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1/*2 * Copyright (c) Yann Collet, Facebook, Inc.3 * All rights reserved.4 *5 * This source code is licensed under both the BSD-style license (found in the6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found7 * in the COPYING file in the root directory of this source tree).8 * You may select, at your option, one of the above-listed licenses.9 */10 11 /*-*************************************12 *  Dependencies13 ***************************************/14#include "zstd_compress_superblock.h"15 16#include "../common/zstd_internal.h"  /* ZSTD_getSequenceLength */17#include "hist.h"                     /* HIST_countFast_wksp */18#include "zstd_compress_internal.h"   /* ZSTD_[huf|fse|entropy]CTablesMetadata_t */19#include "zstd_compress_sequences.h"20#include "zstd_compress_literals.h"21 22/* ZSTD_compressSubBlock_literal() :23 *  Compresses literals section for a sub-block.24 *  When we have to write the Huffman table we will sometimes choose a header25 *  size larger than necessary. This is because we have to pick the header size26 *  before we know the table size + compressed size, so we have a bound on the27 *  table size. If we guessed incorrectly, we fall back to uncompressed literals.28 *29 *  We write the header when writeEntropy=1 and set entropyWritten=1 when we succeeded30 *  in writing the header, otherwise it is set to 0.31 *32 *  hufMetadata->hType has literals block type info.33 *      If it is set_basic, all sub-blocks literals section will be Raw_Literals_Block.34 *      If it is set_rle, all sub-blocks literals section will be RLE_Literals_Block.35 *      If it is set_compressed, first sub-block's literals section will be Compressed_Literals_Block36 *      If it is set_compressed, first sub-block's literals section will be Treeless_Literals_Block37 *      and the following sub-blocks' literals sections will be Treeless_Literals_Block.38 *  @return : compressed size of literals section of a sub-block39 *            Or 0 if it unable to compress.40 *            Or error code */41static size_t ZSTD_compressSubBlock_literal(const HUF_CElt* hufTable,42                                    const ZSTD_hufCTablesMetadata_t* hufMetadata,43                                    const BYTE* literals, size_t litSize,44                                    void* dst, size_t dstSize,45                                    const int bmi2, int writeEntropy, int* entropyWritten)46{47    size_t const header = writeEntropy ? 200 : 0;48    size_t const lhSize = 3 + (litSize >= (1 KB - header)) + (litSize >= (16 KB - header));49    BYTE* const ostart = (BYTE*)dst;50    BYTE* const oend = ostart + dstSize;51    BYTE* op = ostart + lhSize;52    U32 const singleStream = lhSize == 3;53    symbolEncodingType_e hType = writeEntropy ? hufMetadata->hType : set_repeat;54    size_t cLitSize = 0;55 56    (void)bmi2; /* TODO bmi2... */57 58    DEBUGLOG(5, "ZSTD_compressSubBlock_literal (litSize=%zu, lhSize=%zu, writeEntropy=%d)", litSize, lhSize, writeEntropy);59 60    *entropyWritten = 0;61    if (litSize == 0 || hufMetadata->hType == set_basic) {62      DEBUGLOG(5, "ZSTD_compressSubBlock_literal using raw literal");63      return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize);64    } else if (hufMetadata->hType == set_rle) {65      DEBUGLOG(5, "ZSTD_compressSubBlock_literal using rle literal");66      return ZSTD_compressRleLiteralsBlock(dst, dstSize, literals, litSize);67    }68 69    assert(litSize > 0);70    assert(hufMetadata->hType == set_compressed || hufMetadata->hType == set_repeat);71 72    if (writeEntropy && hufMetadata->hType == set_compressed) {73        ZSTD_memcpy(op, hufMetadata->hufDesBuffer, hufMetadata->hufDesSize);74        op += hufMetadata->hufDesSize;75        cLitSize += hufMetadata->hufDesSize;76        DEBUGLOG(5, "ZSTD_compressSubBlock_literal (hSize=%zu)", hufMetadata->hufDesSize);77    }78 79    /* TODO bmi2 */80    {   const size_t cSize = singleStream ? HUF_compress1X_usingCTable(op, oend-op, literals, litSize, hufTable)81                                          : HUF_compress4X_usingCTable(op, oend-op, literals, litSize, hufTable);82        op += cSize;83        cLitSize += cSize;84        if (cSize == 0 || ERR_isError(cSize)) {85            DEBUGLOG(5, "Failed to write entropy tables %s", ZSTD_getErrorName(cSize));86            return 0;87        }88        /* If we expand and we aren't writing a header then emit uncompressed */89        if (!writeEntropy && cLitSize >= litSize) {90            DEBUGLOG(5, "ZSTD_compressSubBlock_literal using raw literal because uncompressible");91            return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize);92        }93        /* If we are writing headers then allow expansion that doesn't change our header size. */94        if (lhSize < (size_t)(3 + (cLitSize >= 1 KB) + (cLitSize >= 16 KB))) {95            assert(cLitSize > litSize);96            DEBUGLOG(5, "Literals expanded beyond allowed header size");97            return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize);98        }99        DEBUGLOG(5, "ZSTD_compressSubBlock_literal (cSize=%zu)", cSize);100    }101 102    /* Build header */103    switch(lhSize)104    {105    case 3: /* 2 - 2 - 10 - 10 */106        {   U32 const lhc = hType + ((!singleStream) << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<14);107            MEM_writeLE24(ostart, lhc);108            break;109        }110    case 4: /* 2 - 2 - 14 - 14 */111        {   U32 const lhc = hType + (2 << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<18);112            MEM_writeLE32(ostart, lhc);113            break;114        }115    case 5: /* 2 - 2 - 18 - 18 */116        {   U32 const lhc = hType + (3 << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<22);117            MEM_writeLE32(ostart, lhc);118            ostart[4] = (BYTE)(cLitSize >> 10);119            break;120        }121    default:  /* not possible : lhSize is {3,4,5} */122        assert(0);123    }124    *entropyWritten = 1;125    DEBUGLOG(5, "Compressed literals: %u -> %u", (U32)litSize, (U32)(op-ostart));126    return op-ostart;127}128 129static size_t ZSTD_seqDecompressedSize(seqStore_t const* seqStore, const seqDef* sequences, size_t nbSeq, size_t litSize, int lastSequence) {130    const seqDef* const sstart = sequences;131    const seqDef* const send = sequences + nbSeq;132    const seqDef* sp = sstart;133    size_t matchLengthSum = 0;134    size_t litLengthSum = 0;135    (void)(litLengthSum); /* suppress unused variable warning on some environments */136    while (send-sp > 0) {137        ZSTD_sequenceLength const seqLen = ZSTD_getSequenceLength(seqStore, sp);138        litLengthSum += seqLen.litLength;139        matchLengthSum += seqLen.matchLength;140        sp++;141    }142    assert(litLengthSum <= litSize);143    if (!lastSequence) {144        assert(litLengthSum == litSize);145    }146    return matchLengthSum + litSize;147}148 149/* ZSTD_compressSubBlock_sequences() :150 *  Compresses sequences section for a sub-block.151 *  fseMetadata->llType, fseMetadata->ofType, and fseMetadata->mlType have152 *  symbol compression modes for the super-block.153 *  The first successfully compressed block will have these in its header.154 *  We set entropyWritten=1 when we succeed in compressing the sequences.155 *  The following sub-blocks will always have repeat mode.156 *  @return : compressed size of sequences section of a sub-block157 *            Or 0 if it is unable to compress158 *            Or error code. */159static size_t ZSTD_compressSubBlock_sequences(const ZSTD_fseCTables_t* fseTables,160                                              const ZSTD_fseCTablesMetadata_t* fseMetadata,161                                              const seqDef* sequences, size_t nbSeq,162                                              const BYTE* llCode, const BYTE* mlCode, const BYTE* ofCode,163                                              const ZSTD_CCtx_params* cctxParams,164                                              void* dst, size_t dstCapacity,165                                              const int bmi2, int writeEntropy, int* entropyWritten)166{167    const int longOffsets = cctxParams->cParams.windowLog > STREAM_ACCUMULATOR_MIN;168    BYTE* const ostart = (BYTE*)dst;169    BYTE* const oend = ostart + dstCapacity;170    BYTE* op = ostart;171    BYTE* seqHead;172 173    DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (nbSeq=%zu, writeEntropy=%d, longOffsets=%d)", nbSeq, writeEntropy, longOffsets);174 175    *entropyWritten = 0;176    /* Sequences Header */177    RETURN_ERROR_IF((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead*/,178                    dstSize_tooSmall, "");179    if (nbSeq < 0x7F)180        *op++ = (BYTE)nbSeq;181    else if (nbSeq < LONGNBSEQ)182        op[0] = (BYTE)((nbSeq>>8) + 0x80), op[1] = (BYTE)nbSeq, op+=2;183    else184        op[0]=0xFF, MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ)), op+=3;185    if (nbSeq==0) {186        return op - ostart;187    }188 189    /* seqHead : flags for FSE encoding type */190    seqHead = op++;191 192    DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (seqHeadSize=%u)", (unsigned)(op-ostart));193 194    if (writeEntropy) {195        const U32 LLtype = fseMetadata->llType;196        const U32 Offtype = fseMetadata->ofType;197        const U32 MLtype = fseMetadata->mlType;198        DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (fseTablesSize=%zu)", fseMetadata->fseTablesSize);199        *seqHead = (BYTE)((LLtype<<6) + (Offtype<<4) + (MLtype<<2));200        ZSTD_memcpy(op, fseMetadata->fseTablesBuffer, fseMetadata->fseTablesSize);201        op += fseMetadata->fseTablesSize;202    } else {203        const U32 repeat = set_repeat;204        *seqHead = (BYTE)((repeat<<6) + (repeat<<4) + (repeat<<2));205    }206 207    {   size_t const bitstreamSize = ZSTD_encodeSequences(208                                        op, oend - op,209                                        fseTables->matchlengthCTable, mlCode,210                                        fseTables->offcodeCTable, ofCode,211                                        fseTables->litlengthCTable, llCode,212                                        sequences, nbSeq,213                                        longOffsets, bmi2);214        FORWARD_IF_ERROR(bitstreamSize, "ZSTD_encodeSequences failed");215        op += bitstreamSize;216        /* zstd versions <= 1.3.4 mistakenly report corruption when217         * FSE_readNCount() receives a buffer < 4 bytes.218         * Fixed by https://github.com/facebook/zstd/pull/1146.219         * This can happen when the last set_compressed table present is 2220         * bytes and the bitstream is only one byte.221         * In this exceedingly rare case, we will simply emit an uncompressed222         * block, since it isn't worth optimizing.223         */224#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION225        if (writeEntropy && fseMetadata->lastCountSize && fseMetadata->lastCountSize + bitstreamSize < 4) {226            /* NCountSize >= 2 && bitstreamSize > 0 ==> lastCountSize == 3 */227            assert(fseMetadata->lastCountSize + bitstreamSize == 3);228            DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.3.4 by "229                        "emitting an uncompressed block.");230            return 0;231        }232#endif233        DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (bitstreamSize=%zu)", bitstreamSize);234    }235 236    /* zstd versions <= 1.4.0 mistakenly report error when237     * sequences section body size is less than 3 bytes.238     * Fixed by https://github.com/facebook/zstd/pull/1664.239     * This can happen when the previous sequences section block is compressed240     * with rle mode and the current block's sequences section is compressed241     * with repeat mode where sequences section body size can be 1 byte.242     */243#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION244    if (op-seqHead < 4) {245        DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.4.0 by emitting "246                    "an uncompressed block when sequences are < 4 bytes");247        return 0;248    }249#endif250 251    *entropyWritten = 1;252    return op - ostart;253}254 255/* ZSTD_compressSubBlock() :256 *  Compresses a single sub-block.257 *  @return : compressed size of the sub-block258 *            Or 0 if it failed to compress. */259static size_t ZSTD_compressSubBlock(const ZSTD_entropyCTables_t* entropy,260                                    const ZSTD_entropyCTablesMetadata_t* entropyMetadata,261                                    const seqDef* sequences, size_t nbSeq,262                                    const BYTE* literals, size_t litSize,263                                    const BYTE* llCode, const BYTE* mlCode, const BYTE* ofCode,264                                    const ZSTD_CCtx_params* cctxParams,265                                    void* dst, size_t dstCapacity,266                                    const int bmi2,267                                    int writeLitEntropy, int writeSeqEntropy,268                                    int* litEntropyWritten, int* seqEntropyWritten,269                                    U32 lastBlock)270{271    BYTE* const ostart = (BYTE*)dst;272    BYTE* const oend = ostart + dstCapacity;273    BYTE* op = ostart + ZSTD_blockHeaderSize;274    DEBUGLOG(5, "ZSTD_compressSubBlock (litSize=%zu, nbSeq=%zu, writeLitEntropy=%d, writeSeqEntropy=%d, lastBlock=%d)",275                litSize, nbSeq, writeLitEntropy, writeSeqEntropy, lastBlock);276    {   size_t cLitSize = ZSTD_compressSubBlock_literal((const HUF_CElt*)entropy->huf.CTable,277                                                        &entropyMetadata->hufMetadata, literals, litSize,278                                                        op, oend-op, bmi2, writeLitEntropy, litEntropyWritten);279        FORWARD_IF_ERROR(cLitSize, "ZSTD_compressSubBlock_literal failed");280        if (cLitSize == 0) return 0;281        op += cLitSize;282    }283    {   size_t cSeqSize = ZSTD_compressSubBlock_sequences(&entropy->fse,284                                                  &entropyMetadata->fseMetadata,285                                                  sequences, nbSeq,286                                                  llCode, mlCode, ofCode,287                                                  cctxParams,288                                                  op, oend-op,289                                                  bmi2, writeSeqEntropy, seqEntropyWritten);290        FORWARD_IF_ERROR(cSeqSize, "ZSTD_compressSubBlock_sequences failed");291        if (cSeqSize == 0) return 0;292        op += cSeqSize;293    }294    /* Write block header */295    {   size_t cSize = (op-ostart)-ZSTD_blockHeaderSize;296        U32 const cBlockHeader24 = lastBlock + (((U32)bt_compressed)<<1) + (U32)(cSize << 3);297        MEM_writeLE24(ostart, cBlockHeader24);298    }299    return op-ostart;300}301 302static size_t ZSTD_estimateSubBlockSize_literal(const BYTE* literals, size_t litSize,303                                                const ZSTD_hufCTables_t* huf,304                                                const ZSTD_hufCTablesMetadata_t* hufMetadata,305                                                void* workspace, size_t wkspSize,306                                                int writeEntropy)307{308    unsigned* const countWksp = (unsigned*)workspace;309    unsigned maxSymbolValue = 255;310    size_t literalSectionHeaderSize = 3; /* Use hard coded size of 3 bytes */311 312    if (hufMetadata->hType == set_basic) return litSize;313    else if (hufMetadata->hType == set_rle) return 1;314    else if (hufMetadata->hType == set_compressed || hufMetadata->hType == set_repeat) {315        size_t const largest = HIST_count_wksp (countWksp, &maxSymbolValue, (const BYTE*)literals, litSize, workspace, wkspSize);316        if (ZSTD_isError(largest)) return litSize;317        {   size_t cLitSizeEstimate = HUF_estimateCompressedSize((const HUF_CElt*)huf->CTable, countWksp, maxSymbolValue);318            if (writeEntropy) cLitSizeEstimate += hufMetadata->hufDesSize;319            return cLitSizeEstimate + literalSectionHeaderSize;320    }   }321    assert(0); /* impossible */322    return 0;323}324 325static size_t ZSTD_estimateSubBlockSize_symbolType(symbolEncodingType_e type,326                        const BYTE* codeTable, unsigned maxCode,327                        size_t nbSeq, const FSE_CTable* fseCTable,328                        const U8* additionalBits,329                        short const* defaultNorm, U32 defaultNormLog, U32 defaultMax,330                        void* workspace, size_t wkspSize)331{332    unsigned* const countWksp = (unsigned*)workspace;333    const BYTE* ctp = codeTable;334    const BYTE* const ctStart = ctp;335    const BYTE* const ctEnd = ctStart + nbSeq;336    size_t cSymbolTypeSizeEstimateInBits = 0;337    unsigned max = maxCode;338 339    HIST_countFast_wksp(countWksp, &max, codeTable, nbSeq, workspace, wkspSize);  /* can't fail */340    if (type == set_basic) {341        /* We selected this encoding type, so it must be valid. */342        assert(max <= defaultMax);343        cSymbolTypeSizeEstimateInBits = max <= defaultMax344                ? ZSTD_crossEntropyCost(defaultNorm, defaultNormLog, countWksp, max)345                : ERROR(GENERIC);346    } else if (type == set_rle) {347        cSymbolTypeSizeEstimateInBits = 0;348    } else if (type == set_compressed || type == set_repeat) {349        cSymbolTypeSizeEstimateInBits = ZSTD_fseBitCost(fseCTable, countWksp, max);350    }351    if (ZSTD_isError(cSymbolTypeSizeEstimateInBits)) return nbSeq * 10;352    while (ctp < ctEnd) {353        if (additionalBits) cSymbolTypeSizeEstimateInBits += additionalBits[*ctp];354        else cSymbolTypeSizeEstimateInBits += *ctp; /* for offset, offset code is also the number of additional bits */355        ctp++;356    }357    return cSymbolTypeSizeEstimateInBits / 8;358}359 360static size_t ZSTD_estimateSubBlockSize_sequences(const BYTE* ofCodeTable,361                                                  const BYTE* llCodeTable,362                                                  const BYTE* mlCodeTable,363                                                  size_t nbSeq,364                                                  const ZSTD_fseCTables_t* fseTables,365                                                  const ZSTD_fseCTablesMetadata_t* fseMetadata,366                                                  void* workspace, size_t wkspSize,367                                                  int writeEntropy)368{369    size_t const sequencesSectionHeaderSize = 3; /* Use hard coded size of 3 bytes */370    size_t cSeqSizeEstimate = 0;371    if (nbSeq == 0) return sequencesSectionHeaderSize;372    cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->ofType, ofCodeTable, MaxOff,373                                         nbSeq, fseTables->offcodeCTable, NULL,374                                         OF_defaultNorm, OF_defaultNormLog, DefaultMaxOff,375                                         workspace, wkspSize);376    cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->llType, llCodeTable, MaxLL,377                                         nbSeq, fseTables->litlengthCTable, LL_bits,378                                         LL_defaultNorm, LL_defaultNormLog, MaxLL,379                                         workspace, wkspSize);380    cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->mlType, mlCodeTable, MaxML,381                                         nbSeq, fseTables->matchlengthCTable, ML_bits,382                                         ML_defaultNorm, ML_defaultNormLog, MaxML,383                                         workspace, wkspSize);384    if (writeEntropy) cSeqSizeEstimate += fseMetadata->fseTablesSize;385    return cSeqSizeEstimate + sequencesSectionHeaderSize;386}387 388static size_t ZSTD_estimateSubBlockSize(const BYTE* literals, size_t litSize,389                                        const BYTE* ofCodeTable,390                                        const BYTE* llCodeTable,391                                        const BYTE* mlCodeTable,392                                        size_t nbSeq,393                                        const ZSTD_entropyCTables_t* entropy,394                                        const ZSTD_entropyCTablesMetadata_t* entropyMetadata,395                                        void* workspace, size_t wkspSize,396                                        int writeLitEntropy, int writeSeqEntropy) {397    size_t cSizeEstimate = 0;398    cSizeEstimate += ZSTD_estimateSubBlockSize_literal(literals, litSize,399                                                         &entropy->huf, &entropyMetadata->hufMetadata,400                                                         workspace, wkspSize, writeLitEntropy);401    cSizeEstimate += ZSTD_estimateSubBlockSize_sequences(ofCodeTable, llCodeTable, mlCodeTable,402                                                         nbSeq, &entropy->fse, &entropyMetadata->fseMetadata,403                                                         workspace, wkspSize, writeSeqEntropy);404    return cSizeEstimate + ZSTD_blockHeaderSize;405}406 407static int ZSTD_needSequenceEntropyTables(ZSTD_fseCTablesMetadata_t const* fseMetadata)408{409    if (fseMetadata->llType == set_compressed || fseMetadata->llType == set_rle)410        return 1;411    if (fseMetadata->mlType == set_compressed || fseMetadata->mlType == set_rle)412        return 1;413    if (fseMetadata->ofType == set_compressed || fseMetadata->ofType == set_rle)414        return 1;415    return 0;416}417 418/* ZSTD_compressSubBlock_multi() :419 *  Breaks super-block into multiple sub-blocks and compresses them.420 *  Entropy will be written to the first block.421 *  The following blocks will use repeat mode to compress.422 *  All sub-blocks are compressed blocks (no raw or rle blocks).423 *  @return : compressed size of the super block (which is multiple ZSTD blocks)424 *            Or 0 if it failed to compress. */425static size_t ZSTD_compressSubBlock_multi(const seqStore_t* seqStorePtr,426                            const ZSTD_compressedBlockState_t* prevCBlock,427                            ZSTD_compressedBlockState_t* nextCBlock,428                            const ZSTD_entropyCTablesMetadata_t* entropyMetadata,429                            const ZSTD_CCtx_params* cctxParams,430                                  void* dst, size_t dstCapacity,431                            const void* src, size_t srcSize,432                            const int bmi2, U32 lastBlock,433                            void* workspace, size_t wkspSize)434{435    const seqDef* const sstart = seqStorePtr->sequencesStart;436    const seqDef* const send = seqStorePtr->sequences;437    const seqDef* sp = sstart;438    const BYTE* const lstart = seqStorePtr->litStart;439    const BYTE* const lend = seqStorePtr->lit;440    const BYTE* lp = lstart;441    BYTE const* ip = (BYTE const*)src;442    BYTE const* const iend = ip + srcSize;443    BYTE* const ostart = (BYTE*)dst;444    BYTE* const oend = ostart + dstCapacity;445    BYTE* op = ostart;446    const BYTE* llCodePtr = seqStorePtr->llCode;447    const BYTE* mlCodePtr = seqStorePtr->mlCode;448    const BYTE* ofCodePtr = seqStorePtr->ofCode;449    size_t targetCBlockSize = cctxParams->targetCBlockSize;450    size_t litSize, seqCount;451    int writeLitEntropy = entropyMetadata->hufMetadata.hType == set_compressed;452    int writeSeqEntropy = 1;453    int lastSequence = 0;454 455    DEBUGLOG(5, "ZSTD_compressSubBlock_multi (litSize=%u, nbSeq=%u)",456                (unsigned)(lend-lp), (unsigned)(send-sstart));457 458    litSize = 0;459    seqCount = 0;460    do {461        size_t cBlockSizeEstimate = 0;462        if (sstart == send) {463            lastSequence = 1;464        } else {465            const seqDef* const sequence = sp + seqCount;466            lastSequence = sequence == send - 1;467            litSize += ZSTD_getSequenceLength(seqStorePtr, sequence).litLength;468            seqCount++;469        }470        if (lastSequence) {471            assert(lp <= lend);472            assert(litSize <= (size_t)(lend - lp));473            litSize = (size_t)(lend - lp);474        }475        /* I think there is an optimization opportunity here.476         * Calling ZSTD_estimateSubBlockSize for every sequence can be wasteful477         * since it recalculates estimate from scratch.478         * For example, it would recount literal distribution and symbol codes every time.479         */480        cBlockSizeEstimate = ZSTD_estimateSubBlockSize(lp, litSize, ofCodePtr, llCodePtr, mlCodePtr, seqCount,481                                                       &nextCBlock->entropy, entropyMetadata,482                                                       workspace, wkspSize, writeLitEntropy, writeSeqEntropy);483        if (cBlockSizeEstimate > targetCBlockSize || lastSequence) {484            int litEntropyWritten = 0;485            int seqEntropyWritten = 0;486            const size_t decompressedSize = ZSTD_seqDecompressedSize(seqStorePtr, sp, seqCount, litSize, lastSequence);487            const size_t cSize = ZSTD_compressSubBlock(&nextCBlock->entropy, entropyMetadata,488                                                       sp, seqCount,489                                                       lp, litSize,490                                                       llCodePtr, mlCodePtr, ofCodePtr,491                                                       cctxParams,492                                                       op, oend-op,493                                                       bmi2, writeLitEntropy, writeSeqEntropy,494                                                       &litEntropyWritten, &seqEntropyWritten,495                                                       lastBlock && lastSequence);496            FORWARD_IF_ERROR(cSize, "ZSTD_compressSubBlock failed");497            if (cSize > 0 && cSize < decompressedSize) {498                DEBUGLOG(5, "Committed the sub-block");499                assert(ip + decompressedSize <= iend);500                ip += decompressedSize;501                sp += seqCount;502                lp += litSize;503                op += cSize;504                llCodePtr += seqCount;505                mlCodePtr += seqCount;506                ofCodePtr += seqCount;507                litSize = 0;508                seqCount = 0;509                /* Entropy only needs to be written once */510                if (litEntropyWritten) {511                    writeLitEntropy = 0;512                }513                if (seqEntropyWritten) {514                    writeSeqEntropy = 0;515                }516            }517        }518    } while (!lastSequence);519    if (writeLitEntropy) {520        DEBUGLOG(5, "ZSTD_compressSubBlock_multi has literal entropy tables unwritten");521        ZSTD_memcpy(&nextCBlock->entropy.huf, &prevCBlock->entropy.huf, sizeof(prevCBlock->entropy.huf));522    }523    if (writeSeqEntropy && ZSTD_needSequenceEntropyTables(&entropyMetadata->fseMetadata)) {524        /* If we haven't written our entropy tables, then we've violated our contract and525         * must emit an uncompressed block.526         */527        DEBUGLOG(5, "ZSTD_compressSubBlock_multi has sequence entropy tables unwritten");528        return 0;529    }530    if (ip < iend) {531        size_t const cSize = ZSTD_noCompressBlock(op, oend - op, ip, iend - ip, lastBlock);532        DEBUGLOG(5, "ZSTD_compressSubBlock_multi last sub-block uncompressed, %zu bytes", (size_t)(iend - ip));533        FORWARD_IF_ERROR(cSize, "ZSTD_noCompressBlock failed");534        assert(cSize != 0);535        op += cSize;536        /* We have to regenerate the repcodes because we've skipped some sequences */537        if (sp < send) {538            seqDef const* seq;539            repcodes_t rep;540            ZSTD_memcpy(&rep, prevCBlock->rep, sizeof(rep));541            for (seq = sstart; seq < sp; ++seq) {542                ZSTD_updateRep(rep.rep, seq->offBase - 1, ZSTD_getSequenceLength(seqStorePtr, seq).litLength == 0);543            }544            ZSTD_memcpy(nextCBlock->rep, &rep, sizeof(rep));545        }546    }547    DEBUGLOG(5, "ZSTD_compressSubBlock_multi compressed");548    return op-ostart;549}550 551size_t ZSTD_compressSuperBlock(ZSTD_CCtx* zc,552                               void* dst, size_t dstCapacity,553                               void const* src, size_t srcSize,554                               unsigned lastBlock) {555    ZSTD_entropyCTablesMetadata_t entropyMetadata;556 557    FORWARD_IF_ERROR(ZSTD_buildBlockEntropyStats(&zc->seqStore,558          &zc->blockState.prevCBlock->entropy,559          &zc->blockState.nextCBlock->entropy,560          &zc->appliedParams,561          &entropyMetadata,562          zc->entropyWorkspace, ENTROPY_WORKSPACE_SIZE /* statically allocated in resetCCtx */), "");563 564    return ZSTD_compressSubBlock_multi(&zc->seqStore,565            zc->blockState.prevCBlock,566            zc->blockState.nextCBlock,567            &entropyMetadata,568            &zc->appliedParams,569            dst, dstCapacity,570            src, srcSize,571            zc->bmi2, lastBlock,572            zc->entropyWorkspace, ENTROPY_WORKSPACE_SIZE /* statically allocated in resetCCtx */);573}574