; This is a shrink/enlarge routine. The masks need some work to produce ;a decent effect, and true to form I've only used two colours. ; M.Meany, Aug 1991. incdir df1:include/ include hardware.i Start bsr.s SysOff disable system, set a5 tst.l d0 error ? beq.s .error if so quit now ! bsr Main do da bsr SysOn enable system .error rts ***************************************************************************** ;-------------- Disable the operating system. ; On exit d0=0 if no gfx library. SysOff lea $dff000,a5 a5->hardware move.w DMACONR(a5),sysDMA save DMA settings lea grafname,a1 a1->lib name moveq.l #0,d0 any version move.l $4.w,a6 a6->SysBase jsr -$0228(a6) OpenLibrary move.l d0,grafbase open ok? beq .error quit if not move.l d0,a6 a6->GfxBase move.l 38(a6),syscop save addr of sys list jsr -$01c8(a6) OwnBlitter move.l $4,a6 a6->sysbase jsr -$0084(a6) Forbid ; Wait for vertical blank and disable unwanted DMA ( eg. Sprites ). .BeamWait move.l VPOSR(a5),d0 d0=VPOSR+VHPOSR and.l #$1ff00,d0 mask off vert position cmp.w #$1000,d0 is this line 16? bne.s .BeamWait if not loop back move.w #$01e0,DMACON(a5) kill all dma move.w #SETIT!COPEN!BPLEN!BLTEN,DMACON(a5) enable copper ; Write bitplane addresses into Copper List. move.l #BitPlane,d0 lea CopPlanes,a0 move.w d0,4(a0) swap d0 move.w d0,(a0) ; Strobe our list move.l #CopList,COP1LCH(a5) clr.w COPJMP1(a5) moveq.l #1,d0 .error rts ***************************************************************************** ;-------------- Bring back the operating system SysOn move.l syscop,COP1LCH(a5) clr.w COPJMP1 restart system list move.w #$8000,d0 set bit 15 of d0 or.w sysDMA,d0 add DMA flags move.w d0,DMACON(a5) enable systems DMA move.l $4.w,a6 a6->SysBase jsr -$008A(a6) Permit move.l grafbase,a6 jsr -$01ce(a6) DisownBlitter move.l $4.w,a6 a6->SysBase move.l grafbase,a1 a1->Graphics base jsr -$019e(a6) CloseLibrary rts ***************************************************************************** ***************************************************************************** ***************************************************************************** Main bsr Init moveq.l #0,d7 initial scaling factor moveq.l #1,d6 step size ( + or - one ) ; wait for beam to reach line 16 VBL moveq.l #50,d5 .VBL move.l VPOSR(a5),d0 d0=VPOSR+VHPOSR and.l #$1ff00,d0 mask off vert position cmp.w #$1000,d0 is this line 16? bne.s .VBL if not loop back dbra d5,.VBL ***************************************************************************** bsr FillBuf bsr DrawBuf bsr ClearBuf add.l d6,d7 cmpi.l #5,d7 bne.s .ok neg.l d6 change direction bra.s .ok1 .ok tst.l d7 bne.s .ok1 neg.l d6 ***************************************************************************** .ok1 btst #6,CIAAPRA lefty ? bne.s VBL if not loop back ; program should shut down here.... bsr DeInit rts ***************************************************************************** ***************************************************************************** **************************** Subroutines ************************************ ***************************************************************************** ***************************************************************************** ***************************************************************************** Init rts ***************************************************************************** DeInit rts ***************************************************************************** ; Clear the image buffer ClearBuf lea ImBuf,a0 moveq.l #0,d0 move.l d0,(a0) move.l d0,4(a0) move.l d0,8(a0) move.l d0,12(a0) rts ***************************************************************************** ; Copy contents of buffer onto the screen at a predefined position DrawBuf lea ImBuf,a0 lea BitPlane,a1 lea 40*10+20(a1),a1 x=20, y=40 move.w (a0)+,(a1) move.w (a0)+,40(a1) move.w (a0)+,80(a1) move.w (a0)+,120(a1) move.w (a0)+,160(a1) move.w (a0)+,200(a1) move.w (a0)+,240(a1) move.w (a0)+,280(a1) rts ***************************************************************************** ; Shrink image into buffer ; Entry d7=level, 0 to 5 ; Exit buffer is filled with shrunken image ; Corrupt d1-d3, a2-a3 FillBuf move.l d7,d3 copy of level asl.w #1,d3 x2 for offset lea HMask0,a3 a3->horizontal masks move.w 0(a3,d3),d1 d1=horizontal mask lea VMask0,a3 a3->vertical masks move.w 0(a3,d3),d2 d2=vertical mask lea Image,a2 a2->image lea ImBuf,a3 a3->buffer moveq.l #7,d3 d3=image line counter .loop move.w (a2)+,d0 d0=next line of image asr.w #1,d2 scroll vert mask bcc.s .dontcopy if clear jump bsr Shrink else shrink this line move.w d0,(a3)+ and save result .dontcopy dbra d3,.loop for all 8 lines rts ***************************************************************************** ; Entry d0= word of data to shrink ; d1= shrinking mask ; Exit d0= shrunken word ; Corrupt d0 ; Comment Timing Shrink movem.l d1-d4,-(sp) save regs 48 moveq.l #0,d2 zero var 4 move.l d2,d3 zero var 4 moveq.l #15,d4 counter 16-1 4 .loop asl.w #1,d1 shift mask 8 bcc.s .no_copy jmp if bit clr 10 T, 8 F roxl.w #1,d0 else copy a 8 roxl.w #1,d2 bit into result 8 addq.l #1,d3 bump counter 8 bra .next for all bits 10 .no_copy rol.w #1,d0 ignore bit 8 .next dbra d4,.loop for all 16 bits 10,12,14 neg.w d3 -ve 4 add.w #16,d3 bits left 8 asr.w #1,d3 div by 2 8 rol.w d3,d2 centralise 6+2 x value move.w d2,d0 result into d0 4 movem.l (sp)+,d1-d4 restore 44 rts and return 16 ***************************************************************************** ***************************************************************************** ***************************************************************************** ***************************************************************************** ***************************************************************************** ***************************************************************************** ***************************** Data ****************************************** ***************************************************************************** ***************************************************************************** grafname dc.b 'graphics.library',0 even grafbase ds.l 1 sysDMA ds.l 1 syscop ds.l 1 ;REG ds.w $300 for debug only ***************************************************************************** ***************************************************************************** ***************************** CHIP Data ************************************* ***************************************************************************** ***************************************************************************** section cop,data_c CopList dc.w DIWSTRT,$2c81 Top left of screen dc.w DIWSTOP,$2cc1 Bottom right of screen (PAL) dc.w DDFSTRT,$38 Data fetch start dc.w DDFSTOP,$d0 Data fetch stop dc.w BPLCON0,$1200 Select lo-res 2 colours dc.w BPLCON1,0 No horizontal offset dc.w BPL1MOD,0 No modulo dc.w COLOR00,$0000 black background dc.w COLOR01,$0fff white foreground dc.w BPL1PTH Plane pointers for 1 plane CopPlanes dc.w 0,BPL1PTL dc.w 0 dc.w $ffff,$fffe end of list BitPlane ds.b (320/8)*256 ; A very simple image to work with ;Image dc.w %0000000000000000 dc.w %0000001111000000 dc.w %0000111111110000 dc.w %0001111111111000 dc.w %0001111111111000 dc.w %0001111111111000 dc.w %0000111111110000 dc.w %0000001111000000 Image dc.w %0000000000000000 dc.w %0011100000011100 dc.w %0011111001111100 dc.w %0011100110011100 dc.w %0011100110011100 dc.w %0011100000011100 dc.w %0011100000011100 dc.w %0000000000000000 ; Buffer to store image in ImBuf dc.w 0,0,0,0,0,0,0,0 ; A sample set of scroll masks ; horizontal ( For the best effect, make right 8 bits=reflection of left 8) HMask0 dc.w %1111111111111111 HMask1 dc.w %1011110110111101 Hmask2 dc.w %0111011111101110 HMask3 dc.w %1011010101101101 Hmask4 dc.w %0101010110111010 Hmask5 dc.w %1001000110001001 HMask6 dc.w 0 ; vertical VMask0 dc.w %11111111 VMask1 dc.w %01111110 VMask2 dc.w %01101110 VMask3 dc.w %01011010 VMask4 dc.w %01010010 VMask5 dc.w %01010010 VMask6 dc.w 0