Load/Save Saving String Data Via Banks

[kevin]

    This example loads/write string data into a stack like cache (for the purposes of the demo)  and includes load and Save array function.  The function spool data into an bank for batch read/writing.    

   Could easily be expanded to support encryption/decryption of  load/saved bank.   But that's left as an exercise for the programmer.

PlayBASIC Code: [Select]

;  Filename of the the temp file will be written (and later deleted)
   Filename$=Currentdir$()+"TestSave.txt"


; Declare the stack array so we have something to 
   Dim Stack$(0)


; Push a bunch of strings to the the STACK$() array   
   AddStr("Hello World")
   AddStr("Some Numbers")
   for lp=0 to 10
         AddStr(STR$(rnd(1000)))
   next
   AddStr("Yeah Yeah Yeah")
   AddStr("This is another string")
   AddStr("Could this be the end of the strings ?")



; Display the contents of the Stack$() array
   Print "Stack$() Contents"
   ShowArray( Stack$())


; Save this String held in the String Array
   SaveStringArray(Stack$(),Filename$)
   


; Declare Another String Array
   Dim MyArray$(0)


   ; Load the previously Saved data back into this second array
   LoadStringArray(MyArray$(),Filename$)


   ; Show the Newly loaded arrays contents
   Print "MyArray$() Contents"
   ShowArray( MyArray$())


   ; ditch the temp file that this demo creates
   if fileexist(filename$) then deletefile filename$
   

   Sync
   waitkey
   


;  *=--------------------------------------------------------------------=*
;                          >> Save String Array <<
;  *=--------------------------------------------------------------------=*
;
;    This function dumps the contents string array into a bank then writes
; them to a file
;
;  *=--------------------------------------------------------------------=*


Function SaveStringArray(me$(),Filename$)

   ; Calc total size
   Items=getarrayelements(me$(),1)
   For lp=0 to Items
      Size=Len(Me$(lp))+1        
      TotalSize=TotalSize+Size
   Next


   ; Add Header Size to TotalSize
     TotalSize=TotalSize+16   
   
   ; Dump to Memory
   Bank=NewBank(Totalsize)
   Address=GetBankPtr(Bank)

   ; Write the Header  
   Pokeint Address,items   ; Number of items
   Address=Address+4

   ; Dump Them as a sseries of null terms strings
   For lp=0 to Items
      Size=Len(me$(lp))+1        
      PokeString Address,Me$(lp),0
      Address=Address+Size
   next

   ; Save bank
   f=getfreefile()
   if f
      p=GetBankPtr(Bank)
      WriteFile  Filename$, f
         writememory f,p,p+TotalSize
      Closefile f
   endif

   ; Clean up
   Deletebank Bank
   
EndFunction




;  *=--------------------------------------------------------------------=*
;                          >> Load String Array <<
;  *=--------------------------------------------------------------------=*
;
;    This function reads data file and decodes it to a string array
;
;  *=--------------------------------------------------------------------=*



Function LoadStringArray(me$(),Filename$)
   
   Size=Filesize(Filename$)
   if Size>0
      Bank=NewBank(size+4)
      Address=GetBankPtr(Bank)

      f=getfreefile()
      ReadFile Filename$,f   
            ReadMemory f,Address,Size         
      Closefile f      

      ; Grab Strings
      StringCount=PeekInt(Address)   
      Address=Address+4
      
      Dim me$(StringCount)
      For lp=0 to StringCount
         me$(lp)=PeekString(Address,0)
         Address=Address+Len(me$(lp))+1
      next

      deletebank bank
   endif

EndFunction





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 Help Files:

     File Commands In PlayBASIC
     Memory Management / Bank Commands In PlayBASIC