244 строки
7.6 KiB
C
244 строки
7.6 KiB
C
/*
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* Common functions of New Generation Entropy library
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* Copyright (C) 2016, Yann Collet.
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*
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* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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*
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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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*
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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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*
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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,
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* 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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*
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* This program is free software; you can redistribute it and/or modify it under
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* the terms of the GNU General Public License version 2 as published by the
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* Free Software Foundation. This program is dual-licensed; you may select
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* either version 2 of the GNU General Public License ("GPL") or BSD license
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* ("BSD").
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*
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* You can contact the author at :
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* - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
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*/
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/* *************************************
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* Dependencies
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***************************************/
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#include "error_private.h" /* ERR_*, ERROR */
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#include "fse.h"
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#include "huf.h"
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#include "mem.h"
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/*=== Version ===*/
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unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
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/*=== Error Management ===*/
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unsigned FSE_isError(size_t code) { return ERR_isError(code); }
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unsigned HUF_isError(size_t code) { return ERR_isError(code); }
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/*-**************************************************************
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* FSE NCount encoding-decoding
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****************************************************************/
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size_t FSE_readNCount(short *normalizedCounter, unsigned *maxSVPtr, unsigned *tableLogPtr, const void *headerBuffer, size_t hbSize)
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{
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const BYTE *const istart = (const BYTE *)headerBuffer;
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const BYTE *const iend = istart + hbSize;
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const BYTE *ip = istart;
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int nbBits;
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int remaining;
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int threshold;
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U32 bitStream;
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int bitCount;
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unsigned charnum = 0;
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int previous0 = 0;
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if (hbSize < 4)
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return ERROR(srcSize_wrong);
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bitStream = ZSTD_readLE32(ip);
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nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
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if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX)
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return ERROR(tableLog_tooLarge);
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bitStream >>= 4;
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bitCount = 4;
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*tableLogPtr = nbBits;
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remaining = (1 << nbBits) + 1;
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threshold = 1 << nbBits;
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nbBits++;
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while ((remaining > 1) & (charnum <= *maxSVPtr)) {
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if (previous0) {
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unsigned n0 = charnum;
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while ((bitStream & 0xFFFF) == 0xFFFF) {
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n0 += 24;
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if (ip < iend - 5) {
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ip += 2;
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bitStream = ZSTD_readLE32(ip) >> bitCount;
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} else {
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bitStream >>= 16;
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bitCount += 16;
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}
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}
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while ((bitStream & 3) == 3) {
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n0 += 3;
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bitStream >>= 2;
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bitCount += 2;
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}
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n0 += bitStream & 3;
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bitCount += 2;
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if (n0 > *maxSVPtr)
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return ERROR(maxSymbolValue_tooSmall);
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while (charnum < n0)
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normalizedCounter[charnum++] = 0;
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if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) {
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ip += bitCount >> 3;
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bitCount &= 7;
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bitStream = ZSTD_readLE32(ip) >> bitCount;
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} else {
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bitStream >>= 2;
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}
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}
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{
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int const max = (2 * threshold - 1) - remaining;
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int count;
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if ((bitStream & (threshold - 1)) < (U32)max) {
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count = bitStream & (threshold - 1);
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bitCount += nbBits - 1;
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} else {
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count = bitStream & (2 * threshold - 1);
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if (count >= threshold)
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count -= max;
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bitCount += nbBits;
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}
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count--; /* extra accuracy */
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remaining -= count < 0 ? -count : count; /* -1 means +1 */
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normalizedCounter[charnum++] = (short)count;
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previous0 = !count;
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while (remaining < threshold) {
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nbBits--;
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threshold >>= 1;
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}
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if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) {
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ip += bitCount >> 3;
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bitCount &= 7;
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} else {
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bitCount -= (int)(8 * (iend - 4 - ip));
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ip = iend - 4;
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}
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bitStream = ZSTD_readLE32(ip) >> (bitCount & 31);
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}
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} /* while ((remaining>1) & (charnum<=*maxSVPtr)) */
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if (remaining != 1)
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return ERROR(corruption_detected);
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if (bitCount > 32)
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return ERROR(corruption_detected);
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*maxSVPtr = charnum - 1;
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ip += (bitCount + 7) >> 3;
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return ip - istart;
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}
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/*! HUF_readStats() :
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Read compact Huffman tree, saved by HUF_writeCTable().
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`huffWeight` is destination buffer.
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`rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
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@return : size read from `src` , or an error Code .
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Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
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*/
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size_t HUF_readStats_wksp(BYTE *huffWeight, size_t hwSize, U32 *rankStats, U32 *nbSymbolsPtr, U32 *tableLogPtr, const void *src, size_t srcSize, void *workspace, size_t workspaceSize)
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{
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U32 weightTotal;
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const BYTE *ip = (const BYTE *)src;
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size_t iSize;
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size_t oSize;
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if (!srcSize)
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return ERROR(srcSize_wrong);
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iSize = ip[0];
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/* memset(huffWeight, 0, hwSize); */ /* is not necessary, even though some analyzer complain ... */
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if (iSize >= 128) { /* special header */
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oSize = iSize - 127;
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iSize = ((oSize + 1) / 2);
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if (iSize + 1 > srcSize)
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return ERROR(srcSize_wrong);
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if (oSize >= hwSize)
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return ERROR(corruption_detected);
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ip += 1;
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{
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U32 n;
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for (n = 0; n < oSize; n += 2) {
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huffWeight[n] = ip[n / 2] >> 4;
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huffWeight[n + 1] = ip[n / 2] & 15;
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}
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}
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} else { /* header compressed with FSE (normal case) */
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if (iSize + 1 > srcSize)
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return ERROR(srcSize_wrong);
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oSize = FSE_decompress_wksp(huffWeight, hwSize - 1, ip + 1, iSize, 6, workspace, workspaceSize); /* max (hwSize-1) values decoded, as last one is implied */
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if (FSE_isError(oSize))
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return oSize;
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}
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/* collect weight stats */
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memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
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weightTotal = 0;
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{
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U32 n;
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for (n = 0; n < oSize; n++) {
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if (huffWeight[n] >= HUF_TABLELOG_MAX)
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return ERROR(corruption_detected);
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rankStats[huffWeight[n]]++;
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weightTotal += (1 << huffWeight[n]) >> 1;
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}
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}
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if (weightTotal == 0)
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return ERROR(corruption_detected);
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/* get last non-null symbol weight (implied, total must be 2^n) */
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{
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U32 const tableLog = BIT_highbit32(weightTotal) + 1;
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if (tableLog > HUF_TABLELOG_MAX)
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return ERROR(corruption_detected);
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*tableLogPtr = tableLog;
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/* determine last weight */
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{
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U32 const total = 1 << tableLog;
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U32 const rest = total - weightTotal;
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U32 const verif = 1 << BIT_highbit32(rest);
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U32 const lastWeight = BIT_highbit32(rest) + 1;
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if (verif != rest)
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return ERROR(corruption_detected); /* last value must be a clean power of 2 */
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huffWeight[oSize] = (BYTE)lastWeight;
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rankStats[lastWeight]++;
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}
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}
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/* check tree construction validity */
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if ((rankStats[1] < 2) || (rankStats[1] & 1))
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return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */
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/* results */
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*nbSymbolsPtr = (U32)(oSize + 1);
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return iSize + 1;
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}
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