FreeBSD/Linux Kernel Cross Reference
sys/contrib/zstd/lib/decompress/zstd_decompress_block.c

     /*
      * Copyright (c) Yann Collet, Facebook, Inc.
      * All rights reserved.
      *
      * 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.
      */
    
    /* zstd_decompress_block :
     * this module takes care of decompressing _compressed_ block */
    
    /*-*******************************************************
    *  Dependencies
    *********************************************************/
    #include "../common/zstd_deps.h"   /* ZSTD_memcpy, ZSTD_memmove, ZSTD_memset */
    #include "../common/compiler.h"    /* prefetch */
    #include "../common/cpu.h"         /* bmi2 */
    #include "../common/mem.h"         /* low level memory routines */
    #define FSE_STATIC_LINKING_ONLY
    #include "../common/fse.h"
    #define HUF_STATIC_LINKING_ONLY
    #include "../common/huf.h"
    #include "../common/zstd_internal.h"
    #include "zstd_decompress_internal.h"   /* ZSTD_DCtx */
    #include "zstd_ddict.h"  /* ZSTD_DDictDictContent */
    #include "zstd_decompress_block.h"
    
    /*_*******************************************************
    *  Macros
    **********************************************************/
    
    /* These two optional macros force the use one way or another of the two
     * ZSTD_decompressSequences implementations. You can't force in both directions
     * at the same time.
     */
    #if defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
        defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
    #error "Cannot force the use of the short and the long ZSTD_decompressSequences variants!"
    #endif
    
    
    /*_*******************************************************
    *  Memory operations
    **********************************************************/
    static void ZSTD_copy4(void* dst, const void* src) { ZSTD_memcpy(dst, src, 4); }
    
    
    /*-*************************************************************
     *   Block decoding
     ***************************************************************/
    
    /*! ZSTD_getcBlockSize() :
     *  Provides the size of compressed block from block header `src` */
    size_t ZSTD_getcBlockSize(const void* src, size_t srcSize,
                              blockProperties_t* bpPtr)
    {
        RETURN_ERROR_IF(srcSize < ZSTD_blockHeaderSize, srcSize_wrong, "");
    
        {   U32 const cBlockHeader = MEM_readLE24(src);
            U32 const cSize = cBlockHeader >> 3;
            bpPtr->lastBlock = cBlockHeader & 1;
            bpPtr->blockType = (blockType_e)((cBlockHeader >> 1) & 3);
            bpPtr->origSize = cSize;   /* only useful for RLE */
            if (bpPtr->blockType == bt_rle) return 1;
            RETURN_ERROR_IF(bpPtr->blockType == bt_reserved, corruption_detected, "");
            return cSize;
        }
    }
    
    /* Allocate buffer for literals, either overlapping current dst, or split between dst and litExtraBuffer, or stored entirely within litExtraBuffer */
    static void ZSTD_allocateLiteralsBuffer(ZSTD_DCtx* dctx, void* const dst, const size_t dstCapacity, const size_t litSize,
        const streaming_operation streaming, const size_t expectedWriteSize, const unsigned splitImmediately)
    {
        if (streaming == not_streaming && dstCapacity > ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH + litSize + WILDCOPY_OVERLENGTH)
        {
            /* room for litbuffer to fit without read faulting */
            dctx->litBuffer = (BYTE*)dst + ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH;
            dctx->litBufferEnd = dctx->litBuffer + litSize;
            dctx->litBufferLocation = ZSTD_in_dst;
        }
        else if (litSize > ZSTD_LITBUFFEREXTRASIZE)
        {
            /* won't fit in litExtraBuffer, so it will be split between end of dst and extra buffer */
            if (splitImmediately) {
                /* won't fit in litExtraBuffer, so it will be split between end of dst and extra buffer */
                dctx->litBuffer = (BYTE*)dst + expectedWriteSize - litSize + ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH;
                dctx->litBufferEnd = dctx->litBuffer + litSize - ZSTD_LITBUFFEREXTRASIZE;
            }
            else {
                /* initially this will be stored entirely in dst during huffman decoding, it will partially shifted to litExtraBuffer after */
                dctx->litBuffer = (BYTE*)dst + expectedWriteSize - litSize;
                dctx->litBufferEnd = (BYTE*)dst + expectedWriteSize;
            }
            dctx->litBufferLocation = ZSTD_split;
        }
        else
        {
           /* fits entirely within litExtraBuffer, so no split is necessary */
           dctx->litBuffer = dctx->litExtraBuffer;
           dctx->litBufferEnd = dctx->litBuffer + litSize;
           dctx->litBufferLocation = ZSTD_not_in_dst;
       }
   }
   
   /* Hidden declaration for fullbench */
   size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
                             const void* src, size_t srcSize,
                             void* dst, size_t dstCapacity, const streaming_operation streaming);
   /*! ZSTD_decodeLiteralsBlock() :
    * Where it is possible to do so without being stomped by the output during decompression, the literals block will be stored
    * in the dstBuffer.  If there is room to do so, it will be stored in full in the excess dst space after where the current
    * block will be output.  Otherwise it will be stored at the end of the current dst blockspace, with a small portion being
    * stored in dctx->litExtraBuffer to help keep it "ahead" of the current output write.
    *
    * @return : nb of bytes read from src (< srcSize )
    *  note : symbol not declared but exposed for fullbench */
   size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
                             const void* src, size_t srcSize,   /* note : srcSize < BLOCKSIZE */
                             void* dst, size_t dstCapacity, const streaming_operation streaming)
   {
       DEBUGLOG(5, "ZSTD_decodeLiteralsBlock");
       RETURN_ERROR_IF(srcSize < MIN_CBLOCK_SIZE, corruption_detected, "");
   
       {   const BYTE* const istart = (const BYTE*) src;
           symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3);
   
           switch(litEncType)
           {
           case set_repeat:
               DEBUGLOG(5, "set_repeat flag : re-using stats from previous compressed literals block");
               RETURN_ERROR_IF(dctx->litEntropy==0, dictionary_corrupted, "");
               ZSTD_FALLTHROUGH;
   
           case set_compressed:
               RETURN_ERROR_IF(srcSize < 5, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3");
               {   size_t lhSize, litSize, litCSize;
                   U32 singleStream=0;
                   U32 const lhlCode = (istart[0] >> 2) & 3;
                   U32 const lhc = MEM_readLE32(istart);
                   size_t hufSuccess;
                   size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity);
                   switch(lhlCode)
                   {
                   case 0: case 1: default:   /* note : default is impossible, since lhlCode into [0..3] */
                       /* 2 - 2 - 10 - 10 */
                       singleStream = !lhlCode;
                       lhSize = 3;
                       litSize  = (lhc >> 4) & 0x3FF;
                       litCSize = (lhc >> 14) & 0x3FF;
                       break;
                   case 2:
                       /* 2 - 2 - 14 - 14 */
                       lhSize = 4;
                       litSize  = (lhc >> 4) & 0x3FFF;
                       litCSize = lhc >> 18;
                       break;
                   case 3:
                       /* 2 - 2 - 18 - 18 */
                       lhSize = 5;
                       litSize  = (lhc >> 4) & 0x3FFFF;
                       litCSize = (lhc >> 22) + ((size_t)istart[4] << 10);
                       break;
                   }
                   RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled");
                   RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, "");
                   RETURN_ERROR_IF(litCSize + lhSize > srcSize, corruption_detected, "");
                   RETURN_ERROR_IF(expectedWriteSize < litSize , dstSize_tooSmall, "");
                   ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 0);
   
                   /* prefetch huffman table if cold */
                   if (dctx->ddictIsCold && (litSize > 768 /* heuristic */)) {
                       PREFETCH_AREA(dctx->HUFptr, sizeof(dctx->entropy.hufTable));
                   }
   
                   if (litEncType==set_repeat) {
                       if (singleStream) {
                           hufSuccess = HUF_decompress1X_usingDTable_bmi2(
                               dctx->litBuffer, litSize, istart+lhSize, litCSize,
                               dctx->HUFptr, ZSTD_DCtx_get_bmi2(dctx));
                       } else {
                           hufSuccess = HUF_decompress4X_usingDTable_bmi2(
                               dctx->litBuffer, litSize, istart+lhSize, litCSize,
                               dctx->HUFptr, ZSTD_DCtx_get_bmi2(dctx));
                       }
                   } else {
                       if (singleStream) {
   #if defined(HUF_FORCE_DECOMPRESS_X2)
                           hufSuccess = HUF_decompress1X_DCtx_wksp(
                               dctx->entropy.hufTable, dctx->litBuffer, litSize,
                               istart+lhSize, litCSize, dctx->workspace,
                               sizeof(dctx->workspace));
   #else
                           hufSuccess = HUF_decompress1X1_DCtx_wksp_bmi2(
                               dctx->entropy.hufTable, dctx->litBuffer, litSize,
                               istart+lhSize, litCSize, dctx->workspace,
                               sizeof(dctx->workspace), ZSTD_DCtx_get_bmi2(dctx));
   #endif
                       } else {
                           hufSuccess = HUF_decompress4X_hufOnly_wksp_bmi2(
                               dctx->entropy.hufTable, dctx->litBuffer, litSize,
                               istart+lhSize, litCSize, dctx->workspace,
                               sizeof(dctx->workspace), ZSTD_DCtx_get_bmi2(dctx));
                       }
                   }
                   if (dctx->litBufferLocation == ZSTD_split)
                   {
                       ZSTD_memcpy(dctx->litExtraBuffer, dctx->litBufferEnd - ZSTD_LITBUFFEREXTRASIZE, ZSTD_LITBUFFEREXTRASIZE);
                       ZSTD_memmove(dctx->litBuffer + ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH, dctx->litBuffer, litSize - ZSTD_LITBUFFEREXTRASIZE);
                       dctx->litBuffer += ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH;
                       dctx->litBufferEnd -= WILDCOPY_OVERLENGTH;
                   }
   
                   RETURN_ERROR_IF(HUF_isError(hufSuccess), corruption_detected, "");
   
                   dctx->litPtr = dctx->litBuffer;
                   dctx->litSize = litSize;
                   dctx->litEntropy = 1;
                   if (litEncType==set_compressed) dctx->HUFptr = dctx->entropy.hufTable;
                   return litCSize + lhSize;
               }
   
           case set_basic:
               {   size_t litSize, lhSize;
                   U32 const lhlCode = ((istart[0]) >> 2) & 3;
                   size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity);
                   switch(lhlCode)
                   {
                   case 0: case 2: default:   /* note : default is impossible, since lhlCode into [0..3] */
                       lhSize = 1;
                       litSize = istart[0] >> 3;
                       break;
                   case 1:
                       lhSize = 2;
                       litSize = MEM_readLE16(istart) >> 4;
                       break;
                   case 3:
                       lhSize = 3;
                       litSize = MEM_readLE24(istart) >> 4;
                       break;
                   }
   
                   RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled");
                   RETURN_ERROR_IF(expectedWriteSize < litSize, dstSize_tooSmall, "");
                   ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 1);
                   if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) {  /* risk reading beyond src buffer with wildcopy */
                       RETURN_ERROR_IF(litSize+lhSize > srcSize, corruption_detected, "");
                       if (dctx->litBufferLocation == ZSTD_split)
                       {
                           ZSTD_memcpy(dctx->litBuffer, istart + lhSize, litSize - ZSTD_LITBUFFEREXTRASIZE);
                           ZSTD_memcpy(dctx->litExtraBuffer, istart + lhSize + litSize - ZSTD_LITBUFFEREXTRASIZE, ZSTD_LITBUFFEREXTRASIZE);
                       }
                       else
                       {
                           ZSTD_memcpy(dctx->litBuffer, istart + lhSize, litSize);
                       }
                       dctx->litPtr = dctx->litBuffer;
                       dctx->litSize = litSize;
                       return lhSize+litSize;
                   }
                   /* direct reference into compressed stream */
                   dctx->litPtr = istart+lhSize;
                   dctx->litSize = litSize;
                   dctx->litBufferEnd = dctx->litPtr + litSize;
                   dctx->litBufferLocation = ZSTD_not_in_dst;
                   return lhSize+litSize;
               }
   
           case set_rle:
               {   U32 const lhlCode = ((istart[0]) >> 2) & 3;
                   size_t litSize, lhSize;
                   size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity);
                   switch(lhlCode)
                   {
                   case 0: case 2: default:   /* note : default is impossible, since lhlCode into [0..3] */
                       lhSize = 1;
                       litSize = istart[0] >> 3;
                       break;
                   case 1:
                       lhSize = 2;
                       litSize = MEM_readLE16(istart) >> 4;
                       break;
                   case 3:
                       lhSize = 3;
                       litSize = MEM_readLE24(istart) >> 4;
                       RETURN_ERROR_IF(srcSize<4, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4");
                       break;
                   }
                   RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled");
                   RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, "");
                   RETURN_ERROR_IF(expectedWriteSize < litSize, dstSize_tooSmall, "");
                   ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 1);
                   if (dctx->litBufferLocation == ZSTD_split)
                   {
                       ZSTD_memset(dctx->litBuffer, istart[lhSize], litSize - ZSTD_LITBUFFEREXTRASIZE);
                       ZSTD_memset(dctx->litExtraBuffer, istart[lhSize], ZSTD_LITBUFFEREXTRASIZE);
                   }
                   else
                   {
                       ZSTD_memset(dctx->litBuffer, istart[lhSize], litSize);
                   }
                   dctx->litPtr = dctx->litBuffer;
                   dctx->litSize = litSize;
                   return lhSize+1;
               }
           default:
               RETURN_ERROR(corruption_detected, "impossible");
           }
       }
   }
   
   /* Default FSE distribution tables.
    * These are pre-calculated FSE decoding tables using default distributions as defined in specification :
    * https://github.com/facebook/zstd/blob/release/doc/zstd_compression_format.md#default-distributions
    * They were generated programmatically with following method :
    * - start from default distributions, present in /lib/common/zstd_internal.h
    * - generate tables normally, using ZSTD_buildFSETable()
    * - printout the content of tables
    * - pretify output, report below, test with fuzzer to ensure it's correct */
   
   /* Default FSE distribution table for Literal Lengths */
   static const ZSTD_seqSymbol LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = {
        {  1,  1,  1, LL_DEFAULTNORMLOG},  /* header : fastMode, tableLog */
        /* nextState, nbAddBits, nbBits, baseVal */
        {  0,  0,  4,    0},  { 16,  0,  4,    0},
        { 32,  0,  5,    1},  {  0,  0,  5,    3},
        {  0,  0,  5,    4},  {  0,  0,  5,    6},
        {  0,  0,  5,    7},  {  0,  0,  5,    9},
        {  0,  0,  5,   10},  {  0,  0,  5,   12},
        {  0,  0,  6,   14},  {  0,  1,  5,   16},
        {  0,  1,  5,   20},  {  0,  1,  5,   22},
        {  0,  2,  5,   28},  {  0,  3,  5,   32},
        {  0,  4,  5,   48},  { 32,  6,  5,   64},
        {  0,  7,  5,  128},  {  0,  8,  6,  256},
        {  0, 10,  6, 1024},  {  0, 12,  6, 4096},
        { 32,  0,  4,    0},  {  0,  0,  4,    1},
        {  0,  0,  5,    2},  { 32,  0,  5,    4},
        {  0,  0,  5,    5},  { 32,  0,  5,    7},
        {  0,  0,  5,    8},  { 32,  0,  5,   10},
        {  0,  0,  5,   11},  {  0,  0,  6,   13},
        { 32,  1,  5,   16},  {  0,  1,  5,   18},
        { 32,  1,  5,   22},  {  0,  2,  5,   24},
        { 32,  3,  5,   32},  {  0,  3,  5,   40},
        {  0,  6,  4,   64},  { 16,  6,  4,   64},
        { 32,  7,  5,  128},  {  0,  9,  6,  512},
        {  0, 11,  6, 2048},  { 48,  0,  4,    0},
        { 16,  0,  4,    1},  { 32,  0,  5,    2},
        { 32,  0,  5,    3},  { 32,  0,  5,    5},
        { 32,  0,  5,    6},  { 32,  0,  5,    8},
        { 32,  0,  5,    9},  { 32,  0,  5,   11},
        { 32,  0,  5,   12},  {  0,  0,  6,   15},
        { 32,  1,  5,   18},  { 32,  1,  5,   20},
        { 32,  2,  5,   24},  { 32,  2,  5,   28},
        { 32,  3,  5,   40},  { 32,  4,  5,   48},
        {  0, 16,  6,65536},  {  0, 15,  6,32768},
        {  0, 14,  6,16384},  {  0, 13,  6, 8192},
   };   /* LL_defaultDTable */
   
   /* Default FSE distribution table for Offset Codes */
   static const ZSTD_seqSymbol OF_defaultDTable[(1<<OF_DEFAULTNORMLOG)+1] = {
       {  1,  1,  1, OF_DEFAULTNORMLOG},  /* header : fastMode, tableLog */
       /* nextState, nbAddBits, nbBits, baseVal */
       {  0,  0,  5,    0},     {  0,  6,  4,   61},
       {  0,  9,  5,  509},     {  0, 15,  5,32765},
       {  0, 21,  5,2097149},   {  0,  3,  5,    5},
       {  0,  7,  4,  125},     {  0, 12,  5, 4093},
       {  0, 18,  5,262141},    {  0, 23,  5,8388605},
       {  0,  5,  5,   29},     {  0,  8,  4,  253},
       {  0, 14,  5,16381},     {  0, 20,  5,1048573},
       {  0,  2,  5,    1},     { 16,  7,  4,  125},
       {  0, 11,  5, 2045},     {  0, 17,  5,131069},
       {  0, 22,  5,4194301},   {  0,  4,  5,   13},
       { 16,  8,  4,  253},     {  0, 13,  5, 8189},
       {  0, 19,  5,524285},    {  0,  1,  5,    1},
       { 16,  6,  4,   61},     {  0, 10,  5, 1021},
       {  0, 16,  5,65533},     {  0, 28,  5,268435453},
       {  0, 27,  5,134217725}, {  0, 26,  5,67108861},
       {  0, 25,  5,33554429},  {  0, 24,  5,16777213},
   };   /* OF_defaultDTable */
   
   
   /* Default FSE distribution table for Match Lengths */
   static const ZSTD_seqSymbol ML_defaultDTable[(1<<ML_DEFAULTNORMLOG)+1] = {
       {  1,  1,  1, ML_DEFAULTNORMLOG},  /* header : fastMode, tableLog */
       /* nextState, nbAddBits, nbBits, baseVal */
       {  0,  0,  6,    3},  {  0,  0,  4,    4},
       { 32,  0,  5,    5},  {  0,  0,  5,    6},
       {  0,  0,  5,    8},  {  0,  0,  5,    9},
       {  0,  0,  5,   11},  {  0,  0,  6,   13},
       {  0,  0,  6,   16},  {  0,  0,  6,   19},
       {  0,  0,  6,   22},  {  0,  0,  6,   25},
       {  0,  0,  6,   28},  {  0,  0,  6,   31},
       {  0,  0,  6,   34},  {  0,  1,  6,   37},
       {  0,  1,  6,   41},  {  0,  2,  6,   47},
       {  0,  3,  6,   59},  {  0,  4,  6,   83},
       {  0,  7,  6,  131},  {  0,  9,  6,  515},
       { 16,  0,  4,    4},  {  0,  0,  4,    5},
       { 32,  0,  5,    6},  {  0,  0,  5,    7},
       { 32,  0,  5,    9},  {  0,  0,  5,   10},
       {  0,  0,  6,   12},  {  0,  0,  6,   15},
       {  0,  0,  6,   18},  {  0,  0,  6,   21},
       {  0,  0,  6,   24},  {  0,  0,  6,   27},
       {  0,  0,  6,   30},  {  0,  0,  6,   33},
       {  0,  1,  6,   35},  {  0,  1,  6,   39},
       {  0,  2,  6,   43},  {  0,  3,  6,   51},
       {  0,  4,  6,   67},  {  0,  5,  6,   99},
       {  0,  8,  6,  259},  { 32,  0,  4,    4},
       { 48,  0,  4,    4},  { 16,  0,  4,    5},
       { 32,  0,  5,    7},  { 32,  0,  5,    8},
       { 32,  0,  5,   10},  { 32,  0,  5,   11},
       {  0,  0,  6,   14},  {  0,  0,  6,   17},
       {  0,  0,  6,   20},  {  0,  0,  6,   23},
       {  0,  0,  6,   26},  {  0,  0,  6,   29},
       {  0,  0,  6,   32},  {  0, 16,  6,65539},
       {  0, 15,  6,32771},  {  0, 14,  6,16387},
       {  0, 13,  6, 8195},  {  0, 12,  6, 4099},
       {  0, 11,  6, 2051},  {  0, 10,  6, 1027},
   };   /* ML_defaultDTable */
   
   
   static void ZSTD_buildSeqTable_rle(ZSTD_seqSymbol* dt, U32 baseValue, U8 nbAddBits)
   {
       void* ptr = dt;
       ZSTD_seqSymbol_header* const DTableH = (ZSTD_seqSymbol_header*)ptr;
       ZSTD_seqSymbol* const cell = dt + 1;
   
       DTableH->tableLog = 0;
       DTableH->fastMode = 0;
   
       cell->nbBits = 0;
       cell->nextState = 0;
       assert(nbAddBits < 255);
       cell->nbAdditionalBits = nbAddBits;
       cell->baseValue = baseValue;
   }
   
   
   /* ZSTD_buildFSETable() :
    * generate FSE decoding table for one symbol (ll, ml or off)
    * cannot fail if input is valid =>
    * all inputs are presumed validated at this stage */
   FORCE_INLINE_TEMPLATE
   void ZSTD_buildFSETable_body(ZSTD_seqSymbol* dt,
               const short* normalizedCounter, unsigned maxSymbolValue,
               const U32* baseValue, const U8* nbAdditionalBits,
               unsigned tableLog, void* wksp, size_t wkspSize)
   {
       ZSTD_seqSymbol* const tableDecode = dt+1;
       U32 const maxSV1 = maxSymbolValue + 1;
       U32 const tableSize = 1 << tableLog;
   
       U16* symbolNext = (U16*)wksp;
       BYTE* spread = (BYTE*)(symbolNext + MaxSeq + 1);
       U32 highThreshold = tableSize - 1;
   
   
       /* Sanity Checks */
       assert(maxSymbolValue <= MaxSeq);
       assert(tableLog <= MaxFSELog);
       assert(wkspSize >= ZSTD_BUILD_FSE_TABLE_WKSP_SIZE);
       (void)wkspSize;
       /* Init, lay down lowprob symbols */
       {   ZSTD_seqSymbol_header DTableH;
           DTableH.tableLog = tableLog;
           DTableH.fastMode = 1;
           {   S16 const largeLimit= (S16)(1 << (tableLog-1));
               U32 s;
               for (s=0; s<maxSV1; s++) {
                   if (normalizedCounter[s]==-1) {
                       tableDecode[highThreshold--].baseValue = s;
                       symbolNext[s] = 1;
                   } else {
                       if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
                       assert(normalizedCounter[s]>=0);
                       symbolNext[s] = (U16)normalizedCounter[s];
           }   }   }
           ZSTD_memcpy(dt, &DTableH, sizeof(DTableH));
       }
   
       /* Spread symbols */
       assert(tableSize <= 512);
       /* Specialized symbol spreading for the case when there are
        * no low probability (-1 count) symbols. When compressing
        * small blocks we avoid low probability symbols to hit this
        * case, since header decoding speed matters more.
        */
       if (highThreshold == tableSize - 1) {
           size_t const tableMask = tableSize-1;
           size_t const step = FSE_TABLESTEP(tableSize);
           /* First lay down the symbols in order.
            * We use a uint64_t to lay down 8 bytes at a time. This reduces branch
            * misses since small blocks generally have small table logs, so nearly
            * all symbols have counts <= 8. We ensure we have 8 bytes at the end of
            * our buffer to handle the over-write.
            */
           {
               U64 const add = 0x0101010101010101ull;
               size_t pos = 0;
               U64 sv = 0;
               U32 s;
               for (s=0; s<maxSV1; ++s, sv += add) {
                   int i;
                   int const n = normalizedCounter[s];
                   MEM_write64(spread + pos, sv);
                   for (i = 8; i < n; i += 8) {
                       MEM_write64(spread + pos + i, sv);
                   }
                   pos += n;
               }
           }
           /* Now we spread those positions across the table.
            * The benefit of doing it in two stages is that we avoid the the
            * variable size inner loop, which caused lots of branch misses.
            * Now we can run through all the positions without any branch misses.
            * We unroll the loop twice, since that is what emperically worked best.
            */
           {
               size_t position = 0;
               size_t s;
               size_t const unroll = 2;
               assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */
               for (s = 0; s < (size_t)tableSize; s += unroll) {
                   size_t u;
                   for (u = 0; u < unroll; ++u) {
                       size_t const uPosition = (position + (u * step)) & tableMask;
                       tableDecode[uPosition].baseValue = spread[s + u];
                   }
                   position = (position + (unroll * step)) & tableMask;
               }
               assert(position == 0);
           }
       } else {
           U32 const tableMask = tableSize-1;
           U32 const step = FSE_TABLESTEP(tableSize);
           U32 s, position = 0;
           for (s=0; s<maxSV1; s++) {
               int i;
               int const n = normalizedCounter[s];
               for (i=0; i<n; i++) {
                   tableDecode[position].baseValue = s;
                   position = (position + step) & tableMask;
                   while (position > highThreshold) position = (position + step) & tableMask;   /* lowprob area */
           }   }
           assert(position == 0); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
       }
   
       /* Build Decoding table */
       {
           U32 u;
           for (u=0; u<tableSize; u++) {
               U32 const symbol = tableDecode[u].baseValue;
               U32 const nextState = symbolNext[symbol]++;
               tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
               tableDecode[u].nextState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
               assert(nbAdditionalBits[symbol] < 255);
               tableDecode[u].nbAdditionalBits = nbAdditionalBits[symbol];
               tableDecode[u].baseValue = baseValue[symbol];
           }
       }
   }
   
   /* Avoids the FORCE_INLINE of the _body() function. */
   static void ZSTD_buildFSETable_body_default(ZSTD_seqSymbol* dt,
               const short* normalizedCounter, unsigned maxSymbolValue,
               const U32* baseValue, const U8* nbAdditionalBits,
               unsigned tableLog, void* wksp, size_t wkspSize)
   {
       ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue,
               baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
   }
   
   #if DYNAMIC_BMI2
   BMI2_TARGET_ATTRIBUTE static void ZSTD_buildFSETable_body_bmi2(ZSTD_seqSymbol* dt,
               const short* normalizedCounter, unsigned maxSymbolValue,
               const U32* baseValue, const U8* nbAdditionalBits,
               unsigned tableLog, void* wksp, size_t wkspSize)
   {
       ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue,
               baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
   }
   #endif
   
   void ZSTD_buildFSETable(ZSTD_seqSymbol* dt,
               const short* normalizedCounter, unsigned maxSymbolValue,
               const U32* baseValue, const U8* nbAdditionalBits,
               unsigned tableLog, void* wksp, size_t wkspSize, int bmi2)
   {
   #if DYNAMIC_BMI2
       if (bmi2) {
           ZSTD_buildFSETable_body_bmi2(dt, normalizedCounter, maxSymbolValue,
                   baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
           return;
       }
   #endif
       (void)bmi2;
       ZSTD_buildFSETable_body_default(dt, normalizedCounter, maxSymbolValue,
               baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
   }
   
   
   /*! ZSTD_buildSeqTable() :
    * @return : nb bytes read from src,
    *           or an error code if it fails */
   static size_t ZSTD_buildSeqTable(ZSTD_seqSymbol* DTableSpace, const ZSTD_seqSymbol** DTablePtr,
                                    symbolEncodingType_e type, unsigned max, U32 maxLog,
                                    const void* src, size_t srcSize,
                                    const U32* baseValue, const U8* nbAdditionalBits,
                                    const ZSTD_seqSymbol* defaultTable, U32 flagRepeatTable,
                                    int ddictIsCold, int nbSeq, U32* wksp, size_t wkspSize,
                                    int bmi2)
   {
       switch(type)
       {
       case set_rle :
           RETURN_ERROR_IF(!srcSize, srcSize_wrong, "");
           RETURN_ERROR_IF((*(const BYTE*)src) > max, corruption_detected, "");
           {   U32 const symbol = *(const BYTE*)src;
               U32 const baseline = baseValue[symbol];
               U8 const nbBits = nbAdditionalBits[symbol];
               ZSTD_buildSeqTable_rle(DTableSpace, baseline, nbBits);
           }
           *DTablePtr = DTableSpace;
           return 1;
       case set_basic :
           *DTablePtr = defaultTable;
           return 0;
       case set_repeat:
           RETURN_ERROR_IF(!flagRepeatTable, corruption_detected, "");
           /* prefetch FSE table if used */
           if (ddictIsCold && (nbSeq > 24 /* heuristic */)) {
               const void* const pStart = *DTablePtr;
               size_t const pSize = sizeof(ZSTD_seqSymbol) * (SEQSYMBOL_TABLE_SIZE(maxLog));
               PREFETCH_AREA(pStart, pSize);
           }
           return 0;
       case set_compressed :
           {   unsigned tableLog;
               S16 norm[MaxSeq+1];
               size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize);
               RETURN_ERROR_IF(FSE_isError(headerSize), corruption_detected, "");
               RETURN_ERROR_IF(tableLog > maxLog, corruption_detected, "");
               ZSTD_buildFSETable(DTableSpace, norm, max, baseValue, nbAdditionalBits, tableLog, wksp, wkspSize, bmi2);
               *DTablePtr = DTableSpace;
               return headerSize;
           }
       default :
           assert(0);
           RETURN_ERROR(GENERIC, "impossible");
       }
   }
   
   size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr,
                                const void* src, size_t srcSize)
   {
       const BYTE* const istart = (const BYTE*)src;
       const BYTE* const iend = istart + srcSize;
       const BYTE* ip = istart;
       int nbSeq;
       DEBUGLOG(5, "ZSTD_decodeSeqHeaders");
   
       /* check */
       RETURN_ERROR_IF(srcSize < MIN_SEQUENCES_SIZE, srcSize_wrong, "");
   
       /* SeqHead */
       nbSeq = *ip++;
       if (!nbSeq) {
           *nbSeqPtr=0;
           RETURN_ERROR_IF(srcSize != 1, srcSize_wrong, "");
           return 1;
       }
       if (nbSeq > 0x7F) {
           if (nbSeq == 0xFF) {
               RETURN_ERROR_IF(ip+2 > iend, srcSize_wrong, "");
               nbSeq = MEM_readLE16(ip) + LONGNBSEQ;
               ip+=2;
           } else {
               RETURN_ERROR_IF(ip >= iend, srcSize_wrong, "");
               nbSeq = ((nbSeq-0x80)<<8) + *ip++;
           }
       }
       *nbSeqPtr = nbSeq;
   
       /* FSE table descriptors */
       RETURN_ERROR_IF(ip+1 > iend, srcSize_wrong, ""); /* minimum possible size: 1 byte for symbol encoding types */
       {   symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6);
           symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3);
           symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3);
           ip++;
   
           /* Build DTables */
           {   size_t const llhSize = ZSTD_buildSeqTable(dctx->entropy.LLTable, &dctx->LLTptr,
                                                         LLtype, MaxLL, LLFSELog,
                                                         ip, iend-ip,
                                                         LL_base, LL_bits,
                                                         LL_defaultDTable, dctx->fseEntropy,
                                                         dctx->ddictIsCold, nbSeq,
                                                         dctx->workspace, sizeof(dctx->workspace),
                                                         ZSTD_DCtx_get_bmi2(dctx));
               RETURN_ERROR_IF(ZSTD_isError(llhSize), corruption_detected, "ZSTD_buildSeqTable failed");
               ip += llhSize;
           }
   
           {   size_t const ofhSize = ZSTD_buildSeqTable(dctx->entropy.OFTable, &dctx->OFTptr,
                                                         OFtype, MaxOff, OffFSELog,
                                                         ip, iend-ip,
                                                         OF_base, OF_bits,
                                                         OF_defaultDTable, dctx->fseEntropy,
                                                         dctx->ddictIsCold, nbSeq,
                                                         dctx->workspace, sizeof(dctx->workspace),
                                                         ZSTD_DCtx_get_bmi2(dctx));
               RETURN_ERROR_IF(ZSTD_isError(ofhSize), corruption_detected, "ZSTD_buildSeqTable failed");
               ip += ofhSize;
           }
   
           {   size_t const mlhSize = ZSTD_buildSeqTable(dctx->entropy.MLTable, &dctx->MLTptr,
                                                         MLtype, MaxML, MLFSELog,
                                                         ip, iend-ip,
                                                         ML_base, ML_bits,
                                                         ML_defaultDTable, dctx->fseEntropy,
                                                         dctx->ddictIsCold, nbSeq,
                                                         dctx->workspace, sizeof(dctx->workspace),
                                                         ZSTD_DCtx_get_bmi2(dctx));
               RETURN_ERROR_IF(ZSTD_isError(mlhSize), corruption_detected, "ZSTD_buildSeqTable failed");
               ip += mlhSize;
           }
       }
   
       return ip-istart;
   }
   
   
   typedef struct {
       size_t litLength;
       size_t matchLength;
       size_t offset;
   } seq_t;
   
   typedef struct {
       size_t state;
       const ZSTD_seqSymbol* table;
   } ZSTD_fseState;
   
   typedef struct {
       BIT_DStream_t DStream;
       ZSTD_fseState stateLL;
       ZSTD_fseState stateOffb;
       ZSTD_fseState stateML;
       size_t prevOffset[ZSTD_REP_NUM];
   } seqState_t;
   
   /*! ZSTD_overlapCopy8() :
    *  Copies 8 bytes from ip to op and updates op and ip where ip <= op.
    *  If the offset is < 8 then the offset is spread to at least 8 bytes.
    *
    *  Precondition: *ip <= *op
    *  Postcondition: *op - *op >= 8
    */
   HINT_INLINE void ZSTD_overlapCopy8(BYTE** op, BYTE const** ip, size_t offset) {
       assert(*ip <= *op);
       if (offset < 8) {
           /* close range match, overlap */
           static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };   /* added */
           static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 };   /* subtracted */
           int const sub2 = dec64table[offset];
           (*op)[0] = (*ip)[0];
           (*op)[1] = (*ip)[1];
           (*op)[2] = (*ip)[2];
           (*op)[3] = (*ip)[3];
           *ip += dec32table[offset];
           ZSTD_copy4(*op+4, *ip);
           *ip -= sub2;
       } else {
           ZSTD_copy8(*op, *ip);
       }
       *ip += 8;
       *op += 8;
       assert(*op - *ip >= 8);
   }
   
   /*! ZSTD_safecopy() :
    *  Specialized version of memcpy() that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer
    *  and write up to 16 bytes past oend_w (op >= oend_w is allowed).
    *  This function is only called in the uncommon case where the sequence is near the end of the block. It
    *  should be fast for a single long sequence, but can be slow for several short sequences.
    *
    *  @param ovtype controls the overlap detection
    *         - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart.
    *         - ZSTD_overlap_src_before_dst: The src and dst may overlap and may be any distance apart.
    *           The src buffer must be before the dst buffer.
    */
   static void ZSTD_safecopy(BYTE* op, const BYTE* const oend_w, BYTE const* ip, ptrdiff_t length, ZSTD_overlap_e ovtype) {
       ptrdiff_t const diff = op - ip;
       BYTE* const oend = op + length;
   
       assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8 || op >= oend_w)) ||
              (ovtype == ZSTD_overlap_src_before_dst && diff >= 0));
   
       if (length < 8) {
           /* Handle short lengths. */
           while (op < oend) *op++ = *ip++;
           return;
       }
       if (ovtype == ZSTD_overlap_src_before_dst) {
           /* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */
           assert(length >= 8);
           ZSTD_overlapCopy8(&op, &ip, diff);
           length -= 8;
           assert(op - ip >= 8);
           assert(op <= oend);
       }
   
       if (oend <= oend_w) {
           /* No risk of overwrite. */
           ZSTD_wildcopy(op, ip, length, ovtype);
           return;
       }
       if (op <= oend_w) {
           /* Wildcopy until we get close to the end. */
           assert(oend > oend_w);
           ZSTD_wildcopy(op, ip, oend_w - op, ovtype);
           ip += oend_w - op;
           op += oend_w - op;
       }
       /* Handle the leftovers. */
       while (op < oend) *op++ = *ip++;
   }
   
   /* ZSTD_safecopyDstBeforeSrc():
    * This version allows overlap with dst before src, or handles the non-overlap case with dst after src
    * Kept separate from more common ZSTD_safecopy case to avoid performance impact to the safecopy common case */
   static void ZSTD_safecopyDstBeforeSrc(BYTE* op, BYTE const* ip, ptrdiff_t length) {
       ptrdiff_t const diff = op - ip;
       BYTE* const oend = op + length;
   
       if (length < 8 || diff > -8) {
           /* Handle short lengths, close overlaps, and dst not before src. */
           while (op < oend) *op++ = *ip++;
           return;
       }
   
       if (op <= oend - WILDCOPY_OVERLENGTH && diff < -WILDCOPY_VECLEN) {
           ZSTD_wildcopy(op, ip, oend - WILDCOPY_OVERLENGTH - op, ZSTD_no_overlap);
           ip += oend - WILDCOPY_OVERLENGTH - op;
           op += oend - WILDCOPY_OVERLENGTH - op;
       }
   
       /* Handle the leftovers. */
       while (op < oend) *op++ = *ip++;
   }
   
   /* ZSTD_execSequenceEnd():
    * This version handles cases that are near the end of the output buffer. It requires
    * more careful checks to make sure there is no overflow. By separating out these hard
    * and unlikely cases, we can speed up the common cases.
    *
    * NOTE: This function needs to be fast for a single long sequence, but doesn't need
    * to be optimized for many small sequences, since those fall into ZSTD_execSequence().
    */
   FORCE_NOINLINE
   size_t ZSTD_execSequenceEnd(BYTE* op,
       BYTE* const oend, seq_t sequence,
       const BYTE** litPtr, const BYTE* const litLimit,
       const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
   {
       BYTE* const oLitEnd = op + sequence.litLength;
       size_t const sequenceLength = sequence.litLength + sequence.matchLength;
       const BYTE* const iLitEnd = *litPtr + sequence.litLength;
       const BYTE* match = oLitEnd - sequence.offset;
       BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
   
       /* bounds checks : careful of address space overflow in 32-bit mode */
       RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer");
       RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer");
       assert(op < op + sequenceLength);
       assert(oLitEnd < op + sequenceLength);
   
       /* copy literals */
       ZSTD_safecopy(op, oend_w, *litPtr, sequence.litLength, ZSTD_no_overlap);
       op = oLitEnd;
       *litPtr = iLitEnd;
   
       /* copy Match */
       if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
           /* offset beyond prefix */
           RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, "");
           match = dictEnd - (prefixStart - match);
           if (match + sequence.matchLength <= dictEnd) {
               ZSTD_memmove(oLitEnd, match, sequence.matchLength);
               return sequenceLength;
           }
           /* span extDict & currentPrefixSegment */
           {   size_t const length1 = dictEnd - match;
           ZSTD_memmove(oLitEnd, match, length1);
           op = oLitEnd + length1;
           sequence.matchLength -= length1;
           match = prefixStart;
           }
       }
       ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst);
       return sequenceLength;
   }
   
   /* ZSTD_execSequenceEndSplitLitBuffer():
    * This version is intended to be used during instances where the litBuffer is still split.  It is kept separate to avoid performance impact for the good case.
    */
   FORCE_NOINLINE
   size_t ZSTD_execSequenceEndSplitLitBuffer(BYTE* op,
       BYTE* const oend, const BYTE* const oend_w, seq_t sequence,
       const BYTE** litPtr, const BYTE* const litLimit,
       const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
   {
       BYTE* const oLitEnd = op + sequence.litLength;
       size_t const sequenceLength = sequence.litLength + sequence.matchLength;
       const BYTE* const iLitEnd = *litPtr + sequence.litLength;
       const BYTE* match = oLitEnd - sequence.offset;
   
   
       /* bounds checks : careful of address space overflow in 32-bit mode */
       RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer");
       RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer");
       assert(op < op + sequenceLength);
       assert(oLitEnd < op + sequenceLength);
   
       /* copy literals */
       RETURN_ERROR_IF(op > *litPtr && op < *litPtr + sequence.litLength, dstSize_tooSmall, "output should not catch up to and overwrite literal buffer");
       ZSTD_safecopyDstBeforeSrc(op, *litPtr, sequence.litLength);
       op = oLitEnd;
       *litPtr = iLitEnd;
   
       /* copy Match */
       if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
           /* offset beyond prefix */
           RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, "");
           match = dictEnd - (prefixStart - match);
           if (match + sequence.matchLength <= dictEnd) {
               ZSTD_memmove(oLitEnd, match, sequence.matchLength);
               return sequenceLength;
           }
           /* span extDict & currentPrefixSegment */
           {   size_t const length1 = dictEnd - match;
           ZSTD_memmove(oLitEnd, match, length1);
           op = oLitEnd + length1;
           sequence.matchLength -= length1;
           match = prefixStart;
           }
       }
       ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst);
       return sequenceLength;
   }
   
   HINT_INLINE
   size_t ZSTD_execSequence(BYTE* op,
       BYTE* const oend, seq_t sequence,
       const BYTE** litPtr, const BYTE* const litLimit,
       const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
   {
       BYTE* const oLitEnd = op + sequence.litLength;
       size_t const sequenceLength = sequence.litLength + sequence.matchLength;
       BYTE* const oMatchEnd = op + sequenceLength;   /* risk : address space overflow (32-bits) */
       BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;   /* risk : address space underflow on oend=NULL */
       const BYTE* const iLitEnd = *litPtr + sequence.litLength;
       const BYTE* match = oLitEnd - sequence.offset;
   
       assert(op != NULL /* Precondition */);
       assert(oend_w < oend /* No underflow */);
       /* Handle edge cases in a slow path:
        *   - Read beyond end of literals
        *   - Match end is within WILDCOPY_OVERLIMIT of oend
        *   - 32-bit mode and the match length overflows
        */
       if (UNLIKELY(
           iLitEnd > litLimit ||
           oMatchEnd > oend_w ||
           (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH)))
           return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
   
       /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */
       assert(op <= oLitEnd /* No overflow */);
       assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */);
       assert(oMatchEnd <= oend /* No underflow */);
       assert(iLitEnd <= litLimit /* Literal length is in bounds */);
       assert(oLitEnd <= oend_w /* Can wildcopy literals */);
       assert(oMatchEnd <= oend_w /* Can wildcopy matches */);
   
       /* Copy Literals:
        * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9.
        * We likely don't need the full 32-byte wildcopy.
        */
       assert(WILDCOPY_OVERLENGTH >= 16);
       ZSTD_copy16(op, (*litPtr));
       if (UNLIKELY(sequence.litLength > 16)) {
           ZSTD_wildcopy(op + 16, (*litPtr) + 16, sequence.litLength - 16, ZSTD_no_overlap);
       }
       op = oLitEnd;
       *litPtr = iLitEnd;   /* update for next sequence */
   
       /* Copy Match */
       if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
          /* offset beyond prefix -> go into extDict */
          RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, "");
          match = dictEnd + (match - prefixStart);
          if (match + sequence.matchLength <= dictEnd) {
              ZSTD_memmove(oLitEnd, match, sequence.matchLength);
              return sequenceLength;
          }
          /* span extDict & currentPrefixSegment */
          {   size_t const length1 = dictEnd - match;
          ZSTD_memmove(oLitEnd, match, length1);
          op = oLitEnd + length1;
          sequence.matchLength -= length1;
          match = prefixStart;
          }
      }
      /* Match within prefix of 1 or more bytes */
      assert(op <= oMatchEnd);
      assert(oMatchEnd <= oend_w);
      assert(match >= prefixStart);
      assert(sequence.matchLength >= 1);
  
      /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy
       * without overlap checking.
       */
      if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) {
          /* We bet on a full wildcopy for matches, since we expect matches to be
           * longer than literals (in general). In silesia, ~10% of matches are longer
           * than 16 bytes.
           */
          ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap);
          return sequenceLength;
      }
      assert(sequence.offset < WILDCOPY_VECLEN);
  
      /* Copy 8 bytes and spread the offset to be >= 8. */
      ZSTD_overlapCopy8(&op, &match, sequence.offset);
  
      /* If the match length is > 8 bytes, then continue with the wildcopy. */
      if (sequence.matchLength > 8) {
          assert(op < oMatchEnd);
          ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength - 8, ZSTD_overlap_src_before_dst);
      }
      return sequenceLength;
  }
  
  HINT_INLINE
  size_t ZSTD_execSequenceSplitLitBuffer(BYTE* op,
      BYTE* const oend, const BYTE* const oend_w, seq_t sequence,
      const BYTE** litPtr, const BYTE* const litLimit,
      const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
  {
      BYTE* const oLitEnd = op + sequence.litLength;
      size_t const sequenceLength = sequence.litLength + sequence.matchLength;
      BYTE* const oMatchEnd = op + sequenceLength;   /* risk : address space overflow (32-bits) */
      const BYTE* const iLitEnd = *litPtr + sequence.litLength;
      const BYTE* match = oLitEnd - sequence.offset;
  
      assert(op != NULL /* Precondition */);
      assert(oend_w < oend /* No underflow */);
      /* Handle edge cases in a slow path:
       *   - Read beyond end of literals
       *   - Match end is within WILDCOPY_OVERLIMIT of oend
       *   - 32-bit mode and the match length overflows
       */
      if (UNLIKELY(
              iLitEnd > litLimit ||
              oMatchEnd > oend_w ||
              (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH)))
          return ZSTD_execSequenceEndSplitLitBuffer(op, oend, oend_w, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
  
      /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */
      assert(op <= oLitEnd /* No overflow */);
      assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */);
      assert(oMatchEnd <= oend /* No underflow */);
      assert(iLitEnd <= litLimit /* Literal length is in bounds */);
      assert(oLitEnd <= oend_w /* Can wildcopy literals */);
      assert(oMatchEnd <= oend_w /* Can wildcopy matches */);
  
      /* Copy Literals:
       * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9.
       * We likely don't need the full 32-byte wildcopy.
       */
      assert(WILDCOPY_OVERLENGTH >= 16);
      ZSTD_copy16(op, (*litPtr));
      if (UNLIKELY(sequence.litLength > 16)) {
          ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap);
      }
      op = oLitEnd;
      *litPtr = iLitEnd;   /* update for next sequence */
  
      /* Copy Match */
      if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
          /* offset beyond prefix -> go into extDict */
          RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, "");
          match = dictEnd + (match - prefixStart);
          if (match + sequence.matchLength <= dictEnd) {
              ZSTD_memmove(oLitEnd, match, sequence.matchLength);
              return sequenceLength;
          }
          /* span extDict & currentPrefixSegment */
          {   size_t const length1 = dictEnd - match;
              ZSTD_memmove(oLitEnd, match, length1);
              op = oLitEnd + length1;
              sequence.matchLength -= length1;
              match = prefixStart;
      }   }
      /* Match within prefix of 1 or more bytes */
      assert(op <= oMatchEnd);
      assert(oMatchEnd <= oend_w);
      assert(match >= prefixStart);
      assert(sequence.matchLength >= 1);
  
      /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy
       * without overlap checking.
       */
      if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) {
          /* We bet on a full wildcopy for matches, since we expect matches to be
           * longer than literals (in general). In silesia, ~10% of matches are longer
           * than 16 bytes.
           */
          ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap);
          return sequenceLength;
      }
      assert(sequence.offset < WILDCOPY_VECLEN);
  
      /* Copy 8 bytes and spread the offset to be >= 8. */
      ZSTD_overlapCopy8(&op, &match, sequence.offset);
  
      /* If the match length is > 8 bytes, then continue with the wildcopy. */
      if (sequence.matchLength > 8) {
          assert(op < oMatchEnd);
          ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst);
      }
      return sequenceLength;
  }
  
  
  static void
  ZSTD_initFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, const ZSTD_seqSymbol* dt)
  {
      const void* ptr = dt;
      const ZSTD_seqSymbol_header* const DTableH = (const ZSTD_seqSymbol_header*)ptr;
      DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
      DEBUGLOG(6, "ZSTD_initFseState : val=%u using %u bits",
                  (U32)DStatePtr->state, DTableH->tableLog);
      BIT_reloadDStream(bitD);
      DStatePtr->table = dt + 1;
  }
  
  FORCE_INLINE_TEMPLATE void
  ZSTD_updateFseStateWithDInfo(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, U16 nextState, U32 nbBits)
  {
      size_t const lowBits = BIT_readBits(bitD, nbBits);
      DStatePtr->state = nextState + lowBits;
  }
  
  /* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum
   * offset bits. But we can only read at most (STREAM_ACCUMULATOR_MIN_32 - 1)
   * bits before reloading. This value is the maximum number of bytes we read
   * after reloading when we are decoding long offsets.
   */
  #define LONG_OFFSETS_MAX_EXTRA_BITS_32                       \
      (ZSTD_WINDOWLOG_MAX_32 > STREAM_ACCUMULATOR_MIN_32       \
          ? ZSTD_WINDOWLOG_MAX_32 - STREAM_ACCUMULATOR_MIN_32  \
          : 0)
  
  typedef enum { ZSTD_lo_isRegularOffset, ZSTD_lo_isLongOffset=1 } ZSTD_longOffset_e;
  
  FORCE_INLINE_TEMPLATE seq_t
  ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets)
  {
      seq_t seq;
      const ZSTD_seqSymbol* const llDInfo = seqState->stateLL.table + seqState->stateLL.state;
      const ZSTD_seqSymbol* const mlDInfo = seqState->stateML.table + seqState->stateML.state;
      const ZSTD_seqSymbol* const ofDInfo = seqState->stateOffb.table + seqState->stateOffb.state;
      seq.matchLength = mlDInfo->baseValue;
      seq.litLength = llDInfo->baseValue;
      {   U32 const ofBase = ofDInfo->baseValue;
          BYTE const llBits = llDInfo->nbAdditionalBits;
          BYTE const mlBits = mlDInfo->nbAdditionalBits;
          BYTE const ofBits = ofDInfo->nbAdditionalBits;
          BYTE const totalBits = llBits+mlBits+ofBits;
  
          U16 const llNext = llDInfo->nextState;
          U16 const mlNext = mlDInfo->nextState;
          U16 const ofNext = ofDInfo->nextState;
          U32 const llnbBits = llDInfo->nbBits;
          U32 const mlnbBits = mlDInfo->nbBits;
          U32 const ofnbBits = ofDInfo->nbBits;
          /*
           * As gcc has better branch and block analyzers, sometimes it is only
           * valuable to mark likelyness for clang, it gives around 3-4% of
           * performance.
           */
  
          /* sequence */
          {   size_t offset;
      #if defined(__clang__)
              if (LIKELY(ofBits > 1)) {
      #else
              if (ofBits > 1) {
      #endif
                  ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1);
                  ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5);
                  assert(ofBits <= MaxOff);
                  if (MEM_32bits() && longOffsets && (ofBits >= STREAM_ACCUMULATOR_MIN_32)) {
                      U32 const extraBits = ofBits - MIN(ofBits, 32 - seqState->DStream.bitsConsumed);
                      offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits);
                      BIT_reloadDStream(&seqState->DStream);
                      if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits);
                      assert(extraBits <= LONG_OFFSETS_MAX_EXTRA_BITS_32);   /* to avoid another reload */
                  } else {
                      offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/);   /* <=  (ZSTD_WINDOWLOG_MAX-1) bits */
                      if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
                  }
                  seqState->prevOffset[2] = seqState->prevOffset[1];
                  seqState->prevOffset[1] = seqState->prevOffset[0];
                  seqState->prevOffset[0] = offset;
              } else {
                  U32 const ll0 = (llDInfo->baseValue == 0);
                  if (LIKELY((ofBits == 0))) {
                      offset = seqState->prevOffset[ll0];
                      seqState->prevOffset[1] = seqState->prevOffset[!ll0];
                      seqState->prevOffset[0] = offset;
                  } else {
                      offset = ofBase + ll0 + BIT_readBitsFast(&seqState->DStream, 1);
                      {   size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
                          temp += !temp;   /* 0 is not valid; input is corrupted; force offset to 1 */
                          if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
                          seqState->prevOffset[1] = seqState->prevOffset[0];
                          seqState->prevOffset[0] = offset = temp;
              }   }   }
              seq.offset = offset;
          }
  
      #if defined(__clang__)
          if (UNLIKELY(mlBits > 0))
      #else
          if (mlBits > 0)
      #endif
              seq.matchLength += BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/);
  
          if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32))
              BIT_reloadDStream(&seqState->DStream);
          if (MEM_64bits() && UNLIKELY(totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog)))
              BIT_reloadDStream(&seqState->DStream);
          /* Ensure there are enough bits to read the rest of data in 64-bit mode. */
          ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64);
  
      #if defined(__clang__)
          if (UNLIKELY(llBits > 0))
      #else
          if (llBits > 0)
      #endif
              seq.litLength += BIT_readBitsFast(&seqState->DStream, llBits/*>0*/);
  
          if (MEM_32bits())
              BIT_reloadDStream(&seqState->DStream);
  
          DEBUGLOG(6, "seq: litL=%u, matchL=%u, offset=%u",
                      (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset);
  
          ZSTD_updateFseStateWithDInfo(&seqState->stateLL, &seqState->DStream, llNext, llnbBits);    /* <=  9 bits */
          ZSTD_updateFseStateWithDInfo(&seqState->stateML, &seqState->DStream, mlNext, mlnbBits);    /* <=  9 bits */
          if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);    /* <= 18 bits */
          ZSTD_updateFseStateWithDInfo(&seqState->stateOffb, &seqState->DStream, ofNext, ofnbBits);  /* <=  8 bits */
      }
  
      return seq;
  }
  
  #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
  MEM_STATIC int ZSTD_dictionaryIsActive(ZSTD_DCtx const* dctx, BYTE const* prefixStart, BYTE const* oLitEnd)
  {
      size_t const windowSize = dctx->fParams.windowSize;
      /* No dictionary used. */
      if (dctx->dictContentEndForFuzzing == NULL) return 0;
      /* Dictionary is our prefix. */
      if (prefixStart == dctx->dictContentBeginForFuzzing) return 1;
      /* Dictionary is not our ext-dict. */
      if (dctx->dictEnd != dctx->dictContentEndForFuzzing) return 0;
      /* Dictionary is not within our window size. */
      if ((size_t)(oLitEnd - prefixStart) >= windowSize) return 0;
      /* Dictionary is active. */
      return 1;
  }
  
  MEM_STATIC void ZSTD_assertValidSequence(
          ZSTD_DCtx const* dctx,
          BYTE const* op, BYTE const* oend,
          seq_t const seq,
          BYTE const* prefixStart, BYTE const* virtualStart)
  {
  #if DEBUGLEVEL >= 1
      size_t const windowSize = dctx->fParams.windowSize;
      size_t const sequenceSize = seq.litLength + seq.matchLength;
      BYTE const* const oLitEnd = op + seq.litLength;
      DEBUGLOG(6, "Checking sequence: litL=%u matchL=%u offset=%u",
              (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset);
      assert(op <= oend);
      assert((size_t)(oend - op) >= sequenceSize);
      assert(sequenceSize <= ZSTD_BLOCKSIZE_MAX);
      if (ZSTD_dictionaryIsActive(dctx, prefixStart, oLitEnd)) {
          size_t const dictSize = (size_t)((char const*)dctx->dictContentEndForFuzzing - (char const*)dctx->dictContentBeginForFuzzing);
          /* Offset must be within the dictionary. */
          assert(seq.offset <= (size_t)(oLitEnd - virtualStart));
          assert(seq.offset <= windowSize + dictSize);
      } else {
          /* Offset must be within our window. */
          assert(seq.offset <= windowSize);
      }
  #else
      (void)dctx, (void)op, (void)oend, (void)seq, (void)prefixStart, (void)virtualStart;
  #endif
  }
  #endif
  
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
  
  
  FORCE_INLINE_TEMPLATE size_t
  DONT_VECTORIZE
  ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
                                 void* dst, size_t maxDstSize,
                           const void* seqStart, size_t seqSize, int nbSeq,
                           const ZSTD_longOffset_e isLongOffset,
                           const int frame)
  {
      const BYTE* ip = (const BYTE*)seqStart;
      const BYTE* const iend = ip + seqSize;
      BYTE* const ostart = (BYTE*)dst;
      BYTE* const oend = ostart + maxDstSize;
      BYTE* op = ostart;
      const BYTE* litPtr = dctx->litPtr;
      const BYTE* litBufferEnd = dctx->litBufferEnd;
      const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart);
      const BYTE* const vBase = (const BYTE*) (dctx->virtualStart);
      const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
      DEBUGLOG(5, "ZSTD_decompressSequences_bodySplitLitBuffer");
      (void)frame;
  
      /* Regen sequences */
      if (nbSeq) {
          seqState_t seqState;
          dctx->fseEntropy = 1;
          { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
          RETURN_ERROR_IF(
              ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)),
              corruption_detected, "");
          ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
          ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
          ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
          assert(dst != NULL);
  
          ZSTD_STATIC_ASSERT(
                  BIT_DStream_unfinished < BIT_DStream_completed &&
                  BIT_DStream_endOfBuffer < BIT_DStream_completed &&
                  BIT_DStream_completed < BIT_DStream_overflow);
  
          /* decompress without overrunning litPtr begins */
          {
              seq_t sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
              /* Align the decompression loop to 32 + 16 bytes.
                  *
                  * zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression
                  * speed swings based on the alignment of the decompression loop. This
                  * performance swing is caused by parts of the decompression loop falling
                  * out of the DSB. The entire decompression loop should fit in the DSB,
                  * when it can't we get much worse performance. You can measure if you've
                  * hit the good case or the bad case with this perf command for some
                  * compressed file test.zst:
                  *
                  *   perf stat -e cycles -e instructions -e idq.all_dsb_cycles_any_uops \
                  *             -e idq.all_mite_cycles_any_uops -- ./zstd -tq test.zst
                  *
                  * If you see most cycles served out of the MITE you've hit the bad case.
                  * If you see most cycles served out of the DSB you've hit the good case.
                  * If it is pretty even then you may be in an okay case.
                  *
                  * This issue has been reproduced on the following CPUs:
                  *   - Kabylake: Macbook Pro (15-inch, 2019) 2.4 GHz Intel Core i9
                  *               Use Instruments->Counters to get DSB/MITE cycles.
                  *               I never got performance swings, but I was able to
                  *               go from the good case of mostly DSB to half of the
                  *               cycles served from MITE.
                  *   - Coffeelake: Intel i9-9900k
                  *   - Coffeelake: Intel i7-9700k
                  *
                  * I haven't been able to reproduce the instability or DSB misses on any
                  * of the following CPUS:
                  *   - Haswell
                  *   - Broadwell: Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GH
                  *   - Skylake
                  *
                  * Alignment is done for each of the three major decompression loops:
                  *   - ZSTD_decompressSequences_bodySplitLitBuffer - presplit section of the literal buffer
                  *   - ZSTD_decompressSequences_bodySplitLitBuffer - postsplit section of the literal buffer
                  *   - ZSTD_decompressSequences_body
                  * Alignment choices are made to minimize large swings on bad cases and influence on performance
                  * from changes external to this code, rather than to overoptimize on the current commit.
                  *
                  * If you are seeing performance stability this script can help test.
                  * It tests on 4 commits in zstd where I saw performance change.
                  *
                  *   https://gist.github.com/terrelln/9889fc06a423fd5ca6e99351564473f4
                  */
  #if defined(__GNUC__) && defined(__x86_64__)
              __asm__(".p2align 6");
  #  if __GNUC__ >= 7
              /* good for gcc-7, gcc-9, and gcc-11 */
              __asm__("nop");
              __asm__(".p2align 5");
              __asm__("nop");
              __asm__(".p2align 4");
  #    if __GNUC__ == 8 || __GNUC__ == 10
              /* good for gcc-8 and gcc-10 */
              __asm__("nop");
              __asm__(".p2align 3");
  #    endif
  #  endif
  #endif
  
              /* Handle the initial state where litBuffer is currently split between dst and litExtraBuffer */
              for (; litPtr + sequence.litLength <= dctx->litBufferEnd; ) {
                  size_t const oneSeqSize = ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence.litLength - WILDCOPY_OVERLENGTH, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
                  assert(!ZSTD_isError(oneSeqSize));
                  if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
  #endif
                  if (UNLIKELY(ZSTD_isError(oneSeqSize)))
                      return oneSeqSize;
                  DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
                  op += oneSeqSize;
                  if (UNLIKELY(!--nbSeq))
                      break;
                  BIT_reloadDStream(&(seqState.DStream));
                  sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
              }
  
              /* If there are more sequences, they will need to read literals from litExtraBuffer; copy over the remainder from dst and update litPtr and litEnd */
              if (nbSeq > 0) {
                  const size_t leftoverLit = dctx->litBufferEnd - litPtr;
                  if (leftoverLit)
                  {
                      RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer");
                      ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit);
                      sequence.litLength -= leftoverLit;
                      op += leftoverLit;
                  }
                  litPtr = dctx->litExtraBuffer;
                  litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
                  dctx->litBufferLocation = ZSTD_not_in_dst;
                  {
                      size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
                      assert(!ZSTD_isError(oneSeqSize));
                      if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
  #endif
                      if (UNLIKELY(ZSTD_isError(oneSeqSize)))
                          return oneSeqSize;
                      DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
                      op += oneSeqSize;
                      if (--nbSeq)
                          BIT_reloadDStream(&(seqState.DStream));
                  }
              }
          }
  
          if (nbSeq > 0) /* there is remaining lit from extra buffer */
          {
  
  #if defined(__GNUC__) && defined(__x86_64__)
              __asm__(".p2align 6");
              __asm__("nop");
  #  if __GNUC__ != 7
              /* worse for gcc-7 better for gcc-8, gcc-9, and gcc-10 and clang */
              __asm__(".p2align 4");
              __asm__("nop");
              __asm__(".p2align 3");
  #  elif __GNUC__ >= 11
              __asm__(".p2align 3");
  #  else
              __asm__(".p2align 5");
              __asm__("nop");
              __asm__(".p2align 3");
  #  endif
  #endif
  
              for (; ; ) {
                  seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
                  size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
                  assert(!ZSTD_isError(oneSeqSize));
                  if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
  #endif
                  if (UNLIKELY(ZSTD_isError(oneSeqSize)))
                      return oneSeqSize;
                  DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
                  op += oneSeqSize;
                  if (UNLIKELY(!--nbSeq))
                      break;
                  BIT_reloadDStream(&(seqState.DStream));
              }
          }
  
          /* check if reached exact end */
          DEBUGLOG(5, "ZSTD_decompressSequences_bodySplitLitBuffer: after decode loop, remaining nbSeq : %i", nbSeq);
          RETURN_ERROR_IF(nbSeq, corruption_detected, "");
          RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected, "");
          /* save reps for next block */
          { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
      }
  
      /* last literal segment */
      if (dctx->litBufferLocation == ZSTD_split)  /* split hasn't been reached yet, first get dst then copy litExtraBuffer */
      {
          size_t const lastLLSize = litBufferEnd - litPtr;
          RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, "");
          if (op != NULL) {
              ZSTD_memmove(op, litPtr, lastLLSize);
              op += lastLLSize;
          }
          litPtr = dctx->litExtraBuffer;
          litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
          dctx->litBufferLocation = ZSTD_not_in_dst;
      }
      {   size_t const lastLLSize = litBufferEnd - litPtr;
          RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
          if (op != NULL) {
              ZSTD_memcpy(op, litPtr, lastLLSize);
              op += lastLLSize;
          }
      }
  
      return op-ostart;
  }
  
  FORCE_INLINE_TEMPLATE size_t
  DONT_VECTORIZE
  ZSTD_decompressSequences_body(ZSTD_DCtx* dctx,
      void* dst, size_t maxDstSize,
      const void* seqStart, size_t seqSize, int nbSeq,
      const ZSTD_longOffset_e isLongOffset,
      const int frame)
  {
      const BYTE* ip = (const BYTE*)seqStart;
      const BYTE* const iend = ip + seqSize;
      BYTE* const ostart = (BYTE*)dst;
      BYTE* const oend = dctx->litBufferLocation == ZSTD_not_in_dst ? ostart + maxDstSize : dctx->litBuffer;
      BYTE* op = ostart;
      const BYTE* litPtr = dctx->litPtr;
      const BYTE* const litEnd = litPtr + dctx->litSize;
      const BYTE* const prefixStart = (const BYTE*)(dctx->prefixStart);
      const BYTE* const vBase = (const BYTE*)(dctx->virtualStart);
      const BYTE* const dictEnd = (const BYTE*)(dctx->dictEnd);
      DEBUGLOG(5, "ZSTD_decompressSequences_body");
      (void)frame;
  
      /* Regen sequences */
      if (nbSeq) {
          seqState_t seqState;
          dctx->fseEntropy = 1;
          { U32 i; for (i = 0; i < ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
          RETURN_ERROR_IF(
              ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend - ip)),
              corruption_detected, "");
          ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
          ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
          ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
          assert(dst != NULL);
  
          ZSTD_STATIC_ASSERT(
              BIT_DStream_unfinished < BIT_DStream_completed &&
              BIT_DStream_endOfBuffer < BIT_DStream_completed &&
              BIT_DStream_completed < BIT_DStream_overflow);
  
  #if defined(__GNUC__) && defined(__x86_64__)
              __asm__(".p2align 6");
              __asm__("nop");
  #  if __GNUC__ >= 7
              __asm__(".p2align 5");
              __asm__("nop");
              __asm__(".p2align 3");
  #  else
              __asm__(".p2align 4");
              __asm__("nop");
              __asm__(".p2align 3");
  #  endif
  #endif
  
          for ( ; ; ) {
              seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
              size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
              assert(!ZSTD_isError(oneSeqSize));
              if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
  #endif
              if (UNLIKELY(ZSTD_isError(oneSeqSize)))
                  return oneSeqSize;
              DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
              op += oneSeqSize;
              if (UNLIKELY(!--nbSeq))
                  break;
              BIT_reloadDStream(&(seqState.DStream));
          }
  
          /* check if reached exact end */
          DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq);
          RETURN_ERROR_IF(nbSeq, corruption_detected, "");
          RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected, "");
          /* save reps for next block */
          { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
      }
  
      /* last literal segment */
      {   size_t const lastLLSize = litEnd - litPtr;
          RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
          if (op != NULL) {
              ZSTD_memcpy(op, litPtr, lastLLSize);
              op += lastLLSize;
          }
      }
  
      return op-ostart;
  }
  
  static size_t
  ZSTD_decompressSequences_default(ZSTD_DCtx* dctx,
                                   void* dst, size_t maxDstSize,
                             const void* seqStart, size_t seqSize, int nbSeq,
                             const ZSTD_longOffset_e isLongOffset,
                             const int frame)
  {
      return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  
  static size_t
  ZSTD_decompressSequencesSplitLitBuffer_default(ZSTD_DCtx* dctx,
                                                 void* dst, size_t maxDstSize,
                                           const void* seqStart, size_t seqSize, int nbSeq,
                                           const ZSTD_longOffset_e isLongOffset,
                                           const int frame)
  {
      return ZSTD_decompressSequences_bodySplitLitBuffer(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
  
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
  
  FORCE_INLINE_TEMPLATE size_t
  ZSTD_prefetchMatch(size_t prefetchPos, seq_t const sequence,
                     const BYTE* const prefixStart, const BYTE* const dictEnd)
  {
      prefetchPos += sequence.litLength;
      {   const BYTE* const matchBase = (sequence.offset > prefetchPos) ? dictEnd : prefixStart;
          const BYTE* const match = matchBase + prefetchPos - sequence.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted.
                                                                                * No consequence though : memory address is only used for prefetching, not for dereferencing */
          PREFETCH_L1(match); PREFETCH_L1(match+CACHELINE_SIZE);   /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
      }
      return prefetchPos + sequence.matchLength;
  }
  
  /* This decoding function employs prefetching
   * to reduce latency impact of cache misses.
   * It's generally employed when block contains a significant portion of long-distance matches
   * or when coupled with a "cold" dictionary */
  FORCE_INLINE_TEMPLATE size_t
  ZSTD_decompressSequencesLong_body(
                                 ZSTD_DCtx* dctx,
                                 void* dst, size_t maxDstSize,
                           const void* seqStart, size_t seqSize, int nbSeq,
                           const ZSTD_longOffset_e isLongOffset,
                           const int frame)
  {
      const BYTE* ip = (const BYTE*)seqStart;
      const BYTE* const iend = ip + seqSize;
      BYTE* const ostart = (BYTE*)dst;
      BYTE* const oend = dctx->litBufferLocation == ZSTD_in_dst ? dctx->litBuffer : ostart + maxDstSize;
      BYTE* op = ostart;
      const BYTE* litPtr = dctx->litPtr;
      const BYTE* litBufferEnd = dctx->litBufferEnd;
      const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart);
      const BYTE* const dictStart = (const BYTE*) (dctx->virtualStart);
      const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
      (void)frame;
  
      /* Regen sequences */
      if (nbSeq) {
  #define STORED_SEQS 8
  #define STORED_SEQS_MASK (STORED_SEQS-1)
  #define ADVANCED_SEQS STORED_SEQS
          seq_t sequences[STORED_SEQS];
          int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS);
          seqState_t seqState;
          int seqNb;
          size_t prefetchPos = (size_t)(op-prefixStart); /* track position relative to prefixStart */
  
          dctx->fseEntropy = 1;
          { int i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
          assert(dst != NULL);
          assert(iend >= ip);
          RETURN_ERROR_IF(
              ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)),
              corruption_detected, "");
          ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
          ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
          ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
  
          /* prepare in advance */
          for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb<seqAdvance); seqNb++) {
              seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
              prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd);
              sequences[seqNb] = sequence;
          }
          RETURN_ERROR_IF(seqNb<seqAdvance, corruption_detected, "");
  
          /* decompress without stomping litBuffer */
          for (; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb < nbSeq); seqNb++) {
              seq_t sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
              size_t oneSeqSize;
  
              if (dctx->litBufferLocation == ZSTD_split && litPtr + sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength > dctx->litBufferEnd)
              {
                  /* lit buffer is reaching split point, empty out the first buffer and transition to litExtraBuffer */
                  const size_t leftoverLit = dctx->litBufferEnd - litPtr;
                  if (leftoverLit)
                  {
                      RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer");
                      ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit);
                      sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength -= leftoverLit;
                      op += leftoverLit;
                  }
                  litPtr = dctx->litExtraBuffer;
                  litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
                  dctx->litBufferLocation = ZSTD_not_in_dst;
                  oneSeqSize = ZSTD_execSequence(op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
                  assert(!ZSTD_isError(oneSeqSize));
                  if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart);
  #endif
                  if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
  
                  prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd);
                  sequences[seqNb & STORED_SEQS_MASK] = sequence;
                  op += oneSeqSize;
              }
              else
              {
                  /* lit buffer is either wholly contained in first or second split, or not split at all*/
                  oneSeqSize = dctx->litBufferLocation == ZSTD_split ?
                      ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength - WILDCOPY_OVERLENGTH, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd) :
                      ZSTD_execSequence(op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
                  assert(!ZSTD_isError(oneSeqSize));
                  if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart);
  #endif
                  if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
  
                  prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd);
                  sequences[seqNb & STORED_SEQS_MASK] = sequence;
                  op += oneSeqSize;
              }
          }
          RETURN_ERROR_IF(seqNb<nbSeq, corruption_detected, "");
  
          /* finish queue */
          seqNb -= seqAdvance;
          for ( ; seqNb<nbSeq ; seqNb++) {
              seq_t *sequence = &(sequences[seqNb&STORED_SEQS_MASK]);
              if (dctx->litBufferLocation == ZSTD_split && litPtr + sequence->litLength > dctx->litBufferEnd)
              {
                  const size_t leftoverLit = dctx->litBufferEnd - litPtr;
                  if (leftoverLit)
                  {
                      RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer");
                      ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit);
                      sequence->litLength -= leftoverLit;
                      op += leftoverLit;
                  }
                  litPtr = dctx->litExtraBuffer;
                  litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
                  dctx->litBufferLocation = ZSTD_not_in_dst;
                  {
                      size_t const oneSeqSize = ZSTD_execSequence(op, oend, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
                      assert(!ZSTD_isError(oneSeqSize));
                      if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart);
  #endif
                      if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
                      op += oneSeqSize;
                  }
              }
              else
              {
                  size_t const oneSeqSize = dctx->litBufferLocation == ZSTD_split ?
                      ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence->litLength - WILDCOPY_OVERLENGTH, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd) :
                      ZSTD_execSequence(op, oend, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
  #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
                  assert(!ZSTD_isError(oneSeqSize));
                  if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart);
  #endif
                  if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
                  op += oneSeqSize;
              }
          }
  
          /* save reps for next block */
          { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
      }
  
      /* last literal segment */
      if (dctx->litBufferLocation == ZSTD_split)  /* first deplete literal buffer in dst, then copy litExtraBuffer */
      {
          size_t const lastLLSize = litBufferEnd - litPtr;
          RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, "");
          if (op != NULL) {
              ZSTD_memmove(op, litPtr, lastLLSize);
              op += lastLLSize;
          }
          litPtr = dctx->litExtraBuffer;
          litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
      }
      {   size_t const lastLLSize = litBufferEnd - litPtr;
          RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
          if (op != NULL) {
              ZSTD_memmove(op, litPtr, lastLLSize);
              op += lastLLSize;
          }
      }
  
      return op-ostart;
  }
  
  static size_t
  ZSTD_decompressSequencesLong_default(ZSTD_DCtx* dctx,
                                   void* dst, size_t maxDstSize,
                             const void* seqStart, size_t seqSize, int nbSeq,
                             const ZSTD_longOffset_e isLongOffset,
                             const int frame)
  {
      return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
  
  
  
  #if DYNAMIC_BMI2
  
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
  static BMI2_TARGET_ATTRIBUTE size_t
  DONT_VECTORIZE
  ZSTD_decompressSequences_bmi2(ZSTD_DCtx* dctx,
                                   void* dst, size_t maxDstSize,
                             const void* seqStart, size_t seqSize, int nbSeq,
                             const ZSTD_longOffset_e isLongOffset,
                             const int frame)
  {
      return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  static BMI2_TARGET_ATTRIBUTE size_t
  DONT_VECTORIZE
  ZSTD_decompressSequencesSplitLitBuffer_bmi2(ZSTD_DCtx* dctx,
                                   void* dst, size_t maxDstSize,
                             const void* seqStart, size_t seqSize, int nbSeq,
                             const ZSTD_longOffset_e isLongOffset,
                             const int frame)
  {
      return ZSTD_decompressSequences_bodySplitLitBuffer(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
  
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
  static BMI2_TARGET_ATTRIBUTE size_t
  ZSTD_decompressSequencesLong_bmi2(ZSTD_DCtx* dctx,
                                   void* dst, size_t maxDstSize,
                             const void* seqStart, size_t seqSize, int nbSeq,
                             const ZSTD_longOffset_e isLongOffset,
                             const int frame)
  {
      return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
  
  #endif /* DYNAMIC_BMI2 */
  
  typedef size_t (*ZSTD_decompressSequences_t)(
                              ZSTD_DCtx* dctx,
                              void* dst, size_t maxDstSize,
                              const void* seqStart, size_t seqSize, int nbSeq,
                              const ZSTD_longOffset_e isLongOffset,
                              const int frame);
  
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
  static size_t
  ZSTD_decompressSequences(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize,
                     const void* seqStart, size_t seqSize, int nbSeq,
                     const ZSTD_longOffset_e isLongOffset,
                     const int frame)
  {
      DEBUGLOG(5, "ZSTD_decompressSequences");
  #if DYNAMIC_BMI2
      if (ZSTD_DCtx_get_bmi2(dctx)) {
          return ZSTD_decompressSequences_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
      }
  #endif
      return ZSTD_decompressSequences_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  static size_t
  ZSTD_decompressSequencesSplitLitBuffer(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize,
                                   const void* seqStart, size_t seqSize, int nbSeq,
                                   const ZSTD_longOffset_e isLongOffset,
                                   const int frame)
  {
      DEBUGLOG(5, "ZSTD_decompressSequencesSplitLitBuffer");
  #if DYNAMIC_BMI2
      if (ZSTD_DCtx_get_bmi2(dctx)) {
          return ZSTD_decompressSequencesSplitLitBuffer_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
      }
  #endif
      return ZSTD_decompressSequencesSplitLitBuffer_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
  
  
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
  /* ZSTD_decompressSequencesLong() :
   * decompression function triggered when a minimum share of offsets is considered "long",
   * aka out of cache.
   * note : "long" definition seems overloaded here, sometimes meaning "wider than bitstream register", and sometimes meaning "farther than memory cache distance".
   * This function will try to mitigate main memory latency through the use of prefetching */
  static size_t
  ZSTD_decompressSequencesLong(ZSTD_DCtx* dctx,
                               void* dst, size_t maxDstSize,
                               const void* seqStart, size_t seqSize, int nbSeq,
                               const ZSTD_longOffset_e isLongOffset,
                               const int frame)
  {
      DEBUGLOG(5, "ZSTD_decompressSequencesLong");
  #if DYNAMIC_BMI2
      if (ZSTD_DCtx_get_bmi2(dctx)) {
          return ZSTD_decompressSequencesLong_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
      }
  #endif
    return ZSTD_decompressSequencesLong_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
  }
  #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
  
  
  
  #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
      !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
  /* ZSTD_getLongOffsetsShare() :
   * condition : offTable must be valid
   * @return : "share" of long offsets (arbitrarily defined as > (1<<23))
   *           compared to maximum possible of (1<<OffFSELog) */
  static unsigned
  ZSTD_getLongOffsetsShare(const ZSTD_seqSymbol* offTable)
  {
      const void* ptr = offTable;
      U32 const tableLog = ((const ZSTD_seqSymbol_header*)ptr)[0].tableLog;
      const ZSTD_seqSymbol* table = offTable + 1;
      U32 const max = 1 << tableLog;
      U32 u, total = 0;
      DEBUGLOG(5, "ZSTD_getLongOffsetsShare: (tableLog=%u)", tableLog);
  
      assert(max <= (1 << OffFSELog));  /* max not too large */
      for (u=0; u<max; u++) {
          if (table[u].nbAdditionalBits > 22) total += 1;
      }
  
      assert(tableLog <= OffFSELog);
      total <<= (OffFSELog - tableLog);  /* scale to OffFSELog */
  
      return total;
  }
  #endif
  
  size_t
  ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
                                void* dst, size_t dstCapacity,
                          const void* src, size_t srcSize, const int frame, const streaming_operation streaming)
  {   /* blockType == blockCompressed */
      const BYTE* ip = (const BYTE*)src;
      /* isLongOffset must be true if there are long offsets.
       * Offsets are long if they are larger than 2^STREAM_ACCUMULATOR_MIN.
       * We don't expect that to be the case in 64-bit mode.
       * In block mode, window size is not known, so we have to be conservative.
       * (note: but it could be evaluated from current-lowLimit)
       */
      ZSTD_longOffset_e const isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (!frame || (dctx->fParams.windowSize > (1ULL << STREAM_ACCUMULATOR_MIN))));
      DEBUGLOG(5, "ZSTD_decompressBlock_internal (size : %u)", (U32)srcSize);
  
      RETURN_ERROR_IF(srcSize >= ZSTD_BLOCKSIZE_MAX, srcSize_wrong, "");
  
      /* Decode literals section */
      {   size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize, dst, dstCapacity, streaming);
          DEBUGLOG(5, "ZSTD_decodeLiteralsBlock : %u", (U32)litCSize);
          if (ZSTD_isError(litCSize)) return litCSize;
          ip += litCSize;
          srcSize -= litCSize;
      }
  
      /* Build Decoding Tables */
      {
          /* These macros control at build-time which decompressor implementation
           * we use. If neither is defined, we do some inspection and dispatch at
           * runtime.
           */
  #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
      !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
          int usePrefetchDecoder = dctx->ddictIsCold;
  #endif
          int nbSeq;
          size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize);
          if (ZSTD_isError(seqHSize)) return seqHSize;
          ip += seqHSize;
          srcSize -= seqHSize;
  
          RETURN_ERROR_IF(dst == NULL && nbSeq > 0, dstSize_tooSmall, "NULL not handled");
  
  #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
      !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
          if ( !usePrefetchDecoder
            && (!frame || (dctx->fParams.windowSize > (1<<24)))
            && (nbSeq>ADVANCED_SEQS) ) {  /* could probably use a larger nbSeq limit */
              U32 const shareLongOffsets = ZSTD_getLongOffsetsShare(dctx->OFTptr);
              U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */
              usePrefetchDecoder = (shareLongOffsets >= minShare);
          }
  #endif
  
          dctx->ddictIsCold = 0;
  
  #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
      !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
          if (usePrefetchDecoder)
  #endif
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
              return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
  #endif
  
  #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
          /* else */
          if (dctx->litBufferLocation == ZSTD_split)
              return ZSTD_decompressSequencesSplitLitBuffer(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
          else
              return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
  #endif
      }
  }
  
  
  void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst, size_t dstSize)
  {
      if (dst != dctx->previousDstEnd && dstSize > 0) {   /* not contiguous */
          dctx->dictEnd = dctx->previousDstEnd;
          dctx->virtualStart = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->prefixStart));
          dctx->prefixStart = dst;
          dctx->previousDstEnd = dst;
      }
  }
  
  
  size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx,
                              void* dst, size_t dstCapacity,
                        const void* src, size_t srcSize)
  {
      size_t dSize;
      ZSTD_checkContinuity(dctx, dst, dstCapacity);
      dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize, /* frame */ 0, not_streaming);
      dctx->previousDstEnd = (char*)dst + dSize;
      return dSize;
  }

Cache object: f237dc2f3730c83972333d1ef688980c