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ext/zstd/lib/legacy/zstd_v06.c  view on Meta::CPAN

    unsigned short newState;
    unsigned char  symbol;
    unsigned char  nbBits;
} FSEv06_decode_t;   /* size == U32 */

MEM_STATIC void FSEv06_initDState(FSEv06_DState_t* DStatePtr, BITv06_DStream_t* bitD, const FSEv06_DTable* dt)
{
    const void* ptr = dt;
    const FSEv06_DTableHeader* const DTableH = (const FSEv06_DTableHeader*)ptr;
    DStatePtr->state = BITv06_readBits(bitD, DTableH->tableLog);
    BITv06_reloadDStream(bitD);
    DStatePtr->table = dt + 1;
}

MEM_STATIC BYTE FSEv06_peekSymbol(const FSEv06_DState_t* DStatePtr)
{
    FSEv06_decode_t const DInfo = ((const FSEv06_decode_t*)(DStatePtr->table))[DStatePtr->state];
    return DInfo.symbol;
}

MEM_STATIC void FSEv06_updateState(FSEv06_DState_t* DStatePtr, BITv06_DStream_t* bitD)
{
    FSEv06_decode_t const DInfo = ((const FSEv06_decode_t*)(DStatePtr->table))[DStatePtr->state];
    U32 const nbBits = DInfo.nbBits;
    size_t const lowBits = BITv06_readBits(bitD, nbBits);
    DStatePtr->state = DInfo.newState + lowBits;
}

MEM_STATIC BYTE FSEv06_decodeSymbol(FSEv06_DState_t* DStatePtr, BITv06_DStream_t* bitD)
{
    FSEv06_decode_t const DInfo = ((const FSEv06_decode_t*)(DStatePtr->table))[DStatePtr->state];
    U32 const nbBits = DInfo.nbBits;
    BYTE const symbol = DInfo.symbol;
    size_t const lowBits = BITv06_readBits(bitD, nbBits);

    DStatePtr->state = DInfo.newState + lowBits;
    return symbol;
}

/*! FSEv06_decodeSymbolFast() :
    unsafe, only works if no symbol has a probability > 50% */
MEM_STATIC BYTE FSEv06_decodeSymbolFast(FSEv06_DState_t* DStatePtr, BITv06_DStream_t* bitD)
{
    FSEv06_decode_t const DInfo = ((const FSEv06_decode_t*)(DStatePtr->table))[DStatePtr->state];
    U32 const nbBits = DInfo.nbBits;
    BYTE const symbol = DInfo.symbol;
    size_t const lowBits = BITv06_readBitsFast(bitD, nbBits);

    DStatePtr->state = DInfo.newState + lowBits;
    return symbol;
}



#ifndef FSEv06_COMMONDEFS_ONLY

/* **************************************************************
*  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 */
#define FSEv06_MAX_MEMORY_USAGE 14
#define FSEv06_DEFAULT_MEMORY_USAGE 13

/*!FSEv06_MAX_SYMBOL_VALUE :
*  Maximum symbol value authorized.
*  Required for proper stack allocation */
#define FSEv06_MAX_SYMBOL_VALUE 255


/* **************************************************************
*  template functions type & suffix
****************************************************************/
#define FSEv06_FUNCTION_TYPE BYTE
#define FSEv06_FUNCTION_EXTENSION
#define FSEv06_DECODE_TYPE FSEv06_decode_t


#endif   /* !FSEv06_COMMONDEFS_ONLY */


/* ***************************************************************
*  Constants
*****************************************************************/
#define FSEv06_MAX_TABLELOG  (FSEv06_MAX_MEMORY_USAGE-2)
#define FSEv06_MAX_TABLESIZE (1U<<FSEv06_MAX_TABLELOG)
#define FSEv06_MAXTABLESIZE_MASK (FSEv06_MAX_TABLESIZE-1)
#define FSEv06_DEFAULT_TABLELOG (FSEv06_DEFAULT_MEMORY_USAGE-2)
#define FSEv06_MIN_TABLELOG 5

#define FSEv06_TABLELOG_ABSOLUTE_MAX 15
#if FSEv06_MAX_TABLELOG > FSEv06_TABLELOG_ABSOLUTE_MAX
#error "FSEv06_MAX_TABLELOG > FSEv06_TABLELOG_ABSOLUTE_MAX is not supported"
#endif

#define FSEv06_TABLESTEP(tableSize) ((tableSize>>1) + (tableSize>>3) + 3)


#if defined (__cplusplus)
}
#endif

#endif  /* FSEv06_STATIC_H */
/*
   Common functions of New Generation Entropy library
   Copyright (C) 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