PSET VRAM.asm

10 ORG 100H
20 JP MAIN
30RPTCHR EQU 0BFEEH
40GPF EQU 0BFD0H
50AOUT EQU 0BD09H
60PUTSTR EQU 0BFF1H
70WAITK EQU 0BFCDH
80LDPSTR EQU 0BD00H
90REGOUT EQU 0BD03H

100MAIN: CALL CLS
110 LD HL,DPSET
120 CALL STRLN
130 LD DE,0
140 CALL PUTSTR
150 CALL GTVRAM ; get copy of vram
160 LD A,12
170 LD (POSY),A
180 LD A,133
190 LD (POSX),A
200 CALL PSET
210 LD A,120
220 LD (POSX),A
230 LD A,22
240 LD (POSY),A
250 CALL PSET
260 CALL DSPLAY ; copy to screen
270 CALL WAIT

280 LD HL,DHLINE
290 CALL STRLN
300 LD DE,0
310 CALL PUTSTR
320 CALL GTVRAM
330 LD A,32
340 LD (POSY),A
350MAIN00: LD A,10
360 LD (POSX),A
370 LD A,133
380 LD (ENDX),A
390 CALL HLINE ; 10,[32-42] to 133,[32-42]
400 LD A,(POSY)
410 INC A
420 INC A ; +2 increment
430 LD (POSY),A
440 CP 42
450 JP NZ,MAIN00
460 CALL DSPLAY
470 CALL WAIT

480 LD HL,DVLINE
490 CALL STRLN
500 LD DE,0100H
510 CALL PUTSTR
520 CALL GTVRAM
530 LD A,80
540 LD (POSX),A
550 LD A,38
560 LD (ENDY),A
570MAIN02: LD A,0
580 LD (POSY),A
590 CALL VLINE ; [80-90],0 to [80-90],38
600 LD A,(POSX)
610 INC A
620 INC A ; +2 increment
630 LD (POSX),A
640 CP 90
650 JP NZ,MAIN02

660 CALL DSPLAY
670 CALL WAIT

680 CALL CLS
690 CALL GTVRAM
700 LD HL,DPLINE
710 CALL STRLN
720 LD DE,0100H
730 CALL PUTSTR
740 LD A,88
750 LD (ENDX),A
760 LD A,38
770 LD (ENDY),A
780 ;pline.c:19: plotLine(50,2,88,38);
790MAIN04: LD H,0
800 LD A,(ENDY)
810 LD L,A
820 PUSH HL
830 LD A,(ENDX)
840 LD L,A
850 PUSH HL
860 LD A,2
870 LD L,A
880 PUSH HL
890 LD A,50
900 LD L,A
910 PUSH HL
920 ; STACK:
930 ; X0  0-1
940 ; Y0  2-3
950 ; X1  4-5
960 ; Y1  6-7
970 CALL PLINE
980 LD HL,8 ; X0, Y0, X1, Y1
990 ADD HL,SP
1000 LD SP,HL ; POP 8 BYTES AT ONCE

1010 LD A,(ENDY)
1020 CP 6
1030 JP Z,MAIN03
1040 DEC A
1050 LD (ENDY),A
1060 LD A,(ENDX)
1070 INC A
1080 INC A
1090 LD (ENDX),A
1100 JP MAIN04

1110MAIN03: CALL DSPLAY
1120 CALL WAIT

1130 CALL CLS
1140 CALL CLVRAM ; clear screen and vram
1150 LD HL,RNDPNT
1160 CALL STRLN
1170 LD DE,0
1180 CALL PUTSTR
1190 CALL GTVRAM
1200 LD B,8 ; 8 TIMES
1210FILL01: PUSH BC
1220 LD B,0 ; 256 TIMES = 2,048 points
1230FILL00: PUSH BC
1240 CALL PRNG ; pseudo-random number
1250 LD D,143
1260 CALL DVDX ; A = A modulo 143
1270 LD (POSX),A
1280 CALL PRNG
1290 LD D,45
1300 CALL DVDX ; A = A modulo 45
1310 LD (POSY),A
1320 CALL PSET
1330 POP BC
1340 DJNZ FILL00
1350 POP BC
1360 DJNZ FILL01

1370 LD A,48
1380 LD (POSY),A
1390MAIN01: LD A,100
1400 LD (POSX),A
1410 LD A,144
1420 LD (ENDX),A
1430 CALL HLINE ; 100,[48-60] to 144,[48-60]
1440 LD A,(POSY)
1450 INC A
1460 INC A ; +2 increment
1470 LD (POSY),A
1480 CP 60
1490 JP NZ,MAIN01
1500 CALL DSPLAY ; copy to screen
1510 CALL WAIT

1520 LD B,16
1530 LD A,50H
1540 OUT (40H),A
1550 CALL VBWEHT
1560 CALL VBWEHT
1570 CALL VBWEHT
1580 CALL VBWEHT ; 1 SEC
1590 CALL VBWEHT
1600 CALL VBWEHT
1610 CALL VBWEHT
1620 CALL VBWEHT ; 1 SEC

1630 LD A,40H
1640 OUT(40H),A
1650 CALL CLS
1660 LD HL,BYEBYE
1670 CALL STRLN
1680 LD DE,0
1690 CALL PUTSTR
1700 RET

1900WAIT: CALL WAITK
1910 OR A
1920 JP Z,WAIT
1930 RET

2000CLS: LD B,144
2010 LD DE,0000H
2020CLS0: LD A,32
2030 CALL RPTCHR
2040 RET
2050CLLN: LD B,24
2060 LD E,0
2070 JP CLS0

2100CLVRAM: LD HL,VRAM0
2110 AND A
2120 LD B,144
2130CVRAM0: LD (HL),A
2140 INC HL ; clear the first 144 bytes
2150 DJNZ CVRAM0
2160 LD DE,VRAM1
2170 LD BC,144
2180 LD HL,VRAM0
2190 LDIR ; copy that to the next 144 bytes
2200 LD BC,288
2210 LD HL,VRAM0
2220 LDIR ; use the top 288 bytes
2230 LD BC,288
2240 LD HL,VRAM0
2250 LDIR ; to clear the rest
2260 LD BC,288
2270 LD HL,VRAM0
2280 LDIR ; EXTRA 2 LINES FOR SCROLL
2290 RET ; Hat Tip @hwreverse

2300VRAM0: DS 144
2310VRAM1: DS 144
2320VRAM2: DS 144
2330VRAM3: DS 144
2340VRAM4: DS 144
2350VRAM5: DS 144
2360VRAM6: DS 144
2370VRAM7: DS 144

2380GTVRAM: LD HL,VRAM0
2390 LD DE,0000H
2400 LD B,144
2410 CALL LDPSTR ; get 144 chars from Y=0,X=0
2420 LD HL,VRAM1
2430 LD DE,0100H
2440 LD B,144
2450 CALL LDPSTR
2460 LD HL,VRAM2
2470 LD DE,0200H
2480 LD B,144
2490 CALL LDPSTR
2500 LD HL,VRAM3
2510 LD DE,0300H
2520 LD B,144
2530 CALL LDPSTR
2540 LD HL,VRAM4
2550 LD DE,0400H
2560 LD B,144
2570 CALL LDPSTR
2580 LD HL,VRAM5
2590 LD DE,0500H
2600 LD B,144
2610 CALL LDPSTR ; get 144 chars from Y=5,X=0
2620 LD HL,VRAM6
2630 LD DE,0600H
2640 LD B,144
2650 CALL LDPSTR
2660 LD HL,VRAM7
2670 LD DE,0700H
2680 LD B,144
2690 CALL LDPSTR ; EXTRA 2 LINES FOR SCROLL
2700 RET

2710DSPLAY: LD HL,VRAM0
2720 LD DE,0000H
2730 LD B,144
2740 CALL GPF ; display 144 8-bit columns from Y=0,X=0
2750 LD HL,VRAM1
2760 LD DE,0100H
2770 LD B,144
2780 CALL GPF
2790 LD HL,VRAM2
2800 LD DE,0200H
2810 LD B,144
2820 CALL GPF
2830 LD HL,VRAM3
2840 LD DE,0300H
2850 LD B,144
2860 CALL GPF
2870 LD HL,VRAM4
2880 LD DE,0400H
2890 LD B,144
2900 CALL GPF
2910 LD HL,VRAM5
2920 LD DE,0500H
2930 LD B,144
2940 CALL GPF ; display 144 8-bit columns from Y=5,X=0
2950 LD HL,VRAM6
2960 LD DE,0600H
2970 LD B,144
2980 CALL GPF
2990 LD HL,VRAM7
3000 LD DE,0700H
3010 LD B,144
3020 CALL GPF ; EXTRA 2 LINES FOR SCROLL
3030 RET

3500BYTE: PUSH AF
3510 AND 0F0H
3520 RRCA
3530 RRCA
3540 RRCA
3550 RRCA
3560 CALL NIBBLE
3570 INC HL
3580 POP AF
3590 AND 15
3600 CALL NIBBLE
3610 INC HL
3620 RET
3630NIBBLE: SUB 10
3640 JP M,ZERO9
3650 ADD A,7
3660ZERO9: ADD A,58
3670 LD (HL),A
3680 RET

4000CALCXY: LD HL,VRAM0
4010 LD A,(POSY)
4020 SRL A
4030 SRL A
4040 SRL A ; Y / 8
4050 OR A ; cp 0
4060 JP Z,CALC00 ; already where we want to be
4070 LD B,A
4080 LD DE,144 ; add a line's worth
4090CALC01: ADD HL,DE
4100 DJNZ CALC01 ; loop
4110CALC00: ; HL = beginning of line Y
4120 LD A,(POSX) ; x
4130 LD C,A
4140 LD B,0
4150 ADD HL,BC ; HL = exactly at pos x,y
4160 LD A,(POSY) ; y
4170 CALL DVD8 ; A = bit offset
4180 LD (REMNY),A
4190 OR A ; cp 0
4200 JP NZ,CALC02 ; if A = 0,set to 1
4210 LD A,1
4220 JP CALC03
4230CALC02: LD B,A ; else shift '1' left B times
4240 LD A,1
4250CALC04: SLA A; A << 1
4260 DJNZ CALC04
4270CALC03: LD B,A ; bit offset in B
4280 LD A,(HL) ; 8 bits in A
4290 RET ; Now do what you want with A (current bit pattern) and B (bit offset)

4380PSET: CALL CALCXY
4390 OR B ; set to black
4400 LD (HL),A
4440 RET

4450PUNSET: CALL CALCXY
4460 XOR B ; set to white
4470 LD (HL),A
4510 RET

4520PGET: CALL CALCXY
4530 AND B ; is it black?
4540 RET

4550HLINE: CALL CALCXY ; don't call PSET (and CALCXY) repeatedly
4560HLINE0: OR B ; DIY. set to black
4570 LD (HL),A
4580 LD A,(ENDX)
4590 LD D,A
4600 LD A,(POSX)
4610 INC A
4620 LD (POSX),A
4630 CP D ; are we done?
4640 RET Z ; yes,bail.
4650 INC HL ; no,increment HL
4660 LD A,(HL)
4670 JP HLINE0 ; and loop
4680 RET

4690VLINE: CALL CALCXY ; harder to optimize as HLINE
4700VLINE0: OR B ; DIY. set to black
4710 LD (HL),A
4720 LD A,(ENDY)
4730 LD D,A
4740 LD A,(POSY)
4750 INC A
4760 LD (POSY),A
4770 CP D ; are we done?
4780 RET Z ; yes,bail.
4790 LD A,B ; No. Do we have to skip one line?
4800 CP 128 ; Last bit in the column?
4810 JP NZ,VLINE1 ; Nah,just increase bit offset
4820 LD DE,144 ; yeah,go one line (8 rows) down
4830 ADD HL,DE
4840 LD B,1 ; reset bit offset
4845 LD A,(HL) ; get the next value
4850 JP VLINE0
4860VLINE1: SLA B ; increase bit offset
4865 LD A,(HL) ; get the next value
4870 JP VLINE0


4880POSX: DB 0
4890POSY: DB 0
4900ENDX: DB 0
4910ENDY: DB 0
4920REMNX: DB 0
4930CHARX: DB 0
4940REMNY: DB 0
4950CHARY: DB 0
4960BUFFER: DB 0,0,0,0,0,0
4970TMP: DB 0

4980HX2DEC: PUSH HL
4990 LD B,'0'
5000 LD (HL),B
5010HDEC00: LD (TMP),A
5020 CP 100
5030 JP M,HDEC01
5040 INC (HL)
5050 SUB 100
5060 JP HDEC00
5070HDEC01: INC HL
5080 LD B,'0'
5090 LD (HL),B
5100 LD A,(TMP)
5110HDEC02: LD (TMP),A
5120 CP 10
5130 JP M,HDEC03
5140 INC (HL)
5150 SUB 10
5160 JP HDEC02
5170HDEC03: INC HL
5180 LD A,(TMP)
5190 ADD A,48
5200 LD (HL),A
5210 POP HL ; remove heading 0s
5220 LD A,(HL)
5230 CP '0'
5240 JP NZ,HDEC05
5250 LD A,' '
5260 LD (HL),A
5270HDEC04: INC HL
5280 LD A,(HL)
5290 CP '0'
5300 JP NZ,HDEC05
5310 LD A,' '
5320 LD (HL),A
5330HDEC05: RET

6000 ; A <-- INPUT
6010 ; A --> REMAINDER. B --> QUOTIENT
6020DVD6: LD B,0
6030DVD6A: CP 6
6040 RET M
6050 SUB 6
6060 INC B
6070 JP DVD6A

6080DVD8: LD B,0
6090DVD8A: CP 8
6100 RET M
6110 SUB 8
6120 INC B
6130 JP DVD8A

6140DVDX: LD B,0
6150DVDXA: CP D
6160 RET M
6170 SUB D
6180 INC B
6190 JP DVDXA

6200STRLN: LD B,0
6210 PUSH HL ;preserve HL
6220STRLN0: LD A,(HL)
6230 OR A
6240 JP Z,STRLN1
6250 INC HL
6260 INC B
6270 JP STRLN0
6280STRLN1: POP HL ;restore HL
6290 RET

6300DPSET:  DB 'PSET         ',0
6310DHLINE: DB 'HLINE        ',0
6320DVLINE: DB 'VLINE        ',0
6330DPLINE: DB 'PLINE        ',0
6340RNDPNT: DB 'Random points',0
6350BYEBYE: DB 'Goodbye!',0

7000 ; change Seed value for LCM PRNG
7010PRNG: PUSH DE ;  Code by @hwreverse
7020 PUSH HL
7030 LD DE,(RVAL16)
7040 LD H,E
7050 LD L,1
7060 ADD HL,DE
7070 ADD HL,DE
7080 ADD HL,DE
7090 ADD HL,DE
7100 ADD HL,DE
7110 LD A,H
7120 LD (RVAL16),HL
7130 POP HL
7140 POP DE
7150 LD A,(RVAL88) ; 0-255
7170 RET ; will use modulo to restrict range

7200RVAL16: DB 30H
7210RVAL88: DB 81H
7300DX: DB 0
7310DY: DB 0
7320MYD: DB 0
7330YI: DB 0

7500VBWEHT: LD B,250
7510BWEHT: PUSH BC
7520 CALL WEHT ; ~1 millisec
7530 POP BC
7540 DJNZ BWEHT
7550 RET

7560WEHT: LD B,241
7570WEHT0: NOP
7580 NOP
7590 NOP
7600 NOP
7610 NOP
7620 DJNZ WEHT0
7630 RET

8000PLINE: PUSH IX
8010 LD IX,0
8020 ADD IX,SP
8030 LD HL,-6
8040 ADD HL,SP
8050 LD SP,HL
8060 ; STACK:
8070 ; IX  0-1
8080 ; RET 2-3
8090 ; X0  4-5
8100 ; Y0  6-7
8110 ; X1  8-9
8120 ; Y1 10-11
8130 ;PLINE.C:4: INT DX = X1 - X0;
8140 LD A,(IX+8) ; X1 LSB
8150 SUB (IX+4) ; X0 LSB
8160 LD L,A
8170 LD A,(IX+9) ; X1 MSB
8180 SBC A,(IX+5) ; X0 MSB
8190 LD H,A ; HL = DX

8200 ;PLINE.C:5: INT DY = Y1 - Y0;
8210 LD A,(IX+10) ; Y1 LSB
8220 SUB (IX+6) ; Y0 LSB
8230 LD E,A
8240 LD A,(IX+11) ; Y1 MSB
8250 SBC A,(IX+7) ; Y0 MSB
8260 LD D,A ; DE = DY

8270 ;PLINE.C:6: INT D = 2*DY - DX;
8280 EX DE,HL
8290 ADD HL,HL
8300 EX DE,HL ; DE = 2*DY
8310 INC SP
8320 INC SP
8330 PUSH DE
8340 LD A,(IX-6) ; DE LSB
8350 SUB L ; MINUS DX LSB
8360 LD C,A
8370 LD A,(IX-5) ; DE MSB
8380 SBC A,H ; MINUS DX MSB
8390 LD B,A ; BC = 2*DY - DX

8400 ;PLINE.C:7: INT Y = Y0;
8410 LD E,(IX+6) ; Y0 LSB
8420 LD D,(IX+7) ; Y0 MSB --> DE = Y

8430 ;PLINE.C:8: FOR (INT X = X0; X <= X1; X++) {
8440 LD A,(IX+4) ; X0 LSB
8450 LD(IX-2),A
8460 LD A,(IX+5) ; X0 MSB
8470 LD(IX-1),A
8480 ADD HL,HL
8490 LD(IX-4),L
8500 LD(IX-3),H ; SAVE 2*SX?
8510L00105: LD A,(IX+8) ; X1 LSB
8520 SUB (IX-2) ; X0 LSB
8530 LD A,(IX+9) ; X1 MSB
8540 SBC A,(IX-1) ; X0 MSB
8550 JP PO,L00125
8560 XOR 80H
8570L00125: JP M,L00107 ; END OF LOOP

8580 ;PLINE.C:9: PLOT(X,Y);
8590 PUSH BC
8600 PUSH DE
8610 ; PUSH DE ; DE = Y
8620 LD L,(IX-2) ; X0 LSB
8630 LD H,(IX-1) ; X0 MSB
8640 ; PUSH HL
8650 ; DON'T PUSH ANYTHING – JUST USE L AND E
8660 LD A,L
8670 CP 143
8680 JP P,PLINE0
8690 LD (POSX),A
8700 LD A,E
8710 CP 47
8720 JP P,PLINE0
8730 LD (POSY),A
8740 CALL PSET
8750PLINE0: POP DE
8760 POP BC

8770 ;PLINE.C:10: IF (D > 0) {
8780 XOR A
8790 CP C
8800 SBC A,B
8810 JP PO,L00126
8820 XOR 80H
8830L00126: JP P,L00102

8840 ;PLINE.C:11: Y = Y + 1;
8850 INC DE

8860 ;PLINE.C:12: D = D - 2*DX;
8870 LD A,C
8880 SUB (IX-4)
8890 LD C,A
8900 LD A,B
8910 SBC A,(IX-3)
8920 LD B,A
8930L00102:
8940 ;PLINE.C:14: D = D + 2*DY;
8950 LD A,C
8960 ADD A,(IX-6)
8970 LD C,A
8980 LD A,B
8990 ADC A,(IX-5)
9000 LD B,A

9010 ;PLINE.C:8: FOR (INT X = X0; X <= X1; X++) {
9020 INC(IX-2)
9030 JR NZ,L00105
9040 INC(IX-1)
9050 JR L00105
9060L00107:
9070 ;PLINE.C:16: }
9080 LD SP,IX
9090 POP IX
9100 ; STACK:
9110 ; RET 0-1
9120 ; X0  2-3
9130 ; Y0  4-5
9140 ; X1  6-7
9150 ; Y1  8-9
9160 RET