; Blitter Example Scroll Texts -- A 32x32 pixel font scroller. ; Bit planes are 352x256, playfield is 320x256 ; and a bitplane modulo of 4 bytes is used. ; Result is 32 pixels off right side that ; is not visible and can be used to write a ; scroll text into! ; The font was designed in DPaint on a ; 320x256x4 display and cut as a brush 320x99x4 ; There are 10 chars per line, starting with ; the character A. ; The screen is scrolled 2 pixels per VBL, so ; a new character is printed every 16 VBL's. include hardware.i include HW_Macros.i include HW_Start.i ; Use macro to set BPL pointers and build colour defenition in Copper List. ; Display is 320x512 in 16 colours. Main COPBPLC CopPlanes,bitplane,(352/8)*256,4 ; Define address of Copper List STARTCOP #MyCopper ; Enable bitplane and Copper DMA. move.w #SETIT!DMAEN!COPEN!BPLEN!BLTEN,DMACON(a5) ; Install vertical blank interrupt handler and enable it. move.l #NewLevel3,$6c install move.w #SETIT!INTEN!VERTB,INTENA(a5) ; Wait for user to press the left mouse button mouse btst #6,CIAAPRA bne.s mouse ; And exit. rts ; ************************ ; * Vert Blank Interrupt * ; ************************ NewLevel3 lea $dff000,a5 a5->hardware base ; Screen is scrolled 2 pixels each VBI so we need to blit next character ;after 16 VBL's. This is the counter that controls this. tst.w VCount 5 second delay bne.s Scroll ; When counter reaches zero, blit a character and reset the counter. bsr DoChar move.w #16,VCount ; Now scroll screen left Scroll subq.w #1,VCount bsr ScrollScreen ; And clear the interrupt move.w INTREQR(a5),d0 get bits and.w #VERTB!COPER!BLIT,d0 move.w d0,INTREQ(a5) clear request rte back to user mode ; ****************************** ; * Scroll Screen Using Blitter* ; ****************************** ScrollScreen move.l #bitplane,d7 address of bitplane ; Scrolling starts at end of last last line of the text area. The text area ;starts 140 lines down the display and is 32 lines high. add.l #173*(352/8),d7 subq.l #2,d7 last word scroll area move.l #256*(352/8),d6 size of bpl moveq.l #3,d5 bpl counter ; Use blitter to scroll each line of the display BWait btst #14,DMACONR(a5) wait for Blitter bne.s BWait move.l d7,BLTAPTH(a5) source move.l d7,BLTDPTH(a5) dest = source move.w #0,BLTAMOD(a5) no modulo move.w #0,BLTDMOD(a5) move.w #-1,BLTAFWM(a5) no masking move.w #$29f0,BLTCON0(a5) A Scrl=2,use A,D, A=D move.w #$0002,BLTCON1(a5) B Scrl=0, Descending move.w #32<<6!22,BLTSIZE(a5) 22 words by 32 lines add.l d6,d7 dbra d5,BWait rts ; ******************************* ; * Next Character Using Blitter* ; ******************************* DoChar move.l Cursor,a0 get next character moveq.l #0,d0 from data. move.b (a0)+,d0 tst.b (a0) bne.s NoWrap lea Message,a0 NoWrap move.l a0,Cursor cmp.b #' ',d0 if a space correct it bne.s NotSpace since space after Z move.b #'Z'+1,d0 NotSpace sub.b #'A',d0 moveq.l #0,d1 ; There are 10 characters per line, so determine which line the character is ;on cmp.b #10,d0 blt.s GotNum sub.b #10,d0 move.l #33*(320/8),d1 next row cmp.b #10,d0 blt.s GotNum sub.b #10,d0 add.l d1,d1 next row ; 4 bytes per character so determine offset from start of line, add to line ;offset and then add result to start of Font data. This is the address of the ;font data. GotNum asl.w #2,d0 num * 4 add.l d1,d0 add.l #Font,d0 a0->char data ; Character is always printed off right side of display 140 lines down. move.l #bitplane,d1 add.l #141*(352/8)-4,d1 moveq.l #3,d2 bpl counter ; Blit the character BWait1 btst #14,DMACONR(a5) wait for Blitter bne.s BWait1 move.l d0,BLTAPTH(a5) source = font move.l d1,BLTDPTH(a5) dest = screen move.w #40-4,BLTAMOD(a5) font modulo move.w #44-4,BLTDMOD(a5) screen modulo move.l #-1,BLTAFWM(a5) no masking move.w #$09f0,BLTCON0(a5) use AD, D=A move.w #0,BLTCON1(a5) normal mode move.w #32<<6!2,BLTSIZE(a5) 32x32 pixels add.l #(320/8)*99,d0 Font bpl size add.l #(352/8)*256,d1 Screen bpl size dbra d2,BWait1 for 4 planes rts ; *************************** ; * Data * ; *************************** VCount dc.w 0 Cursor dc.l Message Message DC.B 'A FIRST SCROLL TEXT USING THE BLITTER SCREEN IS SIXTEEN COLOUR AND THIS ' DC.B 'TEXT IS BEING WRITTEN AND SCROLLED USING THE BLITTER FROM WITHIN A VBI ' DC.B 'HANDLER NO SCROLLER IS COMPLETE WITHOUT A GREETS LIST ' DC.B 'SO HERE GOES MIKE CROSS DAVE EDWARDS PAUL KENT ' DC.B 'STEVE MARSHALL AFRO PAUL CLASBY TIME TO WRAP ',0 EVEN ; *************************** ; * CHIP Memory Data * ; *************************** section data custom,chip **** Use this for A68K **** ; Section custom,data_C **** Use this for Devpac **** MyCopper CMOVE DIWSTRT,$2c81 PAL -- 256 lines CMOVE DIWSTOP,$2cc1 CMOVE DDFSTRT,$0038 LoRes CMOVE DDFSTOP,$00d0 CMOVE BPL1MOD,$0004 4 byte modulos CMOVE BPL2MOD,$0004 CMOVE BPLCON0,$4200 4 bitplanes & colour CMOVE BPLCON1,$0000 No scrolling CMOVE BPLCON2,$0000 Ignore priority CopPlanes CMOVE BPL1PTH,0 Bit plane pointers CMOVE BPL1PTL,0 filled in by the CMOVE BPL2PTH,0 program! CMOVE BPL2PTL,0 CMOVE BPL3PTH,0 CMOVE BPL3PTL,0 CMOVE BPL4PTH,0 CMOVE BPL4PTL,0 CopColours CMOVE COLOR00,$0000 The colours will be CMOVE COLOR01,$0000 filled in by the CMOVE COLOR02,$0000 program! CMOVE COLOR03,$0000 CMOVE COLOR04,$0000 CMOVE COLOR05,$0000 CMOVE COLOR06,$0000 CMOVE COLOR07,$0000 CMOVE COLOR08,$0000 CMOVE COLOR09,$0000 CMOVE COLOR10,$0000 CMOVE COLOR11,$0000 CMOVE COLOR12,$0000 CMOVE COLOR13,$0000 CMOVE COLOR14,$0000 CMOVE COLOR15,$0000 CEND end of list ; The font used in this example contains 32x32x4 character. There are 10 ;characters per line and the first character is 'A'. The screen containing ;the characters is 320x99x4. Font incbin 'font.bm' even ; The display used is 352x256x4. bitplane ds.b (352/8)*256*4 ; The colour data dc.w $0000,$0FFF,$0FEC,$0ED9,$0EC7,$0EB5,$0DA2,$0D90 dc.w $0C80,$0B70,$0A60,$0950,$0840,$0730,$0620,$0510 end