; ; Bitplane Example 12. ; ; Written for OZAmiga by Chris Leathley. ; ; uses the dual playfield mode on the amiga. Puts the frame picture ; in front of the scrolling warning picture in the background. ; ; has the colour cycling routine in again and also changes playfield ; priority for a slight slice of the screen. ; ; ; 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 FRAME_SIZE = 256*40 ; size of frame picture bitplanes ; -------------------------------------------------------------------------- ; a68k code ; SECTION code,CODE,CHIP ; make sure in chip memory ; devpac code SECTION code,CODE_C ; make sure in chip memory ; -------------------------------------------------------------------------- ; program starts here ; START: clr.l $0 ; clear address 0 move.l $4,a6 ; turn off multitasking jsr Forbid(a6) ; ; set up bitplane address into copper list program before copper is ; turned on ; move.l #FRAME,d0 ; put warning picture address move.w d0,BP1LO+2 ; into copper (ODD planes) swap d0 ; (playfield 1) move.w d0,BP1HI+2 move.l #FRAME+FRAME_SIZE,d0 ; plane 2 move.w d0,BP3LO+2 swap d0 move.w d0,BP3HI+2 move.l #PICTURE,d0 ; put warning picture address move.w d0,BP2LO+2 ; into copper (EVEN plane) swap d0 ; (playfield 2) move.w d0,BP2HI+2 ; fire up the copper ; .wait_vb cmp.b #$FF,$00DFF006 ; wait for vb to change bne.s .wait_vb move.l #COPPERLIST,$00DFF080 ; insert new copperlist move.w #$8380,$00DFF096 ; use new control bits ; (turn on copper & bitplane dma) ; wait for user to press the left mouse button and then exit program ; MAIN_LOOP: cmp.b #$FF,$00DFF006 ; wait for vertical blank bne.s MAIN_LOOP bsr SCROLL_WARNING bsr CYCLE_WARNING ; put in our little delay otherwise the above code will execute ; many times while the raster line is still on postion $FF move.w #256,d0 ; count down from 256 to 0 .delay sub.w #1,d0 bne .delay btst #$06,$00BFE001 ; left mouse button ? bne.s MAIN_LOOP ; no? do it all again ; 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 move.l d0,a1 ; d0 has pointer to library move.l $0026(a1),$00DFF080 ; restore original copperlist jsr CloseLibrary(a6) ; close graphics library jsr Permit(a6) ; turn back on multitasking moveq #0,d0 ; no errors rts ; return of amiga dos ; -------------------------------------------------------------------------- ; ; scroll warning bitmap (640 pixels wide) left and right in lo-res ; (displaying only 320 pixels at a time) ; SCROLL_WARNING: tst.w SCROLL_DIRECTION ; test direction flag bne .right ; 0 = left, 1 = right .left sub.w #1,SCROLL_VALUE ; subtract 1 from x position tst.w SCROLL_VALUE ; are we at 0 yet? bne .set move.w #1,SCROLL_DIRECTION ; yes so now go right bra .set .right add.w #1,SCROLL_VALUE cmp.w #320+16,SCROLL_VALUE ; at max right position? ; we go that little bit extra ; to compensate for the frame ; graphics in playfield 1 bne .set move.w #0,SCROLL_DIRECTION ; now go left .set move.l #0,d0 move.w SCROLL_VALUE,d0 ; get x scroll value move.l d0,d1 ; move to a temporary regisiter divu #16,d1 ; calculate number of "words" ; into bitplane pointers mulu #2,d1 ; convert result from bytes ; to "words". (bitplane pointers ; must be a EVEN address) not.b d0 ; invert scroll offset and.w #$000F,d0 ; clip offset to range ($0 - $F) lsl.w #4,d0 ; shift to EVEN HSCROLL pos move.w d0,HSCROLL_COP+2 ; put result into copperlist move.l #PICTURE,d0 ; base address of picture add.l d1,d0 ; add number of "words" onto ; picture start address. move.w d0,BP2LO+2 ; set bitplane pointers swap d0 move.w d0,BP2HI+2 rts SCROLL_DIRECTION dc.w 1 ; (start going right) SCROLL_VALUE dc.w 0 ; -------------------------------------------------------------------------- ; ; make the word "warning' on the bitmap cycle colours from ; bright yellow to black, to bright yellow again. ; CYCLE_WARNING: add.w #1,CYCLE_DELAY ; change colour every 2 cmp.w #2,CYCLE_DELAY ; vertical blanks bne .exit clr.w CYCLE_DELAY ; reset counter move.w CYCLE_OFFSET,d0 ; get colour cycle table offset lea WARNING_COLOURS,a0 ; colour table add.w d0,a0 ; get to required colour move.w (a0),WARNING_COP_COL+2 ; set new colour in copperlist add.w #2,CYCLE_OFFSET ; goto next colour entry in ; table (since each entry is ; one "word" we must add 2 bytes) cmp.w #32*2,CYCLE_OFFSET ; at end of table? bne .exit ; not this time clr.w CYCLE_OFFSET ; reset offset (range is from ; 0 to 31) .exit rts CYCLE_DELAY dc.w 0 CYCLE_OFFSET dc.w 0 ; colour cycle table (32 entrys) ; WARNING_COLOURS dc.w $FF0,$EE0,$DD0,$CC0,$BB0,$AA0,$990,$880 ; fade from dc.w $770,$660,$550,$440,$330,$220,$110,$000 ; yellow to black dc.w $000,$110,$220,$330,$440,$550,$660,$770 ; and then upto dc.w $880,$990,$AA0,$BB0,$CC0,$DD0,$EE0,$FF0 ; yellow again ; -------------------------------------------------------------------------- ; graphics library name ; GFX_NAME: dc.b 'graphics.library',0 EVEN ; ; our copperlist program ; COPPERLIST: dc.w $0180,$0000 ; screen starts off black dc.w $0120,0,$0122,0 ; don't worry about this just dc.w $0124,0,$0126,0 ; yet as all it does is set dc.w $0128,0,$012A,0 ; all sprite positions to zero dc.w $012C,0,$012E,0 ; so no wondering sprites dc.w $0130,0,$0132,0 ; appear on the screen dc.w $0134,0,$0136,0 dc.w $0138,0,$013A,0 dc.w $013C,0,$013E,0 BP1HI dc.w $00E0,0 ; bitplane 1 address pointers BP1LO dc.w $00E2,0 BP2HI dc.w $00E4,0 ; bitplane 2 address pointers BP2LO dc.w $00E6,0 BP3HI dc.w $00E8,0 ; bitplane 3 address pointers BP3LO dc.w $00EA,0 dc.w $100,$3600 ; turn on 3 bitplanes ; (2 ODD and 1 EVEN) ; and duel playfield mode ; (bit 10) HSCROLL_COP dc.w $102,0 ; hardware scroll to be zero dc.w $104,0 ; bitplane / sprite priority dc.w $08E,$2C81 ; window start (top left) dc.w $090,$2CC1 ; window stop (bottom right) ; (STANDARD PAL DISPLAY VALUES) dc.w $092,$38 ; bitplane DMA start dc.w $094,$d0 ; bitplane DMA stop dc.w $108,0 ; odd modulo (frame picture) dc.w $10A,40 ; even modulo (warning picture) dc.w $180,$000 ; frame picture colours dc.w $182,$D72 ; colour 1 dc.w $184,$841 ; colour 2 dc.w $186,$420 ; colour 3 WARNING_COP_COL dc.w $192,$FF0 ; warning text colour (yellow) ; colour 9 dc.w $7009,$FFFE,$192,$DD0 ; set text colour to dull yellow ; after warning colour cycle. dc.w $D409,$FFFE,$180,$005 ; background colour to blue dc.w $104,$0040 ; put playfield 2 in front of ; playfield 1 (swap prioritys) dc.w $F409,$FFFE,$180,$000 ; colour 0 to black again dc.w $104,$0 ; playfield priority back to norm dc.w $FFFF,$FFFE ; end of copper list ; start vertical blank ; -------------------------------------------------------------------------- ; ; include raw picture data into assembly code ; FRAME: INCBIN oz.frame.raw PICTURE: INCBIN oz.warning.raw ; -------------------------------------------------------------------------- END ; end of program