diff --git a/vendor/github.com/DataDog/zstd/zstd_decompress.c b/vendor/github.com/DataDog/zstd/zstd_decompress.c
index 3ec6a1c..e42872a 100644
--- a/vendor/github.com/DataDog/zstd/zstd_decompress.c
+++ b/vendor/github.com/DataDog/zstd/zstd_decompress.c
@@ -37,7 +37,18 @@
  *  It's possible to set a different limit using ZSTD_DCtx_setMaxWindowSize().
  */
 #ifndef ZSTD_MAXWINDOWSIZE_DEFAULT
-#  define ZSTD_MAXWINDOWSIZE_DEFAULT (((U32)1 << ZSTD_WINDOWLOG_DEFAULTMAX) + 1)
+#  define ZSTD_MAXWINDOWSIZE_DEFAULT (((U32)1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT) + 1)
+#endif
+
+/*!
+ *  NO_FORWARD_PROGRESS_MAX :
+ *  maximum allowed nb of calls to ZSTD_decompressStream()
+ *  without any forward progress
+ *  (defined as: no byte read from input, and no byte flushed to output)
+ *  before triggering an error.
+ */
+#ifndef ZSTD_NO_FORWARD_PROGRESS_MAX
+#  define ZSTD_NO_FORWARD_PROGRESS_MAX 16
 #endif
 
 
@@ -45,120 +56,25 @@
 *  Dependencies
 *********************************************************/
 #include <string.h>      /* memcpy, memmove, memset */
-#include "cpu.h"
+#include "cpu.h"         /* bmi2 */
 #include "mem.h"         /* low level memory routines */
 #define FSE_STATIC_LINKING_ONLY
 #include "fse.h"
 #define HUF_STATIC_LINKING_ONLY
 #include "huf.h"
-#include "zstd_internal.h"
+#include "zstd_internal.h"  /* blockProperties_t */
+#include "zstd_decompress_internal.h"   /* ZSTD_DCtx */
+#include "zstd_ddict.h"  /* ZSTD_DDictDictContent */
+#include "zstd_decompress_block.h"   /* ZSTD_decompressBlock_internal */
 
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
 #  include "zstd_legacy.h"
 #endif
 
 
-/*-*************************************
-*  Errors
-***************************************/
-#define ZSTD_isError ERR_isError   /* for inlining */
-#define FSE_isError  ERR_isError
-#define HUF_isError  ERR_isError
-
-
-/*_*******************************************************
-*  Memory operations
-**********************************************************/
-static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); }
-
-
 /*-*************************************************************
 *   Context management
 ***************************************************************/
-typedef enum { ZSTDds_getFrameHeaderSize, ZSTDds_decodeFrameHeader,
-               ZSTDds_decodeBlockHeader, ZSTDds_decompressBlock,
-               ZSTDds_decompressLastBlock, ZSTDds_checkChecksum,
-               ZSTDds_decodeSkippableHeader, ZSTDds_skipFrame } ZSTD_dStage;
-
-typedef enum { zdss_init=0, zdss_loadHeader,
-               zdss_read, zdss_load, zdss_flush } ZSTD_dStreamStage;
-
-
-typedef struct {
-    U32 fastMode;
-    U32 tableLog;
-} ZSTD_seqSymbol_header;
-
-typedef struct {
-    U16  nextState;
-    BYTE nbAdditionalBits;
-    BYTE nbBits;
-    U32  baseValue;
-} ZSTD_seqSymbol;
-
-#define SEQSYMBOL_TABLE_SIZE(log)   (1 + (1 << (log)))
-
-typedef struct {
-    ZSTD_seqSymbol LLTable[SEQSYMBOL_TABLE_SIZE(LLFSELog)];
-    ZSTD_seqSymbol OFTable[SEQSYMBOL_TABLE_SIZE(OffFSELog)];
-    ZSTD_seqSymbol MLTable[SEQSYMBOL_TABLE_SIZE(MLFSELog)];
-    HUF_DTable hufTable[HUF_DTABLE_SIZE(HufLog)];  /* can accommodate HUF_decompress4X */
-    U32 workspace[HUF_DECOMPRESS_WORKSPACE_SIZE_U32];
-    U32 rep[ZSTD_REP_NUM];
-} ZSTD_entropyDTables_t;
-
-struct ZSTD_DCtx_s
-{
-    const ZSTD_seqSymbol* LLTptr;
-    const ZSTD_seqSymbol* MLTptr;
-    const ZSTD_seqSymbol* OFTptr;
-    const HUF_DTable* HUFptr;
-    ZSTD_entropyDTables_t entropy;
-    const void* previousDstEnd;   /* detect continuity */
-    const void* base;             /* start of current segment */
-    const void* vBase;            /* virtual start of previous segment if it was just before current one */
-    const void* dictEnd;          /* end of previous segment */
-    size_t expected;
-    ZSTD_frameHeader fParams;
-    U64 decodedSize;
-    blockType_e bType;            /* used in ZSTD_decompressContinue(), store blockType between block header decoding and block decompression stages */
-    ZSTD_dStage stage;
-    U32 litEntropy;
-    U32 fseEntropy;
-    XXH64_state_t xxhState;
-    size_t headerSize;
-    U32 dictID;
-    ZSTD_format_e format;
-    const BYTE* litPtr;
-    ZSTD_customMem customMem;
-    size_t litSize;
-    size_t rleSize;
-    size_t staticSize;
-    int bmi2;                     /* == 1 if the CPU supports BMI2 and 0 otherwise. CPU support is determined dynamically once per context lifetime. */
-
-    /* streaming */
-    ZSTD_DDict* ddictLocal;
-    const ZSTD_DDict* ddict;
-    ZSTD_dStreamStage streamStage;
-    char*  inBuff;
-    size_t inBuffSize;
-    size_t inPos;
-    size_t maxWindowSize;
-    char*  outBuff;
-    size_t outBuffSize;
-    size_t outStart;
-    size_t outEnd;
-    size_t lhSize;
-    void* legacyContext;
-    U32 previousLegacyVersion;
-    U32 legacyVersion;
-    U32 hostageByte;
-
-    /* workspace */
-    BYTE litBuffer[ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH];
-    BYTE headerBuffer[ZSTD_FRAMEHEADERSIZE_MAX];
-};  /* typedef'd to ZSTD_DCtx within "zstd.h" */
-
 size_t ZSTD_sizeof_DCtx (const ZSTD_DCtx* dctx)
 {
     if (dctx==NULL) return 0;   /* support sizeof NULL */
@@ -173,8 +89,8 @@
 static size_t ZSTD_startingInputLength(ZSTD_format_e format)
 {
     size_t const startingInputLength = (format==ZSTD_f_zstd1_magicless) ?
-                    ZSTD_frameHeaderSize_prefix - ZSTD_frameIdSize :
-                    ZSTD_frameHeaderSize_prefix;
+                    ZSTD_FRAMEHEADERSIZE_PREFIX - ZSTD_FRAMEIDSIZE :
+                    ZSTD_FRAMEHEADERSIZE_PREFIX;
     ZSTD_STATIC_ASSERT(ZSTD_FRAMEHEADERSIZE_PREFIX >= ZSTD_FRAMEIDSIZE);
     /* only supports formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless */
     assert( (format == ZSTD_f_zstd1) || (format == ZSTD_f_zstd1_magicless) );
@@ -188,10 +104,16 @@
     dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
     dctx->ddict       = NULL;
     dctx->ddictLocal  = NULL;
+    dctx->dictEnd     = NULL;
+    dctx->ddictIsCold = 0;
+    dctx->dictUses = ZSTD_dont_use;
     dctx->inBuff      = NULL;
     dctx->inBuffSize  = 0;
     dctx->outBuffSize = 0;
     dctx->streamStage = zdss_init;
+    dctx->legacyContext = NULL;
+    dctx->previousLegacyVersion = 0;
+    dctx->noForwardProgress = 0;
     dctx->bmi2 = ZSTD_cpuid_bmi2(ZSTD_cpuid());
 }
 
@@ -215,8 +137,6 @@
     {   ZSTD_DCtx* const dctx = (ZSTD_DCtx*)ZSTD_malloc(sizeof(*dctx), customMem);
         if (!dctx) return NULL;
         dctx->customMem = customMem;
-        dctx->legacyContext = NULL;
-        dctx->previousLegacyVersion = 0;
         ZSTD_initDCtx_internal(dctx);
         return dctx;
     }
@@ -228,13 +148,20 @@
     return ZSTD_createDCtx_advanced(ZSTD_defaultCMem);
 }
 
+static void ZSTD_clearDict(ZSTD_DCtx* dctx)
+{
+    ZSTD_freeDDict(dctx->ddictLocal);
+    dctx->ddictLocal = NULL;
+    dctx->ddict = NULL;
+    dctx->dictUses = ZSTD_dont_use;
+}
+
 size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx)
 {
     if (dctx==NULL) return 0;   /* support free on NULL */
-    if (dctx->staticSize) return ERROR(memory_allocation);   /* not compatible with static DCtx */
+    RETURN_ERROR_IF(dctx->staticSize, memory_allocation, "not compatible with static DCtx");
     {   ZSTD_customMem const cMem = dctx->customMem;
-        ZSTD_freeDDict(dctx->ddictLocal);
-        dctx->ddictLocal = NULL;
+        ZSTD_clearDict(dctx);
         ZSTD_free(dctx->inBuff, cMem);
         dctx->inBuff = NULL;
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
@@ -265,10 +192,10 @@
  *  Note 3 : Skippable Frame Identifiers are considered valid. */
 unsigned ZSTD_isFrame(const void* buffer, size_t size)
 {
-    if (size < ZSTD_frameIdSize) return 0;
+    if (size < ZSTD_FRAMEIDSIZE) return 0;
     {   U32 const magic = MEM_readLE32(buffer);
         if (magic == ZSTD_MAGICNUMBER) return 1;
-        if ((magic & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) return 1;
+        if ((magic & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) return 1;
     }
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
     if (ZSTD_isLegacy(buffer, size)) return 1;
@@ -284,7 +211,7 @@
 static size_t ZSTD_frameHeaderSize_internal(const void* src, size_t srcSize, ZSTD_format_e format)
 {
     size_t const minInputSize = ZSTD_startingInputLength(format);
-    if (srcSize < minInputSize) return ERROR(srcSize_wrong);
+    RETURN_ERROR_IF(srcSize < minInputSize, srcSize_wrong);
 
     {   BYTE const fhd = ((const BYTE*)src)[minInputSize-1];
         U32 const dictID= fhd & 3;
@@ -298,38 +225,41 @@
 
 /** ZSTD_frameHeaderSize() :
  *  srcSize must be >= ZSTD_frameHeaderSize_prefix.
- * @return : size of the Frame Header */
+ * @return : size of the Frame Header,
+ *           or an error code (if srcSize is too small) */
 size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize)
 {
     return ZSTD_frameHeaderSize_internal(src, srcSize, ZSTD_f_zstd1);
 }
 
 
-/** ZSTD_getFrameHeader_internal() :
+/** ZSTD_getFrameHeader_advanced() :
  *  decode Frame Header, or require larger `srcSize`.
  *  note : only works for formats ZSTD_f_zstd1 and ZSTD_f_zstd1_magicless
  * @return : 0, `zfhPtr` is correctly filled,
  *          >0, `srcSize` is too small, value is wanted `srcSize` amount,
  *           or an error code, which can be tested using ZSTD_isError() */
-static size_t ZSTD_getFrameHeader_internal(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format)
+size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format)
 {
     const BYTE* ip = (const BYTE*)src;
     size_t const minInputSize = ZSTD_startingInputLength(format);
 
+    memset(zfhPtr, 0, sizeof(*zfhPtr));   /* not strictly necessary, but static analyzer do not understand that zfhPtr is only going to be read only if return value is zero, since they are 2 different signals */
     if (srcSize < minInputSize) return minInputSize;
+    RETURN_ERROR_IF(src==NULL, GENERIC, "invalid parameter");
 
     if ( (format != ZSTD_f_zstd1_magicless)
       && (MEM_readLE32(src) != ZSTD_MAGICNUMBER) ) {
-        if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
+        if ((MEM_readLE32(src) & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
             /* skippable frame */
-            if (srcSize < ZSTD_skippableHeaderSize)
-                return ZSTD_skippableHeaderSize; /* magic number + frame length */
+            if (srcSize < ZSTD_SKIPPABLEHEADERSIZE)
+                return ZSTD_SKIPPABLEHEADERSIZE; /* magic number + frame length */
             memset(zfhPtr, 0, sizeof(*zfhPtr));
-            zfhPtr->frameContentSize = MEM_readLE32((const char *)src + ZSTD_frameIdSize);
+            zfhPtr->frameContentSize = MEM_readLE32((const char *)src + ZSTD_FRAMEIDSIZE);
             zfhPtr->frameType = ZSTD_skippableFrame;
             return 0;
         }
-        return ERROR(prefix_unknown);
+        RETURN_ERROR(prefix_unknown);
     }
 
     /* ensure there is enough `srcSize` to fully read/decode frame header */
@@ -347,14 +277,13 @@
         U64 windowSize = 0;
         U32 dictID = 0;
         U64 frameContentSize = ZSTD_CONTENTSIZE_UNKNOWN;
-        if ((fhdByte & 0x08) != 0)
-            return ERROR(frameParameter_unsupported); /* reserved bits, must be zero */
+        RETURN_ERROR_IF((fhdByte & 0x08) != 0, frameParameter_unsupported,
+                        "reserved bits, must be zero");
 
         if (!singleSegment) {
             BYTE const wlByte = ip[pos++];
             U32 const windowLog = (wlByte >> 3) + ZSTD_WINDOWLOG_ABSOLUTEMIN;
-            if (windowLog > ZSTD_WINDOWLOG_MAX)
-                return ERROR(frameParameter_windowTooLarge);
+            RETURN_ERROR_IF(windowLog > ZSTD_WINDOWLOG_MAX, frameParameter_windowTooLarge);
             windowSize = (1ULL << windowLog);
             windowSize += (windowSize >> 3) * (wlByte&7);
         }
@@ -394,7 +323,7 @@
  *           or an error code, which can be tested using ZSTD_isError() */
 size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize)
 {
-    return ZSTD_getFrameHeader_internal(zfhPtr, src, srcSize, ZSTD_f_zstd1);
+    return ZSTD_getFrameHeader_advanced(zfhPtr, src, srcSize, ZSTD_f_zstd1);
 }
 
 
@@ -421,6 +350,23 @@
     }   }
 }
 
+static size_t readSkippableFrameSize(void const* src, size_t srcSize)
+{
+    size_t const skippableHeaderSize = ZSTD_SKIPPABLEHEADERSIZE;
+    U32 sizeU32;
+
+    RETURN_ERROR_IF(srcSize < ZSTD_SKIPPABLEHEADERSIZE, srcSize_wrong);
+
+    sizeU32 = MEM_readLE32((BYTE const*)src + ZSTD_FRAMEIDSIZE);
+    RETURN_ERROR_IF((U32)(sizeU32 + ZSTD_SKIPPABLEHEADERSIZE) < sizeU32,
+                    frameParameter_unsupported);
+    {
+        size_t const skippableSize = skippableHeaderSize + sizeU32;
+        RETURN_ERROR_IF(skippableSize > srcSize, srcSize_wrong);
+        return skippableSize;
+    }
+}
+
 /** ZSTD_findDecompressedSize() :
  *  compatible with legacy mode
  *  `srcSize` must be the exact length of some number of ZSTD compressed and/or
@@ -430,18 +376,15 @@
 {
     unsigned long long totalDstSize = 0;
 
-    while (srcSize >= ZSTD_frameHeaderSize_prefix) {
+    while (srcSize >= ZSTD_FRAMEHEADERSIZE_PREFIX) {
         U32 const magicNumber = MEM_readLE32(src);
 
-        if ((magicNumber & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
-            size_t skippableSize;
-            if (srcSize < ZSTD_skippableHeaderSize)
-                return ERROR(srcSize_wrong);
-            skippableSize = MEM_readLE32((const BYTE *)src + ZSTD_frameIdSize)
-                          + ZSTD_skippableHeaderSize;
-            if (srcSize < skippableSize) {
+        if ((magicNumber & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
+            size_t const skippableSize = readSkippableFrameSize(src, srcSize);
+            if (ZSTD_isError(skippableSize)) {
                 return ZSTD_CONTENTSIZE_ERROR;
             }
+            assert(skippableSize <= srcSize);
 
             src = (const BYTE *)src + skippableSize;
             srcSize -= skippableSize;
@@ -471,9 +414,9 @@
 }
 
 /** ZSTD_getDecompressedSize() :
-*   compatible with legacy mode
-*   @return : decompressed size if known, 0 otherwise
-              note : 0 can mean any of the following :
+ *  compatible with legacy mode
+ * @return : decompressed size if known, 0 otherwise
+             note : 0 can mean any of the following :
                    - frame content is empty
                    - decompressed size field is not present in frame header
                    - frame header unknown / not supported
@@ -487,1255 +430,98 @@
 
 
 /** ZSTD_decodeFrameHeader() :
-*   `headerSize` must be the size provided by ZSTD_frameHeaderSize().
-*   @return : 0 if success, or an error code, which can be tested using ZSTD_isError() */
+ * `headerSize` must be the size provided by ZSTD_frameHeaderSize().
+ * @return : 0 if success, or an error code, which can be tested using ZSTD_isError() */
 static size_t ZSTD_decodeFrameHeader(ZSTD_DCtx* dctx, const void* src, size_t headerSize)
 {
-    size_t const result = ZSTD_getFrameHeader_internal(&(dctx->fParams), src, headerSize, dctx->format);
+    size_t const result = ZSTD_getFrameHeader_advanced(&(dctx->fParams), src, headerSize, dctx->format);
     if (ZSTD_isError(result)) return result;    /* invalid header */
-    if (result>0) return ERROR(srcSize_wrong);  /* headerSize too small */
-    if (dctx->fParams.dictID && (dctx->dictID != dctx->fParams.dictID))
-        return ERROR(dictionary_wrong);
+    RETURN_ERROR_IF(result>0, srcSize_wrong, "headerSize too small");
+#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+    /* Skip the dictID check in fuzzing mode, because it makes the search
+     * harder.
+     */
+    RETURN_ERROR_IF(dctx->fParams.dictID && (dctx->dictID != dctx->fParams.dictID),
+                    dictionary_wrong);
+#endif
     if (dctx->fParams.checksumFlag) XXH64_reset(&dctx->xxhState, 0);
     return 0;
 }
 
-
-/*-*************************************************************
- *   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)
+static ZSTD_frameSizeInfo ZSTD_errorFrameSizeInfo(size_t ret)
 {
-    if (srcSize < ZSTD_blockHeaderSize) return ERROR(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;
-        if (bpPtr->blockType == bt_reserved) return ERROR(corruption_detected);
-        return cSize;
-    }
+    ZSTD_frameSizeInfo frameSizeInfo;
+    frameSizeInfo.compressedSize = ret;
+    frameSizeInfo.decompressedBound = ZSTD_CONTENTSIZE_ERROR;
+    return frameSizeInfo;
 }
 
-
-static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity,
-                          const void* src, size_t srcSize)
+static ZSTD_frameSizeInfo ZSTD_findFrameSizeInfo(const void* src, size_t srcSize)
 {
-    if (srcSize > dstCapacity) return ERROR(dstSize_tooSmall);
-    memcpy(dst, src, srcSize);
-    return srcSize;
-}
+    ZSTD_frameSizeInfo frameSizeInfo;
+    memset(&frameSizeInfo, 0, sizeof(ZSTD_frameSizeInfo));
 
-
-static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity,
-                         const void* src, size_t srcSize,
-                               size_t regenSize)
-{
-    if (srcSize != 1) return ERROR(srcSize_wrong);
-    if (regenSize > dstCapacity) return ERROR(dstSize_tooSmall);
-    memset(dst, *(const BYTE*)src, regenSize);
-    return regenSize;
-}
-
-/*! ZSTD_decodeLiteralsBlock() :
- * @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 */
-{
-    if (srcSize < MIN_CBLOCK_SIZE) return ERROR(corruption_detected);
-
-    {   const BYTE* const istart = (const BYTE*) src;
-        symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3);
-
-        switch(litEncType)
-        {
-        case set_repeat:
-            if (dctx->litEntropy==0) return ERROR(dictionary_corrupted);
-            /* fall-through */
-        case set_compressed:
-            if (srcSize < 5) return ERROR(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);
-                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) + (istart[4] << 10);
-                    break;
-                }
-                if (litSize > ZSTD_BLOCKSIZE_MAX) return ERROR(corruption_detected);
-                if (litCSize + lhSize > srcSize) return ERROR(corruption_detected);
-
-                if (HUF_isError((litEncType==set_repeat) ?
-                                    ( singleStream ?
-                                        HUF_decompress1X_usingDTable_bmi2(dctx->litBuffer, litSize, istart+lhSize, litCSize, dctx->HUFptr, dctx->bmi2) :
-                                        HUF_decompress4X_usingDTable_bmi2(dctx->litBuffer, litSize, istart+lhSize, litCSize, dctx->HUFptr, dctx->bmi2) ) :
-                                    ( singleStream ?
-                                        HUF_decompress1X2_DCtx_wksp_bmi2(dctx->entropy.hufTable, dctx->litBuffer, litSize, istart+lhSize, litCSize,
-                                                                         dctx->entropy.workspace, sizeof(dctx->entropy.workspace), dctx->bmi2) :
-                                        HUF_decompress4X_hufOnly_wksp_bmi2(dctx->entropy.hufTable, dctx->litBuffer, litSize, istart+lhSize, litCSize,
-                                                                           dctx->entropy.workspace, sizeof(dctx->entropy.workspace), dctx->bmi2))))
-                    return ERROR(corruption_detected);
-
-                dctx->litPtr = dctx->litBuffer;
-                dctx->litSize = litSize;
-                dctx->litEntropy = 1;
-                if (litEncType==set_compressed) dctx->HUFptr = dctx->entropy.hufTable;
-                memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH);
-                return litCSize + lhSize;
-            }
-
-        case set_basic:
-            {   size_t litSize, lhSize;
-                U32 const lhlCode = ((istart[0]) >> 2) & 3;
-                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;
-                }
-
-                if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) {  /* risk reading beyond src buffer with wildcopy */
-                    if (litSize+lhSize > srcSize) return ERROR(corruption_detected);
-                    memcpy(dctx->litBuffer, istart+lhSize, litSize);
-                    dctx->litPtr = dctx->litBuffer;
-                    dctx->litSize = litSize;
-                    memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH);
-                    return lhSize+litSize;
-                }
-                /* direct reference into compressed stream */
-                dctx->litPtr = istart+lhSize;
-                dctx->litSize = litSize;
-                return lhSize+litSize;
-            }
-
-        case set_rle:
-            {   U32 const lhlCode = ((istart[0]) >> 2) & 3;
-                size_t litSize, lhSize;
-                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;
-                    if (srcSize<4) return ERROR(corruption_detected);   /* srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4 */
-                    break;
-                }
-                if (litSize > ZSTD_BLOCKSIZE_MAX) return ERROR(corruption_detected);
-                memset(dctx->litBuffer, istart[lhSize], litSize + WILDCOPY_OVERLENGTH);
-                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/master/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, U32 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 = (BYTE)nbAddBits;
-    cell->baseValue = baseValue;
-}
-
-
-/* ZSTD_buildFSETable() :
- * generate FSE decoding table for one symbol (ll, ml or off) */
-static void
-ZSTD_buildFSETable(ZSTD_seqSymbol* dt,
-    const short* normalizedCounter, unsigned maxSymbolValue,
-    const U32* baseValue, const U32* nbAdditionalBits,
-    unsigned tableLog)
-{
-    ZSTD_seqSymbol* const tableDecode = dt+1;
-    U16 symbolNext[MaxSeq+1];
-
-    U32 const maxSV1 = maxSymbolValue + 1;
-    U32 const tableSize = 1 << tableLog;
-    U32 highThreshold = tableSize-1;
-
-    /* Sanity Checks */
-    assert(maxSymbolValue <= MaxSeq);
-    assert(tableLog <= MaxFSELog);
-
-    /* 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;
-                    symbolNext[s] = normalizedCounter[s];
-        }   }   }
-        memcpy(dt, &DTableH, sizeof(DTableH));
-    }
-
-    /* Spread symbols */
-    {   U32 const tableMask = tableSize-1;
-        U32 const step = FSE_TABLESTEP(tableSize);
-        U32 s, position = 0;
-        for (s=0; s<maxSV1; s++) {
-            int i;
-            for (i=0; i<normalizedCounter[s]; 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 = (BYTE)nbAdditionalBits[symbol];
-            tableDecode[u].baseValue = baseValue[symbol];
-    }   }
-}
-
-
-/*! 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, U32 max, U32 maxLog,
-                                 const void* src, size_t srcSize,
-                                 const U32* baseValue, const U32* nbAdditionalBits,
-                                 const ZSTD_seqSymbol* defaultTable, U32 flagRepeatTable)
-{
-    switch(type)
-    {
-    case set_rle :
-        if (!srcSize) return ERROR(srcSize_wrong);
-        if ( (*(const BYTE*)src) > max) return ERROR(corruption_detected);
-        {   U32 const symbol = *(const BYTE*)src;
-            U32 const baseline = baseValue[symbol];
-            U32 const nbBits = nbAdditionalBits[symbol];
-            ZSTD_buildSeqTable_rle(DTableSpace, baseline, nbBits);
-        }
-        *DTablePtr = DTableSpace;
-        return 1;
-    case set_basic :
-        *DTablePtr = defaultTable;
-        return 0;
-    case set_repeat:
-        if (!flagRepeatTable) return ERROR(corruption_detected);
-        return 0;
-    case set_compressed :
-        {   U32 tableLog;
-            S16 norm[MaxSeq+1];
-            size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize);
-            if (FSE_isError(headerSize)) return ERROR(corruption_detected);
-            if (tableLog > maxLog) return ERROR(corruption_detected);
-            ZSTD_buildFSETable(DTableSpace, norm, max, baseValue, nbAdditionalBits, tableLog);
-            *DTablePtr = DTableSpace;
-            return headerSize;
-        }
-    default :   /* impossible */
-        assert(0);
-        return ERROR(GENERIC);
-    }
-}
-
-static const U32 LL_base[MaxLL+1] = {
-                 0,    1,    2,     3,     4,     5,     6,      7,
-                 8,    9,   10,    11,    12,    13,    14,     15,
-                16,   18,   20,    22,    24,    28,    32,     40,
-                48,   64, 0x80, 0x100, 0x200, 0x400, 0x800, 0x1000,
-                0x2000, 0x4000, 0x8000, 0x10000 };
-
-static const U32 OF_base[MaxOff+1] = {
-                 0,        1,       1,       5,     0xD,     0x1D,     0x3D,     0x7D,
-                 0xFD,   0x1FD,   0x3FD,   0x7FD,   0xFFD,   0x1FFD,   0x3FFD,   0x7FFD,
-                 0xFFFD, 0x1FFFD, 0x3FFFD, 0x7FFFD, 0xFFFFD, 0x1FFFFD, 0x3FFFFD, 0x7FFFFD,
-                 0xFFFFFD, 0x1FFFFFD, 0x3FFFFFD, 0x7FFFFFD, 0xFFFFFFD, 0x1FFFFFFD, 0x3FFFFFFD, 0x7FFFFFFD };
-
-static const U32 OF_bits[MaxOff+1] = {
-                     0,  1,  2,  3,  4,  5,  6,  7,
-                     8,  9, 10, 11, 12, 13, 14, 15,
-                    16, 17, 18, 19, 20, 21, 22, 23,
-                    24, 25, 26, 27, 28, 29, 30, 31 };
-
-static const U32 ML_base[MaxML+1] = {
-                     3,  4,  5,    6,     7,     8,     9,    10,
-                    11, 12, 13,   14,    15,    16,    17,    18,
-                    19, 20, 21,   22,    23,    24,    25,    26,
-                    27, 28, 29,   30,    31,    32,    33,    34,
-                    35, 37, 39,   41,    43,    47,    51,    59,
-                    67, 83, 99, 0x83, 0x103, 0x203, 0x403, 0x803,
-                    0x1003, 0x2003, 0x4003, 0x8003, 0x10003 };
-
-
-size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr,
-                             const void* src, size_t srcSize)
-{
-    const BYTE* const istart = (const BYTE* const)src;
-    const BYTE* const iend = istart + srcSize;
-    const BYTE* ip = istart;
-    DEBUGLOG(5, "ZSTD_decodeSeqHeaders");
-
-    /* check */
-    if (srcSize < MIN_SEQUENCES_SIZE) return ERROR(srcSize_wrong);
-
-    /* SeqHead */
-    {   int nbSeq = *ip++;
-        if (!nbSeq) { *nbSeqPtr=0; return 1; }
-        if (nbSeq > 0x7F) {
-            if (nbSeq == 0xFF) {
-                if (ip+2 > iend) return ERROR(srcSize_wrong);
-                nbSeq = MEM_readLE16(ip) + LONGNBSEQ, ip+=2;
-            } else {
-                if (ip >= iend) return ERROR(srcSize_wrong);
-                nbSeq = ((nbSeq-0x80)<<8) + *ip++;
-            }
-        }
-        *nbSeqPtr = nbSeq;
-    }
-
-    /* FSE table descriptors */
-    if (ip+4 > iend) return ERROR(srcSize_wrong); /* minimum possible size */
-    {   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);
-            if (ZSTD_isError(llhSize)) return ERROR(corruption_detected);
-            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);
-            if (ZSTD_isError(ofhSize)) return ERROR(corruption_detected);
-            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);
-            if (ZSTD_isError(mlhSize)) return ERROR(corruption_detected);
-            ip += mlhSize;
-        }
-    }
-
-    return ip-istart;
-}
-
-
-typedef struct {
-    size_t litLength;
-    size_t matchLength;
-    size_t offset;
-    const BYTE* match;
-} 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];
-    const BYTE* prefixStart;
-    const BYTE* dictEnd;
-    size_t pos;
-} seqState_t;
-
-
-FORCE_NOINLINE
-size_t ZSTD_execSequenceLast7(BYTE* op,
-                              BYTE* const oend, seq_t sequence,
-                              const BYTE** litPtr, const BYTE* const litLimit,
-                              const BYTE* const base, const BYTE* const vBase, 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;
-    const BYTE* const iLitEnd = *litPtr + sequence.litLength;
-    const BYTE* match = oLitEnd - sequence.offset;
-
-    /* check */
-    if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
-    if (iLitEnd > litLimit) return ERROR(corruption_detected);   /* over-read beyond lit buffer */
-    if (oLitEnd <= oend_w) return ERROR(GENERIC);   /* Precondition */
-
-    /* copy literals */
-    if (op < oend_w) {
-        ZSTD_wildcopy(op, *litPtr, oend_w - op);
-        *litPtr += oend_w - op;
-        op = oend_w;
-    }
-    while (op < oLitEnd) *op++ = *(*litPtr)++;
-
-    /* copy Match */
-    if (sequence.offset > (size_t)(oLitEnd - base)) {
-        /* offset beyond prefix */
-        if (sequence.offset > (size_t)(oLitEnd - vBase)) return ERROR(corruption_detected);
-        match = dictEnd - (base-match);
-        if (match + sequence.matchLength <= dictEnd) {
-            memmove(oLitEnd, match, sequence.matchLength);
-            return sequenceLength;
-        }
-        /* span extDict & currentPrefixSegment */
-        {   size_t const length1 = dictEnd - match;
-            memmove(oLitEnd, match, length1);
-            op = oLitEnd + length1;
-            sequence.matchLength -= length1;
-            match = base;
-    }   }
-    while (op < oMatchEnd) *op++ = *match++;
-    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 base, const BYTE* const vBase, 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;
-    const BYTE* const iLitEnd = *litPtr + sequence.litLength;
-    const BYTE* match = oLitEnd - sequence.offset;
-
-    /* check */
-    if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
-    if (iLitEnd > litLimit) return ERROR(corruption_detected);   /* over-read beyond lit buffer */
-    if (oLitEnd>oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, base, vBase, dictEnd);
-
-    /* copy Literals */
-    ZSTD_copy8(op, *litPtr);
-    if (sequence.litLength > 8)
-        ZSTD_wildcopy(op+8, (*litPtr)+8, sequence.litLength - 8);   /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
-    op = oLitEnd;
-    *litPtr = iLitEnd;   /* update for next sequence */
-
-    /* copy Match */
-    if (sequence.offset > (size_t)(oLitEnd - base)) {
-        /* offset beyond prefix -> go into extDict */
-        if (sequence.offset > (size_t)(oLitEnd - vBase))
-            return ERROR(corruption_detected);
-        match = dictEnd + (match - base);
-        if (match + sequence.matchLength <= dictEnd) {
-            memmove(oLitEnd, match, sequence.matchLength);
-            return sequenceLength;
-        }
-        /* span extDict & currentPrefixSegment */
-        {   size_t const length1 = dictEnd - match;
-            memmove(oLitEnd, match, length1);
-            op = oLitEnd + length1;
-            sequence.matchLength -= length1;
-            match = base;
-            if (op > oend_w || sequence.matchLength < MINMATCH) {
-              U32 i;
-              for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
-              return sequenceLength;
-            }
-    }   }
-    /* Requirement: op <= oend_w && sequence.matchLength >= MINMATCH */
-
-    /* match within prefix */
-    if (sequence.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[sequence.offset];
-        op[0] = match[0];
-        op[1] = match[1];
-        op[2] = match[2];
-        op[3] = match[3];
-        match += dec32table[sequence.offset];
-        ZSTD_copy4(op+4, match);
-        match -= sub2;
-    } else {
-        ZSTD_copy8(op, match);
-    }
-    op += 8; match += 8;
-
-    if (oMatchEnd > oend-(16-MINMATCH)) {
-        if (op < oend_w) {
-            ZSTD_wildcopy(op, match, oend_w - op);
-            match += oend_w - op;
-            op = oend_w;
-        }
-        while (op < oMatchEnd) *op++ = *match++;
-    } else {
-        ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8);   /* works even if matchLength < 8 */
-    }
-    return sequenceLength;
-}
-
-
-HINT_INLINE
-size_t ZSTD_execSequenceLong(BYTE* op,
-                             BYTE* const oend, seq_t sequence,
-                             const BYTE** litPtr, const BYTE* const litLimit,
-                             const BYTE* const prefixStart, const BYTE* const dictStart, 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;
-    const BYTE* const iLitEnd = *litPtr + sequence.litLength;
-    const BYTE* match = sequence.match;
-
-    /* check */
-    if (oMatchEnd > oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
-    if (iLitEnd > litLimit) return ERROR(corruption_detected);   /* over-read beyond lit buffer */
-    if (oLitEnd > oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, prefixStart, dictStart, dictEnd);
-
-    /* copy Literals */
-    ZSTD_copy8(op, *litPtr);  /* note : op <= oLitEnd <= oend_w == oend - 8 */
-    if (sequence.litLength > 8)
-        ZSTD_wildcopy(op+8, (*litPtr)+8, sequence.litLength - 8);   /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
-    op = oLitEnd;
-    *litPtr = iLitEnd;   /* update for next sequence */
-
-    /* copy Match */
-    if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
-        /* offset beyond prefix */
-        if (sequence.offset > (size_t)(oLitEnd - dictStart)) return ERROR(corruption_detected);
-        if (match + sequence.matchLength <= dictEnd) {
-            memmove(oLitEnd, match, sequence.matchLength);
-            return sequenceLength;
-        }
-        /* span extDict & currentPrefixSegment */
-        {   size_t const length1 = dictEnd - match;
-            memmove(oLitEnd, match, length1);
-            op = oLitEnd + length1;
-            sequence.matchLength -= length1;
-            match = prefixStart;
-            if (op > oend_w || sequence.matchLength < MINMATCH) {
-              U32 i;
-              for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
-              return sequenceLength;
-            }
-    }   }
-    assert(op <= oend_w);
-    assert(sequence.matchLength >= MINMATCH);
-
-    /* match within prefix */
-    if (sequence.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[sequence.offset];
-        op[0] = match[0];
-        op[1] = match[1];
-        op[2] = match[2];
-        op[3] = match[3];
-        match += dec32table[sequence.offset];
-        ZSTD_copy4(op+4, match);
-        match -= sub2;
-    } else {
-        ZSTD_copy8(op, match);
-    }
-    op += 8; match += 8;
-
-    if (oMatchEnd > oend-(16-MINMATCH)) {
-        if (op < oend_w) {
-            ZSTD_wildcopy(op, match, oend_w - op);
-            match += oend_w - op;
-            op = oend_w;
-        }
-        while (op < oMatchEnd) *op++ = *match++;
-    } else {
-        ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8);   /* works even if matchLength < 8 */
-    }
-    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_updateFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD)
-{
-    ZSTD_seqSymbol const DInfo = DStatePtr->table[DStatePtr->state];
-    U32 const nbBits = DInfo.nbBits;
-    size_t const lowBits = BIT_readBits(bitD, nbBits);
-    DStatePtr->state = DInfo.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 offets.
- */
-#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;
-    U32 const llBits = seqState->stateLL.table[seqState->stateLL.state].nbAdditionalBits;
-    U32 const mlBits = seqState->stateML.table[seqState->stateML.state].nbAdditionalBits;
-    U32 const ofBits = seqState->stateOffb.table[seqState->stateOffb.state].nbAdditionalBits;
-    U32 const totalBits = llBits+mlBits+ofBits;
-    U32 const llBase = seqState->stateLL.table[seqState->stateLL.state].baseValue;
-    U32 const mlBase = seqState->stateML.table[seqState->stateML.state].baseValue;
-    U32 const ofBase = seqState->stateOffb.table[seqState->stateOffb.state].baseValue;
-
-    /* sequence */
-    {   size_t offset;
-        if (!ofBits)
-            offset = 0;
-        else {
-            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);
-            }
-        }
-
-        if (ofBits <= 1) {
-            offset += (llBase==0);
-            if (offset) {
-                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;
-            } else {  /* offset == 0 */
-                offset = seqState->prevOffset[0];
-            }
-        } else {
-            seqState->prevOffset[2] = seqState->prevOffset[1];
-            seqState->prevOffset[1] = seqState->prevOffset[0];
-            seqState->prevOffset[0] = offset;
-        }
-        seq.offset = offset;
-    }
-
-    seq.matchLength = mlBase
-                    + ((mlBits>0) ? BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/) : 0);  /* <=  16 bits */
-    if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32))
-        BIT_reloadDStream(&seqState->DStream);
-    if (MEM_64bits() && (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);
-
-    seq.litLength = llBase
-                  + ((llBits>0) ? BIT_readBitsFast(&seqState->DStream, llBits/*>0*/) : 0);    /* <=  16 bits */
-    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);
-
-    /* ANS state update */
-    ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream);    /* <=  9 bits */
-    ZSTD_updateFseState(&seqState->stateML, &seqState->DStream);    /* <=  9 bits */
-    if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);    /* <= 18 bits */
-    ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream);  /* <=  8 bits */
-
-    return seq;
-}
-
-FORCE_INLINE_TEMPLATE size_t
-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 BYTE* ip = (const BYTE*)seqStart;
-    const BYTE* const iend = ip + seqSize;
-    BYTE* const ostart = (BYTE* const)dst;
-    BYTE* const oend = ostart + maxDstSize;
-    BYTE* op = ostart;
-    const BYTE* litPtr = dctx->litPtr;
-    const BYTE* const litEnd = litPtr + dctx->litSize;
-    const BYTE* const base = (const BYTE*) (dctx->base);
-    const BYTE* const vBase = (const BYTE*) (dctx->vBase);
-    const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
-    DEBUGLOG(5, "ZSTD_decompressSequences");
-
-    /* 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]; }
-        CHECK_E(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);
-
-        for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; ) {
-            nbSeq--;
-            {   seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
-                size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, base, vBase, dictEnd);
-                DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
-                if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
-                op += oneSeqSize;
-        }   }
-
-        /* check if reached exact end */
-        DEBUGLOG(5, "ZSTD_decompressSequences: after decode loop, remaining nbSeq : %i", nbSeq);
-        if (nbSeq) return ERROR(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;
-        if (lastLLSize > (size_t)(oend-op)) return ERROR(dstSize_tooSmall);
-        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)
-{
-    return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-}
-
-
-
-FORCE_INLINE_TEMPLATE seq_t
-ZSTD_decodeSequenceLong(seqState_t* seqState, ZSTD_longOffset_e const longOffsets)
-{
-    seq_t seq;
-    U32 const llBits = seqState->stateLL.table[seqState->stateLL.state].nbAdditionalBits;
-    U32 const mlBits = seqState->stateML.table[seqState->stateML.state].nbAdditionalBits;
-    U32 const ofBits = seqState->stateOffb.table[seqState->stateOffb.state].nbAdditionalBits;
-    U32 const totalBits = llBits+mlBits+ofBits;
-    U32 const llBase = seqState->stateLL.table[seqState->stateLL.state].baseValue;
-    U32 const mlBase = seqState->stateML.table[seqState->stateML.state].baseValue;
-    U32 const ofBase = seqState->stateOffb.table[seqState->stateOffb.state].baseValue;
-
-    /* sequence */
-    {   size_t offset;
-        if (!ofBits)
-            offset = 0;
-        else {
-            ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1);
-            ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5);
-            assert(ofBits <= MaxOff);
-            if (MEM_32bits() && longOffsets) {
-                U32 const extraBits = ofBits - MIN(ofBits, STREAM_ACCUMULATOR_MIN_32-1);
-                offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits);
-                if (MEM_32bits() || extraBits) BIT_reloadDStream(&seqState->DStream);
-                if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits);
-            } else {
-                offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits);   /* <=  (ZSTD_WINDOWLOG_MAX-1) bits */
-                if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
-            }
-        }
-
-        if (ofBits <= 1) {
-            offset += (llBase==0);
-            if (offset) {
-                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;
-            } else {
-                offset = seqState->prevOffset[0];
-            }
-        } else {
-            seqState->prevOffset[2] = seqState->prevOffset[1];
-            seqState->prevOffset[1] = seqState->prevOffset[0];
-            seqState->prevOffset[0] = offset;
-        }
-        seq.offset = offset;
-    }
-
-    seq.matchLength = mlBase + ((mlBits>0) ? BIT_readBitsFast(&seqState->DStream, mlBits) : 0);  /* <=  16 bits */
-    if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32))
-        BIT_reloadDStream(&seqState->DStream);
-    if (MEM_64bits() && (totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog)))
-        BIT_reloadDStream(&seqState->DStream);
-    /* Verify that there is enough bits to read the rest of the data in 64-bit mode. */
-    ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64);
-
-    seq.litLength = llBase + ((llBits>0) ? BIT_readBitsFast(&seqState->DStream, llBits) : 0);    /* <=  16 bits */
-    if (MEM_32bits())
-        BIT_reloadDStream(&seqState->DStream);
-
-    {   size_t const pos = seqState->pos + seq.litLength;
-        const BYTE* const matchBase = (seq.offset > pos) ? seqState->dictEnd : seqState->prefixStart;
-        seq.match = matchBase + pos - seq.offset;  /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted.
-                                                    * No consequence though : no memory access will occur, overly large offset will be detected in ZSTD_execSequenceLong() */
-        seqState->pos = pos + seq.matchLength;
-    }
-
-    /* ANS state update */
-    ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream);    /* <=  9 bits */
-    ZSTD_updateFseState(&seqState->stateML, &seqState->DStream);    /* <=  9 bits */
-    if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);    /* <= 18 bits */
-    ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream);  /* <=  8 bits */
-
-    return seq;
-}
-
-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 BYTE* ip = (const BYTE*)seqStart;
-    const BYTE* const iend = ip + seqSize;
-    BYTE* const ostart = (BYTE* const)dst;
-    BYTE* const oend = ostart + maxDstSize;
-    BYTE* op = ostart;
-    const BYTE* litPtr = dctx->litPtr;
-    const BYTE* const litEnd = litPtr + dctx->litSize;
-    const BYTE* const prefixStart = (const BYTE*) (dctx->base);
-    const BYTE* const dictStart = (const BYTE*) (dctx->vBase);
-    const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
-
-    /* Regen sequences */
-    if (nbSeq) {
-#define STORED_SEQS 4
-#define STOSEQ_MASK (STORED_SEQS-1)
-#define ADVANCED_SEQS 4
-        seq_t sequences[STORED_SEQS];
-        int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS);
-        seqState_t seqState;
-        int seqNb;
-        dctx->fseEntropy = 1;
-        { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
-        seqState.prefixStart = prefixStart;
-        seqState.pos = (size_t)(op-prefixStart);
-        seqState.dictEnd = dictEnd;
-        CHECK_E(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++) {
-            sequences[seqNb] = ZSTD_decodeSequenceLong(&seqState, isLongOffset);
-        }
-        if (seqNb<seqAdvance) return ERROR(corruption_detected);
-
-        /* decode and decompress */
-        for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb<nbSeq) ; seqNb++) {
-            seq_t const sequence = ZSTD_decodeSequenceLong(&seqState, isLongOffset);
-            size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STOSEQ_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
-            if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
-            PREFETCH(sequence.match);  /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
-            sequences[seqNb&STOSEQ_MASK] = sequence;
-            op += oneSeqSize;
-        }
-        if (seqNb<nbSeq) return ERROR(corruption_detected);
-
-        /* finish queue */
-        seqNb -= seqAdvance;
-        for ( ; seqNb<nbSeq ; seqNb++) {
-            size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[seqNb&STOSEQ_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
-            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]); }
-#undef STORED_SEQS
-#undef STOSEQ_MASK
-#undef ADVANCED_SEQS
-    }
-
-    /* last literal segment */
-    {   size_t const lastLLSize = litEnd - litPtr;
-        if (lastLLSize > (size_t)(oend-op)) return ERROR(dstSize_tooSmall);
-        memcpy(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)
-{
-    return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-}
-
-
-
-#if DYNAMIC_BMI2
-
-static TARGET_ATTRIBUTE("bmi2") size_t
-ZSTD_decompressSequences_bmi2(ZSTD_DCtx* dctx,
-                                 void* dst, size_t maxDstSize,
-                           const void* seqStart, size_t seqSize, int nbSeq,
-                           const ZSTD_longOffset_e isLongOffset)
-{
-    return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-}
-
-static TARGET_ATTRIBUTE("bmi2") 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)
-{
-    return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-}
-
+#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
+    if (ZSTD_isLegacy(src, srcSize))
+        return ZSTD_findFrameSizeInfoLegacy(src, srcSize);
 #endif
 
-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);
+    if ((srcSize >= ZSTD_SKIPPABLEHEADERSIZE)
+        && (MEM_readLE32(src) & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
+        frameSizeInfo.compressedSize = readSkippableFrameSize(src, srcSize);
+        assert(ZSTD_isError(frameSizeInfo.compressedSize) ||
+               frameSizeInfo.compressedSize <= srcSize);
+        return frameSizeInfo;
+    } else {
+        const BYTE* ip = (const BYTE*)src;
+        const BYTE* const ipstart = ip;
+        size_t remainingSize = srcSize;
+        size_t nbBlocks = 0;
+        ZSTD_frameHeader zfh;
 
-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)
-{
-    DEBUGLOG(5, "ZSTD_decompressSequences");
-#if DYNAMIC_BMI2
-    if (dctx->bmi2) {
-        return ZSTD_decompressSequences_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-    }
-#endif
-  return ZSTD_decompressSequences_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-}
-
-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)
-{
-    DEBUGLOG(5, "ZSTD_decompressSequencesLong");
-#if DYNAMIC_BMI2
-    if (dctx->bmi2) {
-        return ZSTD_decompressSequencesLong_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-    }
-#endif
-  return ZSTD_decompressSequencesLong_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
-}
-
-/* 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;
-}
-
-
-static size_t ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
-                            void* dst, size_t dstCapacity,
-                      const void* src, size_t srcSize, const int frame)
-{   /* 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);
-
-    if (srcSize >= ZSTD_BLOCKSIZE_MAX) return ERROR(srcSize_wrong);
-
-    /* Decode literals section */
-    {   size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize);
-        DEBUGLOG(5, "ZSTD_decodeLiteralsBlock : %u", (U32)litCSize);
-        if (ZSTD_isError(litCSize)) return litCSize;
-        ip += litCSize;
-        srcSize -= litCSize;
-    }
-
-    /* Build Decoding Tables */
-    {   int nbSeq;
-        size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize);
-        if (ZSTD_isError(seqHSize)) return seqHSize;
-        ip += seqHSize;
-        srcSize -= seqHSize;
-
-        if ( (!frame || dctx->fParams.windowSize > (1<<24))
-          && (nbSeq>0) ) {  /* 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% */
-            if (shareLongOffsets >= minShare)
-                return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset);
+        /* Extract Frame Header */
+        {   size_t const ret = ZSTD_getFrameHeader(&zfh, src, srcSize);
+            if (ZSTD_isError(ret))
+                return ZSTD_errorFrameSizeInfo(ret);
+            if (ret > 0)
+                return ZSTD_errorFrameSizeInfo(ERROR(srcSize_wrong));
         }
 
-        return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset);
+        ip += zfh.headerSize;
+        remainingSize -= zfh.headerSize;
+
+        /* Iterate over each block */
+        while (1) {
+            blockProperties_t blockProperties;
+            size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties);
+            if (ZSTD_isError(cBlockSize))
+                return ZSTD_errorFrameSizeInfo(cBlockSize);
+
+            if (ZSTD_blockHeaderSize + cBlockSize > remainingSize)
+                return ZSTD_errorFrameSizeInfo(ERROR(srcSize_wrong));
+
+            ip += ZSTD_blockHeaderSize + cBlockSize;
+            remainingSize -= ZSTD_blockHeaderSize + cBlockSize;
+            nbBlocks++;
+
+            if (blockProperties.lastBlock) break;
+        }
+
+        /* Final frame content checksum */
+        if (zfh.checksumFlag) {
+            if (remainingSize < 4)
+                return ZSTD_errorFrameSizeInfo(ERROR(srcSize_wrong));
+            ip += 4;
+        }
+
+        frameSizeInfo.compressedSize = ip - ipstart;
+        frameSizeInfo.decompressedBound = (zfh.frameContentSize != ZSTD_CONTENTSIZE_UNKNOWN)
+                                        ? zfh.frameContentSize
+                                        : nbBlocks * zfh.blockSizeMax;
+        return frameSizeInfo;
     }
 }
 
-
-static void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst)
-{
-    if (dst != dctx->previousDstEnd) {   /* not contiguous */
-        dctx->dictEnd = dctx->previousDstEnd;
-        dctx->vBase = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base));
-        dctx->base = 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);
-    dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize, /* frame */ 0);
-    dctx->previousDstEnd = (char*)dst + dSize;
-    return dSize;
-}
-
-
-/** ZSTD_insertBlock() :
-    insert `src` block into `dctx` history. Useful to track uncompressed blocks. */
-ZSTDLIB_API size_t ZSTD_insertBlock(ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize)
-{
-    ZSTD_checkContinuity(dctx, blockStart);
-    dctx->previousDstEnd = (const char*)blockStart + blockSize;
-    return blockSize;
-}
-
-
-static size_t ZSTD_generateNxBytes(void* dst, size_t dstCapacity, BYTE byte, size_t length)
-{
-    if (length > dstCapacity) return ERROR(dstSize_tooSmall);
-    memset(dst, byte, length);
-    return length;
-}
-
 /** ZSTD_findFrameCompressedSize() :
  *  compatible with legacy mode
  *  `src` must point to the start of a ZSTD frame, ZSTD legacy frame, or skippable frame
@@ -1743,55 +529,91 @@
  *  @return : the compressed size of the frame starting at `src` */
 size_t ZSTD_findFrameCompressedSize(const void *src, size_t srcSize)
 {
-#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
-    if (ZSTD_isLegacy(src, srcSize))
-        return ZSTD_findFrameCompressedSizeLegacy(src, srcSize);
-#endif
-    if ( (srcSize >= ZSTD_skippableHeaderSize)
-      && (MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START ) {
-        return ZSTD_skippableHeaderSize + MEM_readLE32((const BYTE*)src + ZSTD_frameIdSize);
-    } else {
-        const BYTE* ip = (const BYTE*)src;
-        const BYTE* const ipstart = ip;
-        size_t remainingSize = srcSize;
-        ZSTD_frameHeader zfh;
+    ZSTD_frameSizeInfo const frameSizeInfo = ZSTD_findFrameSizeInfo(src, srcSize);
+    return frameSizeInfo.compressedSize;
+}
 
-        /* Extract Frame Header */
-        {   size_t const ret = ZSTD_getFrameHeader(&zfh, src, srcSize);
-            if (ZSTD_isError(ret)) return ret;
-            if (ret > 0) return ERROR(srcSize_wrong);
-        }
+/** ZSTD_decompressBound() :
+ *  compatible with legacy mode
+ *  `src` must point to the start of a ZSTD frame or a skippeable frame
+ *  `srcSize` must be at least as large as the frame contained
+ *  @return : the maximum decompressed size of the compressed source
+ */
+unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize)
+{
+    unsigned long long bound = 0;
+    /* Iterate over each frame */
+    while (srcSize > 0) {
+        ZSTD_frameSizeInfo const frameSizeInfo = ZSTD_findFrameSizeInfo(src, srcSize);
+        size_t const compressedSize = frameSizeInfo.compressedSize;
+        unsigned long long const decompressedBound = frameSizeInfo.decompressedBound;
+        if (ZSTD_isError(compressedSize) || decompressedBound == ZSTD_CONTENTSIZE_ERROR)
+            return ZSTD_CONTENTSIZE_ERROR;
+        assert(srcSize >= compressedSize);
+        src = (const BYTE*)src + compressedSize;
+        srcSize -= compressedSize;
+        bound += decompressedBound;
+    }
+    return bound;
+}
 
-        ip += zfh.headerSize;
-        remainingSize -= zfh.headerSize;
 
-        /* Loop on each block */
-        while (1) {
-            blockProperties_t blockProperties;
-            size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties);
-            if (ZSTD_isError(cBlockSize)) return cBlockSize;
+/*-*************************************************************
+ *   Frame decoding
+ ***************************************************************/
 
-            if (ZSTD_blockHeaderSize + cBlockSize > remainingSize)
-                return ERROR(srcSize_wrong);
 
-            ip += ZSTD_blockHeaderSize + cBlockSize;
-            remainingSize -= ZSTD_blockHeaderSize + cBlockSize;
-
-            if (blockProperties.lastBlock) break;
-        }
-
-        if (zfh.checksumFlag) {   /* Final frame content checksum */
-            if (remainingSize < 4) return ERROR(srcSize_wrong);
-            ip += 4;
-            remainingSize -= 4;
-        }
-
-        return ip - ipstart;
+void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst)
+{
+    if (dst != dctx->previousDstEnd) {   /* 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;
     }
 }
 
+/** ZSTD_insertBlock() :
+    insert `src` block into `dctx` history. Useful to track uncompressed blocks. */
+size_t ZSTD_insertBlock(ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize)
+{
+    ZSTD_checkContinuity(dctx, blockStart);
+    dctx->previousDstEnd = (const char*)blockStart + blockSize;
+    return blockSize;
+}
+
+
+static size_t ZSTD_copyRawBlock(void* dst, size_t dstCapacity,
+                          const void* src, size_t srcSize)
+{
+    DEBUGLOG(5, "ZSTD_copyRawBlock");
+    if (dst == NULL) {
+        if (srcSize == 0) return 0;
+        RETURN_ERROR(dstBuffer_null);
+    }
+    RETURN_ERROR_IF(srcSize > dstCapacity, dstSize_tooSmall);
+    memcpy(dst, src, srcSize);
+    return srcSize;
+}
+
+static size_t ZSTD_setRleBlock(void* dst, size_t dstCapacity,
+                               BYTE b,
+                               size_t regenSize)
+{
+    if (dst == NULL) {
+        if (regenSize == 0) return 0;
+        RETURN_ERROR(dstBuffer_null);
+    }
+    RETURN_ERROR_IF(regenSize > dstCapacity, dstSize_tooSmall);
+    memset(dst, b, regenSize);
+    return regenSize;
+}
+
+
 /*! ZSTD_decompressFrame() :
-*   @dctx must be properly initialized */
+ * @dctx must be properly initialized
+ *  will update *srcPtr and *srcSizePtr,
+ *  to make *srcPtr progress by one frame. */
 static size_t ZSTD_decompressFrame(ZSTD_DCtx* dctx,
                                    void* dst, size_t dstCapacity,
                              const void** srcPtr, size_t *srcSizePtr)
@@ -1800,31 +622,34 @@
     BYTE* const ostart = (BYTE* const)dst;
     BYTE* const oend = ostart + dstCapacity;
     BYTE* op = ostart;
-    size_t remainingSize = *srcSizePtr;
+    size_t remainingSrcSize = *srcSizePtr;
+
+    DEBUGLOG(4, "ZSTD_decompressFrame (srcSize:%i)", (int)*srcSizePtr);
 
     /* check */
-    if (remainingSize < ZSTD_frameHeaderSize_min+ZSTD_blockHeaderSize)
-        return ERROR(srcSize_wrong);
+    RETURN_ERROR_IF(
+        remainingSrcSize < ZSTD_FRAMEHEADERSIZE_MIN+ZSTD_blockHeaderSize,
+        srcSize_wrong);
 
     /* Frame Header */
-    {   size_t const frameHeaderSize = ZSTD_frameHeaderSize(ip, ZSTD_frameHeaderSize_prefix);
+    {   size_t const frameHeaderSize = ZSTD_frameHeaderSize(ip, ZSTD_FRAMEHEADERSIZE_PREFIX);
         if (ZSTD_isError(frameHeaderSize)) return frameHeaderSize;
-        if (remainingSize < frameHeaderSize+ZSTD_blockHeaderSize)
-            return ERROR(srcSize_wrong);
-        CHECK_F( ZSTD_decodeFrameHeader(dctx, ip, frameHeaderSize) );
-        ip += frameHeaderSize; remainingSize -= frameHeaderSize;
+        RETURN_ERROR_IF(remainingSrcSize < frameHeaderSize+ZSTD_blockHeaderSize,
+                        srcSize_wrong);
+        FORWARD_IF_ERROR( ZSTD_decodeFrameHeader(dctx, ip, frameHeaderSize) );
+        ip += frameHeaderSize; remainingSrcSize -= frameHeaderSize;
     }
 
     /* Loop on each block */
     while (1) {
         size_t decodedSize;
         blockProperties_t blockProperties;
-        size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSize, &blockProperties);
+        size_t const cBlockSize = ZSTD_getcBlockSize(ip, remainingSrcSize, &blockProperties);
         if (ZSTD_isError(cBlockSize)) return cBlockSize;
 
         ip += ZSTD_blockHeaderSize;
-        remainingSize -= ZSTD_blockHeaderSize;
-        if (cBlockSize > remainingSize) return ERROR(srcSize_wrong);
+        remainingSrcSize -= ZSTD_blockHeaderSize;
+        RETURN_ERROR_IF(cBlockSize > remainingSrcSize, srcSize_wrong);
 
         switch(blockProperties.blockType)
         {
@@ -1835,11 +660,11 @@
             decodedSize = ZSTD_copyRawBlock(op, oend-op, ip, cBlockSize);
             break;
         case bt_rle :
-            decodedSize = ZSTD_generateNxBytes(op, oend-op, *ip, blockProperties.origSize);
+            decodedSize = ZSTD_setRleBlock(op, oend-op, *ip, blockProperties.origSize);
             break;
         case bt_reserved :
         default:
-            return ERROR(corruption_detected);
+            RETURN_ERROR(corruption_detected);
         }
 
         if (ZSTD_isError(decodedSize)) return decodedSize;
@@ -1847,33 +672,30 @@
             XXH64_update(&dctx->xxhState, op, decodedSize);
         op += decodedSize;
         ip += cBlockSize;
-        remainingSize -= cBlockSize;
+        remainingSrcSize -= cBlockSize;
         if (blockProperties.lastBlock) break;
     }
 
     if (dctx->fParams.frameContentSize != ZSTD_CONTENTSIZE_UNKNOWN) {
-        if ((U64)(op-ostart) != dctx->fParams.frameContentSize) {
-            return ERROR(corruption_detected);
-    }   }
+        RETURN_ERROR_IF((U64)(op-ostart) != dctx->fParams.frameContentSize,
+                        corruption_detected);
+    }
     if (dctx->fParams.checksumFlag) { /* Frame content checksum verification */
         U32 const checkCalc = (U32)XXH64_digest(&dctx->xxhState);
         U32 checkRead;
-        if (remainingSize<4) return ERROR(checksum_wrong);
+        RETURN_ERROR_IF(remainingSrcSize<4, checksum_wrong);
         checkRead = MEM_readLE32(ip);
-        if (checkRead != checkCalc) return ERROR(checksum_wrong);
+        RETURN_ERROR_IF(checkRead != checkCalc, checksum_wrong);
         ip += 4;
-        remainingSize -= 4;
+        remainingSrcSize -= 4;
     }
 
     /* Allow caller to get size read */
     *srcPtr = ip;
-    *srcSizePtr = remainingSize;
+    *srcSizePtr = remainingSrcSize;
     return op-ostart;
 }
 
-static const void* ZSTD_DDictDictContent(const ZSTD_DDict* ddict);
-static size_t ZSTD_DDictDictSize(const ZSTD_DDict* ddict);
-
 static size_t ZSTD_decompressMultiFrame(ZSTD_DCtx* dctx,
                                         void* dst, size_t dstCapacity,
                                   const void* src, size_t srcSize,
@@ -1881,26 +703,30 @@
                                   const ZSTD_DDict* ddict)
 {
     void* const dststart = dst;
+    int moreThan1Frame = 0;
+
+    DEBUGLOG(5, "ZSTD_decompressMultiFrame");
     assert(dict==NULL || ddict==NULL);  /* either dict or ddict set, not both */
 
     if (ddict) {
-        dict = ZSTD_DDictDictContent(ddict);
-        dictSize = ZSTD_DDictDictSize(ddict);
+        dict = ZSTD_DDict_dictContent(ddict);
+        dictSize = ZSTD_DDict_dictSize(ddict);
     }
 
-    while (srcSize >= ZSTD_frameHeaderSize_prefix) {
-        U32 magicNumber;
+    while (srcSize >= ZSTD_FRAMEHEADERSIZE_PREFIX) {
 
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
         if (ZSTD_isLegacy(src, srcSize)) {
             size_t decodedSize;
             size_t const frameSize = ZSTD_findFrameCompressedSizeLegacy(src, srcSize);
             if (ZSTD_isError(frameSize)) return frameSize;
-            /* legacy support is not compatible with static dctx */
-            if (dctx->staticSize) return ERROR(memory_allocation);
+            RETURN_ERROR_IF(dctx->staticSize, memory_allocation,
+                "legacy support is not compatible with static dctx");
 
             decodedSize = ZSTD_decompressLegacy(dst, dstCapacity, src, frameSize, dict, dictSize);
+            if (ZSTD_isError(decodedSize)) return decodedSize;
 
+            assert(decodedSize <=- dstCapacity);
             dst = (BYTE*)dst + decodedSize;
             dstCapacity -= decodedSize;
 
@@ -1911,45 +737,53 @@
         }
 #endif
 
-        magicNumber = MEM_readLE32(src);
-        DEBUGLOG(4, "reading magic number %08X (expecting %08X)",
-                    (U32)magicNumber, (U32)ZSTD_MAGICNUMBER);
-        if (magicNumber != ZSTD_MAGICNUMBER) {
-            if ((magicNumber & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {
-                size_t skippableSize;
-                if (srcSize < ZSTD_skippableHeaderSize)
-                    return ERROR(srcSize_wrong);
-                skippableSize = MEM_readLE32((const BYTE*)src + ZSTD_frameIdSize)
-                              + ZSTD_skippableHeaderSize;
-                if (srcSize < skippableSize) return ERROR(srcSize_wrong);
+        {   U32 const magicNumber = MEM_readLE32(src);
+            DEBUGLOG(4, "reading magic number %08X (expecting %08X)",
+                        (unsigned)magicNumber, ZSTD_MAGICNUMBER);
+            if ((magicNumber & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {
+                size_t const skippableSize = readSkippableFrameSize(src, srcSize);
+                FORWARD_IF_ERROR(skippableSize);
+                assert(skippableSize <= srcSize);
 
                 src = (const BYTE *)src + skippableSize;
                 srcSize -= skippableSize;
                 continue;
-            }
-            return ERROR(prefix_unknown);
-        }
+        }   }
 
         if (ddict) {
             /* we were called from ZSTD_decompress_usingDDict */
-            CHECK_F(ZSTD_decompressBegin_usingDDict(dctx, ddict));
+            FORWARD_IF_ERROR(ZSTD_decompressBegin_usingDDict(dctx, ddict));
         } else {
             /* this will initialize correctly with no dict if dict == NULL, so
              * use this in all cases but ddict */
-            CHECK_F(ZSTD_decompressBegin_usingDict(dctx, dict, dictSize));
+            FORWARD_IF_ERROR(ZSTD_decompressBegin_usingDict(dctx, dict, dictSize));
         }
         ZSTD_checkContinuity(dctx, dst);
 
         {   const size_t res = ZSTD_decompressFrame(dctx, dst, dstCapacity,
                                                     &src, &srcSize);
+            RETURN_ERROR_IF(
+                (ZSTD_getErrorCode(res) == ZSTD_error_prefix_unknown)
+             && (moreThan1Frame==1),
+                srcSize_wrong,
+                "at least one frame successfully completed, but following "
+                "bytes are garbage: it's more likely to be a srcSize error, "
+                "specifying more bytes than compressed size of frame(s). This "
+                "error message replaces ERROR(prefix_unknown), which would be "
+                "confusing, as the first header is actually correct. Note that "
+                "one could be unlucky, it might be a corruption error instead, "
+                "happening right at the place where we expect zstd magic "
+                "bytes. But this is _much_ less likely than a srcSize field "
+                "error.");
             if (ZSTD_isError(res)) return res;
-            /* no need to bound check, ZSTD_decompressFrame already has */
+            assert(res <= dstCapacity);
             dst = (BYTE*)dst + res;
             dstCapacity -= res;
         }
+        moreThan1Frame = 1;
     }  /* while (srcSize >= ZSTD_frameHeaderSize_prefix) */
 
-    if (srcSize) return ERROR(srcSize_wrong); /* input not entirely consumed */
+    RETURN_ERROR_IF(srcSize, srcSize_wrong, "input not entirely consumed");
 
     return (BYTE*)dst - (BYTE*)dststart;
 }
@@ -1963,9 +797,26 @@
 }
 
 
+static ZSTD_DDict const* ZSTD_getDDict(ZSTD_DCtx* dctx)
+{
+    switch (dctx->dictUses) {
+    default:
+        assert(0 /* Impossible */);
+        /* fall-through */
+    case ZSTD_dont_use:
+        ZSTD_clearDict(dctx);
+        return NULL;
+    case ZSTD_use_indefinitely:
+        return dctx->ddict;
+    case ZSTD_use_once:
+        dctx->dictUses = ZSTD_dont_use;
+        return dctx->ddict;
+    }
+}
+
 size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize)
 {
-    return ZSTD_decompress_usingDict(dctx, dst, dstCapacity, src, srcSize, NULL, 0);
+    return ZSTD_decompress_usingDDict(dctx, dst, dstCapacity, src, srcSize, ZSTD_getDDict(dctx));
 }
 
 
@@ -1974,12 +825,13 @@
 #if defined(ZSTD_HEAPMODE) && (ZSTD_HEAPMODE>=1)
     size_t regenSize;
     ZSTD_DCtx* const dctx = ZSTD_createDCtx();
-    if (dctx==NULL) return ERROR(memory_allocation);
+    RETURN_ERROR_IF(dctx==NULL, memory_allocation);
     regenSize = ZSTD_decompressDCtx(dctx, dst, dstCapacity, src, srcSize);
     ZSTD_freeDCtx(dctx);
     return regenSize;
 #else   /* stack mode */
     ZSTD_DCtx dctx;
+    ZSTD_initDCtx_internal(&dctx);
     return ZSTD_decompressDCtx(&dctx, dst, dstCapacity, src, srcSize);
 #endif
 }
@@ -2021,9 +873,9 @@
  *            or an error code, which can be tested using ZSTD_isError() */
 size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize)
 {
-    DEBUGLOG(5, "ZSTD_decompressContinue (srcSize:%u)", (U32)srcSize);
+    DEBUGLOG(5, "ZSTD_decompressContinue (srcSize:%u)", (unsigned)srcSize);
     /* Sanity check */
-    if (srcSize != dctx->expected) return ERROR(srcSize_wrong);  /* not allowed */
+    RETURN_ERROR_IF(srcSize != dctx->expected, srcSize_wrong, "not allowed");
     if (dstCapacity) ZSTD_checkContinuity(dctx, dst);
 
     switch (dctx->stage)
@@ -2031,10 +883,10 @@
     case ZSTDds_getFrameHeaderSize :
         assert(src != NULL);
         if (dctx->format == ZSTD_f_zstd1) {  /* allows header */
-            assert(srcSize >= ZSTD_frameIdSize);  /* to read skippable magic number */
-            if ((MEM_readLE32(src) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {        /* skippable frame */
+            assert(srcSize >= ZSTD_FRAMEIDSIZE);  /* to read skippable magic number */
+            if ((MEM_readLE32(src) & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {        /* skippable frame */
                 memcpy(dctx->headerBuffer, src, srcSize);
-                dctx->expected = ZSTD_skippableHeaderSize - srcSize;  /* remaining to load to get full skippable frame header */
+                dctx->expected = ZSTD_SKIPPABLEHEADERSIZE - srcSize;  /* remaining to load to get full skippable frame header */
                 dctx->stage = ZSTDds_decodeSkippableHeader;
                 return 0;
         }   }
@@ -2048,7 +900,7 @@
     case ZSTDds_decodeFrameHeader:
         assert(src != NULL);
         memcpy(dctx->headerBuffer + (dctx->headerSize - srcSize), src, srcSize);
-        CHECK_F(ZSTD_decodeFrameHeader(dctx, dctx->headerBuffer, dctx->headerSize));
+        FORWARD_IF_ERROR(ZSTD_decodeFrameHeader(dctx, dctx->headerBuffer, dctx->headerSize));
         dctx->expected = ZSTD_blockHeaderSize;
         dctx->stage = ZSTDds_decodeBlockHeader;
         return 0;
@@ -2094,23 +946,23 @@
                 rSize = ZSTD_copyRawBlock(dst, dstCapacity, src, srcSize);
                 break;
             case bt_rle :
-                rSize = ZSTD_setRleBlock(dst, dstCapacity, src, srcSize, dctx->rleSize);
+                rSize = ZSTD_setRleBlock(dst, dstCapacity, *(const BYTE*)src, dctx->rleSize);
                 break;
             case bt_reserved :   /* should never happen */
             default:
-                return ERROR(corruption_detected);
+                RETURN_ERROR(corruption_detected);
             }
             if (ZSTD_isError(rSize)) return rSize;
-            DEBUGLOG(5, "ZSTD_decompressContinue: decoded size from block : %u", (U32)rSize);
+            DEBUGLOG(5, "ZSTD_decompressContinue: decoded size from block : %u", (unsigned)rSize);
             dctx->decodedSize += rSize;
             if (dctx->fParams.checksumFlag) XXH64_update(&dctx->xxhState, dst, rSize);
 
             if (dctx->stage == ZSTDds_decompressLastBlock) {   /* end of frame */
-                DEBUGLOG(4, "ZSTD_decompressContinue: decoded size from frame : %u", (U32)dctx->decodedSize);
-                if (dctx->fParams.frameContentSize != ZSTD_CONTENTSIZE_UNKNOWN) {
-                    if (dctx->decodedSize != dctx->fParams.frameContentSize) {
-                        return ERROR(corruption_detected);
-                }   }
+                DEBUGLOG(4, "ZSTD_decompressContinue: decoded size from frame : %u", (unsigned)dctx->decodedSize);
+                RETURN_ERROR_IF(
+                    dctx->fParams.frameContentSize != ZSTD_CONTENTSIZE_UNKNOWN
+                 && dctx->decodedSize != dctx->fParams.frameContentSize,
+                    corruption_detected);
                 if (dctx->fParams.checksumFlag) {  /* another round for frame checksum */
                     dctx->expected = 4;
                     dctx->stage = ZSTDds_checkChecksum;
@@ -2130,8 +982,8 @@
         assert(srcSize == 4);  /* guaranteed by dctx->expected */
         {   U32 const h32 = (U32)XXH64_digest(&dctx->xxhState);
             U32 const check32 = MEM_readLE32(src);
-            DEBUGLOG(4, "ZSTD_decompressContinue: checksum : calculated %08X :: %08X read", h32, check32);
-            if (check32 != h32) return ERROR(checksum_wrong);
+            DEBUGLOG(4, "ZSTD_decompressContinue: checksum : calculated %08X :: %08X read", (unsigned)h32, (unsigned)check32);
+            RETURN_ERROR_IF(check32 != h32, checksum_wrong);
             dctx->expected = 0;
             dctx->stage = ZSTDds_getFrameHeaderSize;
             return 0;
@@ -2139,9 +991,9 @@
 
     case ZSTDds_decodeSkippableHeader:
         assert(src != NULL);
-        assert(srcSize <= ZSTD_skippableHeaderSize);
-        memcpy(dctx->headerBuffer + (ZSTD_skippableHeaderSize - srcSize), src, srcSize);   /* complete skippable header */
-        dctx->expected = MEM_readLE32(dctx->headerBuffer + ZSTD_frameIdSize);   /* note : dctx->expected can grow seriously large, beyond local buffer size */
+        assert(srcSize <= ZSTD_SKIPPABLEHEADERSIZE);
+        memcpy(dctx->headerBuffer + (ZSTD_SKIPPABLEHEADERSIZE - srcSize), src, srcSize);   /* complete skippable header */
+        dctx->expected = MEM_readLE32(dctx->headerBuffer + ZSTD_FRAMEIDSIZE);   /* note : dctx->expected can grow seriously large, beyond local buffer size */
         dctx->stage = ZSTDds_skipFrame;
         return 0;
 
@@ -2151,7 +1003,8 @@
         return 0;
 
     default:
-        return ERROR(GENERIC);   /* impossible */
+        assert(0);   /* impossible */
+        RETURN_ERROR(GENERIC);   /* some compiler require default to do something */
     }
 }
 
@@ -2159,38 +1012,52 @@
 static size_t ZSTD_refDictContent(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
 {
     dctx->dictEnd = dctx->previousDstEnd;
-    dctx->vBase = (const char*)dict - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base));
-    dctx->base = dict;
+    dctx->virtualStart = (const char*)dict - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->prefixStart));
+    dctx->prefixStart = dict;
     dctx->previousDstEnd = (const char*)dict + dictSize;
     return 0;
 }
 
-/* ZSTD_loadEntropy() :
- * dict : must point at beginning of a valid zstd dictionary
+/*! ZSTD_loadDEntropy() :
+ *  dict : must point at beginning of a valid zstd dictionary.
  * @return : size of entropy tables read */
-static size_t ZSTD_loadEntropy(ZSTD_entropyDTables_t* entropy, const void* const dict, size_t const dictSize)
+size_t
+ZSTD_loadDEntropy(ZSTD_entropyDTables_t* entropy,
+                  const void* const dict, size_t const dictSize)
 {
     const BYTE* dictPtr = (const BYTE*)dict;
     const BYTE* const dictEnd = dictPtr + dictSize;
 
-    if (dictSize <= 8) return ERROR(dictionary_corrupted);
+    RETURN_ERROR_IF(dictSize <= 8, dictionary_corrupted);
+    assert(MEM_readLE32(dict) == ZSTD_MAGIC_DICTIONARY);   /* dict must be valid */
     dictPtr += 8;   /* skip header = magic + dictID */
 
-
-    {   size_t const hSize = HUF_readDTableX4_wksp(
-            entropy->hufTable, dictPtr, dictEnd - dictPtr,
-            entropy->workspace, sizeof(entropy->workspace));
-        if (HUF_isError(hSize)) return ERROR(dictionary_corrupted);
+    ZSTD_STATIC_ASSERT(offsetof(ZSTD_entropyDTables_t, OFTable) == offsetof(ZSTD_entropyDTables_t, LLTable) + sizeof(entropy->LLTable));
+    ZSTD_STATIC_ASSERT(offsetof(ZSTD_entropyDTables_t, MLTable) == offsetof(ZSTD_entropyDTables_t, OFTable) + sizeof(entropy->OFTable));
+    ZSTD_STATIC_ASSERT(sizeof(entropy->LLTable) + sizeof(entropy->OFTable) + sizeof(entropy->MLTable) >= HUF_DECOMPRESS_WORKSPACE_SIZE);
+    {   void* const workspace = &entropy->LLTable;   /* use fse tables as temporary workspace; implies fse tables are grouped together */
+        size_t const workspaceSize = sizeof(entropy->LLTable) + sizeof(entropy->OFTable) + sizeof(entropy->MLTable);
+#ifdef HUF_FORCE_DECOMPRESS_X1
+        /* in minimal huffman, we always use X1 variants */
+        size_t const hSize = HUF_readDTableX1_wksp(entropy->hufTable,
+                                                dictPtr, dictEnd - dictPtr,
+                                                workspace, workspaceSize);
+#else
+        size_t const hSize = HUF_readDTableX2_wksp(entropy->hufTable,
+                                                dictPtr, dictEnd - dictPtr,
+                                                workspace, workspaceSize);
+#endif
+        RETURN_ERROR_IF(HUF_isError(hSize), dictionary_corrupted);
         dictPtr += hSize;
     }
 
     {   short offcodeNCount[MaxOff+1];
-        U32 offcodeMaxValue = MaxOff, offcodeLog;
+        unsigned offcodeMaxValue = MaxOff, offcodeLog;
         size_t const offcodeHeaderSize = FSE_readNCount(offcodeNCount, &offcodeMaxValue, &offcodeLog, dictPtr, dictEnd-dictPtr);
-        if (FSE_isError(offcodeHeaderSize)) return ERROR(dictionary_corrupted);
-        if (offcodeMaxValue > MaxOff) return ERROR(dictionary_corrupted);
-        if (offcodeLog > OffFSELog) return ERROR(dictionary_corrupted);
-        ZSTD_buildFSETable(entropy->OFTable,
+        RETURN_ERROR_IF(FSE_isError(offcodeHeaderSize), dictionary_corrupted);
+        RETURN_ERROR_IF(offcodeMaxValue > MaxOff, dictionary_corrupted);
+        RETURN_ERROR_IF(offcodeLog > OffFSELog, dictionary_corrupted);
+        ZSTD_buildFSETable( entropy->OFTable,
                             offcodeNCount, offcodeMaxValue,
                             OF_base, OF_bits,
                             offcodeLog);
@@ -2200,10 +1067,10 @@
     {   short matchlengthNCount[MaxML+1];
         unsigned matchlengthMaxValue = MaxML, matchlengthLog;
         size_t const matchlengthHeaderSize = FSE_readNCount(matchlengthNCount, &matchlengthMaxValue, &matchlengthLog, dictPtr, dictEnd-dictPtr);
-        if (FSE_isError(matchlengthHeaderSize)) return ERROR(dictionary_corrupted);
-        if (matchlengthMaxValue > MaxML) return ERROR(dictionary_corrupted);
-        if (matchlengthLog > MLFSELog) return ERROR(dictionary_corrupted);
-        ZSTD_buildFSETable(entropy->MLTable,
+        RETURN_ERROR_IF(FSE_isError(matchlengthHeaderSize), dictionary_corrupted);
+        RETURN_ERROR_IF(matchlengthMaxValue > MaxML, dictionary_corrupted);
+        RETURN_ERROR_IF(matchlengthLog > MLFSELog, dictionary_corrupted);
+        ZSTD_buildFSETable( entropy->MLTable,
                             matchlengthNCount, matchlengthMaxValue,
                             ML_base, ML_bits,
                             matchlengthLog);
@@ -2213,22 +1080,23 @@
     {   short litlengthNCount[MaxLL+1];
         unsigned litlengthMaxValue = MaxLL, litlengthLog;
         size_t const litlengthHeaderSize = FSE_readNCount(litlengthNCount, &litlengthMaxValue, &litlengthLog, dictPtr, dictEnd-dictPtr);
-        if (FSE_isError(litlengthHeaderSize)) return ERROR(dictionary_corrupted);
-        if (litlengthMaxValue > MaxLL) return ERROR(dictionary_corrupted);
-        if (litlengthLog > LLFSELog) return ERROR(dictionary_corrupted);
-        ZSTD_buildFSETable(entropy->LLTable,
+        RETURN_ERROR_IF(FSE_isError(litlengthHeaderSize), dictionary_corrupted);
+        RETURN_ERROR_IF(litlengthMaxValue > MaxLL, dictionary_corrupted);
+        RETURN_ERROR_IF(litlengthLog > LLFSELog, dictionary_corrupted);
+        ZSTD_buildFSETable( entropy->LLTable,
                             litlengthNCount, litlengthMaxValue,
                             LL_base, LL_bits,
                             litlengthLog);
         dictPtr += litlengthHeaderSize;
     }
 
-    if (dictPtr+12 > dictEnd) return ERROR(dictionary_corrupted);
+    RETURN_ERROR_IF(dictPtr+12 > dictEnd, dictionary_corrupted);
     {   int i;
         size_t const dictContentSize = (size_t)(dictEnd - (dictPtr+12));
         for (i=0; i<3; i++) {
             U32 const rep = MEM_readLE32(dictPtr); dictPtr += 4;
-            if (rep==0 || rep >= dictContentSize) return ERROR(dictionary_corrupted);
+            RETURN_ERROR_IF(rep==0 || rep >= dictContentSize,
+                            dictionary_corrupted);
             entropy->rep[i] = rep;
     }   }
 
@@ -2242,11 +1110,11 @@
         if (magic != ZSTD_MAGIC_DICTIONARY) {
             return ZSTD_refDictContent(dctx, dict, dictSize);   /* pure content mode */
     }   }
-    dctx->dictID = MEM_readLE32((const char*)dict + ZSTD_frameIdSize);
+    dctx->dictID = MEM_readLE32((const char*)dict + ZSTD_FRAMEIDSIZE);
 
     /* load entropy tables */
-    {   size_t const eSize = ZSTD_loadEntropy(&dctx->entropy, dict, dictSize);
-        if (ZSTD_isError(eSize)) return ERROR(dictionary_corrupted);
+    {   size_t const eSize = ZSTD_loadDEntropy(&dctx->entropy, dict, dictSize);
+        RETURN_ERROR_IF(ZSTD_isError(eSize), dictionary_corrupted);
         dict = (const char*)dict + eSize;
         dictSize -= eSize;
     }
@@ -2256,7 +1124,6 @@
     return ZSTD_refDictContent(dctx, dict, dictSize);
 }
 
-/* Note : this function cannot fail */
 size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx)
 {
     assert(dctx != NULL);
@@ -2264,8 +1131,8 @@
     dctx->stage = ZSTDds_getFrameHeaderSize;
     dctx->decodedSize = 0;
     dctx->previousDstEnd = NULL;
-    dctx->base = NULL;
-    dctx->vBase = NULL;
+    dctx->prefixStart = NULL;
+    dctx->virtualStart = NULL;
     dctx->dictEnd = NULL;
     dctx->entropy.hufTable[0] = (HUF_DTable)((HufLog)*0x1000001);  /* cover both little and big endian */
     dctx->litEntropy = dctx->fseEntropy = 0;
@@ -2281,201 +1148,36 @@
 
 size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
 {
-    CHECK_F( ZSTD_decompressBegin(dctx) );
+    FORWARD_IF_ERROR( ZSTD_decompressBegin(dctx) );
     if (dict && dictSize)
-        CHECK_E(ZSTD_decompress_insertDictionary(dctx, dict, dictSize), dictionary_corrupted);
+        RETURN_ERROR_IF(
+            ZSTD_isError(ZSTD_decompress_insertDictionary(dctx, dict, dictSize)),
+            dictionary_corrupted);
     return 0;
 }
 
 
 /* ======   ZSTD_DDict   ====== */
 
-struct ZSTD_DDict_s {
-    void* dictBuffer;
-    const void* dictContent;
-    size_t dictSize;
-    ZSTD_entropyDTables_t entropy;
-    U32 dictID;
-    U32 entropyPresent;
-    ZSTD_customMem cMem;
-};  /* typedef'd to ZSTD_DDict within "zstd.h" */
-
-static const void* ZSTD_DDictDictContent(const ZSTD_DDict* ddict)
+size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict)
 {
-    return ddict->dictContent;
-}
-
-static size_t ZSTD_DDictDictSize(const ZSTD_DDict* ddict)
-{
-    return ddict->dictSize;
-}
-
-size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dstDCtx, const ZSTD_DDict* ddict)
-{
-    CHECK_F( ZSTD_decompressBegin(dstDCtx) );
-    if (ddict) {   /* support begin on NULL */
-        dstDCtx->dictID = ddict->dictID;
-        dstDCtx->base = ddict->dictContent;
-        dstDCtx->vBase = ddict->dictContent;
-        dstDCtx->dictEnd = (const BYTE*)ddict->dictContent + ddict->dictSize;
-        dstDCtx->previousDstEnd = dstDCtx->dictEnd;
-        if (ddict->entropyPresent) {
-            dstDCtx->litEntropy = 1;
-            dstDCtx->fseEntropy = 1;
-            dstDCtx->LLTptr = ddict->entropy.LLTable;
-            dstDCtx->MLTptr = ddict->entropy.MLTable;
-            dstDCtx->OFTptr = ddict->entropy.OFTable;
-            dstDCtx->HUFptr = ddict->entropy.hufTable;
-            dstDCtx->entropy.rep[0] = ddict->entropy.rep[0];
-            dstDCtx->entropy.rep[1] = ddict->entropy.rep[1];
-            dstDCtx->entropy.rep[2] = ddict->entropy.rep[2];
-        } else {
-            dstDCtx->litEntropy = 0;
-            dstDCtx->fseEntropy = 0;
-        }
+    DEBUGLOG(4, "ZSTD_decompressBegin_usingDDict");
+    assert(dctx != NULL);
+    if (ddict) {
+        const char* const dictStart = (const char*)ZSTD_DDict_dictContent(ddict);
+        size_t const dictSize = ZSTD_DDict_dictSize(ddict);
+        const void* const dictEnd = dictStart + dictSize;
+        dctx->ddictIsCold = (dctx->dictEnd != dictEnd);
+        DEBUGLOG(4, "DDict is %s",
+                    dctx->ddictIsCold ? "~cold~" : "hot!");
+    }
+    FORWARD_IF_ERROR( ZSTD_decompressBegin(dctx) );
+    if (ddict) {   /* NULL ddict is equivalent to no dictionary */
+        ZSTD_copyDDictParameters(dctx, ddict);
     }
     return 0;
 }
 
-static size_t ZSTD_loadEntropy_inDDict(ZSTD_DDict* ddict, ZSTD_dictContentType_e dictContentType)
-{
-    ddict->dictID = 0;
-    ddict->entropyPresent = 0;
-    if (dictContentType == ZSTD_dct_rawContent) return 0;
-
-    if (ddict->dictSize < 8) {
-        if (dictContentType == ZSTD_dct_fullDict)
-            return ERROR(dictionary_corrupted);   /* only accept specified dictionaries */
-        return 0;   /* pure content mode */
-    }
-    {   U32 const magic = MEM_readLE32(ddict->dictContent);
-        if (magic != ZSTD_MAGIC_DICTIONARY) {
-            if (dictContentType == ZSTD_dct_fullDict)
-                return ERROR(dictionary_corrupted);   /* only accept specified dictionaries */
-            return 0;   /* pure content mode */
-        }
-    }
-    ddict->dictID = MEM_readLE32((const char*)ddict->dictContent + ZSTD_frameIdSize);
-
-    /* load entropy tables */
-    CHECK_E( ZSTD_loadEntropy(&ddict->entropy, ddict->dictContent, ddict->dictSize), dictionary_corrupted );
-    ddict->entropyPresent = 1;
-    return 0;
-}
-
-
-static size_t ZSTD_initDDict_internal(ZSTD_DDict* ddict,
-                                      const void* dict, size_t dictSize,
-                                      ZSTD_dictLoadMethod_e dictLoadMethod,
-                                      ZSTD_dictContentType_e dictContentType)
-{
-    if ((dictLoadMethod == ZSTD_dlm_byRef) || (!dict) || (!dictSize)) {
-        ddict->dictBuffer = NULL;
-        ddict->dictContent = dict;
-    } else {
-        void* const internalBuffer = ZSTD_malloc(dictSize, ddict->cMem);
-        ddict->dictBuffer = internalBuffer;
-        ddict->dictContent = internalBuffer;
-        if (!internalBuffer) return ERROR(memory_allocation);
-        memcpy(internalBuffer, dict, dictSize);
-    }
-    ddict->dictSize = dictSize;
-    ddict->entropy.hufTable[0] = (HUF_DTable)((HufLog)*0x1000001);  /* cover both little and big endian */
-
-    /* parse dictionary content */
-    CHECK_F( ZSTD_loadEntropy_inDDict(ddict, dictContentType) );
-
-    return 0;
-}
-
-ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize,
-                                      ZSTD_dictLoadMethod_e dictLoadMethod,
-                                      ZSTD_dictContentType_e dictContentType,
-                                      ZSTD_customMem customMem)
-{
-    if (!customMem.customAlloc ^ !customMem.customFree) return NULL;
-
-    {   ZSTD_DDict* const ddict = (ZSTD_DDict*) ZSTD_malloc(sizeof(ZSTD_DDict), customMem);
-        if (!ddict) return NULL;
-        ddict->cMem = customMem;
-
-        if (ZSTD_isError( ZSTD_initDDict_internal(ddict, dict, dictSize, dictLoadMethod, dictContentType) )) {
-            ZSTD_freeDDict(ddict);
-            return NULL;
-        }
-
-        return ddict;
-    }
-}
-
-/*! ZSTD_createDDict() :
-*   Create a digested dictionary, to start decompression without startup delay.
-*   `dict` content is copied inside DDict.
-*   Consequently, `dict` can be released after `ZSTD_DDict` creation */
-ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize)
-{
-    ZSTD_customMem const allocator = { NULL, NULL, NULL };
-    return ZSTD_createDDict_advanced(dict, dictSize, ZSTD_dlm_byCopy, ZSTD_dct_auto, allocator);
-}
-
-/*! ZSTD_createDDict_byReference() :
- *  Create a digested dictionary, to start decompression without startup delay.
- *  Dictionary content is simply referenced, it will be accessed during decompression.
- *  Warning : dictBuffer must outlive DDict (DDict must be freed before dictBuffer) */
-ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize)
-{
-    ZSTD_customMem const allocator = { NULL, NULL, NULL };
-    return ZSTD_createDDict_advanced(dictBuffer, dictSize, ZSTD_dlm_byRef, ZSTD_dct_auto, allocator);
-}
-
-
-const ZSTD_DDict* ZSTD_initStaticDDict(
-                                void* workspace, size_t workspaceSize,
-                                const void* dict, size_t dictSize,
-                                ZSTD_dictLoadMethod_e dictLoadMethod,
-                                ZSTD_dictContentType_e dictContentType)
-{
-    size_t const neededSpace =
-            sizeof(ZSTD_DDict) + (dictLoadMethod == ZSTD_dlm_byRef ? 0 : dictSize);
-    ZSTD_DDict* const ddict = (ZSTD_DDict*)workspace;
-    assert(workspace != NULL);
-    assert(dict != NULL);
-    if ((size_t)workspace & 7) return NULL;  /* 8-aligned */
-    if (workspaceSize < neededSpace) return NULL;
-    if (dictLoadMethod == ZSTD_dlm_byCopy) {
-        memcpy(ddict+1, dict, dictSize);  /* local copy */
-        dict = ddict+1;
-    }
-    if (ZSTD_isError( ZSTD_initDDict_internal(ddict, dict, dictSize, ZSTD_dlm_byRef, dictContentType) ))
-        return NULL;
-    return ddict;
-}
-
-
-size_t ZSTD_freeDDict(ZSTD_DDict* ddict)
-{
-    if (ddict==NULL) return 0;   /* support free on NULL */
-    {   ZSTD_customMem const cMem = ddict->cMem;
-        ZSTD_free(ddict->dictBuffer, cMem);
-        ZSTD_free(ddict, cMem);
-        return 0;
-    }
-}
-
-/*! ZSTD_estimateDDictSize() :
- *  Estimate amount of memory that will be needed to create a dictionary for decompression.
- *  Note : dictionary created by reference using ZSTD_dlm_byRef are smaller */
-size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod)
-{
-    return sizeof(ZSTD_DDict) + (dictLoadMethod == ZSTD_dlm_byRef ? 0 : dictSize);
-}
-
-size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict)
-{
-    if (ddict==NULL) return 0;   /* support sizeof on NULL */
-    return sizeof(*ddict) + (ddict->dictBuffer ? ddict->dictSize : 0) ;
-}
-
 /*! ZSTD_getDictID_fromDict() :
  *  Provides the dictID stored within dictionary.
  *  if @return == 0, the dictionary is not conformant with Zstandard specification.
@@ -2484,21 +1186,11 @@
 {
     if (dictSize < 8) return 0;
     if (MEM_readLE32(dict) != ZSTD_MAGIC_DICTIONARY) return 0;
-    return MEM_readLE32((const char*)dict + ZSTD_frameIdSize);
-}
-
-/*! ZSTD_getDictID_fromDDict() :
- *  Provides the dictID of the dictionary loaded into `ddict`.
- *  If @return == 0, the dictionary is not conformant to Zstandard specification, or empty.
- *  Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */
-unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict)
-{
-    if (ddict==NULL) return 0;
-    return ZSTD_getDictID_fromDict(ddict->dictContent, ddict->dictSize);
+    return MEM_readLE32((const char*)dict + ZSTD_FRAMEIDSIZE);
 }
 
 /*! ZSTD_getDictID_fromFrame() :
- *  Provides the dictID required to decompresse frame stored within `src`.
+ *  Provides the dictID required to decompress frame stored within `src`.
  *  If @return == 0, the dictID could not be decoded.
  *  This could for one of the following reasons :
  *  - The frame does not require a dictionary (most common case).
@@ -2560,22 +1252,24 @@
 }
 
 
-/* *** Initialization *** */
+/* ***  Initialization  *** */
 
 size_t ZSTD_DStreamInSize(void)  { return ZSTD_BLOCKSIZE_MAX + ZSTD_blockHeaderSize; }
 size_t ZSTD_DStreamOutSize(void) { return ZSTD_BLOCKSIZE_MAX; }
 
-size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType)
+size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx,
+                                   const void* dict, size_t dictSize,
+                                         ZSTD_dictLoadMethod_e dictLoadMethod,
+                                         ZSTD_dictContentType_e dictContentType)
 {
-    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
-    ZSTD_freeDDict(dctx->ddictLocal);
+    RETURN_ERROR_IF(dctx->streamStage != zdss_init, stage_wrong);
+    ZSTD_clearDict(dctx);
     if (dict && dictSize >= 8) {
         dctx->ddictLocal = ZSTD_createDDict_advanced(dict, dictSize, dictLoadMethod, dictContentType, dctx->customMem);
-        if (dctx->ddictLocal == NULL) return ERROR(memory_allocation);
-    } else {
-        dctx->ddictLocal = NULL;
+        RETURN_ERROR_IF(dctx->ddictLocal == NULL, memory_allocation);
+        dctx->ddict = dctx->ddictLocal;
+        dctx->dictUses = ZSTD_use_indefinitely;
     }
-    dctx->ddict = dctx->ddictLocal;
     return 0;
 }
 
@@ -2591,7 +1285,9 @@
 
 size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType)
 {
-    return ZSTD_DCtx_loadDictionary_advanced(dctx, prefix, prefixSize, ZSTD_dlm_byRef, dictContentType);
+    FORWARD_IF_ERROR(ZSTD_DCtx_loadDictionary_advanced(dctx, prefix, prefixSize, ZSTD_dlm_byRef, dictContentType));
+    dctx->dictUses = ZSTD_use_once;
+    return 0;
 }
 
 size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize)
@@ -2601,28 +1297,21 @@
 
 
 /* ZSTD_initDStream_usingDict() :
- * return : expected size, aka ZSTD_frameHeaderSize_prefix.
+ * return : expected size, aka ZSTD_FRAMEHEADERSIZE_PREFIX.
  * this function cannot fail */
 size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize)
 {
     DEBUGLOG(4, "ZSTD_initDStream_usingDict");
-    zds->streamStage = zdss_init;
-    CHECK_F( ZSTD_DCtx_loadDictionary(zds, dict, dictSize) );
-    return ZSTD_frameHeaderSize_prefix;
+    FORWARD_IF_ERROR( ZSTD_DCtx_reset(zds, ZSTD_reset_session_only) );
+    FORWARD_IF_ERROR( ZSTD_DCtx_loadDictionary(zds, dict, dictSize) );
+    return ZSTD_FRAMEHEADERSIZE_PREFIX;
 }
 
 /* note : this variant can't fail */
 size_t ZSTD_initDStream(ZSTD_DStream* zds)
 {
     DEBUGLOG(4, "ZSTD_initDStream");
-    return ZSTD_initDStream_usingDict(zds, NULL, 0);
-}
-
-size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict)
-{
-    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
-    dctx->ddict = ddict;
-    return 0;
+    return ZSTD_initDStream_usingDDict(zds, NULL);
 }
 
 /* ZSTD_initDStream_usingDDict() :
@@ -2630,51 +1319,119 @@
  * this function cannot fail */
 size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* dctx, const ZSTD_DDict* ddict)
 {
-    size_t const initResult = ZSTD_initDStream(dctx);
-    dctx->ddict = ddict;
-    return initResult;
+    FORWARD_IF_ERROR( ZSTD_DCtx_reset(dctx, ZSTD_reset_session_only) );
+    FORWARD_IF_ERROR( ZSTD_DCtx_refDDict(dctx, ddict) );
+    return ZSTD_FRAMEHEADERSIZE_PREFIX;
 }
 
 /* ZSTD_resetDStream() :
- * return : expected size, aka ZSTD_frameHeaderSize_prefix.
+ * return : expected size, aka ZSTD_FRAMEHEADERSIZE_PREFIX.
  * this function cannot fail */
 size_t ZSTD_resetDStream(ZSTD_DStream* dctx)
 {
-    DEBUGLOG(4, "ZSTD_resetDStream");
-    dctx->streamStage = zdss_loadHeader;
-    dctx->lhSize = dctx->inPos = dctx->outStart = dctx->outEnd = 0;
-    dctx->legacyVersion = 0;
-    dctx->hostageByte = 0;
-    return ZSTD_frameHeaderSize_prefix;
+    FORWARD_IF_ERROR(ZSTD_DCtx_reset(dctx, ZSTD_reset_session_only));
+    return ZSTD_FRAMEHEADERSIZE_PREFIX;
 }
 
-size_t ZSTD_setDStreamParameter(ZSTD_DStream* dctx,
-                                ZSTD_DStreamParameter_e paramType, unsigned paramValue)
+
+size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict)
 {
-    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
-    switch(paramType)
-    {
-        default : return ERROR(parameter_unsupported);
-        case DStream_p_maxWindowSize :
-            DEBUGLOG(4, "setting maxWindowSize = %u KB", paramValue >> 10);
-            dctx->maxWindowSize = paramValue ? paramValue : (U32)(-1);
-            break;
+    RETURN_ERROR_IF(dctx->streamStage != zdss_init, stage_wrong);
+    ZSTD_clearDict(dctx);
+    if (ddict) {
+        dctx->ddict = ddict;
+        dctx->dictUses = ZSTD_use_indefinitely;
     }
     return 0;
 }
 
+/* ZSTD_DCtx_setMaxWindowSize() :
+ * note : no direct equivalence in ZSTD_DCtx_setParameter,
+ * since this version sets windowSize, and the other sets windowLog */
 size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize)
 {
-    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
+    ZSTD_bounds const bounds = ZSTD_dParam_getBounds(ZSTD_d_windowLogMax);
+    size_t const min = (size_t)1 << bounds.lowerBound;
+    size_t const max = (size_t)1 << bounds.upperBound;
+    RETURN_ERROR_IF(dctx->streamStage != zdss_init, stage_wrong);
+    RETURN_ERROR_IF(maxWindowSize < min, parameter_outOfBound);
+    RETURN_ERROR_IF(maxWindowSize > max, parameter_outOfBound);
     dctx->maxWindowSize = maxWindowSize;
     return 0;
 }
 
 size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format)
 {
-    DEBUGLOG(4, "ZSTD_DCtx_setFormat : %u", (unsigned)format);
-    if (dctx->streamStage != zdss_init) return ERROR(stage_wrong);
-    dctx->format = format;
+    return ZSTD_DCtx_setParameter(dctx, ZSTD_d_format, format);
+}
+
+ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam)
+{
+    ZSTD_bounds bounds = { 0, 0, 0 };
+    switch(dParam) {
+        case ZSTD_d_windowLogMax:
+            bounds.lowerBound = ZSTD_WINDOWLOG_ABSOLUTEMIN;
+            bounds.upperBound = ZSTD_WINDOWLOG_MAX;
+            return bounds;
+        case ZSTD_d_format:
+            bounds.lowerBound = (int)ZSTD_f_zstd1;
+            bounds.upperBound = (int)ZSTD_f_zstd1_magicless;
+            ZSTD_STATIC_ASSERT(ZSTD_f_zstd1 < ZSTD_f_zstd1_magicless);
+            return bounds;
+        default:;
+    }
+    bounds.error = ERROR(parameter_unsupported);
+    return bounds;
+}
+
+/* ZSTD_dParam_withinBounds:
+ * @return 1 if value is within dParam bounds,
+ * 0 otherwise */
+static int ZSTD_dParam_withinBounds(ZSTD_dParameter dParam, int value)
+{
+    ZSTD_bounds const bounds = ZSTD_dParam_getBounds(dParam);
+    if (ZSTD_isError(bounds.error)) return 0;
+    if (value < bounds.lowerBound) return 0;
+    if (value > bounds.upperBound) return 0;
+    return 1;
+}
+
+#define CHECK_DBOUNDS(p,v) {                \
+    RETURN_ERROR_IF(!ZSTD_dParam_withinBounds(p, v), parameter_outOfBound); \
+}
+
+size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter dParam, int value)
+{
+    RETURN_ERROR_IF(dctx->streamStage != zdss_init, stage_wrong);
+    switch(dParam) {
+        case ZSTD_d_windowLogMax:
+            if (value == 0) value = ZSTD_WINDOWLOG_LIMIT_DEFAULT;
+            CHECK_DBOUNDS(ZSTD_d_windowLogMax, value);
+            dctx->maxWindowSize = ((size_t)1) << value;
+            return 0;
+        case ZSTD_d_format:
+            CHECK_DBOUNDS(ZSTD_d_format, value);
+            dctx->format = (ZSTD_format_e)value;
+            return 0;
+        default:;
+    }
+    RETURN_ERROR(parameter_unsupported);
+}
+
+size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset)
+{
+    if ( (reset == ZSTD_reset_session_only)
+      || (reset == ZSTD_reset_session_and_parameters) ) {
+        dctx->streamStage = zdss_init;
+        dctx->noForwardProgress = 0;
+    }
+    if ( (reset == ZSTD_reset_parameters)
+      || (reset == ZSTD_reset_session_and_parameters) ) {
+        RETURN_ERROR_IF(dctx->streamStage != zdss_init, stage_wrong);
+        ZSTD_clearDict(dctx);
+        dctx->format = ZSTD_f_zstd1;
+        dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
+    }
     return 0;
 }
 
@@ -2690,7 +1447,8 @@
     unsigned long long const neededRBSize = windowSize + blockSize + (WILDCOPY_OVERLENGTH * 2);
     unsigned long long const neededSize = MIN(frameContentSize, neededRBSize);
     size_t const minRBSize = (size_t) neededSize;
-    if ((unsigned long long)minRBSize != neededSize) return ERROR(frameParameter_windowTooLarge);
+    RETURN_ERROR_IF((unsigned long long)minRBSize != neededSize,
+                    frameParameter_windowTooLarge);
     return minRBSize;
 }
 
@@ -2704,13 +1462,13 @@
 
 size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize)
 {
-    U32 const windowSizeMax = 1U << ZSTD_WINDOWLOG_MAX;   /* note : should be user-selectable */
+    U32 const windowSizeMax = 1U << ZSTD_WINDOWLOG_MAX;   /* note : should be user-selectable, but requires an additional parameter (or a dctx) */
     ZSTD_frameHeader zfh;
     size_t const err = ZSTD_getFrameHeader(&zfh, src, srcSize);
     if (ZSTD_isError(err)) return err;
-    if (err>0) return ERROR(srcSize_wrong);
-    if (zfh.windowSize > windowSizeMax)
-        return ERROR(frameParameter_windowTooLarge);
+    RETURN_ERROR_IF(err>0, srcSize_wrong);
+    RETURN_ERROR_IF(zfh.windowSize > windowSizeMax,
+                    frameParameter_windowTooLarge);
     return ZSTD_estimateDStreamSize((size_t)zfh.windowSize);
 }
 
@@ -2736,16 +1494,16 @@
     U32 someMoreWork = 1;
 
     DEBUGLOG(5, "ZSTD_decompressStream");
-    if (input->pos > input->size) {  /* forbidden */
-        DEBUGLOG(5, "in: pos: %u   vs size: %u",
-                    (U32)input->pos, (U32)input->size);
-        return ERROR(srcSize_wrong);
-    }
-    if (output->pos > output->size) {  /* forbidden */
-        DEBUGLOG(5, "out: pos: %u   vs size: %u",
-                    (U32)output->pos, (U32)output->size);
-        return ERROR(dstSize_tooSmall);
-    }
+    RETURN_ERROR_IF(
+        input->pos > input->size,
+        srcSize_wrong,
+        "forbidden. in: pos: %u   vs size: %u",
+        (U32)input->pos, (U32)input->size);
+    RETURN_ERROR_IF(
+        output->pos > output->size,
+        dstSize_tooSmall,
+        "forbidden. out: pos: %u   vs size: %u",
+        (U32)output->pos, (U32)output->size);
     DEBUGLOG(5, "input size : %u", (U32)(input->size - input->pos));
 
     while (someMoreWork) {
@@ -2753,32 +1511,36 @@
         {
         case zdss_init :
             DEBUGLOG(5, "stage zdss_init => transparent reset ");
-            ZSTD_resetDStream(zds);   /* transparent reset on starting decoding a new frame */
+            zds->streamStage = zdss_loadHeader;
+            zds->lhSize = zds->inPos = zds->outStart = zds->outEnd = 0;
+            zds->legacyVersion = 0;
+            zds->hostageByte = 0;
             /* fall-through */
 
         case zdss_loadHeader :
             DEBUGLOG(5, "stage zdss_loadHeader (srcSize : %u)", (U32)(iend - ip));
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
             if (zds->legacyVersion) {
-                /* legacy support is incompatible with static dctx */
-                if (zds->staticSize) return ERROR(memory_allocation);
+                RETURN_ERROR_IF(zds->staticSize, memory_allocation,
+                    "legacy support is incompatible with static dctx");
                 {   size_t const hint = ZSTD_decompressLegacyStream(zds->legacyContext, zds->legacyVersion, output, input);
                     if (hint==0) zds->streamStage = zdss_init;
                     return hint;
             }   }
 #endif
-            {   size_t const hSize = ZSTD_getFrameHeader_internal(&zds->fParams, zds->headerBuffer, zds->lhSize, zds->format);
+            {   size_t const hSize = ZSTD_getFrameHeader_advanced(&zds->fParams, zds->headerBuffer, zds->lhSize, zds->format);
                 DEBUGLOG(5, "header size : %u", (U32)hSize);
                 if (ZSTD_isError(hSize)) {
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
                     U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart);
                     if (legacyVersion) {
-                        const void* const dict = zds->ddict ? zds->ddict->dictContent : NULL;
-                        size_t const dictSize = zds->ddict ? zds->ddict->dictSize : 0;
+                        ZSTD_DDict const* const ddict = ZSTD_getDDict(zds);
+                        const void* const dict = ddict ? ZSTD_DDict_dictContent(ddict) : NULL;
+                        size_t const dictSize = ddict ? ZSTD_DDict_dictSize(ddict) : 0;
                         DEBUGLOG(5, "ZSTD_decompressStream: detected legacy version v0.%u", legacyVersion);
-                        /* legacy support is incompatible with static dctx */
-                        if (zds->staticSize) return ERROR(memory_allocation);
-                        CHECK_F(ZSTD_initLegacyStream(&zds->legacyContext,
+                        RETURN_ERROR_IF(zds->staticSize, memory_allocation,
+                            "legacy support is incompatible with static dctx");
+                        FORWARD_IF_ERROR(ZSTD_initLegacyStream(&zds->legacyContext,
                                     zds->previousLegacyVersion, legacyVersion,
                                     dict, dictSize));
                         zds->legacyVersion = zds->previousLegacyVersion = legacyVersion;
@@ -2799,7 +1561,7 @@
                             zds->lhSize += remainingInput;
                         }
                         input->pos = input->size;
-                        return (MAX(ZSTD_frameHeaderSize_min, hSize) - zds->lhSize) + ZSTD_blockHeaderSize;   /* remaining header bytes + next block header */
+                        return (MAX(ZSTD_FRAMEHEADERSIZE_MIN, hSize) - zds->lhSize) + ZSTD_blockHeaderSize;   /* remaining header bytes + next block header */
                     }
                     assert(ip != NULL);
                     memcpy(zds->headerBuffer + zds->lhSize, ip, toLoad); zds->lhSize = hSize; ip += toLoad;
@@ -2812,7 +1574,7 @@
                 size_t const cSize = ZSTD_findFrameCompressedSize(istart, iend-istart);
                 if (cSize <= (size_t)(iend-istart)) {
                     /* shortcut : using single-pass mode */
-                    size_t const decompressedSize = ZSTD_decompress_usingDDict(zds, op, oend-op, istart, cSize, zds->ddict);
+                    size_t const decompressedSize = ZSTD_decompress_usingDDict(zds, op, oend-op, istart, cSize, ZSTD_getDDict(zds));
                     if (ZSTD_isError(decompressedSize)) return decompressedSize;
                     DEBUGLOG(4, "shortcut to single-pass ZSTD_decompress_usingDDict()")
                     ip = istart + cSize;
@@ -2825,13 +1587,13 @@
 
             /* Consume header (see ZSTDds_decodeFrameHeader) */
             DEBUGLOG(4, "Consume header");
-            CHECK_F(ZSTD_decompressBegin_usingDDict(zds, zds->ddict));
+            FORWARD_IF_ERROR(ZSTD_decompressBegin_usingDDict(zds, ZSTD_getDDict(zds)));
 
-            if ((MEM_readLE32(zds->headerBuffer) & 0xFFFFFFF0U) == ZSTD_MAGIC_SKIPPABLE_START) {  /* skippable frame */
-                zds->expected = MEM_readLE32(zds->headerBuffer + ZSTD_frameIdSize);
+            if ((MEM_readLE32(zds->headerBuffer) & ZSTD_MAGIC_SKIPPABLE_MASK) == ZSTD_MAGIC_SKIPPABLE_START) {  /* skippable frame */
+                zds->expected = MEM_readLE32(zds->headerBuffer + ZSTD_FRAMEIDSIZE);
                 zds->stage = ZSTDds_skipFrame;
             } else {
-                CHECK_F(ZSTD_decodeFrameHeader(zds, zds->headerBuffer, zds->lhSize));
+                FORWARD_IF_ERROR(ZSTD_decodeFrameHeader(zds, zds->headerBuffer, zds->lhSize));
                 zds->expected = ZSTD_blockHeaderSize;
                 zds->stage = ZSTDds_decodeBlockHeader;
             }
@@ -2841,7 +1603,8 @@
                         (U32)(zds->fParams.windowSize >>10),
                         (U32)(zds->maxWindowSize >> 10) );
             zds->fParams.windowSize = MAX(zds->fParams.windowSize, 1U << ZSTD_WINDOWLOG_ABSOLUTEMIN);
-            if (zds->fParams.windowSize > zds->maxWindowSize) return ERROR(frameParameter_windowTooLarge);
+            RETURN_ERROR_IF(zds->fParams.windowSize > zds->maxWindowSize,
+                            frameParameter_windowTooLarge);
 
             /* Adapt buffer sizes to frame header instructions */
             {   size_t const neededInBuffSize = MAX(zds->fParams.blockSizeMax, 4 /* frame checksum */);
@@ -2855,14 +1618,15 @@
                     if (zds->staticSize) {  /* static DCtx */
                         DEBUGLOG(4, "staticSize : %u", (U32)zds->staticSize);
                         assert(zds->staticSize >= sizeof(ZSTD_DCtx));  /* controlled at init */
-                        if (bufferSize > zds->staticSize - sizeof(ZSTD_DCtx))
-                            return ERROR(memory_allocation);
+                        RETURN_ERROR_IF(
+                            bufferSize > zds->staticSize - sizeof(ZSTD_DCtx),
+                            memory_allocation);
                     } else {
                         ZSTD_free(zds->inBuff, zds->customMem);
                         zds->inBuffSize = 0;
                         zds->outBuffSize = 0;
                         zds->inBuff = (char*)ZSTD_malloc(bufferSize, zds->customMem);
-                        if (zds->inBuff == NULL) return ERROR(memory_allocation);
+                        RETURN_ERROR_IF(zds->inBuff == NULL, memory_allocation);
                     }
                     zds->inBuffSize = neededInBuffSize;
                     zds->outBuff = zds->inBuff + zds->inBuffSize;
@@ -2904,7 +1668,9 @@
                 if (isSkipFrame) {
                     loadedSize = MIN(toLoad, (size_t)(iend-ip));
                 } else {
-                    if (toLoad > zds->inBuffSize - zds->inPos) return ERROR(corruption_detected);   /* should never happen */
+                    RETURN_ERROR_IF(toLoad > zds->inBuffSize - zds->inPos,
+                                    corruption_detected,
+                                    "should never happen");
                     loadedSize = ZSTD_limitCopy(zds->inBuff + zds->inPos, toLoad, ip, iend-ip);
                 }
                 ip += loadedSize;
@@ -2943,12 +1709,24 @@
             someMoreWork = 0;
             break;
 
-        default: return ERROR(GENERIC);   /* impossible */
+        default:
+            assert(0);    /* impossible */
+            RETURN_ERROR(GENERIC);   /* some compiler require default to do something */
     }   }
 
     /* result */
-    input->pos += (size_t)(ip-istart);
-    output->pos += (size_t)(op-ostart);
+    input->pos = (size_t)(ip - (const char*)(input->src));
+    output->pos = (size_t)(op - (char*)(output->dst));
+    if ((ip==istart) && (op==ostart)) {  /* no forward progress */
+        zds->noForwardProgress ++;
+        if (zds->noForwardProgress >= ZSTD_NO_FORWARD_PROGRESS_MAX) {
+            RETURN_ERROR_IF(op==oend, dstSize_tooSmall);
+            RETURN_ERROR_IF(ip==iend, srcSize_wrong);
+            assert(0);
+        }
+    } else {
+        zds->noForwardProgress = 0;
+    }
     {   size_t nextSrcSizeHint = ZSTD_nextSrcSizeToDecompress(zds);
         if (!nextSrcSizeHint) {   /* frame fully decoded */
             if (zds->outEnd == zds->outStart) {  /* output fully flushed */
@@ -2975,13 +1753,7 @@
     }
 }
 
-
-size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx, ZSTD_outBuffer* output, ZSTD_inBuffer* input)
-{
-    return ZSTD_decompressStream(dctx, output, input);
-}
-
-size_t ZSTD_decompress_generic_simpleArgs (
+size_t ZSTD_decompressStream_simpleArgs (
                             ZSTD_DCtx* dctx,
                             void* dst, size_t dstCapacity, size_t* dstPos,
                       const void* src, size_t srcSize, size_t* srcPos)
@@ -2989,15 +1761,8 @@
     ZSTD_outBuffer output = { dst, dstCapacity, *dstPos };
     ZSTD_inBuffer  input  = { src, srcSize, *srcPos };
     /* ZSTD_compress_generic() will check validity of dstPos and srcPos */
-    size_t const cErr = ZSTD_decompress_generic(dctx, &output, &input);
+    size_t const cErr = ZSTD_decompressStream(dctx, &output, &input);
     *dstPos = output.pos;
     *srcPos = input.pos;
     return cErr;
 }
-
-void ZSTD_DCtx_reset(ZSTD_DCtx* dctx)
-{
-    (void)ZSTD_initDStream(dctx);
-    dctx->format = ZSTD_f_zstd1;
-    dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
-}