S-C DocuMentor — Applesoft
SAVE S.F49C
1010 *--------------------------------
1020 * "XDRAW" ONE BIT
1030 *--------------------------------
F49C- 18 1040 LRUDX1 CLC C=0 MEANS NO 90 DEGREE ROTATION
F49D- A5 D1 1050 LRUDX2 LDA HGR.DX+1 C=1 MEANS ROTATE 90 DEGREES
F49F- 29 04 1060 AND #4 IF BIT2=0 THEN DON'T PLOT
F4A1- F0 25 1070 BEQ LRUD4 YES, DO NOT PLOT
F4A3- A9 7F 1080 LDA #$7F NO, LOOK AT WHAT IS ALREADY THERE
F4A5- 25 30 1090 AND MON.HMASK
F4A7- 31 26 1100 AND (MON.GBASL),Y SCREEN BIT = 1?
F4A9- D0 19 1110 BNE LRUD3 YES, GO CLEAR IT
F4AB- E6 EA 1120 INC HGR.COLLISIONS NO, COUNT THE COLLISION
F4AD- A9 7F 1130 LDA #$7F AND TURN THE BIT ON
F4AF- 25 30 1140 AND MON.HMASK
F4B1- 10 11 1150 BPL LRUD3 ...ALWAYS
1160 *--------------------------------
1170 * "DRAW" ONE BIT
1180 *--------------------------------
F4B3- 18 1190 LRUD1 CLC C=0 MEANS NO 90 DEGREE ROTATION
F4B4- A5 D1 1200 LRUD2 LDA HGR.DX+1 C=1 MEANS ROTATE
F4B6- 29 04 1210 AND #4 IF BIT2=0 THEN DO NOT PLOT
F4B8- F0 0E 1220 BEQ LRUD4 DO NOT PLOT
F4BA- B1 26 1230 LDA (MON.GBASL),Y
F4BC- 45 1C 1240 EOR HGR.BITS 1'S WHERE ANY BITS NOT IN COLOR
F4BE- 25 30 1250 AND MON.HMASK LOOK AT JUST THIS BIT POSITION
F4C0- D0 02 1260 BNE LRUD3 THE BIT WAS ZERO, SO PLOT IT
F4C2- E6 EA 1270 INC HGR.COLLISIONS BIT IS ALREADY 1; COUNT COLLSN
1280 *--------------------------------
1290 * TOGGLE BIT ON SCREEN WITH (A)
1300 *--------------------------------
F4C4- 51 26 1310 LRUD3 EOR (MON.GBASL),Y
F4C6- 91 26 1320 STA (MON.GBASL),Y
1330 *--------------------------------
1340 * DETERMINE WHERE NEXT POINT WILL BE, AND MOVE THERE
1350 * C=0 IF NO 90 DEGREE ROTATION
1360 * C=1 ROTATES 90 DEGREES
1370 *--------------------------------
F4C8- A5 D1 1380 LRUD4 LDA HGR.DX+1 CALCULATE THE DIRECTION TO MOVE
F4CA- 65 D3 1390 ADC HGR.QUADRANT
F4CC- 29 03 1400 AND #3 WRAP AROUND THE CIRCLE
F4CD- 1410 CON.03 .EQ *-1 (( A CONSTANT ))
1420 *
1430 * 00 -- UP
1440 * 01 -- DOWN
1450 * 10 -- RIGHT
1460 * 11 -- LEFT
1470 *
F4CE- C9 02 1480 CMP #2 C=0 IF 0 OR 1, C=1 IF 2 OR 3
F4D0- 6A 1490 ROR PUT C INTO SIGN, ODD/EVEN INTO C
F4D1- B0 92 1500 BCS MOVE.LEFT.OR.RIGHT
1510 *--------------------------------
1520 MOVE.UP.OR.DOWN
F4D3- 30 30 1530 BMI MOVE.DOWN SIGN FOR UP/DOWN SELECT.
1540 *--------------------------------
1550 * MOVE UP ONE PIXEL
1560 * IF ALREADY AT TOP, GO TO BOTTOM
1570 *
1580 * REMEMBER: Y-COORD GBASH GBASL
1590 * ABCDEFGH PPPFGHCD EABAB000
1600 *--------------------------------
F4D5- 18 1610 CLC MOVE UP
F4D6- A5 27 1620 LDA MON.GBASH CALC. BASE ADDRESS OF PREV. LINE
F4D8- 2C B9 F5 1630 BIT CON.1C LOOK AT BITS 000FGH00 IN GBASH
F4DB- D0 22 1640 BNE .5 SIMPLE, JUST FGH=FGH-1
1650 * GBASH=PPP000CD, GBASL=EABAB000
F4DD- 06 26 1660 ASL MON.GBASL WHAT IS "E"?
F4DF- B0 1A 1670 BCS .3 E=1, THEN EFGH=EFGH-1
F4E1- 2C CD F4 1680 BIT CON.03 LOOK AT 000000CD IN GBASH
F4E4- F0 05 1690 BEQ .1 Y-POS IS AB000000 FORM
F4E6- 69 1F 1700 ADC #$1F CD <> 0, SO CDEFGH=CDEFGH-1
F4E8- 38 1710 SEC
F4E9- B0 12 1720 BCS .4 ...ALWAYS
F4EB- 69 23 1730 .1 ADC #$23 ENOUGH TO MAKE GBASH=PPP11111 LATER
F4ED- 48 1740 PHA SAVE FOR LATER
F4EE- A5 26 1750 LDA MON.GBASL GBASL IS NOW ABAB0000 (AB=00,01,10)
F4F0- 69 B0 1760 ADC #$B0 0000+1011=1011 AND CARRY CLEAR
1770 * OR 0101+1011=0000 AND CARRY SET
1780 * OR 1010+1011=0101 AND CARRY SET
F4F2- B0 02 1790 BCS .2 NO WRAP-AROUND NEEDED
F4F4- 69 F0 1800 ADC #$F0 CHANGE 1011 TO 1010 (WRAP-AROUND)
F4F6- 85 26 1810 .2 STA MON.GBASL FORM IS NOW STILL ABAB0000
F4F8- 68 1820 PLA PARTIALLY MODIFIED GBASH
F4F9- B0 02 1830 BCS .4 ...ALWAYS
F4FB- 69 1F 1840 .3 ADC #$1F
F4FD- 66 26 1850 .4 ROR MON.GBASL SHIFT IN E, TO GET EABAB000 FORM
F4FF- 69 FC 1860 .5 ADC #$FC FINISH GBASH MODS
F501- 85 27 1870 UD.1 STA MON.GBASH
F503- 60 1880 RTS
1890 *--------------------------------
F504- 18 1900 CLC <<<NEVER USED>>>
1910 *--------------------------------
1920 * MOVE DOWN ONE PIXEL
1930 * IF ALREADY AT BOTTOM, GO TO TOP
1940 *
1950 * REMEMBER: Y-COORD GBASH GBASL
1960 * ABCDEFGH PPPFGHCD EABAB000
1970 *--------------------------------
1980 MOVE.DOWN
F505- A5 27 1990 LDA MON.GBASH TRY IT FIRST, BY FGH=FGH+1
F507- 69 04 2000 ADC #4 GBASH = PPPFGHCD
F508- 2010 CON.04 .EQ *-1 (( CONSTANT ))
F509- 2C B9 F5 2020 BIT CON.1C IS FGH FIELD NOW ZERO?
F50C- D0 F3 2030 BNE UD.1 NO, SO WE ARE FINISHED
2040 * YES, RIPPLE THE CARRY AS HIGH
2050 * AS NECESSARY
F50E- 06 26 2060 ASL MON.GBASL LOOK AT "E" BIT
F510- 90 18 2070 BCC .2 NOW ZERO; MAKE IT 1 AND LEAVE
F512- 69 E0 2080 ADC #$E0 CARRY = 1, SO ADDS $E1
F514- 18 2090 CLC IS "CD" NOT ZERO?
F515- 2C 08 F5 2100 BIT CON.04 TESTS BIT 2 FOR CARRY OUT OF "CD"
F518- F0 12 2110 BEQ .3 NO CARRY, FINISHED
2120 * INCREMENT "AB" THEN
2130 * 0000 --> 0101
2140 * 0101 --> 1010
2150 * 1010 --> WRAP AROUND TO LINE 0
F51A- A5 26 2160 LDA MON.GBASL 0000 0101 1010
F51C- 69 50 2170 ADC #$50 0101 1010 1111
F51E- 49 F0 2180 EOR #$F0 1010 0101 0000
F520- F0 02 2190 BEQ .1
F522- 49 F0 2200 EOR #$F0 0101 1010
F524- 85 26 2210 .1 STA MON.GBASL NEW ABAB0000
F526- A5 E6 2220 LDA HGR.PAGE WRAP AROUND TO LINE ZERO OF GROUP
F528- 90 02 2230 BCC .3 ...ALWAYS
F52A- 69 E0 2240 .2 ADC #$E0
F52C- 66 26 2250 .3 ROR MON.GBASL
F52E- 90 D1 2260 BCC UD.1 ...ALWAYS
2270 *--------------------------------
2280 * HLINRL IS NEVER CALLED BY APPLESOFT
2290 *
2300 * ENTER WITH: (A,X) = DX FROM CURRENT POINT
2310 * (Y) = DY FROM CURRENT POINT
2320 *--------------------------------
F530- 48 2330 HLINRL PHA SAVE (A)
F531- A9 00 2340 LDA #0 CLEAR CURRENT POINT SO HGLIN WILL
F533- 85 E0 2350 STA HGR.X ACT RELATIVELY
F535- 85 E1 2360 STA HGR.X+1
F537- 85 E2 2370 STA HGR.Y
F539- 68 2380 PLA RESTORE (A)
2390 *--------------------------------
2400 * DRAW LINE FROM LAST PLOTTED POINT TO (A,X),(Y)
2410 *
2420 * ENTER WITH: (A,X) = X OF TARGET POINT
2430 * (Y) = Y OF TARGET POINT
2440 *--------------------------------
F53A- 48 2450 HGLIN PHA COMPUTE DX = X- X0
F53B- 38 2460 SEC
F53C- E5 E0 2470 SBC HGR.X
F53E- 48 2480 PHA
F53F- 8A 2490 TXA
F540- E5 E1 2500 SBC HGR.X+1
F542- 85 D3 2510 STA HGR.QUADRANT SAVE DX SIGN (+ = RIGHT, - = LEFT)
F544- B0 0A 2520 BCS .1 NOW FIND ABS (DX)
F546- 68 2530 PLA FORMS 2'S COMPLEMENT
F547- 49 FF 2540 EOR #$FF
F549- 69 01 2550 ADC #1
F54B- 48 2560 PHA
F54C- A9 00 2570 LDA #0
F54E- E5 D3 2580 SBC HGR.QUADRANT
F550- 85 D1 2590 .1 STA HGR.DX+1
F552- 85 D5 2600 STA HGR.E+1 INIT HGR.E TO ABS(X-X0)
F554- 68 2610 PLA
F555- 85 D0 2620 STA HGR.DX
F557- 85 D4 2630 STA HGR.E
F559- 68 2640 PLA
F55A- 85 E0 2650 STA HGR.X TARGET X POINT
F55C- 86 E1 2660 STX HGR.X+1
F55E- 98 2670 TYA TARGET Y POINT
F55F- 18 2680 CLC COMPUTE DY = Y-HGR.Y
F560- E5 E2 2690 SBC HGR.Y AND SAVE -ABS(Y-HGR.Y)-1 IN HGR.DY
F562- 90 04 2700 BCC .2 (SO + MEANS UP, - MEANS DOWN)
F564- 49 FF 2710 EOR #$FF 2'S COMPLEMENT OF DY
F566- 69 FE 2720 ADC #$FE
F568- 85 D2 2730 .2 STA HGR.DY
F56A- 84 E2 2740 STY HGR.Y TARGET Y POINT
F56C- 66 D3 2750 ROR HGR.QUADRANT SHIFT Y-DIRECTION INTO QUADRANT
F56E- 38 2760 SEC COUNT = DX -(-DY) = # OF DOTS NEEDED
F56F- E5 D0 2770 SBC HGR.DX
F571- AA 2780 TAX COUNTL IS IN X-REG
F572- A9 FF 2790 LDA #$FF
F574- E5 D1 2800 SBC HGR.DX+1
F576- 85 1D 2810 STA HGR.COUNT
F578- A4 E5 2820 LDY HGR.HORIZ HORIZONTAL INDEX
F57A- B0 05 2830 BCS MOVEX2 ...ALWAYS
2840 *--------------------------------
2850 * MOVE LEFT OR RIGHT ONE PIXEL
2860 * (A) BIT 6 HAS DIRECTION
2870 *--------------------------------
F57C- 0A 2880 MOVEX ASL PUT BIT 6 INTO SIGN POSITION
F57D- 20 65 F4 2890 JSR MOVE.LEFT.OR.RIGHT
F580- 38 2900 SEC
2910 *--------------------------------
2920 * DRAW LINE NOW
2930 *--------------------------------
F581- A5 D4 2940 MOVEX2 LDA HGR.E CARRY IS SET
F583- 65 D2 2950 ADC HGR.DY E = E-DELTY
F585- 85 D4 2960 STA HGR.E NOTE: DY IS (-DELTA Y)-1
F587- A5 D5 2970 LDA HGR.E+1 CARRY CLR IF HGR.E GOES NEGATIVE
F589- E9 00 2980 SBC #0
F58B- 85 D5 2990 .1 STA HGR.E+1
F58D- B1 26 3000 LDA (MON.GBASL),Y
F58F- 45 1C 3010 EOR HGR.BITS PLOT A DOT
F591- 25 30 3020 AND MON.HMASK
F593- 51 26 3030 EOR (MON.GBASL),Y
F595- 91 26 3040 STA (MON.GBASL),Y
F597- E8 3050 INX FINISHED ALL THE DOTS?
F598- D0 04 3060 BNE .2 NO
F59A- E6 1D 3070 INC HGR.COUNT TEST REST OF COUNT
F59C- F0 62 3080 BEQ RTS.22 YES, FINISHED.
F59E- A5 D3 3090 .2 LDA HGR.QUADRANT TEST DIRECTION
F5A0- B0 DA 3100 BCS MOVEX NEXT MOVE IS IN THE X DIRECTION
F5A2- 20 D3 F4 3110 JSR MOVE.UP.OR.DOWN IF CLR, NEG, MOVE
F5A5- 18 3120 CLC E = E+DX
F5A6- A5 D4 3130 LDA HGR.E
F5A8- 65 D0 3140 ADC HGR.DX
F5AA- 85 D4 3150 STA HGR.E
F5AC- A5 D5 3160 LDA HGR.E+1
F5AE- 65 D1 3170 ADC HGR.DX+1
F5B0- 50 D9 3180 BVC .1 ...ALWAYS
3190 *--------------------------------
F5B2- 81 82 84
F5B5- 88 90 A0
F5B8- C0 3200 MSKTBL .HS 8182848890A0C0
3210 *--------------------------------
F5B9- 1C 3220 CON.1C .HS 1C MASK FOR "FGH" BITS
3230 *--------------------------------
S.F3D8
