/* ****************************************************************** * Common functions of New Generation Entropy library * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc. * * You can contact the author at : * - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy * - Public forum : https://groups.google.com/forum/#!forum/lz4c * * This source code is licensed under both the BSD-style license (found in the * LICENSE file in the root directory of this source tree) and the GPLv2 (found * in the COPYING file in the root directory of this source tree). * You may select, at your option, one of the above-listed licenses. ****************************************************************** */ /* ************************************* * 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<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> 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= 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; }