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Diffstat (limited to 'lib/zstd/fse.h')
| -rw-r--r-- | lib/zstd/fse.h | 575 |
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diff --git a/lib/zstd/fse.h b/lib/zstd/fse.h deleted file mode 100644 index 7460ab04b191..000000000000 --- a/lib/zstd/fse.h +++ /dev/null @@ -1,575 +0,0 @@ -/* - * FSE : Finite State Entropy codec - * Public Prototypes declaration - * Copyright (C) 2013-2016, 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. - * - * This program is free software; you can redistribute it and/or modify it under - * the terms of the GNU General Public License version 2 as published by the - * Free Software Foundation. This program is dual-licensed; you may select - * either version 2 of the GNU General Public License ("GPL") or BSD license - * ("BSD"). - * - * You can contact the author at : - * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy - */ -#ifndef FSE_H -#define FSE_H - -/*-***************************************** -* Dependencies -******************************************/ -#include <linux/types.h> /* size_t, ptrdiff_t */ - -/*-***************************************** -* FSE_PUBLIC_API : control library symbols visibility -******************************************/ -#define FSE_PUBLIC_API - -/*------ Version ------*/ -#define FSE_VERSION_MAJOR 0 -#define FSE_VERSION_MINOR 9 -#define FSE_VERSION_RELEASE 0 - -#define FSE_LIB_VERSION FSE_VERSION_MAJOR.FSE_VERSION_MINOR.FSE_VERSION_RELEASE -#define FSE_QUOTE(str) #str -#define FSE_EXPAND_AND_QUOTE(str) FSE_QUOTE(str) -#define FSE_VERSION_STRING FSE_EXPAND_AND_QUOTE(FSE_LIB_VERSION) - -#define FSE_VERSION_NUMBER (FSE_VERSION_MAJOR * 100 * 100 + FSE_VERSION_MINOR * 100 + FSE_VERSION_RELEASE) -FSE_PUBLIC_API unsigned FSE_versionNumber(void); /**< library version number; to be used when checking dll version */ - -/*-***************************************** -* Tool functions -******************************************/ -FSE_PUBLIC_API size_t FSE_compressBound(size_t size); /* maximum compressed size */ - -/* Error Management */ -FSE_PUBLIC_API unsigned FSE_isError(size_t code); /* tells if a return value is an error code */ - -/*-***************************************** -* FSE detailed API -******************************************/ -/*! -FSE_compress() does the following: -1. count symbol occurrence from source[] into table count[] -2. normalize counters so that sum(count[]) == Power_of_2 (2^tableLog) -3. save normalized counters to memory buffer using writeNCount() -4. build encoding table 'CTable' from normalized counters -5. encode the data stream using encoding table 'CTable' - -FSE_decompress() does the following: -1. read normalized counters with readNCount() -2. build decoding table 'DTable' from normalized counters -3. decode the data stream using decoding table 'DTable' - -The following API allows targeting specific sub-functions for advanced tasks. -For example, it's possible to compress several blocks using the same 'CTable', -or to save and provide normalized distribution using external method. -*/ - -/* *** COMPRESSION *** */ -/*! FSE_optimalTableLog(): - dynamically downsize 'tableLog' when conditions are met. - It saves CPU time, by using smaller tables, while preserving or even improving compression ratio. - @return : recommended tableLog (necessarily <= 'maxTableLog') */ -FSE_PUBLIC_API unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue); - -/*! FSE_normalizeCount(): - normalize counts so that sum(count[]) == Power_of_2 (2^tableLog) - 'normalizedCounter' is a table of short, of minimum size (maxSymbolValue+1). - @return : tableLog, - or an errorCode, which can be tested using FSE_isError() */ -FSE_PUBLIC_API size_t FSE_normalizeCount(short *normalizedCounter, unsigned tableLog, const unsigned *count, size_t srcSize, unsigned maxSymbolValue); - -/*! FSE_NCountWriteBound(): - Provides the maximum possible size of an FSE normalized table, given 'maxSymbolValue' and 'tableLog'. - Typically useful for allocation purpose. */ -FSE_PUBLIC_API size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog); - -/*! FSE_writeNCount(): - Compactly save 'normalizedCounter' into 'buffer'. - @return : size of the compressed table, - or an errorCode, which can be tested using FSE_isError(). */ -FSE_PUBLIC_API size_t FSE_writeNCount(void *buffer, size_t bufferSize, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog); - -/*! Constructor and Destructor of FSE_CTable. - Note that FSE_CTable size depends on 'tableLog' and 'maxSymbolValue' */ -typedef unsigned FSE_CTable; /* don't allocate that. It's only meant to be more restrictive than void* */ - -/*! FSE_compress_usingCTable(): - Compress `src` using `ct` into `dst` which must be already allocated. - @return : size of compressed data (<= `dstCapacity`), - or 0 if compressed data could not fit into `dst`, - or an errorCode, which can be tested using FSE_isError() */ -FSE_PUBLIC_API size_t FSE_compress_usingCTable(void *dst, size_t dstCapacity, const void *src, size_t srcSize, const FSE_CTable *ct); - -/*! -Tutorial : ----------- -The first step is to count all symbols. FSE_count() does this job very fast. -Result will be saved into 'count', a table of unsigned int, which must be already allocated, and have 'maxSymbolValuePtr[0]+1' cells. -'src' is a table of bytes of size 'srcSize'. All values within 'src' MUST be <= maxSymbolValuePtr[0] -maxSymbolValuePtr[0] will be updated, with its real value (necessarily <= original value) -FSE_count() will return the number of occurrence of the most frequent symbol. -This can be used to know if there is a single symbol within 'src', and to quickly evaluate its compressibility. -If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()). - -The next step is to normalize the frequencies. -FSE_normalizeCount() will ensure that sum of frequencies is == 2 ^'tableLog'. -It also guarantees a minimum of 1 to any Symbol with frequency >= 1. -You can use 'tableLog'==0 to mean "use default tableLog value". -If you are unsure of which tableLog value to use, you can ask FSE_optimalTableLog(), -which will provide the optimal valid tableLog given sourceSize, maxSymbolValue, and a user-defined maximum (0 means "default"). - -The result of FSE_normalizeCount() will be saved into a table, -called 'normalizedCounter', which is a table of signed short. -'normalizedCounter' must be already allocated, and have at least 'maxSymbolValue+1' cells. -The return value is tableLog if everything proceeded as expected. -It is 0 if there is a single symbol within distribution. -If there is an error (ex: invalid tableLog value), the function will return an ErrorCode (which can be tested using FSE_isError()). - -'normalizedCounter' can be saved in a compact manner to a memory area using FSE_writeNCount(). -'buffer' must be already allocated. -For guaranteed success, buffer size must be at least FSE_headerBound(). -The result of the function is the number of bytes written into 'buffer'. -If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError(); ex : buffer size too small). - -'normalizedCounter' can then be used to create the compression table 'CTable'. -The space required by 'CTable' must be already allocated, using FSE_createCTable(). -You can then use FSE_buildCTable() to fill 'CTable'. -If there is an error, both functions will return an ErrorCode (which can be tested using FSE_isError()). - -'CTable' can then be used to compress 'src', with FSE_compress_usingCTable(). -Similar to FSE_count(), the convention is that 'src' is assumed to be a table of char of size 'srcSize' -The function returns the size of compressed data (without header), necessarily <= `dstCapacity`. -If it returns '0', compressed data could not fit into 'dst'. -If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()). -*/ - -/* *** DECOMPRESSION *** */ - -/*! FSE_readNCount(): - Read compactly saved 'normalizedCounter' from 'rBuffer'. - @return : size read from 'rBuffer', - or an errorCode, which can be tested using FSE_isError(). - maxSymbolValuePtr[0] and tableLogPtr[0] will also be updated with their respective values */ -FSE_PUBLIC_API size_t FSE_readNCount(short *normalizedCounter, unsigned *maxSymbolValuePtr, unsigned *tableLogPtr, const void *rBuffer, size_t rBuffSize); - -/*! Constructor and Destructor of FSE_DTable. - Note that its size depends on 'tableLog' */ -typedef unsigned FSE_DTable; /* don't allocate that. It's just a way to be more restrictive than void* */ - -/*! FSE_buildDTable(): - Builds 'dt', which must be already allocated, using FSE_createDTable(). - return : 0, or an errorCode, which can be tested using FSE_isError() */ -FSE_PUBLIC_API size_t FSE_buildDTable_wksp(FSE_DTable *dt, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize); - -/*! FSE_decompress_usingDTable(): - Decompress compressed source `cSrc` of size `cSrcSize` using `dt` - into `dst` which must be already allocated. - @return : size of regenerated data (necessarily <= `dstCapacity`), - or an errorCode, which can be tested using FSE_isError() */ -FSE_PUBLIC_API size_t FSE_decompress_usingDTable(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt); - -/*! -Tutorial : ----------- -(Note : these functions only decompress FSE-compressed blocks. - If block is uncompressed, use memcpy() instead - If block is a single repeated byte, use memset() instead ) - -The first step is to obtain the normalized frequencies of symbols. -This can be performed by FSE_readNCount() if it was saved using FSE_writeNCount(). -'normalizedCounter' must be already allocated, and have at least 'maxSymbolValuePtr[0]+1' cells of signed short. -In practice, that means it's necessary to know 'maxSymbolValue' beforehand, -or size the table to handle worst case situations (typically 256). -FSE_readNCount() will provide 'tableLog' and 'maxSymbolValue'. -The result of FSE_readNCount() is the number of bytes read from 'rBuffer'. -Note that 'rBufferSize' must be at least 4 bytes, even if useful information is less than that. -If there is an error, the function will return an error code, which can be tested using FSE_isError(). - -The next step is to build the decompression tables 'FSE_DTable' from 'normalizedCounter'. -This is performed by the function FSE_buildDTable(). -The space required by 'FSE_DTable' must be already allocated using FSE_createDTable(). -If there is an error, the function will return an error code, which can be tested using FSE_isError(). - -`FSE_DTable` can then be used to decompress `cSrc`, with FSE_decompress_usingDTable(). -`cSrcSize` must be strictly correct, otherwise decompression will fail. -FSE_decompress_usingDTable() result will tell how many bytes were regenerated (<=`dstCapacity`). -If there is an error, the function will return an error code, which can be tested using FSE_isError(). (ex: dst buffer too small) -*/ - -/* *** Dependency *** */ -#include "bitstream.h" - -/* ***************************************** -* Static allocation -*******************************************/ -/* FSE buffer bounds */ -#define FSE_NCOUNTBOUND 512 -#define FSE_BLOCKBOUND(size) (size + (size >> 7)) -#define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size)) /* Macro version, useful for static allocation */ - -/* It is possible to statically allocate FSE CTable/DTable as a table of FSE_CTable/FSE_DTable using below macros */ -#define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) (1 + (1 << (maxTableLog - 1)) + ((maxSymbolValue + 1) * 2)) -#define FSE_DTABLE_SIZE_U32(maxTableLog) (1 + (1 << maxTableLog)) - -/* ***************************************** -* FSE advanced API -*******************************************/ -/* FSE_count_wksp() : - * Same as FSE_count(), but using an externally provided scratch buffer. - * `workSpace` size must be table of >= `1024` unsigned - */ -size_t FSE_count_wksp(unsigned *count, unsigned *maxSymbolValuePtr, const void *source, size_t sourceSize, unsigned *workSpace); - -/* FSE_countFast_wksp() : - * Same as FSE_countFast(), but using an externally provided scratch buffer. - * `workSpace` must be a table of minimum `1024` unsigned - */ -size_t FSE_countFast_wksp(unsigned *count, unsigned *maxSymbolValuePtr, const void *src, size_t srcSize, unsigned *workSpace); - -/*! FSE_count_simple - * Same as FSE_countFast(), but does not use any additional memory (not even on stack). - * This function is unsafe, and will segfault if any value within `src` is `> *maxSymbolValuePtr` (presuming it's also the size of `count`). -*/ -size_t FSE_count_simple(unsigned *count, unsigned *maxSymbolValuePtr, const void *src, size_t srcSize); - -unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus); -/**< same as FSE_optimalTableLog(), which used `minus==2` */ - -size_t FSE_buildCTable_raw(FSE_CTable *ct, unsigned nbBits); -/**< build a fake FSE_CTable, designed for a flat distribution, where each symbol uses nbBits */ - -size_t FSE_buildCTable_rle(FSE_CTable *ct, unsigned char symbolValue); -/**< build a fake FSE_CTable, designed to compress always the same symbolValue */ - -/* FSE_buildCTable_wksp() : - * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`). - * `wkspSize` must be >= `(1<<tableLog)`. - */ -size_t FSE_buildCTable_wksp(FSE_CTable *ct, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workSpace, size_t wkspSize); - -size_t FSE_buildDTable_raw(FSE_DTable *dt, unsigned nbBits); -/**< build a fake FSE_DTable, designed to read a flat distribution where each symbol uses nbBits */ - -size_t FSE_buildDTable_rle(FSE_DTable *dt, unsigned char symbolValue); -/**< build a fake FSE_DTable, designed to always generate the same symbolValue */ - -size_t FSE_decompress_wksp(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, unsigned maxLog, void *workspace, size_t workspaceSize); -/**< same as FSE_decompress(), using an externally allocated `workSpace` produced with `FSE_DTABLE_SIZE_U32(maxLog)` */ - -/* ***************************************** -* FSE symbol compression API -*******************************************/ -/*! - This API consists of small unitary functions, which highly benefit from being inlined. - Hence their body are included in next section. -*/ -typedef struct { - ptrdiff_t value; - const void *stateTable; - const void *symbolTT; - unsigned stateLog; -} FSE_CState_t; - -static void FSE_initCState(FSE_CState_t *CStatePtr, const FSE_CTable *ct); - -static void FSE_encodeSymbol(BIT_CStream_t *bitC, FSE_CState_t *CStatePtr, unsigned symbol); - -static void FSE_flushCState(BIT_CStream_t *bitC, const FSE_CState_t *CStatePtr); - -/**< -These functions are inner components of FSE_compress_usingCTable(). -They allow the creation of custom streams, mixing multiple tables and bit sources. - -A key property to keep in mind is that encoding and decoding are done **in reverse direction**. -So the first symbol you will encode is the last you will decode, like a LIFO stack. - -You will need a few variables to track your CStream. They are : - -FSE_CTable ct; // Provided by FSE_buildCTable() -BIT_CStream_t bitStream; // bitStream tracking structure -FSE_CState_t state; // State tracking structure (can have several) - - -The first thing to do is to init bitStream and state. - size_t errorCode = BIT_initCStream(&bitStream, dstBuffer, maxDstSize); - FSE_initCState(&state, ct); - -Note that BIT_initCStream() can produce an error code, so its result should be tested, using FSE_isError(); -You can then encode your input data, byte after byte. -FSE_encodeSymbol() outputs a maximum of 'tableLog' bits at a time. -Remember decoding will be done in reverse direction. - FSE_encodeByte(&bitStream, &state, symbol); - -At any time, you can also add any bit sequence. -Note : maximum allowed nbBits is 25, for compatibility with 32-bits decoders - BIT_addBits(&bitStream, bitField, nbBits); - -The above methods don't commit data to memory, they just store it into local register, for speed. -Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t). -Writing data to memory is a manual operation, performed by the flushBits function. - BIT_flushBits(&bitStream); - -Your last FSE encoding operation shall be to flush your last state value(s). - FSE_flushState(&bitStream, &state); - -Finally, you must close the bitStream. -The function returns the size of CStream in bytes. -If data couldn't fit into dstBuffer, it will return a 0 ( == not compressible) -If there is an error, it returns an errorCode (which can be tested using FSE_isError()). - size_t size = BIT_closeCStream(&bitStream); -*/ - -/* ***************************************** -* FSE symbol decompression API -*******************************************/ -typedef struct { - size_t state; - const void *table; /* precise table may vary, depending on U16 */ -} FSE_DState_t; - -static void FSE_initDState(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD, const FSE_DTable *dt); - -static unsigned char FSE_decodeSymbol(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD); - -static unsigned FSE_endOfDState(const FSE_DState_t *DStatePtr); - -/**< -Let's now decompose FSE_decompress_usingDTable() into its unitary components. -You will decode FSE-encoded symbols from the bitStream, -and also any other bitFields you put in, **in reverse order**. - -You will need a few variables to track your bitStream. They are : - -BIT_DStream_t DStream; // Stream context -FSE_DState_t DState; // State context. Multiple ones are possible -FSE_DTable* DTablePtr; // Decoding table, provided by FSE_buildDTable() - -The first thing to do is to init the bitStream. - errorCode = BIT_initDStream(&DStream, srcBuffer, srcSize); - -You should then retrieve your initial state(s) -(in reverse flushing order if you have several ones) : - errorCode = FSE_initDState(&DState, &DStream, DTablePtr); - -You can then decode your data, symbol after symbol. -For information the maximum number of bits read by FSE_decodeSymbol() is 'tableLog'. -Keep in mind that symbols are decoded in reverse order, like a LIFO stack (last in, first out). - unsigned char symbol = FSE_decodeSymbol(&DState, &DStream); - -You can retrieve any bitfield you eventually stored into the bitStream (in reverse order) -Note : maximum allowed nbBits is 25, for 32-bits compatibility - size_t bitField = BIT_readBits(&DStream, nbBits); - -All above operations only read from local register (which size depends on size_t). -Refueling the register from memory is manually performed by the reload method. - endSignal = FSE_reloadDStream(&DStream); - -BIT_reloadDStream() result tells if there is still some more data to read from DStream. -BIT_DStream_unfinished : there is still some data left into the DStream. -BIT_DStream_endOfBuffer : Dstream reached end of buffer. Its container may no longer be completely filled. -BIT_DStream_completed : Dstream reached its exact end, corresponding in general to decompression completed. -BIT_DStream_tooFar : Dstream went too far. Decompression result is corrupted. - -When reaching end of buffer (BIT_DStream_endOfBuffer), progress slowly, notably if you decode multiple symbols per loop, -to properly detect the exact end of stream. -After each decoded symbol, check if DStream is fully consumed using this simple test : - BIT_reloadDStream(&DStream) >= BIT_DStream_completed - -When it's done, verify decompression is fully completed, by checking both DStream and the relevant states. -Checking if DStream has reached its end is performed by : - BIT_endOfDStream(&DStream); -Check also the states. There might be some symbols left there, if some high probability ones (>50%) are possible. - FSE_endOfDState(&DState); -*/ - -/* ***************************************** -* FSE unsafe API -*******************************************/ -static unsigned char FSE_decodeSymbolFast(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD); -/* faster, but works only if nbBits is always >= 1 (otherwise, result will be corrupted) */ - -/* ***************************************** -* Implementation of inlined functions -*******************************************/ -typedef struct { - int deltaFindState; - U32 deltaNbBits; -} FSE_symbolCompressionTransform; /* total 8 bytes */ - -ZSTD_STATIC void FSE_initCState(FSE_CState_t *statePtr, const FSE_CTable *ct) -{ - const void *ptr = ct; - const U16 *u16ptr = (const U16 *)ptr; - const U32 tableLog = ZSTD_read16(ptr); - statePtr->value = (ptrdiff_t)1 << tableLog; - statePtr->stateTable = u16ptr + 2; - statePtr->symbolTT = ((const U32 *)ct + 1 + (tableLog ? (1 << (tableLog - 1)) : 1)); - statePtr->stateLog = tableLog; -} - -/*! FSE_initCState2() : -* Same as FSE_initCState(), but the first symbol to include (which will be the last to be read) -* uses the smallest state value possible, saving the cost of this symbol */ -ZSTD_STATIC void FSE_initCState2(FSE_CState_t *statePtr, const FSE_CTable *ct, U32 symbol) -{ - FSE_initCState(statePtr, ct); - { - const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform *)(statePtr->symbolTT))[symbol]; - const U16 *stateTable = (const U16 *)(statePtr->stateTable); - U32 nbBitsOut = (U32)((symbolTT.deltaNbBits + (1 << 15)) >> 16); - statePtr->value = (nbBitsOut << 16) - symbolTT.deltaNbBits; - statePtr->value = stateTable[(statePtr->value >> nbBitsOut) + symbolTT.deltaFindState]; - } -} - -ZSTD_STATIC void FSE_encodeSymbol(BIT_CStream_t *bitC, FSE_CState_t *statePtr, U32 symbol) -{ - const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform *)(statePtr->symbolTT))[symbol]; - const U16 *const stateTable = (const U16 *)(statePtr->stateTable); - U32 nbBitsOut = (U32)((statePtr->value + symbolTT.deltaNbBits) >> 16); - BIT_addBits(bitC, statePtr->value, nbBitsOut); - statePtr->value = stateTable[(statePtr->value >> nbBitsOut) + symbolTT.deltaFindState]; -} - -ZSTD_STATIC void FSE_flushCState(BIT_CStream_t *bitC, const FSE_CState_t *statePtr) -{ - BIT_addBits(bitC, statePtr->value, statePtr->stateLog); - BIT_flushBits(bitC); -} - -/* ====== Decompression ====== */ - -typedef struct { - U16 tableLog; - U16 fastMode; -} FSE_DTableHeader; /* sizeof U32 */ - -typedef struct { - unsigned short newState; - unsigned char symbol; - unsigned char nbBits; -} FSE_decode_t; /* size == U32 */ - -ZSTD_STATIC void FSE_initDState(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD, const FSE_DTable *dt) -{ - const void *ptr = dt; - const FSE_DTableHeader *const DTableH = (const FSE_DTableHeader *)ptr; - DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog); - BIT_reloadDStream(bitD); - DStatePtr->table = dt + 1; -} - -ZSTD_STATIC BYTE FSE_peekSymbol(const FSE_DState_t *DStatePtr) -{ - FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state]; - return DInfo.symbol; -} - -ZSTD_STATIC void FSE_updateState(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD) -{ - FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state]; - U32 const nbBits = DInfo.nbBits; - size_t const lowBits = BIT_readBits(bitD, nbBits); - DStatePtr->state = DInfo.newState + lowBits; -} - -ZSTD_STATIC BYTE FSE_decodeSymbol(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD) -{ - FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state]; - U32 const nbBits = DInfo.nbBits; - BYTE const symbol = DInfo.symbol; - size_t const lowBits = BIT_readBits(bitD, nbBits); - - DStatePtr->state = DInfo.newState + lowBits; - return symbol; -} - -/*! FSE_decodeSymbolFast() : - unsafe, only works if no symbol has a probability > 50% */ -ZSTD_STATIC BYTE FSE_decodeSymbolFast(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD) -{ - FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state]; - U32 const nbBits = DInfo.nbBits; - BYTE const symbol = DInfo.symbol; - size_t const lowBits = BIT_readBitsFast(bitD, nbBits); - - DStatePtr->state = DInfo.newState + lowBits; - return symbol; -} - -ZSTD_STATIC unsigned FSE_endOfDState(const FSE_DState_t *DStatePtr) { return DStatePtr->state == 0; } - -/* ************************************************************** -* Tuning parameters -****************************************************************/ -/*!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 -* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */ -#ifndef FSE_MAX_MEMORY_USAGE -#define FSE_MAX_MEMORY_USAGE 14 -#endif -#ifndef FSE_DEFAULT_MEMORY_USAGE -#define FSE_DEFAULT_MEMORY_USAGE 13 -#endif - -/*!FSE_MAX_SYMBOL_VALUE : -* Maximum symbol value authorized. -* Required for proper stack allocation */ -#ifndef FSE_MAX_SYMBOL_VALUE -#define FSE_MAX_SYMBOL_VALUE 255 -#endif - -/* ************************************************************** -* template functions type & suffix -****************************************************************/ -#define FSE_FUNCTION_TYPE BYTE -#define FSE_FUNCTION_EXTENSION -#define FSE_DECODE_TYPE FSE_decode_t - -/* *************************************************************** -* Constants -*****************************************************************/ -#define FSE_MAX_TABLELOG (FSE_MAX_MEMORY_USAGE - 2) -#define FSE_MAX_TABLESIZE (1U << FSE_MAX_TABLELOG) -#define FSE_MAXTABLESIZE_MASK (FSE_MAX_TABLESIZE - 1) -#define FSE_DEFAULT_TABLELOG (FSE_DEFAULT_MEMORY_USAGE - 2) -#define FSE_MIN_TABLELOG 5 - -#define FSE_TABLELOG_ABSOLUTE_MAX 15 -#if FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX -#error "FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX is not supported" -#endif - -#define FSE_TABLESTEP(tableSize) ((tableSize >> 1) + (tableSize >> 3) + 3) - -#endif /* FSE_H */ |