/* * Huffman encoder, part of New Generation Entropy library * Copyright (C) 2013-2016, 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. * * This program is free software; you can redistribute it and/or modify it under * the terms of the GNU General Public License version 2 as published by the * Free Software Foundation. This program is dual-licensed; you may select * either version 2 of the GNU General Public License ("GPL") or BSD license * ("BSD"). * * You can contact the author at : * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy */ /* ************************************************************** * Includes ****************************************************************/ #include "bitstream.h" #include "fse.h" /* header compression */ #include "huf.h" #include <linux/kernel.h> #include <linux/string.h> /* memcpy, memset */ /* ************************************************************** * Error Management ****************************************************************/ #define HUF_STATIC_ASSERT(c) \ { \ enum { HUF_static_assert = 1 / (int)(!!(c)) }; \ } /* use only *after* variable declarations */ #define CHECK_V_F(e, f) \ size_t const e = f; \ if (ERR_isError(e)) \ return f #define CHECK_F(f) \ { \ CHECK_V_F(_var_err__, f); \ } /* ************************************************************** * Utils ****************************************************************/ unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue) { return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 1); } /* ******************************************************* * HUF : Huffman block compression *********************************************************/ /* HUF_compressWeights() : * Same as FSE_compress(), but dedicated to huff0's weights compression. * The use case needs much less stack memory. * Note : all elements within weightTable are supposed to be <= HUF_TABLELOG_MAX. */ #define MAX_FSE_TABLELOG_FOR_HUFF_HEADER 6 size_t HUF_compressWeights_wksp(void *dst, size_t dstSize, const void *weightTable, size_t wtSize, void *workspace, size_t workspaceSize) { BYTE *const ostart = (BYTE *)dst; BYTE *op = ostart; BYTE *const oend = ostart + dstSize; U32 maxSymbolValue = HUF_TABLELOG_MAX; U32 tableLog = MAX_FSE_TABLELOG_FOR_HUFF_HEADER; FSE_CTable *CTable; U32 *count; S16 *norm; size_t spaceUsed32 = 0; HUF_STATIC_ASSERT(sizeof(FSE_CTable) == sizeof(U32)); CTable = (FSE_CTable *)((U32 *)workspace + spaceUsed32); spaceUsed32 += FSE_CTABLE_SIZE_U32(MAX_FSE_TABLELOG_FOR_HUFF_HEADER, HUF_TABLELOG_MAX); count = (U32 *)workspace + spaceUsed32; spaceUsed32 += HUF_TABLELOG_MAX + 1; norm = (S16 *)((U32 *)workspace + spaceUsed32); spaceUsed32 += ALIGN(sizeof(S16) * (HUF_TABLELOG_MAX + 1), sizeof(U32)) >> 2; if ((spaceUsed32 << 2) > workspaceSize) return ERROR(tableLog_tooLarge); workspace = (U32 *)workspace + spaceUsed32; workspaceSize -= (spaceUsed32 << 2); /* init conditions */ if (wtSize <= 1) return 0; /* Not compressible */ /* Scan input and build symbol stats */ { CHECK_V_F(maxCount, FSE_count_simple(count, &maxSymbolValue, weightTable, wtSize)); if (maxCount == wtSize) return 1; /* only a single symbol in src : rle */ if (maxCount == 1) return 0; /* each symbol present maximum once => not compressible */ } tableLog = FSE_optimalTableLog(tableLog, wtSize, maxSymbolValue); CHECK_F(FSE_normalizeCount(norm, tableLog, count, wtSize, maxSymbolValue)); /* Write table description header */ { CHECK_V_F(hSize, FSE_writeNCount(op, oend - op, norm, maxSymbolValue, tableLog)); op += hSize; } /* Compress */ CHECK_F(FSE_buildCTable_wksp(CTable, norm, maxSymbolValue, tableLog, workspace, workspaceSize)); { CHECK_V_F(cSize, FSE_compress_usingCTable(op, oend - op, weightTable, wtSize, CTable)); if (cSize == 0) return 0; /* not enough space for compressed data */ op += cSize; } return op - ostart; } struct HUF_CElt_s { U16 val; BYTE nbBits; }; /* typedef'd to HUF_CElt within "huf.h" */ /*! HUF_writeCTable_wksp() : `CTable` : Huffman tree to save, using huf representation. @return : size of saved CTable */ size_t HUF_writeCTable_wksp(void *dst, size_t maxDstSize, const HUF_CElt *CTable, U32 maxSymbolValue, U32 huffLog, void *workspace, size_t workspaceSize) { BYTE *op = (BYTE *)dst; U32 n; BYTE *bitsToWeight; BYTE *huffWeight; size_t spaceUsed32 = 0; bitsToWeight = (BYTE *)((U32 *)workspace + spaceUsed32); spaceUsed32 += ALIGN(HUF_TABLELOG_MAX + 1, sizeof(U32)) >> 2; huffWeight = (BYTE *)((U32 *)workspace + spaceUsed32); spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX, sizeof(U32)) >> 2; if ((spaceUsed32 << 2) > workspaceSize) return ERROR(tableLog_tooLarge); workspace = (U32 *)workspace + spaceUsed32; workspaceSize -= (spaceUsed32 << 2); /* check conditions */ if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) return ERROR(maxSymbolValue_tooLarge); /* convert to weight */ bitsToWeight[0] = 0; for (n = 1; n < huffLog + 1; n++) bitsToWeight[n] = (BYTE)(huffLog + 1 - n); for (n = 0; n < maxSymbolValue; n++) huffWeight[n] = bitsToWeight[CTable[n].nbBits]; /* attempt weights compression by FSE */ { CHECK_V_F(hSize, HUF_compressWeights_wksp(op + 1, maxDstSize - 1, huffWeight, maxSymbolValue, workspace, workspaceSize)); if ((hSize > 1) & (hSize < maxSymbolValue / 2)) { /* FSE compressed */ op[0] = (BYTE)hSize; return hSize + 1; } } /* write raw values as 4-bits (max : 15) */ if (maxSymbolValue > (256 - 128)) return ERROR(GENERIC); /* should not happen : likely means source cannot be compressed */ if (((maxSymbolValue + 1) / 2) + 1 > maxDstSize) return ERROR(dstSize_tooSmall); /* not enough space within dst buffer */ op[0] = (BYTE)(128 /*special case*/ + (maxSymbolValue - 1)); huffWeight[maxSymbolValue] = 0; /* to be sure it doesn't cause msan issue in final combination */ for (n = 0; n < maxSymbolValue; n += 2) op[(n / 2) + 1] = (BYTE)((huffWeight[n] << 4) + huffWeight[n + 1]); return ((maxSymbolValue + 1) / 2) + 1; } size_t HUF_readCTable_wksp(HUF_CElt *CTable, U32 maxSymbolValue, const void *src, size_t srcSize, void *workspace, size_t workspaceSize) { U32 *rankVal; BYTE *huffWeight; U32 tableLog = 0; U32 nbSymbols = 0; size_t readSize; size_t spaceUsed32 = 0; rankVal = (U32 *)workspace + spaceUsed32; spaceUsed32 += HUF_TABLELOG_ABSOLUTEMAX + 1; huffWeight = (BYTE *)((U32 *)workspace + spaceUsed32); spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX + 1, sizeof(U32)) >> 2; if ((spaceUsed32 << 2) > workspaceSize) return ERROR(tableLog_tooLarge); workspace = (U32 *)workspace + spaceUsed32; workspaceSize -= (spaceUsed32 << 2); /* get symbol weights */ readSize = HUF_readStats_wksp(huffWeight, HUF_SYMBOLVALUE_MAX + 1, rankVal, &nbSymbols, &tableLog, src, srcSize, workspace, workspaceSize); if (ERR_isError(readSize)) return readSize; /* check result */ if (tableLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge); if (nbSymbols > maxSymbolValue + 1) return ERROR(maxSymbolValue_tooSmall); /* Prepare base value per rank */ { U32 n, nextRankStart = 0; for (n = 1; n <= tableLog; n++) { U32 curr = nextRankStart; nextRankStart += (rankVal[n] << (n - 1)); rankVal[n] = curr; } } /* fill nbBits */ { U32 n; for (n = 0; n < nbSymbols; n++) { const U32 w = huffWeight[n]; CTable[n].nbBits = (BYTE)(tableLog + 1 - w); } } /* fill val */ { U16 nbPerRank[HUF_TABLELOG_MAX + 2] = {0}; /* support w=0=>n=tableLog+1 */ U16 valPerRank[HUF_TABLELOG_MAX + 2] = {0}; { U32 n; for (n = 0; n < nbSymbols; n++) nbPerRank[CTable[n].nbBits]++; } /* determine stating value per rank */ valPerRank[tableLog + 1] = 0; /* for w==0 */ { U16 min = 0; U32 n; for (n = tableLog; n > 0; n--) { /* start at n=tablelog <-> w=1 */ valPerRank[n] = min; /* get starting value within each rank */ min += nbPerRank[n]; min >>= 1; } } /* assign value within rank, symbol order */ { U32 n; for (n = 0; n <= maxSymbolValue; n++) CTable[n].val = valPerRank[CTable[n].nbBits]++; } } return readSize; } typedef struct nodeElt_s { U32 count; U16 parent; BYTE byte; BYTE nbBits; } nodeElt; static U32 HUF_setMaxHeight(nodeElt *huffNode, U32 lastNonNull, U32 maxNbBits) { const U32 largestBits = huffNode[lastNonNull].nbBits; if (largestBits <= maxNbBits) return largestBits; /* early exit : no elt > maxNbBits */ /* there are several too large elements (at least >= 2) */ { int totalCost = 0; const U32 baseCost = 1 << (largestBits - maxNbBits); U32 n = lastNonNull; while (huffNode[n].nbBits > maxNbBits) { totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits)); huffNode[n].nbBits = (BYTE)maxNbBits; n--; } /* n stops at huffNode[n].nbBits <= maxNbBits */ while (huffNode[n].nbBits == maxNbBits) n--; /* n end at index of smallest symbol using < maxNbBits */ /* renorm totalCost */ totalCost >>= (largestBits - maxNbBits); /* note : totalCost is necessarily a multiple of baseCost */ /* repay normalized cost */ { U32 const noSymbol = 0xF0F0F0F0; U32 rankLast[HUF_TABLELOG_MAX + 2]; int pos; /* Get pos of last (smallest) symbol per rank */ memset(rankLast, 0xF0, sizeof(rankLast)); { U32 currNbBits = maxNbBits; for (pos = n; pos >= 0; pos--) { if (huffNode[pos].nbBits >= currNbBits) continue; currNbBits = huffNode[pos].nbBits; /* < maxNbBits */ rankLast[maxNbBits - currNbBits] = pos; } } while (totalCost > 0) { U32 nBitsToDecrease = BIT_highbit32(totalCost) + 1; for (; nBitsToDecrease > 1; nBitsToDecrease--) { U32 highPos = rankLast[nBitsToDecrease]; U32 lowPos = rankLast[nBitsToDecrease - 1]; if (highPos == noSymbol) continue; if (lowPos == noSymbol) break; { U32 const highTotal = huffNode[highPos].count; U32 const lowTotal = 2 * huffNode[lowPos].count; if (highTotal <= lowTotal) break; } } /* only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !) */ /* HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary */ while ((nBitsToDecrease <= HUF_TABLELOG_MAX) && (rankLast[nBitsToDecrease] == noSymbol)) nBitsToDecrease++; totalCost -= 1 << (nBitsToDecrease - 1); if (rankLast[nBitsToDecrease - 1] == noSymbol) rankLast[nBitsToDecrease - 1] = rankLast[nBitsToDecrease]; /* this rank is no longer empty */ huffNode[rankLast[nBitsToDecrease]].nbBits++; if (rankLast[nBitsToDecrease] == 0) /* special case, reached largest symbol */ rankLast[nBitsToDecrease] = noSymbol; else { rankLast[nBitsToDecrease]--; if (huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits - nBitsToDecrease) rankLast[nBitsToDecrease] = noSymbol; /* this rank is now empty */ } } /* while (totalCost > 0) */ while (totalCost < 0) { /* Sometimes, cost correction overshoot */ if (rankLast[1] == noSymbol) { /* special case : no rank 1 symbol (using maxNbBits-1); let's create one from largest rank 0 (using maxNbBits) */ while (huffNode[n].nbBits == maxNbBits) n--; huffNode[n + 1].nbBits--; rankLast[1] = n + 1; totalCost++; continue; } huffNode[rankLast[1] + 1].nbBits--; rankLast[1]++; totalCost++; } } } /* there are several too large elements (at least >= 2) */ return maxNbBits; } typedef struct { U32 base; U32 curr; } rankPos; static void HUF_sort(nodeElt *huffNode, const U32 *count, U32 maxSymbolValue) { rankPos rank[32]; U32 n; memset(rank, 0, sizeof(rank)); for (n = 0; n <= maxSymbolValue; n++) { U32 r = BIT_highbit32(count[n] + 1); rank[r].base++; } for (n = 30; n > 0; n--) rank[n - 1].base += rank[n].base; for (n = 0; n < 32; n++) rank[n].curr = rank[n].base; for (n = 0; n <= maxSymbolValue; n++) { U32 const c = count[n]; U32 const r = BIT_highbit32(c + 1) + 1; U32 pos = rank[r].curr++; while ((pos > rank[r].base) && (c > huffNode[pos - 1].count)) huffNode[pos] = huffNode[pos - 1], pos--; huffNode[pos].count = c; huffNode[pos].byte = (BYTE)n; } } /** HUF_buildCTable_wksp() : * Same as HUF_buildCTable(), but using externally allocated scratch buffer. * `workSpace` must be aligned on 4-bytes boundaries, and be at least as large as a table of 1024 unsigned. */ #define STARTNODE (HUF_SYMBOLVALUE_MAX + 1) typedef nodeElt huffNodeTable[2 * HUF_SYMBOLVALUE_MAX + 1 + 1]; size_t HUF_buildCTable_wksp(HUF_CElt *tree, const U32 *count, U32 maxSymbolValue, U32 maxNbBits, void *workSpace, size_t wkspSize) { nodeElt *const huffNode0 = (nodeElt *)workSpace; nodeElt *const huffNode = huffNode0 + 1; U32 n, nonNullRank; int lowS, lowN; U16 nodeNb = STARTNODE; U32 nodeRoot; /* safety checks */ if (wkspSize < sizeof(huffNodeTable)) return ERROR(GENERIC); /* workSpace is not large enough */ if (maxNbBits == 0) maxNbBits = HUF_TABLELOG_DEFAULT; if (maxSymbolValue > HUF_SYMBOLVALUE_MAX) return ERROR(GENERIC); memset(huffNode0, 0, sizeof(huffNodeTable)); /* sort, decreasing order */ HUF_sort(huffNode, count, maxSymbolValue); /* init for parents */ nonNullRank = maxSymbolValue; while (huffNode[nonNullRank].count == 0) nonNullRank--; lowS = nonNullRank; nodeRoot = nodeNb + lowS - 1; lowN = nodeNb; huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS - 1].count; huffNode[lowS].parent = huffNode[lowS - 1].parent = nodeNb; nodeNb++; lowS -= 2; for (n = nodeNb; n <= nodeRoot; n++) huffNode[n].count = (U32)(1U << 30); huffNode0[0].count = (U32)(1U << 31); /* fake entry, strong barrier */ /* create parents */ while (nodeNb <= nodeRoot) { U32 n1 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++; 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; nodeNb++; } /* distribute weights (unlimited tree height) */ huffNode[nodeRoot].nbBits = 0; for (n = nodeRoot - 1; n >= STARTNODE; n--) huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1; for (n = 0; n <= nonNullRank; n++) huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1; /* enforce maxTableLog */ maxNbBits = HUF_setMaxHeight(huffNode, nonNullRank, maxNbBits); /* fill result into tree (val, nbBits) */ { 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 size_t HUF_estimateCompressedSize(HUF_CElt *CTable, const unsigned *count, unsigned maxSymbolValue) { size_t nbBits = 0; int s; for (s = 0; s <= (int)maxSymbolValue; ++s) { nbBits += CTable[s].nbBits * count[s]; } return nbBits >> 3; } static int HUF_validateCTable(const HUF_CElt *CTable, const unsigned *count, unsigned maxSymbolValue) { int bad = 0; int s; for (s = 0; s <= (int)maxSymbolValue; ++s) { bad |= (count[s] != 0) & (CTable[s].nbBits == 0); } return !bad; } 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) 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; BIT_CStream_t bitC; /* init */ if (dstSize < 8) return 0; /* not enough space to compress */ { size_t const initErr = BIT_initCStream(&bitC, op, oend - op); if (HUF_isError(initErr)) 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); /* fall through */ case 2: HUF_encodeSymbol(&bitC, ip[n + 1], CTable); HUF_FLUSHBITS_1(&bitC); /* fall through */ 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 */ { CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable)); if (cSize == 0) return 0; ZSTD_writeLE16(ostart, (U16)cSize); op += cSize; } ip += segmentSize; { CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable)); if (cSize == 0) return 0; ZSTD_writeLE16(ostart + 2, (U16)cSize); op += cSize; } ip += segmentSize; { CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable)); if (cSize == 0) return 0; ZSTD_writeLE16(ostart + 4, (U16)cSize); op += cSize; } ip += segmentSize; { CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, iend - ip, CTable)); if (cSize == 0) return 0; op += cSize; } return op - ostart; } static size_t HUF_compressCTable_internal(BYTE *const ostart, BYTE *op, BYTE *const oend, const void *src, size_t srcSize, unsigned singleStream, const HUF_CElt *CTable) { size_t const cSize = singleStream ? HUF_compress1X_usingCTable(op, oend - op, src, srcSize, CTable) : 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; } /* `workSpace` must a table of at least 1024 unsigned */ static size_t HUF_compress_internal(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, unsigned singleStream, void *workSpace, size_t wkspSize, HUF_CElt *oldHufTable, HUF_repeat *repeat, int preferRepeat) { BYTE *const ostart = (BYTE *)dst; BYTE *const oend = ostart + dstSize; BYTE *op = ostart; U32 *count; size_t const countSize = sizeof(U32) * (HUF_SYMBOLVALUE_MAX + 1); HUF_CElt *CTable; size_t const CTableSize = sizeof(HUF_CElt) * (HUF_SYMBOLVALUE_MAX + 1); /* checks & inits */ if (wkspSize < sizeof(huffNodeTable) + countSize + CTableSize) return ERROR(GENERIC); 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); /* curr block size limit */ if (huffLog > HUF_TABLELOG_MAX) return ERROR(tableLog_tooLarge); if (!maxSymbolValue) maxSymbolValue = HUF_SYMBOLVALUE_MAX; if (!huffLog) huffLog = HUF_TABLELOG_DEFAULT; count = (U32 *)workSpace; workSpace = (BYTE *)workSpace + countSize; wkspSize -= countSize; CTable = (HUF_CElt *)workSpace; workSpace = (BYTE *)workSpace + CTableSize; wkspSize -= CTableSize; /* Heuristic : If we don't need to check the validity of the old table use the old table for small inputs */ if (preferRepeat && repeat && *repeat == HUF_repeat_valid) { return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable); } /* Scan input and build symbol stats */ { CHECK_V_F(largest, FSE_count_wksp(count, &maxSymbolValue, (const BYTE *)src, srcSize, (U32 *)workSpace)); if (largest == srcSize) { *ostart = ((const BYTE *)src)[0]; return 1; } /* single symbol, rle */ if (largest <= (srcSize >> 7) + 1) return 0; /* Fast heuristic : not compressible enough */ } /* Check validity of previous table */ if (repeat && *repeat == HUF_repeat_check && !HUF_validateCTable(oldHufTable, count, maxSymbolValue)) { *repeat = HUF_repeat_none; } /* Heuristic : use existing table for small inputs */ if (preferRepeat && repeat && *repeat != HUF_repeat_none) { return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable); } /* Build Huffman Tree */ huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue); { CHECK_V_F(maxBits, HUF_buildCTable_wksp(CTable, count, maxSymbolValue, huffLog, workSpace, wkspSize)); huffLog = (U32)maxBits; /* Zero the unused symbols so we can check it for validity */ memset(CTable + maxSymbolValue + 1, 0, CTableSize - (maxSymbolValue + 1) * sizeof(HUF_CElt)); } /* Write table description header */ { CHECK_V_F(hSize, HUF_writeCTable_wksp(op, dstSize, CTable, maxSymbolValue, huffLog, workSpace, wkspSize)); /* Check if using the previous table will be beneficial */ if (repeat && *repeat != HUF_repeat_none) { size_t const oldSize = HUF_estimateCompressedSize(oldHufTable, count, maxSymbolValue); size_t const newSize = HUF_estimateCompressedSize(CTable, count, maxSymbolValue); if (oldSize <= hSize + newSize || hSize + 12 >= srcSize) { return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable); } } /* Use the new table */ if (hSize + 12ul >= srcSize) { return 0; } op += hSize; if (repeat) { *repeat = HUF_repeat_none; } if (oldHufTable) { memcpy(oldHufTable, CTable, CTableSize); } /* Save the new table */ } return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, CTable); } size_t HUF_compress1X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace, size_t wkspSize) { return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 1 /* single stream */, workSpace, wkspSize, NULL, NULL, 0); } size_t HUF_compress1X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace, size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat) { return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 1 /* single stream */, workSpace, wkspSize, hufTable, repeat, preferRepeat); } size_t HUF_compress4X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace, size_t wkspSize) { return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 0 /* 4 streams */, workSpace, wkspSize, NULL, NULL, 0); } size_t HUF_compress4X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace, size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat) { return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 0 /* 4 streams */, workSpace, wkspSize, hufTable, repeat, preferRepeat); }