* --------------------------------------------------------------------
* test.s
* --------------------------------------------------------------------

; this initial material would normaly be provided as a separate header 
; file - it provides the _LVO values for the functions being used 
; together with the macros used by the program...

_AbsExecBase         EQU    4

_LVOOpenLibrary      EQU -552

_LVOCloseLibrary     EQU -414

_LVOOutput           EQU  -60  

_LVOWrite            EQU  -48

NULL                 EQU    0
 
LF                   EQU   10

                     XDEF _main

LINKLIB MACRO
   
         IFGT NARG-2

           FAIL   ;too many arguments

         ENDC
    
         move.l   a6,-(sp)
   
         move.l   \2,a6
   
         jsr      \1(a6)
   
         move.l (sp)+,a6
   
         ENDM


CALLSYS  MACRO

         LINKLIB _LVO\1,\2
    
         ENDM


WRITEDOS MACRO

         movem.l  d1-d3,-(sp)               preserve registers d1-d3
         
         move.l   \2,d1                     DOS output file handle
         
         move.l   #\1,d2                    start of message 
         
         move.l   #\1_SIZEOF,d3             size of message
         
         CALLSYS  Write,_DOSBase            DOS call to write message
         
         movem.l  (sp)+,d1-d3               restore registers d1-d3
    
         ENDM

* --------------------------------------------------------------------

; The following stuff is the program itself...


     
_main    move.l   _AbsExecBase,_SysBase      set up SysBase variable

         lea      dos_name,a1                library name start in a1
    
         moveq    #0,d0                      any version will do
    
         CALLSYS  OpenLibrary,_SysBase       macro (see article for details)
    
         move.l   d0,_DOSBase                store returned value

         beq      EXIT                       quit if NULL

; if we reach here the DOS library is open and functions can be used...

         CALLSYS  Output,_DOSBase            get default output handle
         
         move.l   d0,_stdout                 store output handle 

         beq      CLOSELIB

; have obtained valid output handle so message can be written...

         WRITEDOS message,_stdout            get DOS to write message


; all done so now we can close DOS library...

CLOSELIB move.l   _DOSBase,a1                base needed in a1        
    
         CALLSYS  CloseLibrary,_SysBase
    
    
; and terminate the program...    

EXIT     clr.l    d0
         
         rts                                 logical end of program
        
* --------------------------------------------------------------------    
; these are all the variables and static data...

_stdout           ds.l    1

_SysBase          ds.l    1

_DOSBase          ds.l    1
    
dos_name          dc.b 'dos.library',NULL
    
message           dc.b 'Amiga Format Rules OK!',LF
    
message_SIZEOF    EQU *-message

                  END
                      
* --------------------------------------------------------------------