SQLite

  n = (u32)pMem->n;
  if( flags & MEM_Zero ){
    n += pMem->u.nZero;
  }
  return ((n*2) + 12 + ((flags&MEM_Str)!=0));
}

/*
** The sizes for serial types less than 12
*/
static const u8 sqlite3SmallTypeSizes[] = {
  0, 1, 2, 3, 4, 6, 8, 8, 0, 0, 0, 0
};

/*
** Return the length of the data corresponding to the supplied serial-type.
*/
u32 sqlite3VdbeSerialTypeLen(u32 serial_type){
  if( serial_type>=12 ){
    return (serial_type-12)/2;
  }else{
    static const u8 aSize[] = { 0, 1, 2, 3, 4, 6, 8, 8, 0, 0, 0, 0 };
    return aSize[serial_type];
    return sqlite3SmallTypeSizes[serial_type];
  }
}

/*
** If we are on an architecture with mixed-endian floating 
** points (ex: ARM7) then swap the lower 4 bytes with the 
** upper 4 bytes.  Return the result.

    if( serial_type==7 ){
      assert( sizeof(v)==sizeof(pMem->u.r) );
      memcpy(&v, &pMem->u.r, sizeof(v));
      swapMixedEndianFloat(v);
    }else{
      v = pMem->u.i;
    }
    len = i = sqlite3VdbeSerialTypeLen(serial_type);
    len = i = sqlite3SmallTypeSizes[serial_type];
    assert( i>0 );
    do{
      buf[--i] = (u8)(v&0xFF);
      v >>= 8;
    }while( i );
    return len;
  }

  testcase( typeRowid==5 );
  testcase( typeRowid==6 );
  testcase( typeRowid==8 );
  testcase( typeRowid==9 );
  if( unlikely(typeRowid<1 || typeRowid>9 || typeRowid==7) ){
    goto idx_rowid_corruption;
  }
  lenRowid = sqlite3VdbeSerialTypeLen(typeRowid);
  lenRowid = sqlite3SmallTypeSizes[typeRowid];
  testcase( (u32)m.n==szHdr+lenRowid );
  if( unlikely((u32)m.n<szHdr+lenRowid) ){
    goto idx_rowid_corruption;
  }

  /* Fetch the integer off the end of the index record */
  sqlite3VdbeSerialGet((u8*)&m.z[m.n-lenRowid], typeRowid, &v);