0100 ; LIGHT GUN DETECTOR¢0110 ; BY MATTHEW RATCLIFF¢0120 ; (c)1988, ANTIC PUBLISHING¢0130 *= $5000¢0140 .OPT OBJ¢0150 ;¢0160 LPENH = 564¢0170 LPENV = 565¢0180 STICK0 = 632¢0190 GUNHERE = 14 ; Reading on port with gun¢0200 GUNFIRE = 15 ; Gunport=15 when trigger pressed¢0210 GUNPORT = $0600 ; Store gun port index here¢0220 ;¢0230 ; GUNDET -Look for the light gun¢0240 ; don't return until found.¢0250 ; When found, return the port¢0260 ; number of the gun in the¢0270 ; X register, and put it¢0280 ; in the GUNPORT memory location¢0290 ; NOTE:¢0300 ; Detect LOW to HIGH on joystick¢0310 ; ports since the OS on XL/XE's¢0320 ; copy ports 0 & 1 to 2 & 3.¢0330 ; On 400/800, any port 0-3¢0340 ; is valid for gun.¢0350 ;¢0360 GUNDET¢0370 LDX #0 ; First port¢0380 WAIT¢0390 LDA STICK0,X¢0400 CMP #GUNHERE¢0410 BEQ GUNFOUND¢0420 ;¢0430 INX ¢0440 CPX #3¢0450 BNE WAIT¢0460 ;¢0470 BEQ GUNDET¢0480 ;¢0490 GUNFOUND¢0500 STX GUNPORT¢0510 RTS ¢0520 ;¢0530 ; GUNREAD - A successful GUNDET¢0540 ; is assumed, and GUNPORT RAM¢0550 ; register is set to the proper¢0560 ; joystick port for reading¢0570 ; the light gun.¢0580 ;¢0590 ; On Exit:¢0600 ; X = LPENH¢0610 ; Y = LPENV¢0620 ; A = STICk(GUNPORT)¢0630 ; Zero flag is SET if the¢0640 ; trigger is being pressed.¢0650 ;¢0660 GUNREAD¢0670 LDX GUNPORT¢0680 LDA STICK0,X¢0690 LDX LPENH¢0700 LDY LPENV¢0710 CMP #GUNFIRE¢0720 RTS ¢0730 ;¢0740 ; A simple test routine¢0750 ; to use from DDT.¢0760 ; The first BRK occurs after¢0770 ; the gun is detected.¢0780 ; At this BRK inspect¢0790 ; the X register for the proper¢0800 ; port number. Continue program¢0810 ; from there. The next break¢0820 ; occurs when the trigger is¢0830 ; pressed.¢0840 ;¢0850 *= $6000¢0860 GUNTEST¢0870 JSR GUNDET¢0880 BRK ¢0890 ;¢0900 SHOOTEMUP¢0910 JSR GUNREAD¢0920 BNE SHOOTEMUP¢0930 ;¢0940 BRK ¢əəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəəə
