSTD_WINDOWLOG_MAX : 30)
1077	#define ZSTD_HASHLOG_MIN 6
1078	#define ZSTD_CHAINLOG_MAX_32 29
1079	#define ZSTD_CHAINLOG_MAX_64 30
1080	#define ZSTD_CHAINLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_CHAINLOG_MAX_32 : ZSTD_CHAINLOG_MAX_64))
1081	#define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN
1082	#define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1)
1083	#define ZSTD_SEARCHLOG_MIN 1
1084	#define ZSTD_MINMATCH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */
1085	#define ZSTD_MINMATCH_MIN 3 /* only for ZSTD_btopt+, faster strategies are limited to 4 */
1086	#define ZSTD_TARGETLENGTH_MAX ZSTD_BLOCKSIZE_MAX
1087	#define ZSTD_TARGETLENGTH_MIN 0 /* note : comparing this constant to an unsigned results in a tautological test */
1088	#define ZSTD_STRATEGY_MIN ZSTD_fast
1089	#define ZSTD_STRATEGY_MAX ZSTD_btultra2
1090
1091
1092	#define ZSTD_OVERLAPLOG_MIN 0
1093	#define ZSTD_OVERLAPLOG_MAX 9
1094
1095	#define ZSTD_WINDOWLOG_LIMIT_DEFAULT 27 /* by default, the streaming decoder will refuse any frame
1096	* requiring larger than (1<<ZSTD_WINDOWLOG_LIMIT_DEFAULT) window size,
1097	* to preserve host's memory from unreasonable requirements.
1098	* This limit can be overridden using ZSTD_DCtx_setParameter(,ZSTD_d_windowLogMax,).
1099	* The limit does not apply for one-pass decoders (such as ZSTD_decompress()), since no additional memory is allocated */
1100
1101
1102	/* LDM parameter bounds */
1103	#define ZSTD_LDM_HASHLOG_MIN ZSTD_HASHLOG_MIN
1104	#define ZSTD_LDM_HASHLOG_MAX ZSTD_HASHLOG_MAX
1105	#define ZSTD_LDM_MINMATCH_MIN 4
1106	#define ZSTD_LDM_MINMATCH_MAX 4096
1107	#define ZSTD_LDM_BUCKETSIZELOG_MIN 1
1108	#define ZSTD_LDM_BUCKETSIZELOG_MAX 8
1109	#define ZSTD_LDM_HASHRATELOG_MIN 0
1110	#define ZSTD_LDM_HASHRATELOG_MAX (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN)
1111
1112	/* Advanced parameter bounds */
1113	#define ZSTD_TARGETCBLOCKSIZE_MIN 64
1114	#define ZSTD_TARGETCBLOCKSIZE_MAX ZSTD_BLOCKSIZE_MAX
1115	#define ZSTD_SRCSIZEHINT_MIN 0
1116	#define ZSTD_SRCSIZEHINT_MAX INT_MAX
1117
1118	/* internal */
1119	#define ZSTD_HASHLOG3_MAX 17
1120
1121
1122	/* --- Advanced types --- */
1123
1124	typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params;
1125
1126	typedef struct {
1127	unsigned int offset; /* The offset of the match. (NOT the same as the offset code)
1128	* If offset == 0 and matchLength == 0, this sequence represents the last
1129	* literals in the block of litLength size.
1130	*/
1131
1132	unsigned int litLength; /* Literal length of the sequence. */
1133	unsigned int matchLength; /* Match length of the sequence. */
1134
1135	/* Note: Users of this API may provide a sequence with matchLength == litLength == offset == 0.
1136	* In this case, we will treat the sequence as a marker for a block boundary.
1137	*/
1138
1139	unsigned int rep; /* Represents which repeat offset is represented by the field 'offset'.
1140	* Ranges from [0, 3].
1141	*
1142	* Repeat offsets are essentially previous offsets from previous sequences sorted in
1143	* recency order. For more detail, see doc/zstd_compression_format.md
1144	*
1145	* If rep == 0, then 'offset' does not contain a repeat offset.
1146	* If rep > 0:
1147	* If litLength != 0:
1148	* rep == 1 --> offset == repeat_offset_1
1149	* rep == 2 --> offset == repeat_offset_2
1150	* rep == 3 --> offset == repeat_offset_3
1151	* If litLength == 0:
1152	* rep == 1 --> offset == repeat_offset_2
1153	* rep == 2 --> offset == repeat_offset_3
1154	* rep == 3 --> offset == repeat_offset_1 - 1
1155	*
1156	* Note: This field is optional. ZSTD_generateSequences() will calculate the value of
1157	* 'rep', but repeat offsets do not necessarily need to be calculated from an external
1158	* sequence provider's perspective. For example, ZSTD_compressSequences() does not
1159	* use this 'rep' field at all (as of now).
1160	*/
1161	} ZSTD_Sequence;
1162
1163	typedef struct {
1164	unsigned windowLog; /**< largest match distance : larger == more compression, more memory needed during decompression */
1165	unsigned chainLog; /**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */
1166	unsigned hashLog; /**< dispatch table : larger == faster, more memory */
1167	unsigned searchLog; /**< nb of searches : larger == more compression, slower */
1168	unsigned minMatch; /**< match length searched : larger == faster decompression, sometimes less compression */
1169	unsigned targetLength; /**< acceptable match size for optimal parser (only) : larger == more compression, slower */
1170	ZSTD_strategy strategy; /**< see ZSTD_strategy definition above */
1171	} ZSTD_compressionParameters;
1172
1173	typedef struct {
1174	int contentSizeFlag; /**< 1: content size will be in frame header (when known) */
1175	int checksumFlag; /**< 1: generate a 32-bits checksum using XXH64 algorithm at end of frame, for error detection */
1176	int noDictIDFlag; /**< 1: no dictID will be saved into frame header (dictID is only useful for dictionary compression) */
1177	} ZSTD_frameParameters;
1178
1179	typedef struct {
1180	ZSTD_compressionParameters cParams;
1181	ZSTD_frameParameters fParams;
1182	} ZSTD_parameters;
1183
1184	typedef enum {
1185	ZSTD_dct_auto = 0, /* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */
1186	ZSTD_dct_rawContent = 1, /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */
1187	ZSTD_dct_fullDict = 2 /* refuses to load a dictionary if it does not respect Zstandard's specification, starting with ZSTD_MAGIC_DICTIONARY */
1188	} ZSTD_dictContentType_e;
1189
1190	typedef enum {
1191	ZSTD_dlm_byCopy = 0, /**< Copy dictionary content internally */
1192	ZSTD_dlm_byRef = 1 /**< Reference dictionary content -- the dictionary buffer must outlive its users. */
1193	} ZSTD_dictLoadMethod_e;
1194
1195	typedef enum {
1196	ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */
1197	ZSTD_f_zstd1_magicless = 1 /* Variant of zstd frame format, without initial 4-bytes magic number.
1198	* Useful to save 4 bytes per generated frame.
1199	* Decoder cannot recognise automatically this format, requiring this instruction. */
1200	} ZSTD_format_e;
1201
1202	typedef enum {
1203	/* Note: this enum controls ZSTD_d_forceIgnoreChecksum */
1204	ZSTD_d_validateChecksum = 0,
1205	ZSTD_d_ignoreChecksum = 1
1206	} ZSTD_forceIgnoreChecksum_e;
1207
1208	typedef enum {
1209	/* Note: this enum and the behavior it controls are effectively internal
1210	* implementation details of the compressor. They are expected to continue
1211	* to evolve and should be considered only in the context of extremely
1212	* advanced performance tuning.
1213	*
1214	* Zstd currently supports the use of a CDict in three ways:
1215	*
1216	* - The contents of the CDict can be copied into the working context. This
1217	* means that the compression can search both the dictionary and input
1218	* while operating on a single set of internal tables. This makes
1219	* the compression faster per-byte of input. However, the initial copy of
1220	* the CDict's tables incurs a fixed cost at the beginning of the
1221	* compression. For small compressions (< 8 KB), that copy can dominate
1222	* the cost of the compression.
1223	*
1224	* - The CDict's tables can be used in-place. In this model, compression is
1225	* slower per input byte, because the compressor has to search two sets of
1226	* tables. However, this model incurs no start-up cost (as long as the
1227	* working context's tables can be reused). For small inputs, this can be
1228	* faster than copying the CDict's tables.
1229	*
1230	* - The CDict's tables are not used at all, and instead we use the working
1231	* context alone to reload the dictionary and use params based on the source
1232	* size. See ZSTD_compress_insertDictionary() and ZSTD_compress_usingDict().
1233	* This method is effective when the dictionary sizes are very small relative
1234	* to the input size, and the input size is fairly large to begin with.
1235	*
1236	* Zstd has a simple internal heuristic that selects which strategy to use
1237	* at the beginning of a compression. However, if experimentation shows that
1238	* Zstd is making poor choices, it is possible to override that choice with
1239	* this enum.
1240	*/
1241	ZSTD_dictDefaultAttach = 0, /* Use the default heuristic. */
1242	ZSTD_dictForceAttach = 1, /* Never copy the dictionary. */
1243	ZSTD_dictForceCopy = 2, /* Always copy the dictionary. */
1244	ZSTD_dictForceLoad = 3 /* Always reload the dictionary */
1245	} ZSTD_dictAttachPref_e;
1246
1247	typedef enum {
1248	ZSTD_lcm_auto = 0, /**< Automatically determine the compression mode based on the compression level.
1249	* Negative compression levels will be uncompressed, and positive compression
1250	* levels will be compressed. */
1251	ZSTD_lcm_huffman = 1, /**< Always attempt Huffman compression. Uncompressed literals will still be
1252	* emitted if Huffman compression is not profitable. */
1253	ZSTD_lcm_uncompressed = 2 /**< Always emit uncompressed literals. */
1254	} ZSTD_literalCompressionMode_e;
1255
1256
1257	/***************************************
1258	* Frame size functions
1259	***************************************/
1260
1261	/*! ZSTD_findDecompressedSize() :
1262	* `src` should point to the start of a series of ZSTD encoded and/or skippable frames
1263	* `srcSize` must be the _exact_ size of this series
1264	* (i.e. there should be a frame boundary at `src + srcSize`)
1265	* @return : - decompressed size of all data in all successive frames
1266	* - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN
1267	* - if an error occurred: ZSTD_CONTENTSIZE_ERROR
1268	*
1269	* note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode.
1270	* When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size.
1271	* In which case, it's necessary to use streaming mode to decompress data.
1272	* note 2 : decompressed size is always present when compression is done with ZSTD_compress()
1273	* note 3 : decompressed size can be very large (64-bits value),
1274	* potentially larger than what local system can handle as a single memory segment.
1275	* In which case, it's necessary to use streaming mode to decompress data.
1276	* note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified.
1277	* Always ensure result fits within application's authorized limits.
1278	* Each application can set its own limits.
1279	* note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to
1280	* read each contained frame header. This is fast as most of the data is skipped,
1281	* however it does mean that all frame data must be present and valid. */
1282	ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);
1283
1284	/*! ZSTD_decompressBound() :
1285	* `src` should point to the start of a series of ZSTD encoded and/or skippable frames
1286	* `srcSize` must be the _exact_ size of this series
1287	* (i.e. there should be a frame boundary at `src + srcSize`)
1288	* @return : - upper-bound for the decompressed size of all data in all successive frames
1289	* - if an error occured: ZSTD_CONTENTSIZE_ERROR
1290	*
1291	* note 1 : an error can occur if `src` contains an invalid or incorrectly formatted frame.
1292	* note 2 : the upper-bound is exact when the decompressed size field is available in every ZSTD encoded frame of `src`.
1293	* in this case, `ZSTD_findDecompressedSize` and `ZSTD_decompressBound` return the same value.
1294	* note 3 : when the decompressed size field isn't available, the upper-bound for that frame is calculated by:
1295	* upper-bound = # blocks * min(128 KB, Window_Size)
1296	*/
1297	ZSTDLIB_API unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize);
1298
1299	/*! ZSTD_frameHeaderSize() :
1300	* srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX.
1301	* @return : size of the Frame Header,
1302	* or an error code (if srcSize is too small) */
1303	ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
1304
1305	typedef enum {
1306	ZSTD_sf_noBlockDelimiters = 0, /* Representation of ZSTD_Sequence has no block delimiters, sequences only */
1307	ZSTD_sf_explicitBlockDelimiters = 1 /* Representation of ZSTD_Sequence contains explicit block delimiters */
1308	} ZSTD_sequenceFormat_e;
1309
1310	/*! ZSTD_generateSequences() :
1311	* Generate sequences using ZSTD_compress2, given a source buffer.
1312	*
1313	* Each block will end with a dummy sequence
1314	* with offset == 0, matchLength == 0, and litLength == length of last literals.
1315	* litLength may be == 0, and if so, then the sequence of (of: 0 ml: 0 ll: 0)
1316	* simply acts as a block delimiter.
1317	*
1318	* zc can be used to insert custom compression params.
1319	* This function invokes ZSTD_compress2
1320	*
1321	* The output of this function can be fed into ZSTD_compressSequences() with CCtx
1322	* setting of ZSTD_c_blockDelimiters as ZSTD_sf_explicitBlockDelimiters
1323	* @return : number of sequences generated
1324	*/
1325
1326	ZSTDLIB_API size_t ZSTD_generateSequences(ZSTD_CCtx* zc, ZSTD_Sequence* outSeqs,
1327	size_t outSeqsSize, const void* src, size_t srcSize);
1328
1329	/*! ZSTD_mergeBlockDelimiters() :
1330	* Given an array of ZSTD_Sequence, remove all sequences that represent block delimiters/last literals
1331	* by merging them into into the literals of the next sequence.
1332	*
1333	* As such, the final generated result has no explicit representation of block boundaries,
1334	* and the final last literals segment is not represented in the sequences.
1335	*
1336	* The output of this function can be fed into ZSTD_compressSequences() with CCtx
1337	* setting of ZSTD_c_blockDelimiters as ZSTD_sf_noBlockDelimiters
1338	* @return : number of sequences left after merging
1339	*/
1340	ZSTDLIB_API size_t ZSTD_mergeBlockDelimiters(ZSTD_Sequence* sequences, size_t seqsSize);
1341
1342	/*! ZSTD_compressSequences() :
1343	* Compress an array of ZSTD_Sequence, generated from the original source buffer, into dst.
1344	* If a dictionary is included, then the cctx should reference the dict. (see: ZSTD_CCtx_refCDict(), ZSTD_CCtx_loadDictionary(), etc.)
1345	* The entire source is compressed into a single frame.
1346	*
1347	* The compression behavior changes based on cctx params. In particular:
1348	* If ZSTD_c_blockDelimiters == ZSTD_sf_noBlockDelimiters, the array of ZSTD_Sequence is expected to contain
1349	* no block delimiters (defined in ZSTD_Sequence). Block boundaries are roughly determined based on
1350	* the block size derived from the cctx, and sequences may be split. This is the default setting.
1351	*
1352	* If ZSTD_c_blockDelimiters == ZSTD_sf_explicitBlockDelimiters, the array of ZSTD_Sequence is expected to contain
1353	* block delimiters (defined in ZSTD_Sequence). Behavior is undefined if no block delimiters are provided.
1354	*
1355	* If ZSTD_c_validateSequences == 0, this function will blindly accept the sequences provided. Invalid sequences cause undefined
1356	* behavior. If ZSTD_c_validateSequences == 1, then if sequence is invalid (see doc/zstd_compression_format.md for
1357	* specifics regarding offset/matchlength requirements) then the function will bail out and return an error.
1358	*
1359	* In addition to the two adjustable experimental params, there are other important cctx params.
1360	* - ZSTD_c_minMatch MUST be set as less than or equal to the smallest match generated by the match finder. It has a minimum value of ZSTD_MINMATCH_MIN.
1361	* - ZSTD_c_compressionLevel accordingly adjusts the strength of the entropy coder, as it would in typical compression.
1362	* - ZSTD_c_windowLog affects offset validation: this function will return an error at higher debug levels if a provided offset
1363	* is larger than what the spec allows for a given window log and dictionary (if present). See: doc/zstd_compression_format.md
1364	*
1365	* Note: Repcodes are, as of now, always re-calculated within this function, so ZSTD_Sequence::rep is unused.
1366	* Note 2: Once we integrate ability to ingest repcodes, the explicit block delims mode must respect those repcodes exactly,
1367	* and cannot emit an RLE block that disagrees with the repcode history
1368	* @return : final compressed size or a ZSTD error.
1369	*/
1370	ZSTDLIB_API size_t ZSTD_compressSequences(ZSTD_CCtx* const cctx, void* dst, size_t dstSize,
1371	const ZSTD_Sequence* inSeqs, size_t inSeqsSize,
1372	const void* src, size_t srcSize);
1373
1374
1375	/***************************************
1376	* Memory management
1377	***************************************/
1378
1379	/*! ZSTD_estimate*() :
1380	* These functions make it possible to estimate memory usage
1381	* of a future {D,C}Ctx, before its creation.
1382	*
1383	* ZSTD_estimateCCtxSize() will provide a memory budget large enough
1384	* for any compression level up to selected one.
1385	* Note : Unlike ZSTD_estimateCStreamSize*(), this estimate
1386	* does not include space for a window buffer.
1387	* Therefore, the estimation is only guaranteed for single-shot compressions, not streaming.
1388	* The estimate will assume the input may be arbitrarily large,
1389	* which is the worst case.
1390	*
1391	* When srcSize can be bound by a known and rather "small" value,
1392	* this fact can be used to provide a tighter estimation
1393	* because the CCtx compression context will need less memory.
1394	* This tighter estimation can be provided by more advanced functions
1395	* ZSTD_estimateCCtxSize_usingCParams(), which can be used in tandem with ZSTD_getCParams(),
1396	* and ZSTD_estimateCCtxSize_usingCCtxParams(), which can be used in tandem with ZSTD_CCtxParams_setParameter().
1397	* Both can be used to estimate memory using custom compression parameters and arbitrary srcSize limits.
1398	*
1399	* Note 2 : only single-threaded compression is supported.
1400	* ZSTD_estimateCCtxSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1.
1401	*/
1402	ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel);
1403	ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams);
1404	ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params);
1405	ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
1406
1407	/*! ZSTD_estimateCStreamSize() :
1408	* ZSTD_estimateCStreamSize() will provide a budget large enough for any compression level up to selected one.
1409	* It will also consider src size to be arbitrarily "large", which is worst case.
1410	* If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation.
1411	* ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
1412	* ZSTD_estimateCStreamSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParams_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_c_nbWorkers is >= 1.
1413	* Note : CStream size estimation is only correct for single-threaded compression.
1414	* ZSTD_DStream memory budget depends on window Size.
1415	* This information can be passed manually, using ZSTD_estimateDStreamSize,
1416	* or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame();
1417	* Note : if streaming is init with function ZSTD_init?Stream_usingDict(),
1418	* an internal ?Dict will be created, which additional size is not estimated here.
1419	* In this case, get total size by adding ZSTD_estimate?DictSize */
1420	ZSTDLIB_API size_t ZSTD_estimateCStreamSize(int compressionLevel);
1421	ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams);
1422	ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params);
1423	ZSTDLIB_API size_t ZSTD_estimateDStreamSize(size_t windowSize);
1424	ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize);
1425
1426	/*! ZSTD_estimate?DictSize() :
1427	* ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict().
1428	* ZSTD_estimateCDictSize_advanced() makes it possible to control compression parameters precisely, like ZSTD_createCDict_advanced().
1429	* Note : dictionaries created by reference (`ZSTD_dlm_byRef`) are logically smaller.
1430	*/
1431	ZSTDLIB_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel);
1432	ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod);
1433	ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod);
1434
1435	/*! ZSTD_initStatic*() :
1436	* Initialize an object using a pre-allocated fixed-size buffer.
1437	* workspace: The memory area to emplace the object into.
1438	* Provided pointer *must be 8-bytes aligned*.
1439	* Buffer must outlive object.
1440	* workspaceSize: Use ZSTD_estimate*Size() to determine
1441	* how large workspace must be to support target scenario.
1442	* @return : pointer to object (same address as workspace, just different type),
1443	* or NULL if error (size too small, incorrect alignment, etc.)
1444	* Note : zstd will never resize nor malloc() when using a static buffer.
1445	* If the object requires more memory than available,
1446	* zstd will just error out (typically ZSTD_error_memory_allocation).
1447	* Note 2 : there is no corresponding "free" function.
1448	* Since workspace is allocated externally, it must be freed externally too.
1449	* Note 3 : cParams : use ZSTD_getCParams() to convert a compression level
1450	* into its associated cParams.
1451	* Limitation 1 : currently not compatible with internal dictionary creation, triggered by
1452	* ZSTD_CCtx_loadDictionary(), ZSTD_initCStream_usingDict() or ZSTD_initDStream_usingDict().
1453	* Limitation 2 : static cctx currently not compatible with multi-threading.
1454	* Limitation 3 : static dctx is incompatible with legacy support.
1455	*/
1456	ZSTDLIB_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize);
1457	ZSTDLIB_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */
1458
1459	ZSTDLIB_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize);
1460	ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */
1461
1462	ZSTDLIB_API const ZSTD_CDict* ZSTD_initStaticCDict(
1463	void* workspace, size_t workspaceSize,
1464	const void* dict, size_t dictSize,
1465	ZSTD_dictLoadMethod_e dictLoadMethod,
1466	ZSTD_dictContentType_e dictContentType,
1467	ZSTD_compressionParameters cParams);
1468
1469	ZSTDLIB_API const ZSTD_DDict* ZSTD_initStaticDDict(
1470	void* workspace, size_t workspaceSize,
1471	const void* dict, size_t dictSize,
1472	ZSTD_dictLoadMethod_e dictLoadMethod,
1473	ZSTD_dictContentType_e dictContentType);
1474
1475
1476	/*! Custom memory allocation :
1477	* These prototypes make it possible to pass your own allocation/free functions.
1478	* ZSTD_customMem is provided at creation time, using ZSTD_create*_advanced() variants listed below.
1479	* All allocation/free operations will be completed using these custom variants instead of regular <stdlib.h> ones.
1480	*/
1481	typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size);
1482	typedef void (*ZSTD_freeFunction) (void* opaque, void* address);
1483	typedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem;
1484	static
1485	#ifdef __GNUC__
1486	__attribute__((__unused__))
1487	#endif
1488	ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; /**< this constant defers to stdlib's functions */
1489
1490	ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem);
1491	ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem);
1492	ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem);
1493	ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem);
1494
1495	ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize,
1496	ZSTD_dictLoadMethod_e dictLoadMethod,
1497	ZSTD_dictContentType_e dictContentType,
1498	ZSTD_compressionParameters cParams,
1499	ZSTD_customMem customMem);
1500
1501	/* ! Thread pool :
1502	* These prototypes make it possible to share a thread pool among multiple compression contexts.
1503	* This can limit resources for applications with multiple threads where each one uses
1504	* a threaded compression mode (via ZSTD_c_nbWorkers parameter).
1505	* ZSTD_createThreadPool creates a new thread pool with a given number of threads.
1506	* Note that the lifetime of such pool must exist while being used.
1507	* ZSTD_CCtx_refThreadPool assigns a thread pool to a context (use NULL argument value
1508	* to use an internal thread pool).
1509	* ZSTD_freeThreadPool frees a thread pool.
1510	*/
1511	typedef struct POOL_ctx_s ZSTD_threadPool;
1512	ZSTDLIB_API ZSTD_threadPool* ZSTD_createThreadPool(size_t numThreads);
1513	ZSTDLIB_API void ZSTD_freeThreadPool (ZSTD_threadPool* pool);
1514	ZSTDLIB_API size_t ZSTD_CCtx_refThreadPool(ZSTD_CCtx* cctx, ZSTD_threadPool* pool);
1515
1516	/*
1517	* This API is temporary and is expected to change or disappear in the future!
1518	*/
1519	ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced2(
1520	const void* dict, size_t dictSize,
1521	ZSTD_dictLoadMethod_e dictLoadMethod,
1522	ZSTD_dictContentType_e dictContentType,
1523	const ZSTD_CCtx_params* cctxParams,
1524	ZSTD_customMem customMem);
1525
1526	ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize,
1527	ZSTD_dictLoadMethod_e dictLoadMethod,
1528	ZSTD_dictContentType_e dictContentType,
1529	ZSTD_customMem customMem);
1530
1531	/***************************************
1532	* Advanced compression functions
1533	***************************************/
1534
1535	/*! ZSTD_createCDict_byReference() :
1536	* Create a digested dictionary for compression
1537	* Dictionary content is just referenced, not duplicated.
1538	* As a consequence, `dictBuffer` **must** outlive CDict,
1539	* and its content must remain unmodified throughout the lifetime of CDict.
1540	* note: equivalent to ZSTD_createCDict_advanced(), with dictLoadMethod==ZSTD_dlm_byRef */
1541	ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
1542
1543	/*! ZSTD_getDictID_fromCDict() :
1544	* Provides the dictID of the dictionary loaded into `cdict`.
1545	* If @return == 0, the dictionary is not conformant to Zstandard specification, or empty.
1546	* Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */
1547	ZSTDLIB_API unsigned ZSTD_getDictID_fromCDict(const ZSTD_CDict* cdict);
1548
1549	/*! ZSTD_getCParams() :
1550	* @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize.
1551	* `estimatedSrcSize` value is optional, select 0 if not known */
1552	ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize);
1553
1554	/*! ZSTD_getParams() :
1555	* same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of sub-component `ZSTD_compressionParameters`.
1556	* All fields of `ZSTD_frameParameters` are set to default : contentSize=1, checksum=0, noDictID=0 */
1557	ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize);
1558
1559	/*! ZSTD_checkCParams() :
1560	* Ensure param values remain within authorized range.
1561	* @return 0 on success, or an error code (can be checked with ZSTD_isError()) */
1562	ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params);
1563
1564	/*! ZSTD_adjustCParams() :
1565	* optimize params for a given `srcSize` and `dictSize`.
1566	* `srcSize` can be unknown, in which case use ZSTD_CONTENTSIZE_UNKNOWN.
1567	* `dictSize` must be `0` when there is no dictionary.
1568	* cPar can be invalid : all parameters will be clamped within valid range in the @return struct.
1569	* This function never fails (wide contract) */
1570	ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize);
1571
1572	/*! ZSTD_compress_advanced() :
1573	* Note : this function is now DEPRECATED.
1574	* It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_setParameter() and other parameter setters.
1575	* This prototype will be marked as deprecated and generate compilation warning on reaching v1.5.x */
1576	ZSTDLIB_API size_t ZSTD_compress_advanced(ZSTD_CCtx* cctx,
1577	void* dst, size_t dstCapacity,
1578	const void* src, size_t srcSize,
1579	const void* dict,size_t dictSize,
1580	ZSTD_parameters params);
1581
1582	/*! ZSTD_compress_usingCDict_advanced() :
1583	* Note : this function is now REDUNDANT.
1584	* It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_loadDictionary() and other parameter setters.
1585	* This prototype will be marked as deprecated and generate compilation warning in some future version */
1586	ZSTDLIB_API size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx,
1587	void* dst, size_t dstCapacity,
1588	const void* src, size_t srcSize,
1589	const ZSTD_CDict* cdict,
1590	ZSTD_frameParameters fParams);
1591
1592
1593	/*! ZSTD_CCtx_loadDictionary_byReference() :
1594	* Same as ZSTD_CCtx_loadDictionary(), but dictionary content is referenced, instead of being copied into CCtx.
1595	* It saves some memory, but also requires that `dict` outlives its usage within `cctx` */
1596	ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
1597
1598	/*! ZSTD_CCtx_loadDictionary_advanced() :
1599	* Same as ZSTD_CCtx_loadDictionary(), but gives finer control over
1600	* how to load the dictionary (by copy ? by reference ?)
1601	* and how to interpret it (automatic ? force raw mode ? full mode only ?) */
1602	ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
1603
1604	/*! ZSTD_CCtx_refPrefix_advanced() :
1605	* Same as ZSTD_CCtx_refPrefix(), but gives finer control over
1606	* how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */
1607	ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
1608
1609	/* === experimental parameters === */
1610	/* these parameters can be used with ZSTD_setParameter()
1611	* they are not guaranteed to remain supported in the future */
1612
1613	/* Enables rsyncable mode,
1614	* which makes compressed files more rsync friendly
1615	* by adding periodic synchronization points to the compressed data.
1616	* The target average block size is ZSTD_c_jobSize / 2.
1617	* It's possible to modify the job size to increase or decrease
1618	* the granularity of the synchronization point.
1619	* Once the jobSize is smaller than the window size,
1620	* it will result in compression ratio degradation.
1621	* NOTE 1: rsyncable mode only works when multithreading is enabled.
1622	* NOTE 2: rsyncable performs poorly in combination with long range mode,
1623	* since it will decrease the effectiveness of synchronization points,
1624	* though mileage may vary.
1625	* NOTE 3: Rsyncable mode limits maximum compression speed to ~400 MB/s.
1626	* If the selected compression level is already running significantly slower,
1627	* the overall speed won't be significantly impacted.
1628	*/
1629	#define ZSTD_c_rsyncable ZSTD_c_experimentalParam1
1630
1631	/* Select a compression format.
1632	* The value must be of type ZSTD_format_e.
1633	* See ZSTD_format_e enum definition for details */
1634	#define ZSTD_c_format ZSTD_c_experimentalParam2
1635
1636	/* Force back-reference distances to remain < windowSize,
1637	* even when referencing into Dictionary content (default:0) */
1638	#define ZSTD_c_forceMaxWindow ZSTD_c_experimentalParam3
1639
1640	/* Controls whether the contents of a CDict
1641	* are used in place, or copied into the working context.
1642	* Accepts values from the ZSTD_dictAttachPref_e enum.
1643	* See the comments on that enum for an explanation of the feature. */
1644	#define ZSTD_c_forceAttachDict ZSTD_c_experimentalParam4
1645
1646	/* Controls how the literals are compressed (default is auto).
1647	* The value must be of type ZSTD_literalCompressionMode_e.
1648	* See ZSTD_literalCompressionMode_t enum definition for details.
1649	*/
1650	#define ZSTD_c_literalCompressionMode ZSTD_c_experimentalParam5
1651
1652	/* Tries to fit compressed block size to be around targetCBlockSize.
1653	* No target when targetCBlockSize == 0.
1654	* There is no guarantee on compressed block size (default:0) */
1655	#define ZSTD_c_targetCBlockSize ZSTD_c_experimentalParam6
1656
1657	/* User's best guess of source size.
1658	* Hint is not valid when srcSizeHint == 0.
1659	* There is no guarantee that hint is close to actual source size,
1660	* but compression ratio may regress significantly if guess considerably underestimates */
1661	#define ZSTD_c_srcSizeHint ZSTD_c_experimentalParam7
1662
1663	/* Controls whether the new and experimental "dedicated dictionary search
1664	* structure" can be used. This feature is still rough around the edges, be
1665	* prepared for surprising behavior!
1666	*
1667	* How to use it:
1668	*
1669	* When using a CDict, whether to use this feature or not is controlled at
1670	* CDict creation, and it must be set in a CCtxParams set passed into that
1671	* construction (via ZSTD_createCDict_advanced2()). A compression will then
1672	* use the feature or not based on how the CDict was constructed; the value of
1673	* this param, set in the CCtx, will have no effect.
1674	*
1675	* However, when a dictionary buffer is passed into a CCtx, such as via
1676	* ZSTD_CCtx_loadDictionary(), this param can be set on the CCtx to control
1677	* whether the CDict that is created internally can use the feature or not.
1678	*
1679	* What it does:
1680	*
1681	* Normally, the internal data structures of the CDict are analogous to what
1682	* would be stored in a CCtx after compressing the contents of a dictionary.
1683	* To an approximation, a compression using a dictionary can then use those
1684	* data structures to simply continue what is effectively a streaming
1685	* compression where the simulated compression of the dictionary left off.
1686	* Which is to say, the search structures in the CDict are normally the same
1687	* format as in the CCtx.
1688	*
1689	* It is possible to do better, since the CDict is not like a CCtx: the search
1690	* structures are written once during CDict creation, and then are only read
1691	* after that, while the search structures in the CCtx are both read and
1692	* written as the compression goes along. This means we can choose a search
1693	* structure for the dictionary that is read-optimized.
1694	*
1695	* This feature enables the use of that different structure.
1696	*
1697	* Note that some of the members of the ZSTD_compressionParameters struct have
1698	* different semantics and constraints in the dedicated search structure. It is
1699	* highly recommended that you simply set a compression level in the CCtxParams
1700	* you pass into the CDict creation call, and avoid messing with the cParams
1701	* directly.
1702	*
1703	* Effects:
1704	*
1705	* This will only have any effect when the selected ZSTD_strategy
1706	* implementation supports this feature. Currently, that's limited to
1707	* ZSTD_greedy, ZSTD_lazy, and ZSTD_lazy2.
1708	*
1709	* Note that this means that the CDict tables can no longer be copied into the
1710	* CCtx, so the dict attachment mode ZSTD_dictForceCopy will no longer be
1711	* useable. The dictionary can only be attached or reloaded.
1712	*
1713	* In general, you should expect compression to be faster--sometimes very much
1714	* so--and CDict creation to be slightly slower. Eventually, we will probably
1715	* make this mode the default.
1716	*/
1717	#define ZSTD_c_enableDedicatedDictSearch ZSTD_c_experimentalParam8
1718
1719	/* ZSTD_c_stableInBuffer
1720	* Experimental parameter.
1721	* Default is 0 == disabled. Set to 1 to enable.
1722	*
1723	* Tells the compressor that the ZSTD_inBuffer will ALWAYS be the same
1724	* between calls, except for the modifications that zstd makes to pos (the
1725	* caller must not modify pos). This is checked by the compressor, and
1726	* compression will fail if it ever changes. This means the only flush
1727	* mode that makes sense is ZSTD_e_end, so zstd will error if ZSTD_e_end
1728	* is not used. The data in the ZSTD_inBuffer in the range [src, src + pos)
1729	* MUST not be modified during compression or you will get data corruption.
1730	*
1731	* When this flag is enabled zstd won't allocate an input window buffer,
1732	* because the user guarantees it can reference the ZSTD_inBuffer until
1733	* the frame is complete. But, it will still allocate an output buffer
1734	* large enough to fit a block (see ZSTD_c_stableOutBuffer). This will also
1735	* avoid the memcpy() from the input buffer to the input window buffer.
1736	*
1737	* NOTE: ZSTD_compressStream2() will error if ZSTD_e_end is not used.
1738	* That means this flag cannot be used with ZSTD_compressStream().
1739	*
1740	* NOTE: So long as the ZSTD_inBuffer always points to valid memory, using
1741	* this flag is ALWAYS memory safe, and will never access out-of-bounds
1742	* memory. However, compression WILL fail if you violate the preconditions.
1743	*
1744	* WARNING: The data in the ZSTD_inBuffer in the range [dst, dst + pos) MUST
1745	* not be modified during compression or you will get data corruption. This
1746	* is because zstd needs to reference data in the ZSTD_inBuffer to find
1747	* matches. Normally zstd maintains its own window buffer for this purpose,
1748	* but passing this flag tells zstd to use the user provided buffer.
1749	*/
1750	#define ZSTD_c_stableInBuffer ZSTD_c_experimentalParam9
1751
1752	/* ZSTD_c_stableOutBuffer
1753	* Experimental parameter.
1754	* Default is 0 == disabled. Set to 1 to enable.
1755	*
1756	* Tells he compressor that the ZSTD_outBuffer will not be resized between
1757	* calls. Specifically: (out.size - out.pos) will never grow. This gives the
1758	* compressor the freedom to say: If the compressed data doesn't fit in the
1759	* output buffer then return ZSTD_error_dstSizeTooSmall. This allows us to
1760	* always decompress directly into the output buffer, instead of decompressing
1761	* into an internal buffer and copying to the output buffer.
1762	*
1763	* When this flag is enabled zstd won't allocate an output buffer, because
1764	* it can write directly to the ZSTD_outBuffer. It will still allocate the
1765	* input window buffer (see ZSTD_c_stableInBuffer).
1766	*
1767	* Zstd will check that (out.size - out.pos) never grows and return an error
1768	* if it does. While not strictly necessary, this should prevent surprises.
1769	*/
1770	#define ZSTD_c_stableOutBuffer ZSTD_c_experimentalParam10
1771
1772	/* ZSTD_c_blockDelimiters
1773	* Default is 0 == ZSTD_sf_noBlockDelimiters.
1774	*
1775	* For use with sequence compression API: ZSTD_compressSequences().
1776	*
1777	* Designates whether or not the given array of ZSTD_Sequence contains block delimiters
1778	* and last literals, which are defined as sequences with offset == 0 and matchLength == 0.
1779	* See the definition of ZSTD_Sequence for more specifics.
1780	*/
1781	#define ZSTD_c_blockDelimiters ZSTD_c_experimentalParam11
1782
1783	/* ZSTD_c_validateSequences
1784	* Default is 0 == disabled. Set to 1 to enable sequence validation.
1785	*
1786	* For use with sequence compression API: ZSTD_compressSequences().
1787	* Designates whether or not we validate sequences provided to ZSTD_compressSequences()
1788	* during function execution.
1789	*
1790	* Without validation, providing a sequence that does not conform to the zstd spec will cause
1791	* undefined behavior, and may produce a corrupted block.
1792	*
1793	* With validation enabled, a if sequence is invalid (see doc/zstd_compression_format.md for
1794	* specifics regarding offset/matchlength requirements) then the function will bail out and
1795	* return an error.
1796	*
1797	*/
1798	#define ZSTD_c_validateSequences ZSTD_c_experimentalParam12
1799
1800	/*! ZSTD_CCtx_getParameter() :
1801	* Get the requested compression parameter value, selected by enum ZSTD_cParameter,
1802	* and store it into int* value.
1803	* @return : 0, or an error code (which can be tested with ZSTD_isError()).
1804	*/
1805	ZSTDLIB_API size_t ZSTD_CCtx_getParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int* value);
1806
1807
1808	/*! ZSTD_CCtx_params :
1809	* Quick howto :
1810	* - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure
1811	* - ZSTD_CCtxParams_setParameter() : Push parameters one by one into
1812	* an existing ZSTD_CCtx_params structure.
1813	* This is similar to
1814	* ZSTD_CCtx_setParameter().
1815	* - ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to
1816	* an existing CCtx.
1817	* These parameters will be applied to
1818	* all subsequent frames.
1819	* - ZSTD_compressStream2() : Do compression using the CCtx.
1820	* - ZSTD_freeCCtxParams() : Free the memory.
1821	*
1822	* This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams()
1823	* for static allocation of CCtx for single-threaded compression.
1824	*/
1825	ZSTDLIB_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void);
1826	ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
1827
1828	/*! ZSTD_CCtxParams_reset() :
1829	* Reset params to default values.
1830	*/
1831	ZSTDLIB_API size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params);
1832
1833	/*! ZSTD_CCtxParams_init() :
1834	* Initializes the compression parameters of cctxParams according to
1835	* compression level. All other parameters are reset to their default values.
1836	*/
1837	ZSTDLIB_API size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel);
1838
1839	/*! ZSTD_CCtxParams_init_advanced() :
1840	* Initializes the compression and frame parameters of cctxParams according to
1841	* params. All other parameters are reset to their default values.
1842	*/
1843	ZSTDLIB_API size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params);
1844
1845	/*! ZSTD_CCtxParams_setParameter() :
1846	* Similar to ZSTD_CCtx_setParameter.
1847	* Set one compression parameter, selected by enum ZSTD_cParameter.
1848	* Parameters must be applied to a ZSTD_CCtx using
1849	* ZSTD_CCtx_setParametersUsingCCtxParams().
1850	* @result : a code representing success or failure (which can be tested with
1851	* ZSTD_isError()).
1852	*/
1853	ZSTDLIB_API size_t ZSTD_CCtxParams_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int value);
1854
1855	/*! ZSTD_CCtxParams_getParameter() :
1856	* Similar to ZSTD_CCtx_getParameter.
1857	* Get the requested value of one compression parameter, selected by enum ZSTD_cParameter.
1858	* @result : 0, or an error code (which can be tested with ZSTD_isError()).
1859	*/
1860	ZSTDLIB_API size_t ZSTD_CCtxParams_getParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int* value);
1861
1862	/*! ZSTD_CCtx_setParametersUsingCCtxParams() :
1863	* Apply a set of ZSTD_CCtx_params to the compression context.
1864	* This can be done even after compression is started,
1865	* if nbWorkers==0, this will have no impact until a new compression is started.
1866	* if nbWorkers>=1, new parameters will be picked up at next job,
1867	* with a few restrictions (windowLog, pledgedSrcSize, nbWorkers, jobSize, and overlapLog are not updated).
1868	*/
1869	ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams(
1870	ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params);
1871
1872	/*! ZSTD_compressStream2_simpleArgs() :
1873	* Same as ZSTD_compressStream2(),
1874	* but using only integral types as arguments.
1875	* This variant might be helpful for binders from dynamic languages
1876	* which have troubles handling structures containing memory pointers.
1877	*/
1878	ZSTDLIB_API size_t ZSTD_compressStream2_simpleArgs (
1879	ZSTD_CCtx* cctx,
1880	void* dst, size_t dstCapacity, size_t* dstPos,
1881	const void* src, size_t srcSize, size_t* srcPos,
1882	ZSTD_EndDirective endOp);
1883
1884
1885	/***************************************
1886	* Advanced decompression functions
1887	***************************************/
1888
1889	/*! ZSTD_isFrame() :
1890	* Tells if the content of `buffer` starts with a valid Frame Identifier.
1891	* Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0.
1892	* Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled.
1893	* Note 3 : Skippable Frame Identifiers are considered valid. */
1894	ZSTDLIB_API unsigned ZSTD_isFrame(const void* buffer, size_t size);
1895
1896	/*! ZSTD_createDDict_byReference() :
1897	* Create a digested dictionary, ready to start decompression operation without startup delay.
1898	* Dictionary content is referenced, and therefore stays in dictBuffer.
1899	* It is important that dictBuffer outlives DDict,
1900	* it must remain read accessible throughout the lifetime of DDict */
1901	ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize);
1902
1903	/*! ZSTD_DCtx_loadDictionary_byReference() :
1904	* Same as ZSTD_DCtx_loadDictionary(),
1905	* but references `dict` content instead of copying it into `dctx`.
1906	* This saves memory if `dict` remains around.,
1907	* However, it's imperative that `dict` remains accessible (and unmodified) while being used, so it must outlive decompression. */
1908	ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
1909
1910	/*! ZSTD_DCtx_loadDictionary_advanced() :
1911	* Same as ZSTD_DCtx_loadDictionary(),
1912	* but gives direct control over
1913	* how to load the dictionary (by copy ? by reference ?)
1914	* and how to interpret it (automatic ? force raw mode ? full mode only ?). */
1915	ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType);
1916
1917	/*! ZSTD_DCtx_refPrefix_advanced() :
1918	* Same as ZSTD_DCtx_refPrefix(), but gives finer control over
1919	* how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */
1920	ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);
1921
1922	/*! ZSTD_DCtx_setMaxWindowSize() :
1923	* Refuses allocating internal buffers for frames requiring a window size larger than provided limit.
1924	* This protects a decoder context from reserving too much memory for itself (potential attack scenario).
1925	* This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode.
1926	* By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT)
1927	* @return : 0, or an error code (which can be tested using ZSTD_isError()).
1928	*/
1929	ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize);
1930
1931	/*! ZSTD_DCtx_getParameter() :
1932	* Get the requested decompression parameter value, selected by enum ZSTD_dParameter,
1933	* and store it into int* value.
1934	* @return : 0, or an error code (which can be tested with ZSTD_isError()).
1935	*/
1936	ZSTDLIB_API size_t ZSTD_DCtx_getParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int* value);
1937
1938	/* ZSTD_d_format
1939	* experimental parameter,
1940	* allowing selection between ZSTD_format_e input compression formats
1941	*/
1942	#define ZSTD_d_format ZSTD_d_experimentalParam1
1943	/* ZSTD_d_stableOutBuffer
1944	* Experimental parameter.
1945	* Default is 0 == disabled. Set to 1 to enable.
1946	*
1947	* Tells the decompressor that the ZSTD_outBuffer will ALWAYS be the same
1948	* between calls, except for the modifications that zstd makes to pos (the
1949	* caller must not modify pos). This is checked by the decompressor, and
1950	* decompression will fail if it ever changes. Therefore the ZSTD_outBuffer
1951	* MUST be large enough to fit the entire decompressed frame. This will be
1952	* checked when the frame content size is known. The data in the ZSTD_outBuffer
1953	* in the range [dst, dst + pos) MUST not be modified during decompression
1954	* or you will get data corruption.
1955	*
1956	* When this flags is enabled zstd won't allocate an output buffer, because
1957	* it can write directly to the ZSTD_outBuffer, but it will still allocate
1958	* an input buffer large enough to fit any compressed block. This will also
1959	* avoid the memcpy() from the internal output buffer to the ZSTD_outBuffer.
1960	* If you need to avoid the input buffer allocation use the buffer-less
1961	* streaming API.
1962	*
1963	* NOTE: So long as the ZSTD_outBuffer always points to valid memory, using
1964	* this flag is ALWAYS memory safe, and will never access out-of-bounds
1965	* memory. However, decompression WILL fail if you violate the preconditions.
1966	*
1967	* WARNING: The data in the ZSTD_outBuffer in the range [dst, dst + pos) MUST
1968	* not be modified during decompression or you will get data corruption. This
1969	* is because zstd needs to reference data in the ZSTD_outBuffer to regenerate
1970	* matches. Normally zstd maintains its own buffer for this purpose, but passing
1971	* this flag tells zstd to use the user provided buffer.
1972	*/
1973	#define ZSTD_d_stableOutBuffer ZSTD_d_experimentalParam2
1974
1975	/* ZSTD_d_forceIgnoreChecksum
1976	* Experimental parameter.
1977	* Default is 0 == disabled. Set to 1 to enable
1978	*
1979	* Tells the decompressor to skip checksum validation during decompression, regardless
1980	* of whether checksumming was specified during compression. This offers some
1981	* slight performance benefits, and may be useful for debugging.
1982	* Param has values of type ZSTD_forceIgnoreChecksum_e
1983	*/
1984	#define ZSTD_d_forceIgnoreChecksum ZSTD_d_experimentalParam3
1985
1986	/*! ZSTD_DCtx_setFormat() :
1987	* Instruct the decoder context about what kind of data to decode next.
1988	* This instruction is mandatory to decode data without a fully-formed header,
1989	* such ZSTD_f_zstd1_magicless for example.
1990	* @return : 0, or an error code (which can be tested using ZSTD_isError()). */
1991	ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format);
1992
1993	/*! ZSTD_decompressStream_simpleArgs() :
1994	* Same as ZSTD_decompressStream(),
1995	* but using only integral types as arguments.
1996	* This can be helpful for binders from dynamic languages
1997	* which have troubles handling structures containing memory pointers.
1998	*/
1999	ZSTDLIB_API size_t ZSTD_decompressStream_simpleArgs (
2000	ZSTD_DCtx* dctx,
2001	void* dst, size_t dstCapacity, size_t* dstPos,
2002	const void* src, size_t srcSize, size_t* srcPos);
2003
2004
2005	/********************************************************************
2006	* Advanced streaming functions
2007	* Warning : most of these functions are now redundant with the Advanced API.
2008	* Once Advanced API reaches "stable" status,
2009	* redundant functions will be deprecated, and then at some point removed.
2010	********************************************************************/
2011
2012	/*===== Advanced Streaming compression functions =====*/
2013
2014	/*! ZSTD_initCStream_srcSize() :
2015	* This function is deprecated, and equivalent to:
2016	* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
2017	* ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any)
2018	* ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
2019	* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
2020	*
2021	* pledgedSrcSize must be correct. If it is not known at init time, use
2022	* ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs,
2023	* "0" also disables frame content size field. It may be enabled in the future.
2024	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2025	*/
2026	ZSTDLIB_API size_t
2027	ZSTD_initCStream_srcSize(ZSTD_CStream* zcs,
2028	int compressionLevel,
2029	unsigned long long pledgedSrcSize);
2030
2031	/*! ZSTD_initCStream_usingDict() :
2032	* This function is deprecated, and is equivalent to:
2033	* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
2034	* ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
2035	* ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
2036	*
2037	* Creates of an internal CDict (incompatible with static CCtx), except if
2038	* dict == NULL or dictSize < 8, in which case no dict is used.
2039	* Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if
2040	* it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.
2041	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2042	*/
2043	ZSTDLIB_API size_t
2044	ZSTD_initCStream_usingDict(ZSTD_CStream* zcs,
2045	const void* dict, size_t dictSize,
2046	int compressionLevel);
2047
2048	/*! ZSTD_initCStream_advanced() :
2049	* This function is deprecated, and is approximately equivalent to:
2050	* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
2051	* // Pseudocode: Set each zstd parameter and leave the rest as-is.
2052	* for ((param, value) : params) {
2053	* ZSTD_CCtx_setParameter(zcs, param, value);
2054	* }
2055	* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
2056	* ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
2057	*
2058	* dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy.
2059	* pledgedSrcSize must be correct.
2060	* If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN.
2061	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2062	*/
2063	ZSTDLIB_API size_t
2064	ZSTD_initCStream_advanced(ZSTD_CStream* zcs,
2065	const void* dict, size_t dictSize,
2066	ZSTD_parameters params,
2067	unsigned long long pledgedSrcSize);
2068
2069	/*! ZSTD_initCStream_usingCDict() :
2070	* This function is deprecated, and equivalent to:
2071	* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
2072	* ZSTD_CCtx_refCDict(zcs, cdict);
2073	*
2074	* note : cdict will just be referenced, and must outlive compression session
2075	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2076	*/
2077	ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict);
2078
2079	/*! ZSTD_initCStream_usingCDict_advanced() :
2080	* This function is DEPRECATED, and is approximately equivalent to:
2081	* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
2082	* // Pseudocode: Set each zstd frame parameter and leave the rest as-is.
2083	* for ((fParam, value) : fParams) {
2084	* ZSTD_CCtx_setParameter(zcs, fParam, value);
2085	* }
2086	* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
2087	* ZSTD_CCtx_refCDict(zcs, cdict);
2088	*
2089	* same as ZSTD_initCStream_usingCDict(), with control over frame parameters.
2090	* pledgedSrcSize must be correct. If srcSize is not known at init time, use
2091	* value ZSTD_CONTENTSIZE_UNKNOWN.
2092	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2093	*/
2094	ZSTDLIB_API size_t
2095	ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs,
2096	const ZSTD_CDict* cdict,
2097	ZSTD_frameParameters fParams,
2098	unsigned long long pledgedSrcSize);
2099
2100	/*! ZSTD_resetCStream() :
2101	* This function is deprecated, and is equivalent to:
2102	* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
2103	* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
2104	*
2105	* start a new frame, using same parameters from previous frame.
2106	* This is typically useful to skip dictionary loading stage, since it will re-use it in-place.
2107	* Note that zcs must be init at least once before using ZSTD_resetCStream().
2108	* If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN.
2109	* If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end.
2110	* For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs,
2111	* but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead.
2112	* @return : 0, or an error code (which can be tested using ZSTD_isError())
2113	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2114	*/
2115	ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);
2116
2117
2118	typedef struct {
2119	unsigned long long ingested; /* nb input bytes read and buffered */
2120	unsigned long long consumed; /* nb input bytes actually compressed */
2121	unsigned long long produced; /* nb of compressed bytes generated and buffered */
2122	unsigned long long flushed; /* nb of compressed bytes flushed : not provided; can be tracked from caller side */
2123	unsigned currentJobID; /* MT only : latest started job nb */
2124	unsigned nbActiveWorkers; /* MT only : nb of workers actively compressing at probe time */
2125	} ZSTD_frameProgression;
2126
2127	/* ZSTD_getFrameProgression() :
2128	* tells how much data has been ingested (read from input)
2129	* consumed (input actually compressed) and produced (output) for current frame.
2130	* Note : (ingested - consumed) is amount of input data buffered internally, not yet compressed.
2131	* Aggregates progression inside active worker threads.
2132	*/
2133	ZSTDLIB_API ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx);
2134
2135	/*! ZSTD_toFlushNow() :
2136	* Tell how many bytes are ready to be flushed immediately.
2137	* Useful for multithreading scenarios (nbWorkers >= 1).
2138	* Probe the oldest active job, defined as oldest job not yet entirely flushed,
2139	* and check its output buffer.
2140	* @return : amount of data stored in oldest job and ready to be flushed immediately.
2141	* if @return == 0, it means either :
2142	* + there is no active job (could be checked with ZSTD_frameProgression()), or
2143	* + oldest job is still actively compressing data,
2144	* but everything it has produced has also been flushed so far,
2145	* therefore flush speed is limited by production speed of oldest job
2146	* irrespective of the speed of concurrent (and newer) jobs.
2147	*/
2148	ZSTDLIB_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx);
2149
2150
2151	/*===== Advanced Streaming decompression functions =====*/
2152
2153	/*!
2154	* This function is deprecated, and is equivalent to:
2155	*
2156	* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
2157	* ZSTD_DCtx_loadDictionary(zds, dict, dictSize);
2158	*
2159	* note: no dictionary will be used if dict == NULL or dictSize < 8
2160	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2161	*/
2162	ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize);
2163
2164	/*!
2165	* This function is deprecated, and is equivalent to:
2166	*
2167	* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
2168	* ZSTD_DCtx_refDDict(zds, ddict);
2169	*
2170	* note : ddict is referenced, it must outlive decompression session
2171	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2172	*/
2173	ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict);
2174
2175	/*!
2176	* This function is deprecated, and is equivalent to:
2177	*
2178	* ZSTD_DCtx_reset(zds, ZSTD_reset_session_only);
2179	*
2180	* re-use decompression parameters from previous init; saves dictionary loading
2181	* Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x
2182	*/
2183	ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds);
2184
2185
2186	/*********************************************************************
2187	* Buffer-less and synchronous inner streaming functions
2188	*
2189	* This is an advanced API, giving full control over buffer management, for users which need direct control over memory.
2190	* But it's also a complex one, with several restrictions, documented below.
2191	* Prefer normal streaming API for an easier experience.
2192	********************************************************************* */
2193
2194	/**
2195	Buffer-less streaming compression (synchronous mode)
2196
2197	A ZSTD_CCtx object is required to track streaming operations.
2198	Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource.
2199	ZSTD_CCtx object can be re-used multiple times within successive compression operations.
2200
2201	Start by initializing a context.
2202	Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression,
2203	or ZSTD_compressBegin_advanced(), for finer parameter control.
2204	It's also possible to duplicate a reference context which has already been initialized, using ZSTD_copyCCtx()
2205
2206	Then, consume your input using ZSTD_compressContinue().
2207	There are some important considerations to keep in mind when using this advanced function :
2208	- ZSTD_compressContinue() has no internal buffer. It uses externally provided buffers only.
2209	- Interface is synchronous : input is consumed entirely and produces 1+ compressed blocks.
2210	- Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario.
2211	Worst case evaluation is provided by ZSTD_compressBound().
2212	ZSTD_compressContinue() doesn't guarantee recover after a failed compression.
2213	- ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog).
2214	It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks)
2215	- ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps.
2216	In which case, it will "discard" the relevant memory section from its history.
2217
2218	Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum.
2219	It's possible to use srcSize==0, in which case, it will write a final empty block to end the frame.
2220	Without last block mark, frames are considered unfinished (hence corrupted) by compliant decoders.
2221
2222	`ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress again.
2223	*/
2224
2225	/*===== Buffer-less streaming compression functions =====*/
2226	ZSTDLIB_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel);
2227	ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel);
2228	ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize : If srcSize is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN */
2229	ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); /**< note: fails if cdict==NULL */
2230	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 must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */
2231	ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); /**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */
2232
2233	ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
2234	ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
2235
2236
2237	/**
2238	Buffer-less streaming decompression (synchronous mode)
2239
2240	A ZSTD_DCtx object is required to track streaming operations.
2241	Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it.
2242	A ZSTD_DCtx object can be re-used multiple times.
2243
2244	First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader().
2245	Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough.
2246	Data fragment must be large enough to ensure successful decoding.
2247	`ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough.
2248	@result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled.
2249	>0 : `srcSize` is too small, please provide at least @result bytes on next attempt.
2250	errorCode, which can be tested using ZSTD_isError().
2251
2252	It fills a ZSTD_frameHeader structure with important information to correctly decode the frame,
2253	such as the dictionary ID, content size, or maximum back-reference distance (`windowSize`).
2254	Note that these values could be wrong, either because of data corruption, or because a 3rd party deliberately spoofs false information.
2255	As a consequence, check that values remain within valid application range.
2256	For example, do not allocate memory blindly, check that `windowSize` is within expectation.
2257	Each application can set its own limits, depending on local restrictions.
2258	For extended interoperability, it is recommended to support `windowSize` of at least 8 MB.
2259
2260	ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize` bytes.
2261	ZSTD_decompressContinue() is very sensitive to contiguity,
2262	if 2 blocks don't follow each other, make sure that either the compressor breaks contiguity at the same place,
2263	or that previous contiguous segment is large enough to properly handle maximum back-reference distance.
2264	There are multiple ways to guarantee this condition.
2265
2266	The most memory efficient way is to use a round buffer of sufficient size.
2267	Sufficient size is determined by invoking ZSTD_decodingBufferSize_min(),
2268	which can @return an error code if required value is too large for current system (in 32-bits mode).
2269	In a round buffer methodology, ZSTD_decompressContinue() decompresses each block next to previous one,
2270	up to the moment there is not enough room left in the buffer to guarantee decoding another full block,
2271	which maximum size is provided in `ZSTD_frameHeader` structure, field `blockSizeMax`.
2272	At which point, decoding can resume from the beginning of the buffer.
2273	Note that already decoded data stored in the buffer should be flushed before being overwritten.
2274
2275	There are alternatives possible, for example using two or more buffers of size `windowSize` each, though they consume more memory.
2276
2277	Finally, if you control the compression process, you can also ignore all buffer size rules,
2278	as long as the encoder and decoder progress in "lock-step",
2279	aka use exactly the same buffer sizes, break contiguity at the same place, etc.
2280
2281	Once buffers are setup, start decompression, with ZSTD_decompressBegin().
2282	If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict().
2283
2284	Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively.
2285	ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue().
2286	ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail.
2287
2288	@result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity).
2289	It can be zero : it just means ZSTD_decompressContinue() has decoded some metadata item.
2290	It can also be an error code, which can be tested with ZSTD_isError().
2291
2292	A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero.
2293	Context can then be reset to start a new decompression.
2294
2295	Note : it's possible to know if next input to present is a header or a block, using ZSTD_nextInputType().
2296	This information is not required to properly decode a frame.
2297
2298	== Special case : skippable frames ==
2299
2300	Skippable frames allow integration of user-defined data into a flow of concatenated frames.
2301	Skippable frames will be ignored (skipped) by decompressor.
2302	The format of skippable frames is as follows :
2303	a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F
2304	b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits
2305	c) Frame Content - any content (User Data) of length equal to Frame Size
2306	For skippable frames ZSTD_getFrameHeader() returns zfhPtr->frameType==ZSTD_skippableFrame.
2307	For skippable frames ZSTD_decompressContinue() always returns 0 : it only skips the content.
2308	*/
2309
2310	/*===== Buffer-less streaming decompression functions =====*/
2311	typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_frameType_e;
2312	typedef struct {
2313	unsigned long long frameContentSize; /* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */
2314	unsigned long long windowSize; /* can be very large, up to <= frameContentSize */
2315	unsigned blockSizeMax;
2316	ZSTD_frameType_e frameType; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */
2317	unsigned headerSize;
2318	unsigned dictID;
2319	unsigned checksumFlag;
2320	} ZSTD_frameHeader;
2321
2322	/*! ZSTD_getFrameHeader() :
2323	* decode Frame Header, or requires larger `srcSize`.
2324	* @return : 0, `zfhPtr` is correctly filled,
2325	* >0, `srcSize` is too small, value is wanted `srcSize` amount,
2326	* or an error code, which can be tested using ZSTD_isError() */
2327	ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */
2328	/*! ZSTD_getFrameHeader_advanced() :
2329	* same as ZSTD_getFrameHeader(),
2330	* with added capability to select a format (like ZSTD_f_zstd1_magicless) */
2331	ZSTDLIB_API size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format);
2332	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 */
2333
2334	ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
2335	ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
2336	ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);
2337
2338	ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx);
2339	ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
2340
2341	/* misc */
2342	ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx);
2343	typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
2344	ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx);
2345
2346
2347
2348
2349	/* ============================ */
2350	/** Block level API */
2351	/* ============================ */
2352
2353	/*!
2354	Block functions produce and decode raw zstd blocks, without frame metadata.
2355	Frame metadata cost is typically ~12 bytes, which can be non-negligible for very small blocks (< 100 bytes).
2356	But users will have to take in charge needed metadata to regenerate data, such as compressed and content sizes.
2357
2358	A few rules to respect :
2359	- Compressing and decompressing require a context structure
2360	+ Use ZSTD_createCCtx() and ZSTD_createDCtx()
2361	- It is necessary to init context before starting
2362	+ compression : any ZSTD_compressBegin*() variant, including with dictionary
2363	+ decompression : any ZSTD_decompressBegin*() variant, including with dictionary
2364	+ copyCCtx() and copyDCtx() can be used too
2365	- Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB
2366	+ If input is larger than a block size, it's necessary to split input data into multiple blocks
2367	+ For inputs larger than a single block, consider using regular ZSTD_compress() instead.
2368	Frame metadata is not that costly, and quickly becomes negligible as source size grows larger than a block.
2369	- When a block is considered not compressible enough, ZSTD_compressBlock() result will be 0 (zero) !
2370	===> In which case, nothing is produced into `dst` !
2371	+ User __must__ test for such outcome and deal directly with uncompressed data
2372	+ A block cannot be declared incompressible if ZSTD_compressBlock() return value was != 0.
2373	Doing so would mess up with statistics history, leading to potential data corruption.
2374	+ ZSTD_decompressBlock() _doesn't accept uncompressed data as input_ !!
2375	+ In case of multiple successive blocks, should some of them be uncompressed,
2376	decoder must be informed of their existence in order to follow proper history.
2377	Use ZSTD_insertBlock() for such a case.
2378	*/
2379
2380	/*===== Raw zstd block functions =====*/
2381	ZSTDLIB_API size_t ZSTD_getBlockSize (const ZSTD_CCtx* cctx);
2382	ZSTDLIB_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
2383	ZSTDLIB_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
2384	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. */
2385
2386
2387	#endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */
2388
2389	#if defined (__cplusplus)
2390	}
2391	#endif
2392