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lz4/lib/lz4.h
Przemyslaw Skibinski 2ecce6f151 lz4.h: added Introduction section
2016-11-10 17:22:59 +01:00

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/*
LZ4 - Fast LZ compression algorithm
Header File
Copyright (C) 2011-2016, Yann Collet.
BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
You can contact the author at :
- LZ4 homepage : http://www.lz4.org
- LZ4 source repository : https://github.com/lz4/lz4
*/
#ifndef LZ4_H_2983827168210
#define LZ4_H_2983827168210
#if defined (__cplusplus)
extern "C" {
#endif
/**
Introduction
LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core,
scalable with multi-cores CPU. It features an extremely fast decoder, with speed in
multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.
The LZ4 compression library provides in-memory compression and decompression functions.
Compression can be done in:
- a single step (described as Simple Functions)
- a single step, reusing a context (described in Advanced Functions)
- unbounded multiple steps (described as Streaming compression)
lz4.h provides block compression functions. It gives full buffer control to user.
Block compression functions are not-enough to send information,
since it's still necessary to provide metadata (such as compressed size),
and each application can do it in whichever way it wants.
For interoperability, there is LZ4 frame specification (doc/lz4_Frame_format.md).
A library is provided to take care of it, see lz4frame.h.
*/
/*^***************************************************************
* Export parameters
*****************************************************************/
/*
* LZ4_DLL_EXPORT :
* Enable exporting of functions when building a Windows DLL
*/
#if defined(LZ4_DLL_EXPORT) && (LZ4_DLL_EXPORT==1)
# define LZ4LIB_API __declspec(dllexport)
#elif defined(LZ4_DLL_IMPORT) && (LZ4_DLL_IMPORT==1)
# define LZ4LIB_API __declspec(dllimport) /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/
#else
# define LZ4LIB_API
#endif
/*========== Version =========== */
LZ4LIB_API int LZ4_versionNumber (void);
LZ4LIB_API const char* LZ4_versionString (void);
#define LZ4_VERSION_MAJOR 1 /* for breaking interface changes */
#define LZ4_VERSION_MINOR 7 /* for new (non-breaking) interface capabilities */
#define LZ4_VERSION_RELEASE 2 /* for tweaks, bug-fixes, or development */
#define LZ4_VERSION_NUMBER (LZ4_VERSION_MAJOR *100*100 + LZ4_VERSION_MINOR *100 + LZ4_VERSION_RELEASE)
#define LZ4_LIB_VERSION LZ4_VERSION_MAJOR.LZ4_VERSION_MINOR.LZ4_VERSION_RELEASE
#define LZ4_QUOTE(str) #str
#define LZ4_EXPAND_AND_QUOTE(str) LZ4_QUOTE(str)
#define LZ4_VERSION_STRING LZ4_EXPAND_AND_QUOTE(LZ4_LIB_VERSION)
/*-************************************
* Tuning parameter
**************************************/
/*!
* LZ4_MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
*/
#define LZ4_MEMORY_USAGE 14
/*-************************************
* Simple Functions
**************************************/
/*! LZ4_compress_default() :
Compresses 'sourceSize' bytes from buffer 'source'
into already allocated 'dest' buffer of size 'maxDestSize'.
Compression is guaranteed to succeed if 'maxDestSize' >= LZ4_compressBound(sourceSize).
It also runs faster, so it's a recommended setting.
If the function cannot compress 'source' into a more limited 'dest' budget,
compression stops *immediately*, and the function result is zero.
As a consequence, 'dest' content is not valid.
This function never writes outside 'dest' buffer, nor read outside 'source' buffer.
sourceSize : Max supported value is LZ4_MAX_INPUT_VALUE
maxDestSize : full or partial size of buffer 'dest' (which must be already allocated)
return : the number of bytes written into buffer 'dest' (necessarily <= maxOutputSize)
or 0 if compression fails */
LZ4LIB_API int LZ4_compress_default(const char* source, char* dest, int sourceSize, int maxDestSize);
/*! LZ4_decompress_safe() :
compressedSize : is the precise full size of the compressed block.
maxDecompressedSize : is the size of destination buffer, which must be already allocated.
return : the number of bytes decompressed into destination buffer (necessarily <= maxDecompressedSize)
If destination buffer is not large enough, decoding will stop and output an error code (<0).
If the source stream is detected malformed, the function will stop decoding and return a negative result.
This function is protected against buffer overflow exploits, including malicious data packets.
It never writes outside output buffer, nor reads outside input buffer.
*/
LZ4LIB_API int LZ4_decompress_safe (const char* source, char* dest, int compressedSize, int maxDecompressedSize);
/*-************************************
* Advanced Functions
**************************************/
#define LZ4_MAX_INPUT_SIZE 0x7E000000 /* 2 113 929 216 bytes */
#define LZ4_COMPRESSBOUND(isize) ((unsigned)(isize) > (unsigned)LZ4_MAX_INPUT_SIZE ? 0 : (isize) + ((isize)/255) + 16)
/*!
LZ4_compressBound() :
Provides the maximum size that LZ4 compression may output in a "worst case" scenario (input data not compressible)
This function is primarily useful for memory allocation purposes (destination buffer size).
Macro LZ4_COMPRESSBOUND() is also provided for compilation-time evaluation (stack memory allocation for example).
Note that LZ4_compress_default() compress faster when dest buffer size is >= LZ4_compressBound(srcSize)
inputSize : max supported value is LZ4_MAX_INPUT_SIZE
return : maximum output size in a "worst case" scenario
or 0, if input size is too large ( > LZ4_MAX_INPUT_SIZE)
*/
LZ4LIB_API int LZ4_compressBound(int inputSize);
/*!
LZ4_compress_fast() :
Same as LZ4_compress_default(), but allows to select an "acceleration" factor.
The larger the acceleration value, the faster the algorithm, but also the lesser the compression.
It's a trade-off. It can be fine tuned, with each successive value providing roughly +~3% to speed.
An acceleration value of "1" is the same as regular LZ4_compress_default()
Values <= 0 will be replaced by ACCELERATION_DEFAULT (see lz4.c), which is 1.
*/
LZ4LIB_API int LZ4_compress_fast (const char* source, char* dest, int sourceSize, int maxDestSize, int acceleration);
/*!
LZ4_compress_fast_extState() :
Same compression function, just using an externally allocated memory space to store compression state.
Use LZ4_sizeofState() to know how much memory must be allocated,
and allocate it on 8-bytes boundaries (using malloc() typically).
Then, provide it as 'void* state' to compression function.
*/
LZ4LIB_API int LZ4_sizeofState(void);
LZ4LIB_API int LZ4_compress_fast_extState (void* state, const char* source, char* dest, int inputSize, int maxDestSize, int acceleration);
/*!
LZ4_compress_destSize() :
Reverse the logic, by compressing as much data as possible from 'source' buffer
into already allocated buffer 'dest' of size 'targetDestSize'.
This function either compresses the entire 'source' content into 'dest' if it's large enough,
or fill 'dest' buffer completely with as much data as possible from 'source'.
*sourceSizePtr : will be modified to indicate how many bytes where read from 'source' to fill 'dest'.
New value is necessarily <= old value.
return : Nb bytes written into 'dest' (necessarily <= targetDestSize)
or 0 if compression fails
*/
LZ4LIB_API int LZ4_compress_destSize (const char* source, char* dest, int* sourceSizePtr, int targetDestSize);
/*!
LZ4_decompress_fast() :
originalSize : is the original and therefore uncompressed size
return : the number of bytes read from the source buffer (in other words, the compressed size)
If the source stream is detected malformed, the function will stop decoding and return a negative result.
Destination buffer must be already allocated. Its size must be a minimum of 'originalSize' bytes.
note : This function fully respect memory boundaries for properly formed compressed data.
It is a bit faster than LZ4_decompress_safe().
However, it does not provide any protection against intentionally modified data stream (malicious input).
Use this function in trusted environment only (data to decode comes from a trusted source).
*/
LZ4LIB_API int LZ4_decompress_fast (const char* source, char* dest, int originalSize);
/*!
LZ4_decompress_safe_partial() :
This function decompress a compressed block of size 'compressedSize' at position 'source'
into destination buffer 'dest' of size 'maxDecompressedSize'.
The function tries to stop decompressing operation as soon as 'targetOutputSize' has been reached,
reducing decompression time.
return : the number of bytes decoded in the destination buffer (necessarily <= maxDecompressedSize)
Note : this number can be < 'targetOutputSize' should the compressed block to decode be smaller.
Always control how many bytes were decoded.
If the source stream is detected malformed, the function will stop decoding and return a negative result.
This function never writes outside of output buffer, and never reads outside of input buffer. It is therefore protected against malicious data packets
*/
LZ4LIB_API int LZ4_decompress_safe_partial (const char* source, char* dest, int compressedSize, int targetOutputSize, int maxDecompressedSize);
/*-*********************************************
* Streaming Compression Functions
***********************************************/
#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4)
#define LZ4_STREAMSIZE (LZ4_STREAMSIZE_U64 * sizeof(long long))
/*!
* LZ4_stream_t :
* information structure to track an LZ4 stream.
* important : init this structure content before first use !
* note : only allocated directly the structure if you are statically linking LZ4
* If you are using liblz4 as a DLL, please use below construction methods instead.
*/
typedef struct { long long table[LZ4_STREAMSIZE_U64]; } LZ4_stream_t;
/*! LZ4_resetStream() :
* Use this function to init an allocated `LZ4_stream_t` structure
*/
LZ4LIB_API void LZ4_resetStream (LZ4_stream_t* streamPtr);
/*! LZ4_createStream() and LZ4_freeStream() :
* LZ4_createStream() will allocate and initialize an `LZ4_stream_t` structure.
* LZ4_freeStream() releases its memory.
* In the context of a DLL (liblz4), please use these methods rather than the static struct.
* They are more future proof, in case of a change of `LZ4_stream_t` size.
*/
LZ4LIB_API LZ4_stream_t* LZ4_createStream(void);
LZ4LIB_API int LZ4_freeStream (LZ4_stream_t* streamPtr);
/*! LZ4_loadDict() :
* Use this function to load a static dictionary into LZ4_stream.
* Any previous data will be forgotten, only 'dictionary' will remain in memory.
* Loading a size of 0 is allowed.
* Return : dictionary size, in bytes (necessarily <= 64 KB)
*/
LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, int dictSize);
/*! LZ4_compress_fast_continue() :
* Compress buffer content 'src', using data from previously compressed blocks as dictionary to improve compression ratio.
* Important : Previous data blocks are assumed to still be present and unmodified !
* 'dst' buffer must be already allocated.
* If maxDstSize >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster.
* If not, and if compressed data cannot fit into 'dst' buffer size, compression stops, and function returns a zero.
*/
LZ4LIB_API int LZ4_compress_fast_continue (LZ4_stream_t* streamPtr, const char* src, char* dst, int srcSize, int maxDstSize, int acceleration);
/*! LZ4_saveDict() :
* If previously compressed data block is not guaranteed to remain available at its memory location,
* save it into a safer place (char* safeBuffer).
* Note : you don't need to call LZ4_loadDict() afterwards,
* dictionary is immediately usable, you can therefore call LZ4_compress_fast_continue().
* Return : saved dictionary size in bytes (necessarily <= dictSize), or 0 if error.
*/
LZ4LIB_API int LZ4_saveDict (LZ4_stream_t* streamPtr, char* safeBuffer, int dictSize);
/*-**********************************************
* Streaming Decompression Functions
************************************************/
#define LZ4_STREAMDECODESIZE_U64 4
#define LZ4_STREAMDECODESIZE (LZ4_STREAMDECODESIZE_U64 * sizeof(unsigned long long))
typedef struct { unsigned long long table[LZ4_STREAMDECODESIZE_U64]; } LZ4_streamDecode_t;
/*!
* LZ4_streamDecode_t
* information structure to track an LZ4 stream.
* init this structure content using LZ4_setStreamDecode or memset() before first use !
*
* In the context of a DLL (liblz4) please prefer usage of construction methods below.
* They are more future proof, in case of a change of LZ4_streamDecode_t size in the future.
* LZ4_createStreamDecode will allocate and initialize an LZ4_streamDecode_t structure
* LZ4_freeStreamDecode releases its memory.
*/
LZ4LIB_API LZ4_streamDecode_t* LZ4_createStreamDecode(void);
LZ4LIB_API int LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_stream);
/*! LZ4_setStreamDecode() :
* Use this function to instruct where to find the dictionary.
* Setting a size of 0 is allowed (same effect as reset).
* @return : 1 if OK, 0 if error
*/
LZ4LIB_API int LZ4_setStreamDecode (LZ4_streamDecode_t* LZ4_streamDecode, const char* dictionary, int dictSize);
/*!
*_continue() :
These decoding functions allow decompression of multiple blocks in "streaming" mode.
Previously decoded blocks *must* remain available at the memory position where they were decoded (up to 64 KB)
In the case of a ring buffers, decoding buffer must be either :
- Exactly same size as encoding buffer, with same update rule (block boundaries at same positions)
In which case, the decoding & encoding ring buffer can have any size, including very small ones ( < 64 KB).
- Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
maxBlockSize is implementation dependent. It's the maximum size you intend to compress into a single block.
In which case, encoding and decoding buffers do not need to be synchronized,
and encoding ring buffer can have any size, including small ones ( < 64 KB).
- _At least_ 64 KB + 8 bytes + maxBlockSize.
In which case, encoding and decoding buffers do not need to be synchronized,
and encoding ring buffer can have any size, including larger than decoding buffer.
Whenever these conditions are not possible, save the last 64KB of decoded data into a safe buffer,
and indicate where it is saved using LZ4_setStreamDecode()
*/
LZ4LIB_API int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int compressedSize, int maxDecompressedSize);
LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int originalSize);
/*!
*_usingDict() :
Advanced decoding functions :
These decoding functions work the same as
a combination of LZ4_setStreamDecode() followed by LZ4_decompress_x_continue()
They are stand-alone. They don't need nor update an LZ4_streamDecode_t structure.
*/
LZ4LIB_API int LZ4_decompress_safe_usingDict (const char* source, char* dest, int compressedSize, int maxDecompressedSize, const char* dictStart, int dictSize);
LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* source, char* dest, int originalSize, const char* dictStart, int dictSize);
/*=************************************
* Obsolete Functions
**************************************/
/* Deprecate Warnings */
/* Should these warnings messages be a problem,
it is generally possible to disable them,
with -Wno-deprecated-declarations for gcc
or _CRT_SECURE_NO_WARNINGS in Visual for example.
Otherwise, you can also define LZ4_DISABLE_DEPRECATE_WARNINGS */
#define LZ4_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
#ifdef LZ4_DISABLE_DEPRECATE_WARNINGS
# define LZ4_DEPRECATED() /* disable deprecation warnings */
#else
# if (LZ4_GCC_VERSION >= 405) || defined(__clang__)
# define LZ4_DEPRECATED(message) __attribute__((deprecated(message)))
# elif (LZ4_GCC_VERSION >= 301)
# define LZ4_DEPRECATED(message) __attribute__((deprecated))
# elif defined(_MSC_VER)
# define LZ4_DEPRECATED(message) __declspec(deprecated(message))
# else
# pragma message("WARNING: You need to implement LZ4_DEPRECATED for this compiler")
# define LZ4_DEPRECATED(message)
# endif
#endif /* LZ4_DISABLE_DEPRECATE_WARNINGS */
/* Obsolete compression functions */
/* These functions will generate warnings in a future release */
LZ4LIB_API int LZ4_compress (const char* source, char* dest, int sourceSize);
LZ4LIB_API int LZ4_compress_limitedOutput (const char* source, char* dest, int sourceSize, int maxOutputSize);
LZ4LIB_API int LZ4_compress_withState (void* state, const char* source, char* dest, int inputSize);
LZ4LIB_API int LZ4_compress_limitedOutput_withState (void* state, const char* source, char* dest, int inputSize, int maxOutputSize);
LZ4LIB_API int LZ4_compress_continue (LZ4_stream_t* LZ4_streamPtr, const char* source, char* dest, int inputSize);
LZ4LIB_API int LZ4_compress_limitedOutput_continue (LZ4_stream_t* LZ4_streamPtr, const char* source, char* dest, int inputSize, int maxOutputSize);
/* Obsolete decompression functions */
/* These function names are completely deprecated and must no longer be used.
They are only provided in lz4.c for compatibility with older programs.
- LZ4_uncompress is the same as LZ4_decompress_fast
- LZ4_uncompress_unknownOutputSize is the same as LZ4_decompress_safe
These function prototypes are now disabled; uncomment them only if you really need them.
It is highly recommended to stop using these prototypes and migrate to maintained ones */
/* int LZ4_uncompress (const char* source, char* dest, int outputSize); */
/* int LZ4_uncompress_unknownOutputSize (const char* source, char* dest, int isize, int maxOutputSize); */
/* Obsolete streaming functions; use new streaming interface whenever possible */
LZ4_DEPRECATED("use LZ4_createStream() instead") void* LZ4_create (char* inputBuffer);
LZ4_DEPRECATED("use LZ4_createStream() instead") int LZ4_sizeofStreamState(void);
LZ4_DEPRECATED("use LZ4_resetStream() instead") int LZ4_resetStreamState(void* state, char* inputBuffer);
LZ4_DEPRECATED("use LZ4_saveDict() instead") char* LZ4_slideInputBuffer (void* state);
/* Obsolete streaming decoding functions */
LZ4_DEPRECATED("use LZ4_decompress_safe_usingDict() instead") int LZ4_decompress_safe_withPrefix64k (const char* src, char* dst, int compressedSize, int maxDstSize);
LZ4_DEPRECATED("use LZ4_decompress_fast_usingDict() instead") int LZ4_decompress_fast_withPrefix64k (const char* src, char* dst, int originalSize);
#if defined (__cplusplus)
}
#endif
#endif /* LZ4_H_2983827168210 */
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