; ; Copperlist Example 1. ; ; Written for OZAmiga by Chris Leathley. ; ; The code is fully comented to help you understand what is going on ; as a lot of new areas are covered in one program. ; ; ; Branch offsets into the Amiga's rom kernal librarys (exec) ; Forbid = -132 ; turn off Multitasking Permit = -138 ; turn it back on again CloseLibrary = -414 ; open a library (from ram or disk) OpenLibrary = -552 ; close an opened library ; -------------------------------------------------------------------------- ; a68k code SECTION code,CODE,CHIP ; make sure in chip memory ; devpac code ; SECTION code,CODE_C ; make sure in chip memory ; any part of the program that the custom chips use (ie the copper, blitter) ; must be in CHIP type memory for it to work ; ; If you are using Devpac as your assembler then comment out the A68k ; version of the SECTION command and insert the devpac one ; ; -------------------------------------------------------------------------- ; program starts here ; START: clr.l $0 ; clear address 0 ; it is best to clear this ; location as it will stop ; any bitplane or sprite ; flicking if those registers ; havn't been initalized move.l $4,a6 ; turn off multitasking jsr Forbid(a6) ; ; the amiga contains many librarys so the user can easily code system ; friendly programs using allready existing code ; ; address $4 holds the address of the master library the 'exec.library'. ; This library contains a lot of routines to open other librarys and to ; control aspects of the operating system. ; ; there are quite a few library to help the Amiga operate, most of them are ; all ready in ram (kickstart), others can be found in the LIBS: directory. ; Librarys include the 'graphics.library' which has routines to control any ; type of graphics on the screen. Unless you are writting in C or writing ; system code we don't need to use the 'graphics.library' execept to get ; the old copperlist pointer (expained later). Other librarys include the ; 'dos.library' which handles all disk input and output. ; .wait_vb cmp.b #$FF,$00DFF006 ; wait for vb to change bne.s .wait_vb ; ; as mentioned in the artical, the display has a count of where the ; display beem is on the monitor. As it moves down the screen this ; address holds the line number it is currently on ; ; the vertical blank is the best time to trigger the copperlist as ; when the beem is in this area nothing is being sent to the monitor ; display, so not glitches are noticed as the copperlist changes ; move.l #FIRSTCOPPER,$00DFF080 ; insert new copperlist move.w #$8280,$00DFF096 ; use new control bits ; ; move the address of the copperlist program (FIRSTCOPPER) into the ; address which runs the copper ; ; address $00DFF096 can switch all the individual DMA channels ; either on or off. ; ; unlike normal address, some of the Amiga's hardware address work ; very differently. Instead of over-writing the entire word with the ; new one it will individually set or clear single bits within that ; address. Bit 15 (msb) is set to 1 if you want to set bits, and 0 ; if you want to turn them off. The remaining bits stand for special ; DMA control. The $x2xx above enables all dma set while the $xx80 ; enables Copper DMA. All other DMA channels remain unchanged. ; ; wait for user to press the left mouse button and then exit program ; MAIN_LOOP: cmp.b #$FF,$00DFF006 ; wait for vertical blank bne.s MAIN_LOOP btst #$06,$00BFE001 ; left mouse button ? bne.s MAIN_LOOP ; no? do it all again ; ; bit 6 in address $00BFE001 can tell if the left mouse button is being ; pressed. It will be set to 0 when this happens. Bit 7 is the ; joystick button. Try changing it to 7, you will then have to press ; the joystick button to exit. ; ; The btst instruction tests a bit within a byte and sets the flags ; accordinly. It compare's the bit with zero. ; ; program finished, exit back to dos ; EXIT: move.l $4,a6 ; exec pointer lea GFX_NAME,a1 ; library name moveq #0,d0 ; library version jsr OpenLibrary(a6) ; open graphics library ; open library returns the address of the opened library in d0 move.l d0,a1 ; d0 has pointer to library ; move this to an address register to we can use the offset addressing mode move.l $0026(a1),$00DFF080 ; restore original copperlist ; ; the graphic library contain many varables and programs usefull to the ; programmer and operating system. As hardware programmer we only need to ; get one varable (or address) from the library. Offset $26 contains the ; address of the previous copperlist (in most cases it is the workbench ; copperlist program) ; ; we need to restore the copperlist pointer to the old one otherwise the ; amiga will display the wrong display. ie. you'll have our very nice ; colour bars instead of the CLI screen. Since the COP1LC ($00DFF180) ; register is WRITE-ONLY we cannot get the copperlist address at the start ; of the program, so we have to use the operating system. ; jsr CloseLibrary(a6) ; close graphics library jsr Permit(a6) ; turn back on multitasking moveq #0,d0 ; no errors rts ; return of amiga dos ; ; It is general convention to return a zero in D0 so the Amiga knows ; that the program worked correctly and there wasn't any errors. ; ; -------------------------------------------------------------------------- ; graphics library name ; GFX_NAME: dc.b 'graphics.library',0 EVEN ; ; the library name open library uses. It must have a 0 byte at the ; end of the string. ; The EVEN makes sure that any data or code following is on a word ; boundary (an even address) otherwise the 68000 gets very cross and ; sulks. ; ; ; our first copperlist program ; ; It puts 7 coloured bars onto the screen ; FIRSTCOPPER: dc.w $0180,$0000 ; make sure screen starts ; off being black dc.w $0100,$0000 ; turn off bitplane display ; ; $0180 is the register for colour zero. If the 68000 wanted to use ; it, it would be $00DFF180. ; dc.w $4009,$FFFE,$0180,$0200 ; red bar dc.w $4109,$FFFE,$0180,$0400 dc.w $4209,$FFFE,$0180,$0600 dc.w $4309,$FFFE,$0180,$0800 dc.w $4409,$FFFE,$0180,$0A00 dc.w $4509,$FFFE,$0180,$0C00 dc.w $4609,$FFFE,$0180,$0E00 dc.w $4709,$FFFE,$0180,$0F00 ; the brightest point dc.w $4809,$FFFE,$0180,$0E00 dc.w $4909,$FFFE,$0180,$0C00 dc.w $4A09,$FFFE,$0180,$0A00 dc.w $4B09,$FFFE,$0180,$0800 dc.w $4C09,$FFFE,$0180,$0600 dc.w $4D09,$FFFE,$0180,$0400 dc.w $4E09,$FFFE,$0180,$0200 dc.w $4F09,$FFFE,$0180,$0000 ; ; the last colour must be the screen colour, otherwise you would see a pale ; red section on the screen. Try changing it to $0FFF to see what I mean. ; dc.w $6009,$FFFE,$0180,$0210 ; orange bar dc.w $6109,$FFFE,$0180,$0420 dc.w $6209,$FFFE,$0180,$0630 dc.w $6309,$FFFE,$0180,$0840 dc.w $6409,$FFFE,$0180,$0A50 dc.w $6509,$FFFE,$0180,$0C60 dc.w $6609,$FFFE,$0180,$0E70 dc.w $6709,$FFFE,$0180,$0F80 dc.w $6809,$FFFE,$0180,$0E70 dc.w $6909,$FFFE,$0180,$0C60 dc.w $6A09,$FFFE,$0180,$0A50 dc.w $6B09,$FFFE,$0180,$0840 dc.w $6C09,$FFFE,$0180,$0630 dc.w $6D09,$FFFE,$0180,$0420 dc.w $6E09,$FFFE,$0180,$0210 dc.w $6F09,$FFFE,$0180,$0000 dc.w $8009,$FFFE,$0180,$0220 ; yellow bar dc.w $8109,$FFFE,$0180,$0440 dc.w $8209,$FFFE,$0180,$0660 dc.w $8309,$FFFE,$0180,$0880 dc.w $8409,$FFFE,$0180,$0AA0 dc.w $8509,$FFFE,$0180,$0CC0 dc.w $8609,$FFFE,$0180,$0EE0 dc.w $8709,$FFFE,$0180,$0FF0 dc.w $8809,$FFFE,$0180,$0EE0 dc.w $8909,$FFFE,$0180,$0CC0 dc.w $8A09,$FFFE,$0180,$0AA0 dc.w $8B09,$FFFE,$0180,$0880 dc.w $8C09,$FFFE,$0180,$0660 dc.w $8D09,$FFFE,$0180,$0440 dc.w $8E09,$FFFE,$0180,$0220 dc.w $8F09,$FFFE,$0180,$0000 dc.w $A009,$FFFE,$0180,$0020 ; green bar dc.w $A109,$FFFE,$0180,$0040 dc.w $A209,$FFFE,$0180,$0060 dc.w $A309,$FFFE,$0180,$0080 dc.w $A409,$FFFE,$0180,$00A0 dc.w $A509,$FFFE,$0180,$00C0 dc.w $A609,$FFFE,$0180,$00E0 dc.w $A709,$FFFE,$0180,$00F0 dc.w $A809,$FFFE,$0180,$00E0 dc.w $A909,$FFFE,$0180,$00C0 dc.w $AA09,$FFFE,$0180,$00A0 dc.w $AB09,$FFFE,$0180,$0080 dc.w $AC09,$FFFE,$0180,$0060 dc.w $AD09,$FFFE,$0180,$0040 dc.w $AE09,$FFFE,$0180,$0020 dc.w $AF09,$FFFE,$0180,$0000 dc.w $C009,$FFFE,$0180,$0022 ; cyan dc.w $C109,$FFFE,$0180,$0044 dc.w $C209,$FFFE,$0180,$0066 dc.w $C309,$FFFE,$0180,$0088 dc.w $C409,$FFFE,$0180,$00AA dc.w $C509,$FFFE,$0180,$00CC dc.w $C609,$FFFE,$0180,$00EE dc.w $C709,$FFFE,$0180,$00FF dc.w $C809,$FFFE,$0180,$00EE dc.w $C909,$FFFE,$0180,$00CC dc.w $CA09,$FFFE,$0180,$00AA dc.w $CB09,$FFFE,$0180,$0088 dc.w $CC09,$FFFE,$0180,$0066 dc.w $CD09,$FFFE,$0180,$0044 dc.w $CE09,$FFFE,$0180,$0022 dc.w $CF09,$FFFE,$0180,$0000 dc.w $E009,$FFFE,$0180,$0002 ; blue dc.w $E109,$FFFE,$0180,$0004 dc.w $E209,$FFFE,$0180,$0006 dc.w $E309,$FFFE,$0180,$0008 dc.w $E409,$FFFE,$0180,$000A dc.w $E509,$FFFE,$0180,$000C dc.w $E609,$FFFE,$0180,$000E dc.w $E709,$FFFE,$0180,$000F dc.w $E809,$FFFE,$0180,$000E dc.w $E909,$FFFE,$0180,$000C dc.w $EA09,$FFFE,$0180,$000A dc.w $EB09,$FFFE,$0180,$0008 dc.w $EC09,$FFFE,$0180,$0006 dc.w $ED09,$FFFE,$0180,$0004 dc.w $EE09,$FFFE,$0180,$0002 dc.w $EF09,$FFFE,$0180,$0000 dc.w $FFDF,$FFFE ; ; unless the copperlist has this command, it will start the vertical blank ; at this point. thats ok for NTSC machines but we lose the bottom 2 inches ; of the display. The above command tricks the copper into missing the ; first vertical blank position. It will how ever happen around $38 (the ; very bottom of the screen. ; dc.w $0009,$FFFE,$0180,$0202 ; pink dc.w $0109,$FFFE,$0180,$0404 dc.w $0209,$FFFE,$0180,$0606 dc.w $0309,$FFFE,$0180,$0808 dc.w $0409,$FFFE,$0180,$0A0A dc.w $0509,$FFFE,$0180,$0C0C dc.w $0609,$FFFE,$0180,$0E0E dc.w $0709,$FFFE,$0180,$0F0F dc.w $0809,$FFFE,$0180,$0E0E dc.w $0909,$FFFE,$0180,$0C0C dc.w $0A09,$FFFE,$0180,$0A0A dc.w $0B09,$FFFE,$0180,$0808 dc.w $0C09,$FFFE,$0180,$0606 dc.w $0D09,$FFFE,$0180,$0404 dc.w $0E09,$FFFE,$0180,$0202 dc.w $0F09,$FFFE,$0180,$0000 dc.w $FFFF,$FFFE ; end of copper list ; start vertical blank ; -------------------------------------------------------------------------- END ; end of program