MemPage *pOvfl = 0;
  MemPage *pToRelease = 0;
  unsigned char *pPrior;
  unsigned char *pPayload;
  BtShared *pBt = pPage->pBt;
  Pgno pgnoOvfl = 0;
  int nHeader;
  CellInfo info;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  /* pPage is not necessarily writeable since pCell might be auxiliary
  ** buffer space that is separate from the pPage buffer area */
  assert( pCell<pPage->aData || pCell>=&pPage->aData[pBt->pageSize]
            || sqlite3PagerIswriteable(pPage->pDbPage) );

  /* Fill in the header. */
  nHeader = 0;
  if( !pPage->leaf ){
    nHeader += 4;
  }
  if( pPage->hasData ){

    nHeader += putVarint32(&pCell[nHeader], nData+nZero);
  }else{

    nData = nZero = 0;
  }
  nHeader += putVarint(&pCell[nHeader], *(u64*)&nKey);
  btreeParseCellPtr(pPage, pCell, &info);
  assert( nHeader=(int)(info.pPayload - pCell) );
  assert( info.nKey==nKey );
  assert( pPage->intKey==0 || info.nPayload==(u32)(nData+nZero) );
  assert( pPage->intKey==1 || info.nPayload==nKey );
  
  /* Fill in the payload */
  nPayload = nData + nZero;
  if( pPage->intKey ){
    pSrc = pData;
    nSrc = nData;
    nData = 0;
  }else{ 
    if( NEVER(nKey>0x7fffffff || pKey==0) ){
      return SQLITE_CORRUPT_BKPT;
    }
    nPayload += (int)nKey;
    pSrc = pKey;
    nSrc = (int)nKey;
  }





  *pnSize = info.nSize;








  spaceLeft = info.nLocal;



  pPayload = &pCell[nHeader];





















  pPrior = &pCell[info.iOverflow];




  while( nPayload>0 ){
    if( spaceLeft==0 ){
#ifndef SQLITE_OMIT_AUTOVACUUM
      Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
      if( pBt->autoVacuum ){
        do{
          pgnoOvfl++;

  MemPage *pOvfl = 0;
  MemPage *pToRelease = 0;
  unsigned char *pPrior;
  unsigned char *pPayload;
  BtShared *pBt = pPage->pBt;
  Pgno pgnoOvfl = 0;
  int nHeader;


  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  /* pPage is not necessarily writeable since pCell might be auxiliary
  ** buffer space that is separate from the pPage buffer area */
  assert( pCell<pPage->aData || pCell>=&pPage->aData[pBt->pageSize]
            || sqlite3PagerIswriteable(pPage->pDbPage) );

  /* Fill in the header. */
  nHeader = pPage->childPtrSize;
  nPayload = nData + nZero;


  if( pPage->hasData ){
    assert( pPage->intKey );
    nHeader += putVarint32(&pCell[nHeader], nPayload);
  }else{
    assert( nData==0 );
    assert( nZero==0 );
  }
  nHeader += putVarint(&pCell[nHeader], *(u64*)&nKey);





  
  /* Fill in the payload size */

  if( pPage->intKey ){
    pSrc = pData;
    nSrc = nData;
    nData = 0;
  }else{ 
    if( NEVER(nKey>0x7fffffff || pKey==0) ){
      return SQLITE_CORRUPT_BKPT;
    }
    nPayload = (int)nKey;
    pSrc = pKey;
    nSrc = (int)nKey;
  }
  if( nPayload<=pPage->maxLocal ){
    n = nHeader + nPayload;
    testcase( n==3 );
    testcase( n==4 );
    if( n<4 ) n = 4;
    *pnSize = n;
    spaceLeft = nPayload;
    pPrior = pCell;
  }else{
    int mn = pPage->minLocal;
    n = mn + (nPayload - mn) % (pPage->pBt->usableSize - 4);
    testcase( n==pPage->maxLocal );
    testcase( n==pPage->maxLocal+1 );
    if( n > pPage->maxLocal ) n = mn;
    spaceLeft = n;
    *pnSize = n + nHeader + 4;
    pPrior = &pCell[nHeader+n];
  }
  pPayload = &pCell[nHeader];

  /* At this point variables should be set as follows:
  **
  **   nPayload           Total payload size in bytes
  **   pPayload           Begin writing payload here
  **   spaceLeft          Space available at pPayload.  If nPayload>spaceLeft,
  **                      that means content must spill into overflow pages.
  **   *pnSize            Size of the local cell (not counting overflow pages)
  **   pPrior             Where to write the pgno of the first overflow page
  **
  ** Use a call to btreeParseCellPtr() to verify that the values above
  ** were computed correctly.
  */
#if SQLITE_DEBUG
  {
    CellInfo info;
    btreeParseCellPtr(pPage, pCell, &info);
    assert( nHeader=(int)(info.pPayload - pCell) );
    assert( info.nKey==nKey );
    assert( *pnSize == info.nSize );
    assert( spaceLeft == info.nLocal );
    assert( pPrior == &pCell[info.iOverflow] );
  }
#endif

  /* Write the payload into the local Cell and any extra into overflow pages */
  while( nPayload>0 ){
    if( spaceLeft==0 ){
#ifndef SQLITE_OMIT_AUTOVACUUM
      Pgno pgnoPtrmap = pgnoOvfl; /* Overflow page pointer-map entry page */
      if( pBt->autoVacuum ){
        do{
          pgnoOvfl++;