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Diffstat (limited to 'lib/zstd/huf_compress.c')
| -rw-r--r-- | lib/zstd/huf_compress.c | 770 |
1 files changed, 770 insertions, 0 deletions
diff --git a/lib/zstd/huf_compress.c b/lib/zstd/huf_compress.c new file mode 100644 index 000000000000..40055a7016e6 --- /dev/null +++ b/lib/zstd/huf_compress.c @@ -0,0 +1,770 @@ +/* + * 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); + 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 */ + + { + 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); +} |