* QL WORLD DIY TOOLKIT - FAST pixel graphics routines * Version 1.6, Copyright 1989,90 Simon N Goodwin. * Modified 10/9/89 to support Thor XVI MODE 12. * Modified 19/7/90 to suit Metacomco's Assembler. * xstore equ 84 Offsets of old X & Y ystore equ 78 in the channel block * start lea.l define,a1 move.w $110,a2 BP.INIT vector jmp (a2) * draw lea.l drawer,a4 bra.s get_params plot lea.l plotter,a4 * * Handler for 2 or 3 parameters * get_params move.w $112,a2 Vector to get integers jsr (a2) CA.GTINT bne.s bad_exit moveq #1,d0 First assume channel 1 subq.w #2,d3 At least 2 parameters? beq.s get_coords Exactly 2, use #1 bmi.s bad_param Less than 2: an error subq.w #1,d3 Only 1 parameter left? bne.s bad_param No, too many, complain move.w 0(a1,a6.l),d0 Get BASIC channel No. addq.l #2,a1 Discard channel param. get_coords move.w 0(a1,a6.l),d1 Get X co-ordinate move.w 2(a1,a6.l),d2 Get Y co-ordinate * * Convert channel number in D0 to ID in A0 and call EXTOP * chan_sel mulu #40,d0 Channel table size add.l $30(a6),d0 Add base offset cmp.l $34(a6),d0 bge.s what_chan Past end of table? move.l 0(a6,d0.l),d0 bmi.s what_chan Negative if closed call_extop move.l d0,a0 A0 is channel ID move.l a4,a2 Address of routine moveq #-1,d3 Allow infinite time moveq #9,d0 SD.EXTOP key trap #3 Call the device driver rts Return D0 from EXTOP * bad_param moveq #-15,d0 BAD PARAMETER error rts what_chan moveq #-6,d0 CHANNEL NOT OPEN error bad_exit rts Error code is in D0 * * Line DRAW routine * drawer move.w xstore(a0),d4 Fetch previous X move.w ystore(a0),d5 Fetch previous Y bsr range_chk Line must fit window find_DX suba.l a2,a2 DX := 0 sub.w d4,d1 beq.s set_X_step bmi.s neg_DX addq.l #1,a2 A2 := SIGN( Delta X ) bra.s set_X_step neg_DX subq.l #1,a2 neg.w d1 D1 := ABS( Delta X ) set_X_step btst #3,52(a6) Check mode (SV.MCSTA) beq.s find_DY MODE 4, D1 & A2 are OK adda.l a2,a2 MODE 8/12, double X step ror.w #1,d1 And halve X dot count find_DY suba.l a3,a3 DY := 0 sub.w d5,d2 beq.s find_DD bmi.s neg_DY addq.l #1,a3 A3 := SIGN( Delta Y ) bra.s find_DD neg_DY subq.l #1,a3 neg.w d2 D2 := ABS( Delta Y ) find_DD cmp.w d1,d2 D1 := MAX( D1, D2 ) bhi.s y_bigger no_match move.w a2,a4 DDX := DX suba.l a5,a5 DDY := 0 bra.s find_TEMP y_bigger exg d1,d2 D1 := MAX( D1,D2 ) suba.l a4,a4 DDX := 0 move.w a3,a5 DDY := DY find_TEMP move.w d1,d0 asr.w #1,d0 TEMP := STEPS DIV 2 move.w d2,d6 D6 := PARTS move.w d1,d2 subq.w #1,d2 D2 is DOT for DBRA bmi.s null_draw Exit if line length=0 exg d1,d4 OLDX = D1; STEPS = D4 exg d2,d5 OLDY = D2; DOT = D5 * * Now draw a line of D5 pixels; D1,D2 = X,Y of next point * dot_loop add.w d6,d0 TEMP := TEMP + PARTS cmp.w d4,d0 Flag TEMP - STEPS bcs.s use_DD sub.w d4,d0 TEMP := TEMP - STEPS add.w a2,d1 OLDX := OLDX + DX add.w a3,d2 OLDY := OLDY + DY bra.s do_dot * use_DD add.w a4,d1 OLDX := OLDX + DDX add.w a5,d2 OLDY := OLDY + DDY do_dot movem.w d1-d2,-(a7) Preserve OLDX & OLDY bsr.s plot_pixel movem.w (a7)+,d1-d2 Restore OLDX & OLDY dbra d5,dot_loop null_draw moveq #0,d0 rts * * Co-ordinate checker; D1=X, D2=Y, ERR.OR if beyond window * range_chk tst.b 51(a6) Test SV.SCRST bne.s screen_off Abort if CTRL-F5 set tst.w d2 Check Y >= 0 bmi.s range_err cmp.w 30(a0),d2 Check Y < CH.HEIGHT bcc.s range_err tst.w d1 Check X >= 0 bmi.s range_err cmp.w 28(a0),d1 Check X < CH.WIDTH bcc.s range_err move.w #$8080,d7 Set MODE 4 pixel mask btst #3,52(a6) Check MODE (SV.MCSTA) beq.s range_ok MODE 4, no problems bclr #0,d1 MODE 8/12, X must be EVEN btst #2,52(a6) Test Thor MODE 12 bit beq.s not_a_thor move.w #$C0C0,d7 Use the Thor mask not_a_thor move.b #$C0,d7 Mask 8 colours range_ok add.w 24(a0),d1 Add window offset to X add.w 26(a0),d2 Add window offset to Y move.w d1,xstore(a0) Store end X on SD.XORG move.w d2,ystore(a0) Store end Y on SD.YORG rts * screen_off moveq #-1,d0 NOT COMPLETE error bra.s quick_exit range_err moveq #-4,d0 OUT OF RANGE error quick_exit addq.l #4,a7 Return to after TRAP rts * * Pixel PLOT code, uses A0, A6, D7; alters A1, D1, D2, D3 * plotter bsr.s range_chk moveq #0,d0 Preset ERR.OK report plot_pixel move.l 62(a0),d3 Grab the ink mask btst #0,d2 Find out if Y is odd beq.s find_word It's even, mask is OK swap d3 Odd, so use other mask * * Point A1 at the relevant word in video memory * find_word move.l 50(a0),a1 A1 := screen RAM start lsl.w #7,d2 1 line= 2^7= 128 bytes adda.w d2,a1 A1 := line RAM start moveq #7,d2 and.w d1,d2 Save X MOD 8 in D2 lsr.w #3,d1 D1 := offset on line add.w d1,d1 Offset := 0-126 (EVEN) adda.w d1,a1 A1 -> screen RAM word * * Set the pixel in MODE 4 or 8, allowing for OVER -1 * set_pixel move.w d7,d1 Select pixel mask ror.w d2,d1 Align pixel mask and.w d1,d3 D3 := 1 pixel of ink btst #3,66(a0) Check for OVER -1 bne.s overplot not.w d1 Mask out the rest and.w (a1),d1 Fetch the background or.w d3,d1 Insert the pixel move.w d1,(a1) Store the combination rts PLOT returns ERR.OK overplot eor.w d3,(a1) Exclusive OR the pixel rts * define dc.w 2 Number of procs dc.w plot-* dc.b 4,'PLOT' dc.w draw-* dc.b 4,'DRAW' dc.w 0,0,0 End of procs, no fns end