if( rc==SQLITE4_OK ){
          rc = sqlite4KVCursorSeek(pCsr->pCsr, aKey, nKey, 0);
          if( rc==SQLITE4_NOTFOUND ){
            rc = SQLITE4_CORRUPT_BKPT;
          }
        }

        if( rc==SQLITE4_OK ){
          rc = sqlite4KVCursorData(pCsr->pCsr, 0, -1, &aData, &nData);
        }

        if( rc==SQLITE4_OK ){
          int i;
          RowDecoder *pCodec;   /* The decoder object */

          rc = sqlite4VdbeCreateDecoder(db, aData, nData, pInfo->nCol, &pCodec);
          for(i=0; rc==SQLITE4_OK && i<pInfo->nCol; i++){
            rc = sqlite4VdbeExtractColumn(pCodec, i, 0, &pCsr->aMem[i]);
          }
          sqlite4VdbeDestroyDecoder(pCodec);
        }

        if( rc==SQLITE4_OK ) pCsr->bMemValid = 1;
      }
    }

    if( rc==SQLITE4_OK ){

        if( rc==SQLITE4_OK ){
          rc = sqlite4KVCursorSeek(pCsr->pCsr, aKey, nKey, 0);
          if( rc==SQLITE4_NOTFOUND ){
            rc = SQLITE4_CORRUPT_BKPT;
          }
        }





        if( rc==SQLITE4_OK ){
          int i;
          RowDecoder *pCodec;   /* The decoder object */

          rc = sqlite4VdbeDecoderCreate(db,0, pCsr->pCsr, pInfo->nCol, &pCodec);
          for(i=0; rc==SQLITE4_OK && i<pInfo->nCol; i++){
            rc = sqlite4VdbeDecoderGetColumn(pCodec, i, 0, &pCsr->aMem[i]);
          }
          sqlite4VdbeDecoderDestroy(pCodec);
        }

        if( rc==SQLITE4_OK ) pCsr->bMemValid = 1;
      }
    }

    if( rc==SQLITE4_OK ){

  if( p->apCsr[iCur] ){
    sqlite4VdbeFreeCursor(p->apCsr[iCur]);
    p->apCsr[iCur] = 0;
  }
  if( SQLITE4_OK==sqlite4VdbeMemGrow(pMem, nByte, 0) ){
    p->apCsr[iCur] = pCx = (VdbeCursor*)pMem->z;
    memset(pCx, 0, sizeof(VdbeCursor));

    pCx->iDb = iDb;
    pCx->nField = nField;

    sqlite4_buffer_init(&pCx->sSeekKey, p->db->pEnv->pMM);
  }
  return pCx;
}

/*
** Try to convert a value into a numeric representation if we can
................................................................................
**
** If the OPFLAG_CLEARCACHE bit is set on P5 and P1 is a pseudo-table cursor,
** then the cache of the cursor is reset prior to extracting the column.
** The first OP_Column against a pseudo-table after the value of the content
** register has changed should have this bit set.
*/
case OP_Column: {
  KVCursor *pKVCur;         /* Cursor for current entry in the KV storage */
  RowDecoder *pCodec;       /* The decoder object */
  int p1;                   /* Index of VdbeCursor to decode */

  VdbeCursor *pC;           /* The VDBE cursor */
  Mem *pDest;               /* Where to write the results */
  const KVByteArray *aData; /* The content to be decoded */
  KVSize nData;             /* Size of aData[] in bytes */
  Mem *pDefault;            /* Default value from P4 */
  Mem *pReg;                /* */

  p1 = pOp->p1;
  assert( p1<p->nCursor );
  assert( pOp->p3>0 && pOp->p3<=p->nMem );
  pDest = &aMem[pOp->p3];
  memAboutToChange(p, pDest);
  pC = p->apCsr[p1];
  assert( pC!=0 );
#ifndef SQLITE4_OMIT_VIRTUALTABLE
  assert( pC->pVtabCursor==0 );
#endif
  pKVCur = pC->pKVCur;
  if( pKVCur!=0 ){
    rc = sqlite4VdbeCursorMoveto(pC);
    if( rc!=SQLITE4_OK ) break;
    if( pC->nullRow ){
      aData = 0;
    }else{
      rc = sqlite4KVCursorData(pKVCur, 0, -1, &aData, &nData);
    }
  }else if( ALWAYS(pC->pseudoTableReg>0) ){
    pReg = &aMem[pC->pseudoTableReg];
    assert( pReg->flags & MEM_Blob );
    assert( memIsValid(pReg) );
    aData = (const KVByteArray*)pReg->z;
    nData = pReg->n;
  }else{
    aData = 0;
    MemSetTypeFlag(pDest, MEM_Null);
  }
  if( rc==SQLITE4_OK && aData ){
    /* TODO: Fix this somehow... */
    int nField = pC->nField;
    if( pC->pKeyInfo && pC->pKeyInfo->nData ) nField = pC->pKeyInfo->nData;



    rc = sqlite4VdbeCreateDecoder(db, aData, nData, nField, &pCodec);
    if( rc==0 ){
      pDefault = (pOp->p4type==P4_MEM) ? pOp->p4.pMem : 0;
      rc = sqlite4VdbeExtractColumn(pCodec, pOp->p2, pDefault, pDest);
      sqlite4VdbeDestroyDecoder(pCodec);
    }
  }else{
    sqlite4VdbeMemSetNull(pDest);
  }
  UPDATE_MAX_BLOBSIZE(pDest);
  REGISTER_TRACE(pOp->p3, pDest);
  assert( rc<100 );
  break;
}

/* Opcode: Affinity P1 P2 * P4 *
**
** Apply affinities to a range of P2 registers starting with P1.
**
................................................................................
case OP_OpenPseudo: {
  VdbeCursor *pCx;

  assert( pOp->p1>=0 );
  pCx = allocateCursor(p, pOp->p1, pOp->p3, -1, 0);
  if( pCx==0 ) goto no_mem;
  pCx->nullRow = 1;
  pCx->pseudoTableReg = pOp->p2;
  break;
}

/* Opcode: Close P1 * * * *
**
** Close a cursor previously opened as P1.  If P1 is not
** currently open, this instruction is a no-op.
................................................................................
    );
    nVarint = sqlite4VarintLen(pPk->iRoot);
    rc = sqlite4_buffer_resize(&pPk->sSeekKey, nVarint + nKey - nShort);
    if( rc!=SQLITE4_OK ) break;
    putVarint32((u8 *)(pPk->sSeekKey.p), pPk->iRoot);
    memcpy(((u8*)pPk->sSeekKey.p) + nVarint, &aKey[nShort], nKey-nShort);
    assert( pPk->sSeekKey.n>0 );

  }

  break;
}

/* Opcode: SeekGe P1 P2 P3 P4 *
**
................................................................................
** If there are no records greater than or equal to the key and P2 is 
** not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekLt, SeekGt, SeekLe
*/
/* Opcode: SeekGt P1 P2 P3 P4 *
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the smallest entry that 
** is greater than the key value. If there are no records greater than 
** the key and P2 is not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekLt, SeekGe, SeekLe
*/
/* Opcode: SeekLt P1 P2 P3 P4 * 
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the largest entry that 
** is less than the key value. If there are no records less than 
** the key and P2 is not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLe
*/
/* Opcode: SeekLe P1 P2 P3 P4 *
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that it points to the largest entry that 
** is less than or equal to the key value. If there are no records 
** less than or equal to the key and P2 is not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLt
*/
case OP_SeekLt:         /* jump, in3 */
case OP_SeekLe:         /* jump, in3 */
case OP_SeekGe:         /* jump, in3 */
case OP_SeekGt: {       /* jump, in3 */
................................................................................
  int dir;                        /* KV search dir (+ve or -ve) */
  const KVByteArray *aKey;        /* Pointer to final cursor key */
  KVSize nKey;                    /* Size of aKey[] in bytes */

  pC = p->apCsr[pOp->p1];
  pC->nullRow = 0;
  pC->sSeekKey.n = 0;


  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p2!=0 );
  assert( pC!=0 );
  assert( pC->pseudoTableReg==0 );
  assert( OP_SeekLe == OP_SeekLt+1 );
  assert( OP_SeekGe == OP_SeekLt+2 );
  assert( OP_SeekGt == OP_SeekLt+3 );

  /* Encode a database key consisting of the contents of the P4 registers
  ** starting at register P3. Have the vdbecodec module allocate an extra
  ** free byte at the end of the database key (see below).  */
................................................................................
#endif

  alreadyExists = 0;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p4type==P4_INT32 );
  pC = p->apCsr[pOp->p1];
  pC->sSeekKey.n = 0;

  assert( pC!=0 );
  pIn3 = &aMem[pOp->p3];
  assert( pC->pKVCur!=0 );
  if( pOp->p4.i>0 ){
    rc = sqlite4VdbeEncodeKey(
        db, pIn3, pOp->p4.i, pOp->p4.i + (pOp->p5 & OPFLAG_PARTIALKEY),
        pC->iRoot, pC->pKeyInfo, &pProbe, &nProbe, 0
................................................................................
*/
case OP_Delete: {
  VdbeCursor *pC;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->sSeekKey.n==0 );

  rc = sqlite4KVCursorDelete(pC->pKVCur);
  if( pOp->p2 & OPFLAG_NCHANGE ) p->nChange++;
  break;
}

/* Opcode: ResetCount * * * * *
**
................................................................................

  /* Note that RowKey and RowData are really exactly the same instruction */
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  rc = sqlite4VdbeCursorMoveto(pC);
  if( rc!=SQLITE4_OK ) break;
  assert( pC->nullRow==0 );
  assert( pC->pseudoTableReg==0 );
  assert( pC->pKVCur!=0 );
  pCrsr = pC->pKVCur;

  if( pOp->opcode==OP_RowKey ){
    rc = sqlite4KVCursorKey(pCrsr, &pData, &nData);
    if( pOp->p5 ){
      nData = sqlite4VdbeShortKey(pData, nData, 1, 0);
................................................................................

  pKey = &aMem[pOp->p2];
  aIncr = &aMem[pOp->p3];
  nTotal = pOp->p4.i;
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->nullRow==0 );
  assert( pC->pseudoTableReg==0 );
  assert( pC->pKVCur!=0 );
  assert( pOp->p4type==P4_INT32 );

  rc = sqlite4KVCursorKey(pC->pKVCur, &pNew, &nNew);
  if( rc==SQLITE4_OK ){
    assert( pKey->flags & (MEM_Blob|MEM_Null) );
    if( pKey->flags & MEM_Blob ){
................................................................................
  int n;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  rc = sqlite4VdbeCursorMoveto(pC);
  if( rc!=SQLITE4_OK ) break;
  assert( pC->sSeekKey.n==0 );
  assert( pC->pseudoTableReg==0 );
  if( pC->nullRow ){
    pOut->flags = MEM_Null;
    break;
#ifndef SQLITE4_OMIT_VIRTUALTABLE
  }else if( pC->pVtabCursor ){
    pVtab = pC->pVtabCursor->pVtab;
    pModule = pVtab->pModule;

  if( p->apCsr[iCur] ){
    sqlite4VdbeFreeCursor(p->apCsr[iCur]);
    p->apCsr[iCur] = 0;
  }
  if( SQLITE4_OK==sqlite4VdbeMemGrow(pMem, nByte, 0) ){
    p->apCsr[iCur] = pCx = (VdbeCursor*)pMem->z;
    memset(pCx, 0, sizeof(VdbeCursor));
    pCx->db = p->db;
    pCx->iDb = iDb;
    pCx->nField = nField;
    pCx->rowChnged = 1;
    sqlite4_buffer_init(&pCx->sSeekKey, p->db->pEnv->pMM);
  }
  return pCx;
}

/*
** Try to convert a value into a numeric representation if we can
................................................................................
**
** If the OPFLAG_CLEARCACHE bit is set on P5 and P1 is a pseudo-table cursor,
** then the cache of the cursor is reset prior to extracting the column.
** The first OP_Column against a pseudo-table after the value of the content
** register has changed should have this bit set.
*/
case OP_Column: {


  int p1;                   /* Index of VdbeCursor to decode */
  int mxField;              /* Maximum column number */
  VdbeCursor *pC;           /* The VDBE cursor */
  Mem *pDest;               /* Where to write the results */


  Mem *pDefault;            /* Default value from P4 */


  p1 = pOp->p1;
  assert( p1<p->nCursor );
  assert( pOp->p3>0 && pOp->p3<=p->nMem );
  pDest = &aMem[pOp->p3];
  memAboutToChange(p, pDest);
  pC = p->apCsr[p1];
  assert( pC!=0 );
#ifndef SQLITE4_OMIT_VIRTUALTABLE
  assert( pC->pVtabCursor==0 );
#endif




  if( pC->pDecoder==0 ){
















    mxField = pC->nField;
    if( pC->pKeyInfo && pC->pKeyInfo->nData ) mxField = pC->pKeyInfo->nData;
    rc = sqlite4VdbeDecoderCreate(db, pC, 0, mxField, &pC->pDecoder);
    pC->rowChnged = 1;
  }

  if( rc==SQLITE4_OK ){
    pDefault = (pOp->p4type==P4_MEM) ? pOp->p4.pMem : 0;
    rc = sqlite4VdbeDecoderGetColumn(pC->pDecoder, pOp->p2, pDefault, pDest);


  }else{
    sqlite4VdbeMemSetNull(pDest);
  }
  UPDATE_MAX_BLOBSIZE(pDest);
  REGISTER_TRACE(pOp->p3, pDest);

  break;
}

/* Opcode: Affinity P1 P2 * P4 *
**
** Apply affinities to a range of P2 registers starting with P1.
**
................................................................................
case OP_OpenPseudo: {
  VdbeCursor *pCx;

  assert( pOp->p1>=0 );
  pCx = allocateCursor(p, pOp->p1, pOp->p3, -1, 0);
  if( pCx==0 ) goto no_mem;
  pCx->nullRow = 1;
  pCx->pPseudoTab = aMem + pOp->p2;
  break;
}

/* Opcode: Close P1 * * * *
**
** Close a cursor previously opened as P1.  If P1 is not
** currently open, this instruction is a no-op.
................................................................................
    );
    nVarint = sqlite4VarintLen(pPk->iRoot);
    rc = sqlite4_buffer_resize(&pPk->sSeekKey, nVarint + nKey - nShort);
    if( rc!=SQLITE4_OK ) break;
    putVarint32((u8 *)(pPk->sSeekKey.p), pPk->iRoot);
    memcpy(((u8*)pPk->sSeekKey.p) + nVarint, &aKey[nShort], nKey-nShort);
    assert( pPk->sSeekKey.n>0 );
    pPk->rowChnged = 1;
  }

  break;
}

/* Opcode: SeekGe P1 P2 P3 P4 *
**
................................................................................
** If there are no records greater than or equal to the key and P2 is 
** not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekLt, SeekGt, SeekLe
*/
/* Opcode: SeekGt P1 P2 P3 P4 *
**
** P1 identifies an open database cursor. The cursor is repositioned so
** that it points to the smallest entry in its index that is greater than
** the key formed by the array of P4 registers starting at
** register P3.
**

** If there are no records greater than the key and P2 is 
** not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekLt, SeekGe, SeekLe
*/
/* Opcode: SeekLt P1 P2 P3 P4 * 
**
** P1 identifies an open database cursor. The cursor is repositioned so
** that it points to the largest entry in its index that is less than
** the key formed by the array of P4 registers starting at
** register P3.
**

** If there are no records less than the key and P2 is 
** not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLe
*/
/* Opcode: SeekLe P1 P2 P3 P4 *
**
** P1 identifies an open database cursor. The cursor is repositioned so
** that it points to the largest entry in its index that is less than or
** equal to the key formed by the array of P4 registers starting at
** register P3.
**

** If there are no records less than or equal to the key and P2 is 
** not zero, then jump to P2.
**
** See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLt
*/
case OP_SeekLt:         /* jump, in3 */
case OP_SeekLe:         /* jump, in3 */
case OP_SeekGe:         /* jump, in3 */
case OP_SeekGt: {       /* jump, in3 */
................................................................................
  int dir;                        /* KV search dir (+ve or -ve) */
  const KVByteArray *aKey;        /* Pointer to final cursor key */
  KVSize nKey;                    /* Size of aKey[] in bytes */

  pC = p->apCsr[pOp->p1];
  pC->nullRow = 0;
  pC->sSeekKey.n = 0;
  pC->rowChnged = 1;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p2!=0 );
  assert( pC!=0 );
  assert( pC->pPseudoTab==0 );
  assert( OP_SeekLe == OP_SeekLt+1 );
  assert( OP_SeekGe == OP_SeekLt+2 );
  assert( OP_SeekGt == OP_SeekLt+3 );

  /* Encode a database key consisting of the contents of the P4 registers
  ** starting at register P3. Have the vdbecodec module allocate an extra
  ** free byte at the end of the database key (see below).  */
................................................................................
#endif

  alreadyExists = 0;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p4type==P4_INT32 );
  pC = p->apCsr[pOp->p1];
  pC->sSeekKey.n = 0;
  pC->rowChnged = 1;
  assert( pC!=0 );
  pIn3 = &aMem[pOp->p3];
  assert( pC->pKVCur!=0 );
  if( pOp->p4.i>0 ){
    rc = sqlite4VdbeEncodeKey(
        db, pIn3, pOp->p4.i, pOp->p4.i + (pOp->p5 & OPFLAG_PARTIALKEY),
        pC->iRoot, pC->pKeyInfo, &pProbe, &nProbe, 0
................................................................................
*/
case OP_Delete: {
  VdbeCursor *pC;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->sSeekKey.n==0 );
  pC->rowChnged = 1;
  rc = sqlite4KVCursorDelete(pC->pKVCur);
  if( pOp->p2 & OPFLAG_NCHANGE ) p->nChange++;
  break;
}

/* Opcode: ResetCount * * * * *
**
................................................................................

  /* Note that RowKey and RowData are really exactly the same instruction */
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  rc = sqlite4VdbeCursorMoveto(pC);
  if( rc!=SQLITE4_OK ) break;
  assert( pC->nullRow==0 );
  assert( pC->pPseudoTab==0 );
  assert( pC->pKVCur!=0 );
  pCrsr = pC->pKVCur;

  if( pOp->opcode==OP_RowKey ){
    rc = sqlite4KVCursorKey(pCrsr, &pData, &nData);
    if( pOp->p5 ){
      nData = sqlite4VdbeShortKey(pData, nData, 1, 0);
................................................................................

  pKey = &aMem[pOp->p2];
  aIncr = &aMem[pOp->p3];
  nTotal = pOp->p4.i;
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->nullRow==0 );
  assert( pC->pPseudoTab==0 );
  assert( pC->pKVCur!=0 );
  assert( pOp->p4type==P4_INT32 );

  rc = sqlite4KVCursorKey(pC->pKVCur, &pNew, &nNew);
  if( rc==SQLITE4_OK ){
    assert( pKey->flags & (MEM_Blob|MEM_Null) );
    if( pKey->flags & MEM_Blob ){
................................................................................
  int n;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  rc = sqlite4VdbeCursorMoveto(pC);
  if( rc!=SQLITE4_OK ) break;
  assert( pC->sSeekKey.n==0 );
  assert( pC->pPseudoTab==0 );
  if( pC->nullRow ){
    pOut->flags = MEM_Null;
    break;
#ifndef SQLITE4_OMIT_VIRTUALTABLE
  }else if( pC->pVtabCursor ){
    pVtab = pC->pVtabCursor->pVtab;
    pModule = pVtab->pModule;

** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
*/
struct VdbeCursor {

  KVCursor *pKVCur;     /* The cursor structure of the storage engine */
  KVStore *pTmpKV;      /* Separate file holding a temporary table */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
  int iRoot;            /* Root page of the table */
  int pseudoTableReg;   /* Register holding pseudotable content. */
  int nField;           /* Number of fields in the header */
  Bool nullRow;         /* True if pointing to a row with no data */

  i64 seqCount;         /* Sequence counter */

  VdbeSorter *pSorter;  /* Sorter object for OP_SorterOpen cursors */
  Fts5Cursor *pFts;     /* Fts5 cursor object (or NULL) */

  sqlite4_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  const sqlite4_module *pModule;     /* Module for cursor pVtabCursor */
  sqlite4_buffer sSeekKey;           /* Key for deferred seek */
};

/* Methods for the VdbeCursor object */
void sqlite4VdbeFreeCursor(VdbeCursor*);
................................................................................
*/
void sqliteVdbePopStack(Vdbe*,int);
#if defined(SQLITE4_DEBUG) || defined(VDBE_PROFILE)
void sqlite4VdbePrintOp(FILE*, int, Op*);
#endif
void sqlite4VdbeDeleteAuxData(VdbeFunc*, int);

int sqlite4VdbeCreateDecoder(
  sqlite4 *db,                /* The database connection */
  const unsigned char *aIn,   /* The input data blob */
  int nIn,                    /* Number of bytes in aIn[] */
  int mxCol,                  /* Maximum number of columns in aIn[] */
  RowDecoder **ppOut          /* The newly generated decoder object */
);
int sqlite4VdbeDestroyDecoder(RowDecoder *pDecoder);
int sqlite4VdbeExtractColumn(
  RowDecoder *pDecoder,        /* The decoder for the whole string */
  int iVal,                    /* Index of the value to decode.  First is 0 */
  Mem *pDefault,               /* The default value.  Often NULL */
  Mem *pOut                    /* Write the result here */
);
int sqlite4VdbeEncodeData(
  sqlite4 *db,                /* The database connection */

** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
*/
struct VdbeCursor {
  sqlite4 *db;          /* The connection that owns this cursor */
  KVCursor *pKVCur;     /* The cursor structure of the storage engine */
  KVStore *pTmpKV;      /* Separate file holding a temporary table */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
  int iRoot;            /* Root page of the table */

  int nField;           /* Number of fields in the header */
  Bool nullRow;         /* True if pointing to a row with no data */
  Bool rowChnged;       /* True if row has changed out from under pDecoder */
  i64 seqCount;         /* Sequence counter */
  Mem *pPseudoTab;      /* Register holding pseudotable content */
  VdbeSorter *pSorter;  /* Sorter object for OP_SorterOpen cursors */
  Fts5Cursor *pFts;     /* Fts5 cursor object (or NULL) */
  RowDecoder *pDecoder;              /* Decoder for row content */
  sqlite4_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  const sqlite4_module *pModule;     /* Module for cursor pVtabCursor */
  sqlite4_buffer sSeekKey;           /* Key for deferred seek */
};

/* Methods for the VdbeCursor object */
void sqlite4VdbeFreeCursor(VdbeCursor*);
................................................................................
*/
void sqliteVdbePopStack(Vdbe*,int);
#if defined(SQLITE4_DEBUG) || defined(VDBE_PROFILE)
void sqlite4VdbePrintOp(FILE*, int, Op*);
#endif
void sqlite4VdbeDeleteAuxData(VdbeFunc*, int);

int sqlite4VdbeDecoderCreate(
  sqlite4 *db,                /* The database connection */
  VdbeCursor *pCur,           /* Cursor associated with this decoder */
  KVCursor *pKVCur,           /* Alternative cursor if pCur is NULL */
  int mxCol,                  /* Maximum number of columns in aIn[] */
  RowDecoder **ppOut          /* The newly generated decoder object */
);
int sqlite4VdbeDecoderDestroy(RowDecoder *pDecoder);
int sqlite4VdbeDecoderGetColumn(
  RowDecoder *pDecoder,        /* The decoder for the whole string */
  int iVal,                    /* Index of the value to decode.  First is 0 */
  Mem *pDefault,               /* The default value.  Often NULL */
  Mem *pOut                    /* Write the result here */
);
int sqlite4VdbeEncodeData(
  sqlite4 *db,                /* The database connection */

**
** When the VDBE needs to extract multiple columns from the same row, it will
** try to reuse a single decoder object.  The decoder, therefore, should attempt
** to cache any intermediate results that might be useful on later invocations.
*/
struct RowDecoder {
  sqlite4 *db;                /* The database connection */


  const u8 *a;                /* Content to be decoded */

  int n;                      /* Bytes of content in a[] */

  int mxCol;                  /* Maximum number of columns */
};

/*
** Create an object that can be used to decode fields of the data encoding.
**
** The aIn[] value must remain stable for the life of the decoder.
*/
int sqlite4VdbeCreateDecoder(
  sqlite4 *db,                /* The database connection */
  const unsigned char *aIn,   /* The input data blob */
  int nIn,                    /* Number of bytes in aIn[] */
  int mxCol,                  /* Maximum number of columns in aIn[] */
  RowDecoder **ppOut          /* The newly generated decoder object */
){
  RowDecoder *p;



  p = sqlite4DbMallocZero(db, sizeof(*p));
  *ppOut = p;
  if( p==0 ) return SQLITE4_NOMEM;
  p->db = db;
  p->a = aIn;
  p->n = nIn;
  p->mxCol = mxCol;
  return SQLITE4_OK;
}

/*
** Destroy a decoder object previously created
** using sqlite4VdbeCreateDecoder().
*/
int sqlite4VdbeDestroyDecoder(RowDecoder *p){
  if( p ){
    sqlite4DbFree(p->db, p);
  }
  return SQLITE4_OK;
}




































/*
** Decode a single value from a data string.  Store that value in pOut.
**
** If the value is a FROM-KEY reference (header codes 22 and 23) then the
** pOut->flags field is set to MEM_FromKey and pOut->iOfst is the offset into
** the key of the start of the actual value.  The pOut->type field is set to
** SQLITE_FLOAT if a numeric value extracted from the key should be interpreted
** as a floating point even if it has no fractional part.
*/
int sqlite4VdbeExtractColumn(
  RowDecoder *p,             /* The decoder for the whole string */
  int iVal,                    /* Index of the value to decode.  First is 0 */
  Mem *pDefault,               /* The default value.  Often NULL */
  Mem *pOut                    /* Write the result here */
){
  u32 size;                    /* Size of a field */
  sqlite4_uint64 ofst;         /* Offset to the payload */
................................................................................
  sqlite4_uint64 type;         /* Datatype */
  sqlite4_uint64 subtype;      /* Subtype for a typed blob */
  int cclass;                  /* class of content */
  int n;                       /* Offset into the header */
  int i;                       /* Loop counter */
  int sz;                      /* Size of a varint */
  int endHdr;                  /* First byte past header */


  sqlite4VdbeMemSetNull(pOut);
  assert( iVal<=p->mxCol );



  n = sqlite4GetVarint64(p->a, p->n, &ofst);
  if( n==0 ) return SQLITE4_CORRUPT;
  ofst += n;
  endHdr = ofst;
  if( endHdr>p->n ) return SQLITE4_CORRUPT;
  for(i=0; i<=iVal && n<endHdr; i++){
    sz = sqlite4GetVarint64(p->a+n, p->n-n, &type);

**
** When the VDBE needs to extract multiple columns from the same row, it will
** try to reuse a single decoder object.  The decoder, therefore, should attempt
** to cache any intermediate results that might be useful on later invocations.
*/
struct RowDecoder {
  sqlite4 *db;                /* The database connection */
  VdbeCursor *pCur;           /* The cursor for being decoded */
  KVCursor *pKVCur;           /* Alternative KVCursor if pCur is NULL */
  const KVByteArray *a;       /* Content to be decoded */
  const KVByteArray *aKey;    /* Key content */
  KVSize n;                   /* Bytes of content in a[] */
  KVSize nKey;                /* Bytes of key content */
  int mxCol;                  /* Maximum number of columns */
};

/*
** Create an object that can be used to decode fields of the data encoding.
**
** The aIn[] value must remain stable for the life of the decoder.
*/
int sqlite4VdbeDecoderCreate(
  sqlite4 *db,                /* The database connection */
  VdbeCursor *pCur,           /* The cursor associated with this decoder */
  KVCursor *pKVCur,           /* Alternative KVCursor */
  int mxCol,                  /* Maximum number of columns to ever decode */
  RowDecoder **ppOut          /* Return the answer here */
){
  RowDecoder *p;

  assert( pCur==0 || pKVCur==0 );
  assert( pCur!=0 || pKVCur!=0 );
  p = sqlite4DbMallocZero(db, sizeof(*p));
  *ppOut = p;
  if( p==0 ) return SQLITE4_NOMEM;
  p->db = db;
  p->pCur = pCur;
  p->pKVCur = pKVCur;
  p->mxCol = mxCol;
  return SQLITE4_OK;
}

/*
** Destroy a decoder object previously created
** using sqlite4VdbeCreateDecoder().
*/
int sqlite4VdbeDecoderDestroy(RowDecoder *p){
  if( p ){
    sqlite4DbFree(p->db, p);
  }
  return SQLITE4_OK;
}

/*
** Make sure the p->a and p->n fields are valid and current.
*/
static int decoderFetchData(RowDecoder *p){
  VdbeCursor *pCur = p->pCur;
  int rc;
  if( pCur==0 ){
    rc = sqlite4KVCursorData(p->pKVCur, 0, -1, &p->a, &p->n);
    return rc;
  }
  if( 1 /*pCur->rowChnged*/ ){  /* FIXME:  Row cache not always cleared */
    p->a = 0;
    p->aKey = 0;
    pCur->rowChnged = pCur->pPseudoTab!=0;
  }
  if( p->a ) return SQLITE4_OK;
  rc = sqlite4VdbeCursorMoveto(pCur);
  if( rc ) return rc;
  if( pCur->nullRow ){
    p->a = 0;
    p->n = 0;
    return SQLITE4_OK;
  }
  if( pCur->pKVCur ){
    rc = sqlite4KVCursorData(pCur->pKVCur, 0, -1, &p->a, &p->n);
  }else{
    Mem *pReg = pCur->pPseudoTab;
    assert( pReg!=0 );
    p->a = (const KVByteArray*)pReg->z;
    p->n = pReg->n;
    rc = SQLITE4_OK;
  }
  return rc;
}

/*
** Decode a single value from a data string.  Store that value in pOut.
**
** If the value is a FROM-KEY reference (header codes 22 and 23) then the
** pOut->flags field is set to MEM_FromKey and pOut->iOfst is the offset into
** the key of the start of the actual value.  The pOut->type field is set to
** SQLITE_FLOAT if a numeric value extracted from the key should be interpreted
** as a floating point even if it has no fractional part.
*/
int sqlite4VdbeDecoderGetColumn(
  RowDecoder *p,             /* The decoder for the whole string */
  int iVal,                    /* Index of the value to decode.  First is 0 */
  Mem *pDefault,               /* The default value.  Often NULL */
  Mem *pOut                    /* Write the result here */
){
  u32 size;                    /* Size of a field */
  sqlite4_uint64 ofst;         /* Offset to the payload */
................................................................................
  sqlite4_uint64 type;         /* Datatype */
  sqlite4_uint64 subtype;      /* Subtype for a typed blob */
  int cclass;                  /* class of content */
  int n;                       /* Offset into the header */
  int i;                       /* Loop counter */
  int sz;                      /* Size of a varint */
  int endHdr;                  /* First byte past header */
  int rc;                      /* Return code */

  sqlite4VdbeMemSetNull(pOut);
  assert( iVal<=p->mxCol );
  rc = decoderFetchData(p);
  if( rc ) return rc;
  if( p->a==0 ) return SQLITE4_OK;
  n = sqlite4GetVarint64(p->a, p->n, &ofst);
  if( n==0 ) return SQLITE4_CORRUPT;
  ofst += n;
  endHdr = ofst;
  if( endHdr>p->n ) return SQLITE4_CORRUPT;
  for(i=0; i<=iVal && n<endHdr; i++){
    sz = sqlite4GetVarint64(p->a+n, p->n-n, &type);

    rc = SQLITE4_CORRUPT_BKPT;
  }else if( rc==SQLITE4_INEXACT ){
    rc = sqlite4KVCursorKey(pCur, &aKey, &nKey);
    if( rc==SQLITE4_OK && (nKey<nProbe || memcmp(aKey, aProbe, nProbe)!=0) ){
      rc = SQLITE4_NOTFOUND;
    }
  }


  return rc;
}

/*
** Move a VDBE cursor to the next element in its table.
** Return SQLITE4_NOTFOUND if the seek falls of the end of the table.
................................................................................
    rc = sqlite4KVCursorKey(pCur, &aKey, &nKey);
    if( rc==SQLITE4_OK ){
      iTabno = 0;
      sqlite4GetVarint64(aKey, nKey, &iTabno);
      if( iTabno!=pC->iRoot ) rc = SQLITE4_NOTFOUND;
    }
  }

  return rc;
}

/*
** Move a VDBE cursor to the previous element in its table.
** Return SQLITE4_NOTFOUND if the seek falls of the end of the table.
*/
................................................................................
    rc = sqlite4KVCursorKey(pCur, &aKey, &nKey);
    if( rc==SQLITE4_OK ){
      iTabno = 0;
      sqlite4GetVarint64(aKey, nKey, &iTabno);
      if( iTabno!=pC->iRoot ) rc = SQLITE4_NOTFOUND;
    }
  }

  return rc;
}


/*
** Close a VDBE cursor and release all the resources that cursor 
** happens to hold.
................................................................................
  }
  sqlite4Fts5Close(pCx->pFts);
  if( pCx->pKVCur ){
    sqlite4KVCursorClose(pCx->pKVCur);
  }
  if( pCx->pTmpKV ){
    sqlite4KVStoreClose(pCx->pTmpKV);




  }
  sqlite4_buffer_clear(&pCx->sSeekKey);
#ifndef SQLITE4_OMIT_VIRTUALTABLE
  if( pCx->pVtabCursor ){
    sqlite4_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
    const sqlite4_module *pModule = pCx->pModule;
    p->inVtabMethod = 1;
................................................................................
    assert( pPk->pKeyInfo->nPK==0 );
    rc = sqlite4KVCursorSeek(pPk->pKVCur, pPk->sSeekKey.p, pPk->sSeekKey.n, 0);
    if( rc==SQLITE4_NOTFOUND ){
      rc = SQLITE4_CORRUPT_BKPT;
    }
    pPk->nullRow = 0;
    pPk->sSeekKey.n = 0;

  }
  return rc;
}

    rc = SQLITE4_CORRUPT_BKPT;
  }else if( rc==SQLITE4_INEXACT ){
    rc = sqlite4KVCursorKey(pCur, &aKey, &nKey);
    if( rc==SQLITE4_OK && (nKey<nProbe || memcmp(aKey, aProbe, nProbe)!=0) ){
      rc = SQLITE4_NOTFOUND;
    }
  }
  pC->rowChnged = 1;

  return rc;
}

/*
** Move a VDBE cursor to the next element in its table.
** Return SQLITE4_NOTFOUND if the seek falls of the end of the table.
................................................................................
    rc = sqlite4KVCursorKey(pCur, &aKey, &nKey);
    if( rc==SQLITE4_OK ){
      iTabno = 0;
      sqlite4GetVarint64(aKey, nKey, &iTabno);
      if( iTabno!=pC->iRoot ) rc = SQLITE4_NOTFOUND;
    }
  }
  pC->rowChnged = 1;
  return rc;
}

/*
** Move a VDBE cursor to the previous element in its table.
** Return SQLITE4_NOTFOUND if the seek falls of the end of the table.
*/
................................................................................
    rc = sqlite4KVCursorKey(pCur, &aKey, &nKey);
    if( rc==SQLITE4_OK ){
      iTabno = 0;
      sqlite4GetVarint64(aKey, nKey, &iTabno);
      if( iTabno!=pC->iRoot ) rc = SQLITE4_NOTFOUND;
    }
  }
  pC->rowChnged = 1;
  return rc;
}


/*
** Close a VDBE cursor and release all the resources that cursor 
** happens to hold.
................................................................................
  }
  sqlite4Fts5Close(pCx->pFts);
  if( pCx->pKVCur ){
    sqlite4KVCursorClose(pCx->pKVCur);
  }
  if( pCx->pTmpKV ){
    sqlite4KVStoreClose(pCx->pTmpKV);
  }
  if( pCx->pDecoder ){
    sqlite4VdbeDecoderDestroy(pCx->pDecoder);
    pCx->pDecoder = 0;
  }
  sqlite4_buffer_clear(&pCx->sSeekKey);
#ifndef SQLITE4_OMIT_VIRTUALTABLE
  if( pCx->pVtabCursor ){
    sqlite4_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
    const sqlite4_module *pModule = pCx->pModule;
    p->inVtabMethod = 1;
................................................................................
    assert( pPk->pKeyInfo->nPK==0 );
    rc = sqlite4KVCursorSeek(pPk->pKVCur, pPk->sSeekKey.p, pPk->sSeekKey.n, 0);
    if( rc==SQLITE4_NOTFOUND ){
      rc = SQLITE4_CORRUPT_BKPT;
    }
    pPk->nullRow = 0;
    pPk->sSeekKey.n = 0;
    pPk->rowChnged = 1;
  }
  return rc;
}