;*** Lines with the Blitter ;Custom chip register INTENA = $9A ;Interrupt enable register (write) DMACON = $96 ;DMA-Control register (write) DMACONR = $2 ;DMA-Control register (read) COLOR00 = $180 ;Color palette register VHPOSR = $6 ;Position (read) ;Copper Register COP1LC = $80 ;Addresse of 1st. Copper-List COP2LC = $84 ;Addersse of 2nd. Copper-List COPJMP1 = $88 ;Jump to Copper-List 1 COPJMP2 = $8a ;Jump to Copper-List 2 ;Bitplane Register BPLCON0 = $100 ;Bitplane control register 0 BPLCON1 = $102 ;1 (Scroll value) BPLCON2 = $104 ;2 (Sprite<>Playfield Priority) BPL1PTH = $0E0 ;Pointer to 1st. bitplane BPL1PTL = $0E2 ; BPL1MOD = $108 ;Modulo value for odd Bit-Planes BPL2MOD = $10A ;Modulo value for even Bit-Planes DIWSTRT = $08E ;Start of screen window DIWSTOP = $090 ;End of screen window DDFSTRT = $092 ;Bit-Plane DMA Start DDFSTOP = $094 ;Bit-Plane DMA Stop ;Blitter Register BLTCON0 = $40 ;Blitter control register 0 (ShiftA,Usex,LFx) BLTCON1 = $42 ;Blitter control register 1 (ShiftB,misc. Bits) BLTCPTH = $48 ;Pointer to source C BLTCPTL = $4a BLTBPTH = $4c ;Pointer to source B BLTBPTL = $4e BLTAPTH = $50 ;Pointer to source A BLTAPTL = $52 BLTDPTH = $54 ;Pointer to targer data D BLTDPTL = $56 BLTCMOD = $60 ;Modulo value for source C BLTBMOD = $62 ;Modulo value for source B BLTAMOD = $64 ;Modulo value for source A BLTDMOD = $66 ;Modulo value for target D BLTSIZE = $58 ;HBlitter window width/height BLTCDAT = $70 ;Source C data register BLTBDAT = $72 ;Source B data register BLTADAT = $74 ;Source A data register BLTAFWM = $44 ;Mask for first data word from source A BLTALWM = $46 ;Mask for first data word from source B ;CIA-A Port register A (Mouse key) CIAAPRA = $bfe001 ;Exec Library Base Offsets OpenLibrary = -30-522 ;LibName,Version/a1,d0 Forbid = -30-102 Permit = -30-108 AllocMem = -30-168 ;ByteSize,Requirements/d0,d1 FreeMem = -30-180 ;MemoryBlock,ByteSize/a1,d0 ;Graphics Library Base Offsets OwnBlitter = -30-426 DisownBlitter = -30-432 ;graphics base StartList = 38 ;other Labels Execbase = 4 Planesize = 80*200 ;Bitplane size: 80 Bytes by 200 lines Planewidth = 80 CLsize = 3*4 ;The Copper-List contains 3 commands Chip = 2 ;allocate Chip-RAM Clear = Chip+$10000 ;Clear Chip-RAM first ;*** Initialization *** Start: ;A;llocate memory for bit plane move.l Execbase,a6 move.l #Planesize,d0 ;Memory requirment for bit plane move.l #clear,d1 jsr AllocMem(a6) ;Allocate memory move.l d0,Planeadr beq Ende ;Error! -> End ;Allocate memory for Copper-List moveq #Clsize,d0 moveq #chip,d1 jsr AllocMem(a6) move.l d0,CLadr beq FreePlane ;Error! -> FreePlane ;Create Copper-List move.l d0,a0 ;Address of Copper-List from a0 move.l Planeadr,d0 ;Address of Bitplane move.w #bpl1pth,(a0)+ ;First Copper coommand in RAM swap d0 move.w d0,(a0)+ ;Hi-Word of Bit plane address in RAM move.w #bpl1ptl,(a0)+ ;second command in RAM swap d0 move.w d0,(a0)+ ;Lo-Word of Bitplane address in RAM move.l #$fffffffe,(a0) ;End of Copper-List ;Allocate Blitter move.l #GRname,a1 clr.l d0 jsr OpenLibrary(a6) move.l a6,-(sp) ;ExecBase from the Stack move.l d0,a6 ;GraphicsBase from a6 move.l a6,-(sp) ;and from the Stack jsr OwnBlitter(a6) ;Take over Blitter ;*** Main program *** ;DMA and Task-Switching off move.l 4(sp),a6 ;ExecBase to a6 jsr forbid(a6) ;Task-Switching off lea $dff000,a5 move.w #$03e0,dmacon(a5) ;Copper initialization move.l CLadr,cop1lc(a5) clr.w copjmp1(a5) ;Set color move.w #$0000,color00(a5) ;Black background move.w #$0fa0,color00+2(a5) ;Yellow line ;Playfield initialization move.w #$2081,diwstrt(a5) ;20,129 move.w #$20c1,diwstop(a5) ;20,449 move.w #$003c,ddfstrt(a5) ;Normal Hires Screen move.w #$00d4,ddfstop(a5) move.w #%1001001000000000,bplcon0(a5) clr.w bplcon1(a5) clr.w bplcon2(a5) clr.w bpl1mod(a5) clr.w bpl2mod(a5) ;DMA on move.w #$83C0,dmacon(a5) ;Draw lines ;Determine start values: move.l Planeadr,a0 ;Constant parameter for DrawLine move.w #Planewidth,a1 ;into correct register move.w #255,a3 ;Size of Bitplane in Register move.w #639,a4 move.w #$0303,d7 ;Start pattern Loop: rol.w #2,d7 ;Shift pattern move.w d7,a2 ;Pattern in register for DrawLine clr.w d6 ;Clear loop variable LoopX: clr.w d1 ;Y1 = 0 move.w a3,d3 ;Y2 = 255 move.w d6,d0 ;X1 = Loop variable move.w a4,d2 sub.w d6,d2 ;X2 = 639-Loop variable bsr DrawLine addq.w #4,d6 ;Increment loop variable cmp.w a4,d6 ;Test if greater than 639 ble.s LoopX ;if not. continue loop clr.w d6 ;Clear loop variable LoopY: move.w a4,d0 ;X1 = 639 clr.w d2 ;X2 = 0 move.w d6,d1 ;Y1 = loop variable move.w a3,d3 sub.w d6,d3 ;Y2 = 255-loop variable bsr DrawLine ;Draw line addq.w #2,d6 ;Increment loop variable cmp.w a3,d6 ;Is loop variable greater than 255? ble.s LoopY ;if not, continue loop btst #6,ciaapra ;Mouse key pressed? bne Loop ;No, continue ;*** End program *** ;Wait till blitter is ready Wait: btst #14,dmaconr(a5) bne Wait ;Activate old Copper-List move.l (sp)+,a6 ;Get GraphicsBase from Stack move.l StartList(a6),cop1lc(a5) clr.w copjmp1(a5) ;Activare Startup-Copper-List move.w #$8020,dmacon(a5) jsr DisownBlitter(a6) ;Release blitter move.l (sp)+,a6 ;ExecBase from Stack jsr Permit(a6) ;Task Switching on ;Release memory for Copper-List move.l CLadr,a1 ;Set parameter for FreeMem moveq #CLsize,d0 jsr FreeMem(a6) ;Release memory ;Release Bitplane memory FreePlane: move.l Planeadr,a1 move.l #Planesize,d0 jsr FreeMem(a6) Ende: clr.l d0 rts ;Program end ;Variablen CLadr: dc.l 0 ;Address of Copper-List Planeadr: dc.l 0 ;Address of Bitplane ;Constants GRname: dc.b "graphics.library",0 align ;even ;*** DrawLine Routine *** ;DrawLine draws a line with the Blitter. ;The following parameters are used: ;d0 = X1 X-coordinate of Start points ;d1 = Y1 Y-coordinate of Start points ;d2 = X2 X-coordinate of End points ;d3 = Y2 Y-coordinate of End points ;a0 must point to the first word of the bitplane ;a1 contains bitplane width in bytes ;a2 word written directly to mask register ;d4 to d6 are used as work registers DrawLine: ;Compute the lines starting address move.l a1,d4 ;Width in work register mulu d1,d4 ;Y1 * Bytes per line moveq #-$10,d5 ;No leading characters: $f0 and.w d0,d5 ;Bottom four bits masked from X1 lsr.w #3,d5 ;Remainder divided by 8 add.w d5,d4 ;Y1 * Bytes per line + X1/8 add.l a0,d4 ;plus starting address of the Bitplane ;d4 now contains the starting address ;of the line ;Compute octants and deltas clr.l d5 ;Clear work register sub.w d1,d3 ;Y2-Y1 DeltaY from D3 roxl.b #1,d5 ;shift leading char from DeltaY in d5 tst.w d3 ;Restore N-Flag bge.s y2gy1 ;When DeltaY positive, goto y2gy1 neg.w d3 ;DeltaY invert (if not positive) y2gy1: sub.w d0,d2 ;X2-X1 DeltaX to D2 roxl.b #1,d5 ;Move leading char in DeltaX to d5 tst.w d2 ;Restore N-Flag bge.s x2gx1 ;When DeltaX positive, goto x2gx1 neg.w d2 ;DeltaX invert (if not positive) x2gx1: move.w d3,d1 ;DeltaY to d1 sub.w d2,d1 ;DeltaY-DeltaX bge.s dygdx ;When DeltaY > DeltaX, goto dygdx exg d2,d3 ;Smaller Delta goto d2 dygdx: roxl.b #1,d5 ;d5 contains results of 3 comparisons move.b Octant_table(pc,d5),d5 ;get matching octants add.w d2,d2 ;Smaller Delta * 2 ;Test, for end of last blitter operation WBlit: btst #14,dmaconr(a5);BBUSY-Bit test bne.s WBlit ;Wait until equal to 0 move.w d2,bltbmod(a5) ;2* smaller Delta to BLTBMOD sub.w d3,d2 ;2* smaller Delta - larger Delta bge.s signnl ;When 2* small delta > large delta to signnl or.b #$40,d5 ;Sign flag set signnl: move.w d2,bltaptl(a5) ;2*small delta-large delta in BLTAPTL sub.w d3,d2 ;2* smaller Delta - 2* larger Delta move.w d2,bltamod(a5) ;to BLTAMOD ;Initialization other info move.w #$8000,bltadat(a5) move.w a2,bltbdat(a5) ;Mask from a2 in BLTBDAT move.w #$ffff,bltafwm(a5) and.w #$000f,d0 ;bottom 4 Bits from X1 ror.w #4,d0 ;to START0-3 or.w #$0bca,d0 ;USEx and LFx set move.w d0,bltcon0(a5) move.w d5,bltcon1(a5) ;Octant in Blitter move.l d4,bltcpth(a5) ;Start address of line to move.l d4,bltdpth(a5) ;BLTCPT and BLTDPT move.w a1,bltcmod(a5) ;Width of Bitplane in both move.w a1,bltdmod(a5) ;Modulo Registers ;BLTSIZE initialization and Blitter start lsl.w #6,d3 ;LENGTH * 64 addq.w #2,d3 ;plus (Width = 2) move.w d3,bltsize(a5) rts ;Octant table with LINE =1: ;The octant table contains code values ;for each octant, shifted to the correct position Octant_table: dc.b 0 *4+1 ;y1dy = Okt7 dc.b 2 *4+1 ;y1x2, dxx2, dx>dy = Okt4 dc.b 1 *4+1 ;y1>y2, x1y2, x1dy = Okt0 dc.b 3 *4+1 ;y1>y2, x1>x2, dxy2, x1>x2, dx>dy = Okt3 end