Section takeover,Code Opt C-,O+,w- Start: lea $dff000,a5 ; hardware base address ; needed to allow address register with ; offset to access hardware resisters Move.w $1c(a5),OldInt ; Save Old Interupts (INTENAR, save the ; contents of interupt enable bits read) Move.w $02(a5),OldDma ; Save Old DMA (DMACONR, save the ; contents of DMA control bits read) Move.w #$7fff,$96(a5) ; Clear DMA (turn all DMA channels ; etc. off) Move.w #$7fff,$9a(a5) ; Clear Interupts (turn all Interupts ; off) Move.w #$7fff,$9c(a5) ; Clear Interupt Requests (turn all ; interupt requests etc. off) Move.b #$7f,$bfed01 ; kill timers Move.l $6c.w,OldV3 ; save addess of the level 3 interupt ; routine Move.l #my_level3,$6c.w ; put new interupt level 3 server ; address in level 3 vector Move.l #my_copper,$80(a5) ; put address of my copperlist into ; COP1LCH Lea Sprites+2,a0 ; This bit points all the sprites to Move.l #Dumsprite,d0 ; a dummy sprite to prevent them from Move.w #7,d1 ; leaving vertical lines all over! Clrsprite: ; Swap d0 ; Get low word of address Move.w d0,(a0) ; put it in copper list Swap d0 ; Get high word Move.w d0,4(a0) ; put it in copper list Add.l #8,a0 ; point to next entry in copper list Dbra d1,Clrsprite ; Do all 8 sprites Move.w #$c010,$9a(a5) ; Start interupts (turn on the level 3 ; interupt) Move.w #$83ef,$96(a5) ; Start DMA ( all DMA except disk DMA) Move.w #1,$88(a5) ; Strobe for copper start (needed ; because graphics library is no longer ; automatically strobing for the copper ; to restart) ******************** bsr my_programme ; this is where your program goes ******************** ; this section now returns control back the OS, if you packing below ; $20000, your demo should not be able to quit and therefore should ; not do the following, if you wish to exit you must put the reset ; routine given later here (instead of the OS Restore). The demo will ; just Guru if you try to exit when it is absolute packed to low a ; address ; ****** OS restore ****** lea $dff000,a5 ; hardware base address Move.l OldV3,$6c.w ; restore old level 3 vector Lea GfxLib,a1 ; Pointer to Library Text move.l 4.w,a6 ; Get the address of exec library jsr -132(a6) ; Forbid() - this is needed because ; the old level 3 interupt is now ; running again Move.l 4.w,a6 ; Exec base Moveq.l #0,d0 ; Clear D0 Jsr -$228(a6) ; OpenLibrary() - opening the gfx ; library gives you the addresses of ; the old copperlists cmp.l #0,d0 ; if gfx library not open dont restore beq no_gfx_lib ; copper library, this can cause a ; crash if the demo is packed below ; $20000 and the reason you shouldn't ; exit Move.l d0,a1 ; move the address of the gfx library ; into a1 for offset addressing Move.l $26(a1),$80(a5) ; restore address of CLI copper 1 Move.l $32(a1),$84(a5) ; restore address of CLI copper 2 ; from the gfx library. no_gfx_lib: Move.w OldInt,d0 ; start old interupts Or.w #$8000,d0 ; enables you to set bits 0-14 Move.w d0,$9a(a5) ; set INTENA Move.w OldDma,d0 ; start old DMA Or.w #$8000,d0 ; enables you to set bits 0-14 Move.w d0,$96(a5) ; set DMACON Move.b #$9b,$bfed01 ; Re-start CIA Timers Move.l 4.w,a6 ; Close Gfx lib Jsr -$19e(a6) move.l 4.w,a6 jsr -138(a6) ; Permit() Moveq.l #0,d0 ; No errors, always clear before ; returning to prevent RETURN CODE ; errors on the CLI Rts ; Exit my_level3: Movem.l d0-d7/a0-a6,-(a7) ; New copper Move.w #$10,$dff09c ; Serviced Interupt **************** bsr my_interupt ; your stuff goes here **************** Exit: Movem.l (a7)+,d0-d7/a0-a6 ; Return from Interupt Rte section Copperdata,data_c ; force to chipmem my_copper: dc.w $100,$0200 ; no bitpplanes dc.w $104,$a ; bp control reg dc.w $108,0 ; bp modulo - odd dc.w $10a,0 ; bp modulo - even dc.w $180,0 ; colour 0 to black dc.w $102,0 ; no scroll dc.w $08e,$2c81 ; bp window start left dc.w $090,$2cc1 ; bp window bot right dc.w $094,$d0 ; bp stop horz dc.w $92,$38 sprites: dc.w $120,0,$122,0,$124,0,$126,0 ; Sprite pointers should dc.w $128,0,$12a,0,$12c,0,$12e,0 ; be pointed to a location dc.w $130,0,$132,0,$134,0,$136,0 ; which is initialised to dc.w $138,0,$13a,0,$13c,0,$13e,0 ; 0 dc.w $ffe1,$fffe ; end of ntsc screen dc.w $3001,$ff00 ; end of pal screen dc.w $9c,$8010 ; irq set bits - restart copper dc.w $ffff,$fffe ; end of copper list Section Variables,Data ; This is where the old system ; pointers etc are saved DumSpite: dc.l 0,0 oldint: dc.l 0 olddma: dc.l 0 oldv3: dc.l 0 gfxlib: dc.b "graphics.library",0 even ; End of takover/return control routine ; This is the reset routine, use this to reset the computer ; when exiting a demo packed to a low address move.l #$fc00d0,$80 ; Address of reset routine in rom trap #0 ; call reset routine in supervisor mode