diff options
Diffstat (limited to 'thirdparty/zstd/common/fse.h')
| -rw-r--r-- | thirdparty/zstd/common/fse.h | 92 |
1 files changed, 48 insertions, 44 deletions
diff --git a/thirdparty/zstd/common/fse.h b/thirdparty/zstd/common/fse.h index 6a1d272be5..811c670bdd 100644 --- a/thirdparty/zstd/common/fse.h +++ b/thirdparty/zstd/common/fse.h @@ -72,6 +72,7 @@ extern "C" { #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 */ + /*-**************************************** * FSE simple functions ******************************************/ @@ -129,7 +130,7 @@ FSE_PUBLIC_API size_t FSE_compress2 (void* dst, size_t dstSize, const void* src, ******************************************/ /*! FSE_compress() does the following: -1. count symbol occurrence from source[] into table count[] +1. count symbol occurrence from source[] into table count[] (see hist.h) 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 @@ -147,15 +148,6 @@ or to save and provide normalized distribution using external method. /* *** COMPRESSION *** */ -/*! FSE_count(): - Provides the precise count of each byte within a table 'count'. - 'count' is a table of unsigned int, of minimum size (*maxSymbolValuePtr+1). - *maxSymbolValuePtr will be updated if detected smaller than initial value. - @return : the count of the most frequent symbol (which is not identified). - if return == srcSize, there is only one symbol. - Can also return an error code, which can be tested with FSE_isError(). */ -FSE_PUBLIC_API size_t FSE_count(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize); - /*! FSE_optimalTableLog(): dynamically downsize 'tableLog' when conditions are met. It saves CPU time, by using smaller tables, while preserving or even improving compression ratio. @@ -167,7 +159,8 @@ FSE_PUBLIC_API unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize '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_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'. @@ -178,8 +171,9 @@ FSE_PUBLIC_API size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tab 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); - +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' */ @@ -250,7 +244,9 @@ If there is an error, the function will return an ErrorCode (which can be tested @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); +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' */ @@ -325,33 +321,8 @@ If there is an error, the function will return an error code, which can be teste /* ***************************************** -* 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() : - * same as FSE_count(), but blindly trusts that all byte values within src are <= *maxSymbolValuePtr - */ -size_t FSE_countFast(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize); - -/* 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); - - + * FSE advanced API + ***************************************** */ unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus); /**< same as FSE_optimalTableLog(), which used `minus==2` */ @@ -387,7 +358,7 @@ size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size typedef enum { FSE_repeat_none, /**< Cannot use the previous table */ FSE_repeat_check, /**< Can use the previous table but it must be checked */ - FSE_repeat_valid /**< Can use the previous table and it is asumed to be valid */ + FSE_repeat_valid /**< Can use the previous table and it is assumed to be valid */ } FSE_repeat; /* ***************************************** @@ -541,7 +512,7 @@ MEM_STATIC void FSE_initCState(FSE_CState_t* statePtr, const FSE_CTable* ct) const U32 tableLog = MEM_read16(ptr); statePtr->value = (ptrdiff_t)1<<tableLog; statePtr->stateTable = u16ptr+2; - statePtr->symbolTT = ((const U32*)ct + 1 + (tableLog ? (1<<(tableLog-1)) : 1)); + statePtr->symbolTT = ct + 1 + (tableLog ? (1<<(tableLog-1)) : 1); statePtr->stateLog = tableLog; } @@ -560,7 +531,7 @@ MEM_STATIC void FSE_initCState2(FSE_CState_t* statePtr, const FSE_CTable* ct, U3 } } -MEM_STATIC void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* statePtr, U32 symbol) +MEM_STATIC void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* statePtr, unsigned symbol) { FSE_symbolCompressionTransform const symbolTT = ((const FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol]; const U16* const stateTable = (const U16*)(statePtr->stateTable); @@ -576,6 +547,39 @@ MEM_STATIC void FSE_flushCState(BIT_CStream_t* bitC, const FSE_CState_t* statePt } +/* FSE_getMaxNbBits() : + * Approximate maximum cost of a symbol, in bits. + * Fractional get rounded up (i.e : a symbol with a normalized frequency of 3 gives the same result as a frequency of 2) + * note 1 : assume symbolValue is valid (<= maxSymbolValue) + * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */ +MEM_STATIC U32 FSE_getMaxNbBits(const void* symbolTTPtr, U32 symbolValue) +{ + const FSE_symbolCompressionTransform* symbolTT = (const FSE_symbolCompressionTransform*) symbolTTPtr; + return (symbolTT[symbolValue].deltaNbBits + ((1<<16)-1)) >> 16; +} + +/* FSE_bitCost() : + * Approximate symbol cost, as fractional value, using fixed-point format (accuracyLog fractional bits) + * note 1 : assume symbolValue is valid (<= maxSymbolValue) + * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */ +MEM_STATIC U32 FSE_bitCost(const void* symbolTTPtr, U32 tableLog, U32 symbolValue, U32 accuracyLog) +{ + const FSE_symbolCompressionTransform* symbolTT = (const FSE_symbolCompressionTransform*) symbolTTPtr; + U32 const minNbBits = symbolTT[symbolValue].deltaNbBits >> 16; + U32 const threshold = (minNbBits+1) << 16; + assert(tableLog < 16); + assert(accuracyLog < 31-tableLog); /* ensure enough room for renormalization double shift */ + { U32 const tableSize = 1 << tableLog; + U32 const deltaFromThreshold = threshold - (symbolTT[symbolValue].deltaNbBits + tableSize); + U32 const normalizedDeltaFromThreshold = (deltaFromThreshold << accuracyLog) >> tableLog; /* linear interpolation (very approximate) */ + U32 const bitMultiplier = 1 << accuracyLog; + assert(symbolTT[symbolValue].deltaNbBits + tableSize <= threshold); + assert(normalizedDeltaFromThreshold <= bitMultiplier); + return (minNbBits+1)*bitMultiplier - normalizedDeltaFromThreshold; + } +} + + /* ====== Decompression ====== */ typedef struct { |