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diff --git a/vendor/github.com/DataDog/zstd/entropy_common.c b/vendor/github.com/DataDog/zstd/entropy_common.c
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+/*
+ 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
+ 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.
+
+ You can contact the author at :
+ - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ - Public forum : https://groups.google.com/forum/#!forum/lz4c
+*************************************************************************** */
+
+/* *************************************
+* Dependencies
+***************************************/
+#include "mem.h"
+#include "error_private.h" /* ERR_*, ERROR */
+#define FSE_STATIC_LINKING_ONLY /* FSE_MIN_TABLELOG */
+#include "fse.h"
+#define HUF_STATIC_LINKING_ONLY /* HUF_TABLELOG_ABSOLUTEMAX */
+#include "huf.h"
+
+
+/*=== Version ===*/
+unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
+
+
+/*=== Error Management ===*/
+unsigned FSE_isError(size_t code) { return ERR_isError(code); }
+const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }
+
+unsigned HUF_isError(size_t code) { return ERR_isError(code); }
+const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }
+
+
+/*-**************************************************************
+* FSE NCount encoding-decoding
+****************************************************************/
+size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
+ const void* headerBuffer, size_t hbSize)
+{
+ const BYTE* const istart = (const BYTE*) headerBuffer;
+ const BYTE* const iend = istart + hbSize;
+ const BYTE* ip = istart;
+ int nbBits;
+ int remaining;
+ int threshold;
+ U32 bitStream;
+ int bitCount;
+ unsigned charnum = 0;
+ int previous0 = 0;
+
+ if (hbSize < 4) {
+ /* This function only works when hbSize >= 4 */
+ char buffer[4];
+ memset(buffer, 0, sizeof(buffer));
+ memcpy(buffer, headerBuffer, hbSize);
+ { size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr,
+ buffer, sizeof(buffer));
+ if (FSE_isError(countSize)) return countSize;
+ if (countSize > hbSize) return ERROR(corruption_detected);
+ return countSize;
+ } }
+ assert(hbSize >= 4);
+
+ /* init */
+ memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0])); /* all symbols not present in NCount have a frequency of 0 */
+ bitStream = MEM_readLE32(ip);
+ nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
+ if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
+ bitStream >>= 4;
+ bitCount = 4;
+ *tableLogPtr = nbBits;
+ remaining = (1<<nbBits)+1;
+ threshold = 1<<nbBits;
+ nbBits++;
+
+ while ((remaining>1) & (charnum<=*maxSVPtr)) {
+ if (previous0) {
+ unsigned n0 = charnum;
+ while ((bitStream & 0xFFFF) == 0xFFFF) {
+ n0 += 24;
+ if (ip < iend-5) {
+ ip += 2;
+ bitStream = MEM_readLE32(ip) >> bitCount;
+ } else {
+ bitStream >>= 16;
+ bitCount += 16;
+ } }
+ while ((bitStream & 3) == 3) {
+ n0 += 3;
+ bitStream >>= 2;
+ bitCount += 2;
+ }
+ n0 += bitStream & 3;
+ bitCount += 2;
+ if (n0 > *maxSVPtr) return ERROR(maxSymbolValue_tooSmall);
+ while (charnum < n0) normalizedCounter[charnum++] = 0;
+ if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
+ assert((bitCount >> 3) <= 3); /* For first condition to work */
+ ip += bitCount>>3;
+ bitCount &= 7;
+ bitStream = MEM_readLE32(ip) >> bitCount;
+ } else {
+ bitStream >>= 2;
+ } }
+ { int const max = (2*threshold-1) - remaining;
+ int count;
+
+ if ((bitStream & (threshold-1)) < (U32)max) {
+ count = bitStream & (threshold-1);
+ bitCount += nbBits-1;
+ } else {
+ count = bitStream & (2*threshold-1);
+ if (count >= threshold) count -= max;
+ bitCount += nbBits;
+ }
+
+ count--; /* extra accuracy */
+ remaining -= count < 0 ? -count : count; /* -1 means +1 */
+ normalizedCounter[charnum++] = (short)count;
+ previous0 = !count;
+ while (remaining < threshold) {
+ nbBits--;
+ threshold >>= 1;
+ }
+
+ if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
+ ip += bitCount>>3;
+ bitCount &= 7;
+ } else {
+ bitCount -= (int)(8 * (iend - 4 - ip));
+ ip = iend - 4;
+ }
+ bitStream = MEM_readLE32(ip) >> (bitCount & 31);
+ } } /* while ((remaining>1) & (charnum<=*maxSVPtr)) */
+ if (remaining != 1) return ERROR(corruption_detected);
+ if (bitCount > 32) return ERROR(corruption_detected);
+ *maxSVPtr = charnum-1;
+
+ ip += (bitCount+7)>>3;
+ return ip-istart;
+}
+
+
+/*! HUF_readStats() :
+ Read compact Huffman tree, saved by HUF_writeCTable().
+ `huffWeight` is destination buffer.
+ `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
+ @return : size read from `src` , or an error Code .
+ Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
+*/
+size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
+ U32* nbSymbolsPtr, U32* tableLogPtr,
+ const void* src, size_t srcSize)
+{
+ U32 weightTotal;
+ const BYTE* ip = (const BYTE*) src;
+ size_t iSize;
+ size_t oSize;
+
+ if (!srcSize) return ERROR(srcSize_wrong);
+ iSize = ip[0];
+ /* memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */
+
+ if (iSize >= 128) { /* special header */
+ oSize = iSize - 127;
+ iSize = ((oSize+1)/2);
+ if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
+ if (oSize >= hwSize) return ERROR(corruption_detected);
+ ip += 1;
+ { U32 n;
+ for (n=0; n<oSize; n+=2) {
+ huffWeight[n] = ip[n/2] >> 4;
+ huffWeight[n+1] = ip[n/2] & 15;
+ } } }
+ else { /* header compressed with FSE (normal case) */
+ FSE_DTable fseWorkspace[FSE_DTABLE_SIZE_U32(6)]; /* 6 is max possible tableLog for HUF header (maybe even 5, to be tested) */
+ if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
+ oSize = FSE_decompress_wksp(huffWeight, hwSize-1, ip+1, iSize, fseWorkspace, 6); /* max (hwSize-1) values decoded, as last one is implied */
+ if (FSE_isError(oSize)) return oSize;
+ }
+
+ /* collect weight stats */
+ memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
+ weightTotal = 0;
+ { U32 n; for (n=0; n<oSize; n++) {
+ if (huffWeight[n] >= HUF_TABLELOG_MAX) return ERROR(corruption_detected);
+ rankStats[huffWeight[n]]++;
+ weightTotal += (1 << huffWeight[n]) >> 1;
+ } }
+ if (weightTotal == 0) return ERROR(corruption_detected);
+
+ /* get last non-null symbol weight (implied, total must be 2^n) */
+ { U32 const tableLog = BIT_highbit32(weightTotal) + 1;
+ if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected);
+ *tableLogPtr = tableLog;
+ /* determine last weight */
+ { U32 const total = 1 << tableLog;
+ U32 const rest = total - weightTotal;
+ U32 const verif = 1 << BIT_highbit32(rest);
+ U32 const lastWeight = BIT_highbit32(rest) + 1;
+ if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */
+ huffWeight[oSize] = (BYTE)lastWeight;
+ rankStats[lastWeight]++;
+ } }
+
+ /* check tree construction validity */
+ if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */
+
+ /* results */
+ *nbSymbolsPtr = (U32)(oSize+1);
+ return iSize+1;
+}