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576
C/zstd/huf_compress.c
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576
C/zstd/huf_compress.c
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@@ -0,0 +1,576 @@
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/* ******************************************************************
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Huffman encoder, part of New Generation Entropy library
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Copyright (C) 2013-2016, Yann Collet.
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BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following disclaimer
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||||
in the documentation and/or other materials provided with the
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distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
||||
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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You can contact the author at :
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- FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
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- Public forum : https://groups.google.com/forum/#!forum/lz4c
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****************************************************************** */
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/* **************************************************************
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* Compiler specifics
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****************************************************************/
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#if defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
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/* inline is defined */
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#elif defined(_MSC_VER)
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# define inline __inline
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#else
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# define inline /* disable inline */
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#endif
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#ifdef _MSC_VER /* Visual Studio */
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# define FORCE_INLINE static __forceinline
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# pragma warning(disable : 4127) /* disable: C4127: conditional expression is constant */
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#else
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# ifdef __GNUC__
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# define FORCE_INLINE static inline __attribute__((always_inline))
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# else
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# define FORCE_INLINE static inline
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# endif
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#endif
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/* **************************************************************
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* Includes
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****************************************************************/
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#include <string.h> /* memcpy, memset */
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#include <stdio.h> /* printf (debug) */
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#include "bitstream.h"
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#define FSE_STATIC_LINKING_ONLY /* FSE_optimalTableLog_internal */
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#include "fse.h" /* header compression */
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#define HUF_STATIC_LINKING_ONLY
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#include "huf.h"
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/* **************************************************************
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* Error Management
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****************************************************************/
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#define HUF_STATIC_ASSERT(c) { enum { HUF_static_assert = 1/(int)(!!(c)) }; } /* use only *after* variable declarations */
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/* **************************************************************
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* Utils
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****************************************************************/
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unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue)
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{
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return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 1);
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}
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/* *******************************************************
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* HUF : Huffman block compression
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*********************************************************/
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struct HUF_CElt_s {
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U16 val;
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BYTE nbBits;
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}; /* typedef'd to HUF_CElt within huf_static.h */
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typedef struct nodeElt_s {
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U32 count;
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U16 parent;
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BYTE byte;
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BYTE nbBits;
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} nodeElt;
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/*! HUF_writeCTable() :
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`CTable` : huffman tree to save, using huf representation.
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@return : size of saved CTable */
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size_t HUF_writeCTable (void* dst, size_t maxDstSize,
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const HUF_CElt* CTable, U32 maxSymbolValue, U32 huffLog)
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{
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BYTE bitsToWeight[HUF_TABLELOG_MAX + 1];
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BYTE huffWeight[HUF_SYMBOLVALUE_MAX + 1];
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U32 n;
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BYTE* op = (BYTE*)dst;
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size_t size;
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/* check conditions */
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if (maxSymbolValue > HUF_SYMBOLVALUE_MAX + 1)
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return ERROR(GENERIC);
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/* convert to weight */
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bitsToWeight[0] = 0;
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for (n=1; n<=huffLog; n++)
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bitsToWeight[n] = (BYTE)(huffLog + 1 - n);
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for (n=0; n<maxSymbolValue; n++)
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huffWeight[n] = bitsToWeight[CTable[n].nbBits];
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size = FSE_compress(op+1, maxDstSize-1, huffWeight, maxSymbolValue); /* don't need last symbol stat : implied */
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if (HUF_isError(size)) return size;
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if (size >= 128) return ERROR(GENERIC); /* should never happen, since maxSymbolValue <= 255 */
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if ((size <= 1) || (size >= maxSymbolValue/2)) {
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if (size==1) { /* RLE */
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/* only possible case : series of 1 (because there are at least 2) */
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/* can only be 2^n or (2^n-1), otherwise not an huffman tree */
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BYTE code;
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switch(maxSymbolValue)
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{
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case 1: code = 0; break;
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case 2: code = 1; break;
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case 3: code = 2; break;
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case 4: code = 3; break;
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case 7: code = 4; break;
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case 8: code = 5; break;
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case 15: code = 6; break;
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case 16: code = 7; break;
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case 31: code = 8; break;
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case 32: code = 9; break;
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case 63: code = 10; break;
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case 64: code = 11; break;
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case 127: code = 12; break;
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case 128: code = 13; break;
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default : return ERROR(corruption_detected);
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}
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op[0] = (BYTE)(255-13 + code);
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return 1;
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}
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/* Not compressible */
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if (maxSymbolValue > (241-128)) return ERROR(GENERIC); /* not implemented (not possible with current format) */
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if (((maxSymbolValue+1)/2) + 1 > maxDstSize) return ERROR(dstSize_tooSmall); /* not enough space within dst buffer */
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op[0] = (BYTE)(128 /*special case*/ + 0 /* Not Compressible */ + (maxSymbolValue-1));
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huffWeight[maxSymbolValue] = 0; /* to be sure it doesn't cause issue in final combination */
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for (n=0; n<maxSymbolValue; n+=2)
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op[(n/2)+1] = (BYTE)((huffWeight[n] << 4) + huffWeight[n+1]);
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return ((maxSymbolValue+1)/2) + 1;
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}
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/* normal header case */
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op[0] = (BYTE)size;
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return size+1;
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}
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size_t HUF_readCTable (HUF_CElt* CTable, U32 maxSymbolValue, const void* src, size_t srcSize)
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{
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BYTE huffWeight[HUF_SYMBOLVALUE_MAX + 1];
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U32 rankVal[HUF_TABLELOG_ABSOLUTEMAX + 1]; /* large enough for values from 0 to 16 */
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U32 tableLog = 0;
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size_t readSize;
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U32 nbSymbols = 0;
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//memset(huffWeight, 0, sizeof(huffWeight)); /* is not necessary, even though some analyzer complain ... */
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/* get symbol weights */
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readSize = HUF_readStats(huffWeight, HUF_SYMBOLVALUE_MAX+1, rankVal, &nbSymbols, &tableLog, src, srcSize);
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if (HUF_isError(readSize)) return readSize;
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/* check result */
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if (tableLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge);
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if (nbSymbols > maxSymbolValue+1) return ERROR(maxSymbolValue_tooSmall);
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/* Prepare base value per rank */
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{ U32 n, nextRankStart = 0;
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for (n=1; n<=tableLog; n++) {
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U32 current = nextRankStart;
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nextRankStart += (rankVal[n] << (n-1));
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rankVal[n] = current;
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} }
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/* fill nbBits */
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{ U32 n; for (n=0; n<nbSymbols; n++) {
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const U32 w = huffWeight[n];
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CTable[n].nbBits = (BYTE)(tableLog + 1 - w);
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}}
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/* fill val */
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{ U16 nbPerRank[HUF_TABLELOG_MAX+1] = {0};
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U16 valPerRank[HUF_TABLELOG_MAX+1] = {0};
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{ U32 n; for (n=0; n<nbSymbols; n++) nbPerRank[CTable[n].nbBits]++; }
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/* determine stating value per rank */
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{ U16 min = 0;
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U32 n; for (n=HUF_TABLELOG_MAX; n>0; n--) {
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valPerRank[n] = min; /* get starting value within each rank */
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min += nbPerRank[n];
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min >>= 1;
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} }
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/* assign value within rank, symbol order */
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{ U32 n; for (n=0; n<=maxSymbolValue; n++) CTable[n].val = valPerRank[CTable[n].nbBits]++; }
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}
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return readSize;
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}
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static U32 HUF_setMaxHeight(nodeElt* huffNode, U32 lastNonNull, U32 maxNbBits)
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{
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const U32 largestBits = huffNode[lastNonNull].nbBits;
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if (largestBits <= maxNbBits) return largestBits; /* early exit : no elt > maxNbBits */
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/* there are several too large elements (at least >= 2) */
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{ int totalCost = 0;
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const U32 baseCost = 1 << (largestBits - maxNbBits);
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U32 n = lastNonNull;
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while (huffNode[n].nbBits > maxNbBits) {
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totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits));
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huffNode[n].nbBits = (BYTE)maxNbBits;
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n --;
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} /* n stops at huffNode[n].nbBits <= maxNbBits */
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while (huffNode[n].nbBits == maxNbBits) n--; /* n end at index of smallest symbol using < maxNbBits */
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/* renorm totalCost */
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totalCost >>= (largestBits - maxNbBits); /* note : totalCost is necessarily a multiple of baseCost */
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/* repay normalized cost */
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{ U32 const noSymbol = 0xF0F0F0F0;
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U32 rankLast[HUF_TABLELOG_MAX+1];
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int pos;
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/* Get pos of last (smallest) symbol per rank */
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memset(rankLast, 0xF0, sizeof(rankLast));
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{ U32 currentNbBits = maxNbBits;
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for (pos=n ; pos >= 0; pos--) {
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if (huffNode[pos].nbBits >= currentNbBits) continue;
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currentNbBits = huffNode[pos].nbBits; /* < maxNbBits */
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rankLast[maxNbBits-currentNbBits] = pos;
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} }
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while (totalCost > 0) {
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U32 nBitsToDecrease = BIT_highbit32(totalCost) + 1;
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for ( ; nBitsToDecrease > 1; nBitsToDecrease--) {
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U32 highPos = rankLast[nBitsToDecrease];
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U32 lowPos = rankLast[nBitsToDecrease-1];
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if (highPos == noSymbol) continue;
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if (lowPos == noSymbol) break;
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{ U32 const highTotal = huffNode[highPos].count;
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U32 const lowTotal = 2 * huffNode[lowPos].count;
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if (highTotal <= lowTotal) break;
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} }
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/* only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !) */
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while ((nBitsToDecrease<=HUF_TABLELOG_MAX) && (rankLast[nBitsToDecrease] == noSymbol)) /* HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary */
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nBitsToDecrease ++;
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totalCost -= 1 << (nBitsToDecrease-1);
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if (rankLast[nBitsToDecrease-1] == noSymbol)
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rankLast[nBitsToDecrease-1] = rankLast[nBitsToDecrease]; /* this rank is no longer empty */
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huffNode[rankLast[nBitsToDecrease]].nbBits ++;
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if (rankLast[nBitsToDecrease] == 0) /* special case, reached largest symbol */
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rankLast[nBitsToDecrease] = noSymbol;
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else {
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rankLast[nBitsToDecrease]--;
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if (huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits-nBitsToDecrease)
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rankLast[nBitsToDecrease] = noSymbol; /* this rank is now empty */
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} } /* while (totalCost > 0) */
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while (totalCost < 0) { /* Sometimes, cost correction overshoot */
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if (rankLast[1] == noSymbol) { /* special case : no rank 1 symbol (using maxNbBits-1); let's create one from largest rank 0 (using maxNbBits) */
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while (huffNode[n].nbBits == maxNbBits) n--;
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huffNode[n+1].nbBits--;
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rankLast[1] = n+1;
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totalCost++;
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continue;
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}
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huffNode[ rankLast[1] + 1 ].nbBits--;
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rankLast[1]++;
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totalCost ++;
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} } } /* there are several too large elements (at least >= 2) */
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return maxNbBits;
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}
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typedef struct {
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U32 base;
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U32 current;
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} rankPos;
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static void HUF_sort(nodeElt* huffNode, const U32* count, U32 maxSymbolValue)
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{
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rankPos rank[32];
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U32 n;
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memset(rank, 0, sizeof(rank));
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for (n=0; n<=maxSymbolValue; n++) {
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U32 r = BIT_highbit32(count[n] + 1);
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rank[r].base ++;
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}
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for (n=30; n>0; n--) rank[n-1].base += rank[n].base;
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for (n=0; n<32; n++) rank[n].current = rank[n].base;
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for (n=0; n<=maxSymbolValue; n++) {
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U32 const c = count[n];
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U32 const r = BIT_highbit32(c+1) + 1;
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U32 pos = rank[r].current++;
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while ((pos > rank[r].base) && (c > huffNode[pos-1].count)) huffNode[pos]=huffNode[pos-1], pos--;
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huffNode[pos].count = c;
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huffNode[pos].byte = (BYTE)n;
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}
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}
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#define STARTNODE (HUF_SYMBOLVALUE_MAX+1)
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size_t HUF_buildCTable (HUF_CElt* tree, const U32* count, U32 maxSymbolValue, U32 maxNbBits)
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{
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nodeElt huffNode0[2*HUF_SYMBOLVALUE_MAX+1 +1];
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nodeElt* huffNode = huffNode0 + 1;
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U32 n, nonNullRank;
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int lowS, lowN;
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U16 nodeNb = STARTNODE;
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U32 nodeRoot;
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/* safety checks */
|
||||
if (maxNbBits == 0) maxNbBits = HUF_TABLELOG_DEFAULT;
|
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if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) return ERROR(GENERIC);
|
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memset(huffNode0, 0, sizeof(huffNode0));
|
||||
|
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/* sort, decreasing order */
|
||||
HUF_sort(huffNode, count, maxSymbolValue);
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||||
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/* init for parents */
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nonNullRank = maxSymbolValue;
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||||
while(huffNode[nonNullRank].count == 0) nonNullRank--;
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lowS = nonNullRank; nodeRoot = nodeNb + lowS - 1; lowN = nodeNb;
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huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS-1].count;
|
||||
huffNode[lowS].parent = huffNode[lowS-1].parent = nodeNb;
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nodeNb++; lowS-=2;
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for (n=nodeNb; n<=nodeRoot; n++) huffNode[n].count = (U32)(1U<<30);
|
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huffNode0[0].count = (U32)(1U<<31);
|
||||
|
||||
/* create parents */
|
||||
while (nodeNb <= nodeRoot) {
|
||||
U32 n1 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;
|
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U32 n2 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;
|
||||
huffNode[nodeNb].count = huffNode[n1].count + huffNode[n2].count;
|
||||
huffNode[n1].parent = huffNode[n2].parent = nodeNb;
|
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nodeNb++;
|
||||
}
|
||||
|
||||
/* distribute weights (unlimited tree height) */
|
||||
huffNode[nodeRoot].nbBits = 0;
|
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for (n=nodeRoot-1; n>=STARTNODE; n--)
|
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huffNode[n].nbBits = huffNode[ huffNode[n].parent ].nbBits + 1;
|
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for (n=0; n<=nonNullRank; n++)
|
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huffNode[n].nbBits = huffNode[ huffNode[n].parent ].nbBits + 1;
|
||||
|
||||
/* enforce maxTableLog */
|
||||
maxNbBits = HUF_setMaxHeight(huffNode, nonNullRank, maxNbBits);
|
||||
|
||||
/* fill result into tree (val, nbBits) */
|
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{ U16 nbPerRank[HUF_TABLELOG_MAX+1] = {0};
|
||||
U16 valPerRank[HUF_TABLELOG_MAX+1] = {0};
|
||||
if (maxNbBits > HUF_TABLELOG_MAX) return ERROR(GENERIC); /* check fit into table */
|
||||
for (n=0; n<=nonNullRank; n++)
|
||||
nbPerRank[huffNode[n].nbBits]++;
|
||||
/* determine stating value per rank */
|
||||
{ U16 min = 0;
|
||||
for (n=maxNbBits; n>0; n--) {
|
||||
valPerRank[n] = min; /* get starting value within each rank */
|
||||
min += nbPerRank[n];
|
||||
min >>= 1;
|
||||
} }
|
||||
for (n=0; n<=maxSymbolValue; n++)
|
||||
tree[huffNode[n].byte].nbBits = huffNode[n].nbBits; /* push nbBits per symbol, symbol order */
|
||||
for (n=0; n<=maxSymbolValue; n++)
|
||||
tree[n].val = valPerRank[tree[n].nbBits]++; /* assign value within rank, symbol order */
|
||||
}
|
||||
|
||||
return maxNbBits;
|
||||
}
|
||||
|
||||
static void HUF_encodeSymbol(BIT_CStream_t* bitCPtr, U32 symbol, const HUF_CElt* CTable)
|
||||
{
|
||||
BIT_addBitsFast(bitCPtr, CTable[symbol].val, CTable[symbol].nbBits);
|
||||
}
|
||||
|
||||
size_t HUF_compressBound(size_t size) { return HUF_COMPRESSBOUND(size); }
|
||||
|
||||
#define HUF_FLUSHBITS(s) (fast ? BIT_flushBitsFast(s) : BIT_flushBits(s))
|
||||
|
||||
#define HUF_FLUSHBITS_1(stream) \
|
||||
if (sizeof((stream)->bitContainer)*8 < HUF_TABLELOG_MAX*2+7) HUF_FLUSHBITS(stream)
|
||||
|
||||
#define HUF_FLUSHBITS_2(stream) \
|
||||
if (sizeof((stream)->bitContainer)*8 < HUF_TABLELOG_MAX*4+7) HUF_FLUSHBITS(stream)
|
||||
|
||||
size_t HUF_compress1X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable)
|
||||
{
|
||||
const BYTE* ip = (const BYTE*) src;
|
||||
BYTE* const ostart = (BYTE*)dst;
|
||||
BYTE* const oend = ostart + dstSize;
|
||||
BYTE* op = ostart;
|
||||
size_t n;
|
||||
const unsigned fast = (dstSize >= HUF_BLOCKBOUND(srcSize));
|
||||
BIT_CStream_t bitC;
|
||||
|
||||
/* init */
|
||||
if (dstSize < 8) return 0; /* not enough space to compress */
|
||||
{ size_t const errorCode = BIT_initCStream(&bitC, op, oend-op);
|
||||
if (HUF_isError(errorCode)) return 0; }
|
||||
|
||||
n = srcSize & ~3; /* join to mod 4 */
|
||||
switch (srcSize & 3)
|
||||
{
|
||||
case 3 : HUF_encodeSymbol(&bitC, ip[n+ 2], CTable);
|
||||
HUF_FLUSHBITS_2(&bitC);
|
||||
case 2 : HUF_encodeSymbol(&bitC, ip[n+ 1], CTable);
|
||||
HUF_FLUSHBITS_1(&bitC);
|
||||
case 1 : HUF_encodeSymbol(&bitC, ip[n+ 0], CTable);
|
||||
HUF_FLUSHBITS(&bitC);
|
||||
case 0 :
|
||||
default: ;
|
||||
}
|
||||
|
||||
for (; n>0; n-=4) { /* note : n&3==0 at this stage */
|
||||
HUF_encodeSymbol(&bitC, ip[n- 1], CTable);
|
||||
HUF_FLUSHBITS_1(&bitC);
|
||||
HUF_encodeSymbol(&bitC, ip[n- 2], CTable);
|
||||
HUF_FLUSHBITS_2(&bitC);
|
||||
HUF_encodeSymbol(&bitC, ip[n- 3], CTable);
|
||||
HUF_FLUSHBITS_1(&bitC);
|
||||
HUF_encodeSymbol(&bitC, ip[n- 4], CTable);
|
||||
HUF_FLUSHBITS(&bitC);
|
||||
}
|
||||
|
||||
return BIT_closeCStream(&bitC);
|
||||
}
|
||||
|
||||
|
||||
size_t HUF_compress4X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable)
|
||||
{
|
||||
size_t const segmentSize = (srcSize+3)/4; /* first 3 segments */
|
||||
const BYTE* ip = (const BYTE*) src;
|
||||
const BYTE* const iend = ip + srcSize;
|
||||
BYTE* const ostart = (BYTE*) dst;
|
||||
BYTE* const oend = ostart + dstSize;
|
||||
BYTE* op = ostart;
|
||||
|
||||
if (dstSize < 6 + 1 + 1 + 1 + 8) return 0; /* minimum space to compress successfully */
|
||||
if (srcSize < 12) return 0; /* no saving possible : too small input */
|
||||
op += 6; /* jumpTable */
|
||||
|
||||
{ size_t const cSize = HUF_compress1X_usingCTable(op, oend-op, ip, segmentSize, CTable);
|
||||
if (HUF_isError(cSize)) return cSize;
|
||||
if (cSize==0) return 0;
|
||||
MEM_writeLE16(ostart, (U16)cSize);
|
||||
op += cSize;
|
||||
}
|
||||
|
||||
ip += segmentSize;
|
||||
{ size_t const cSize = HUF_compress1X_usingCTable(op, oend-op, ip, segmentSize, CTable);
|
||||
if (HUF_isError(cSize)) return cSize;
|
||||
if (cSize==0) return 0;
|
||||
MEM_writeLE16(ostart+2, (U16)cSize);
|
||||
op += cSize;
|
||||
}
|
||||
|
||||
ip += segmentSize;
|
||||
{ size_t const cSize = HUF_compress1X_usingCTable(op, oend-op, ip, segmentSize, CTable);
|
||||
if (HUF_isError(cSize)) return cSize;
|
||||
if (cSize==0) return 0;
|
||||
MEM_writeLE16(ostart+4, (U16)cSize);
|
||||
op += cSize;
|
||||
}
|
||||
|
||||
ip += segmentSize;
|
||||
{ size_t const cSize = HUF_compress1X_usingCTable(op, oend-op, ip, iend-ip, CTable);
|
||||
if (HUF_isError(cSize)) return cSize;
|
||||
if (cSize==0) return 0;
|
||||
op += cSize;
|
||||
}
|
||||
|
||||
return op-ostart;
|
||||
}
|
||||
|
||||
|
||||
static size_t HUF_compress_internal (
|
||||
void* dst, size_t dstSize,
|
||||
const void* src, size_t srcSize,
|
||||
unsigned maxSymbolValue, unsigned huffLog,
|
||||
unsigned singleStream)
|
||||
{
|
||||
BYTE* const ostart = (BYTE*)dst;
|
||||
BYTE* const oend = ostart + dstSize;
|
||||
BYTE* op = ostart;
|
||||
|
||||
U32 count[HUF_SYMBOLVALUE_MAX+1];
|
||||
HUF_CElt CTable[HUF_SYMBOLVALUE_MAX+1];
|
||||
|
||||
/* checks & inits */
|
||||
if (!srcSize) return 0; /* Uncompressed (note : 1 means rle, so first byte must be correct) */
|
||||
if (!dstSize) return 0; /* cannot fit within dst budget */
|
||||
if (srcSize > HUF_BLOCKSIZE_MAX) return ERROR(srcSize_wrong); /* current block size limit */
|
||||
if (huffLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge);
|
||||
if (!maxSymbolValue) maxSymbolValue = HUF_SYMBOLVALUE_MAX;
|
||||
if (!huffLog) huffLog = HUF_TABLELOG_DEFAULT;
|
||||
|
||||
/* Scan input and build symbol stats */
|
||||
{ size_t const largest = FSE_count (count, &maxSymbolValue, (const BYTE*)src, srcSize);
|
||||
if (HUF_isError(largest)) return largest;
|
||||
if (largest == srcSize) { *ostart = ((const BYTE*)src)[0]; return 1; } /* rle */
|
||||
if (largest <= (srcSize >> 7)+1) return 0; /* Fast heuristic : not compressible enough */
|
||||
}
|
||||
|
||||
/* Build Huffman Tree */
|
||||
huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue);
|
||||
{ size_t const maxBits = HUF_buildCTable (CTable, count, maxSymbolValue, huffLog);
|
||||
if (HUF_isError(maxBits)) return maxBits;
|
||||
huffLog = (U32)maxBits;
|
||||
}
|
||||
|
||||
/* Write table description header */
|
||||
{ size_t const hSize = HUF_writeCTable (op, dstSize, CTable, maxSymbolValue, huffLog);
|
||||
if (HUF_isError(hSize)) return hSize;
|
||||
if (hSize + 12 >= srcSize) return 0; /* not useful to try compression */
|
||||
op += hSize;
|
||||
}
|
||||
|
||||
/* Compress */
|
||||
{ size_t const cSize = (singleStream) ?
|
||||
HUF_compress1X_usingCTable(op, oend - op, src, srcSize, CTable) : /* single segment */
|
||||
HUF_compress4X_usingCTable(op, oend - op, src, srcSize, CTable);
|
||||
if (HUF_isError(cSize)) return cSize;
|
||||
if (cSize==0) return 0; /* uncompressible */
|
||||
op += cSize;
|
||||
}
|
||||
|
||||
/* check compressibility */
|
||||
if ((size_t)(op-ostart) >= srcSize-1)
|
||||
return 0;
|
||||
|
||||
return op-ostart;
|
||||
}
|
||||
|
||||
|
||||
size_t HUF_compress1X (void* dst, size_t dstSize,
|
||||
const void* src, size_t srcSize,
|
||||
unsigned maxSymbolValue, unsigned huffLog)
|
||||
{
|
||||
return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 1);
|
||||
}
|
||||
|
||||
size_t HUF_compress2 (void* dst, size_t dstSize,
|
||||
const void* src, size_t srcSize,
|
||||
unsigned maxSymbolValue, unsigned huffLog)
|
||||
{
|
||||
return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 0);
|
||||
}
|
||||
|
||||
|
||||
size_t HUF_compress (void* dst, size_t maxDstSize, const void* src, size_t srcSize)
|
||||
{
|
||||
return HUF_compress2(dst, maxDstSize, src, (U32)srcSize, 255, HUF_TABLELOG_DEFAULT);
|
||||
}
|
||||
Reference in New Issue
Block a user