mirror of
https://github.com/a2-4am/4cade.git
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88 lines
3.0 KiB
Plaintext
88 lines
3.0 KiB
Plaintext
;------------------------------------------------------------------------------
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; HasJoystick
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; Checks whether computer has joystick connected
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;
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; in: ROM banked in for reading
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; out: C set if joystick found
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; C clear if no joystick found
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; other flags clobbered
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; A,X clobbered
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; Y preserved
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;
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; adapted from "Prince of Persia" by Jordan Mechner
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; (c) 1989 Broderbund Software
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; https://github.com/jmechner/Prince-of-Persia-Apple-II/blob/master/01%20POP%20Source/Source/GRAFIX.S#L1225
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;------------------------------------------------------------------------------
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; Fastchip firmware 0.4b-compatibility fix by Frank M. (0.5b seems unaffected)
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;------------------------------------------------------------------------------
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HasJoystick
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lda ROM_MACHINEID ; requires ROM read
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cmp #$06
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bne ++
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lda $FBC0
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cmp #$E0
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beq + ; test for Fastchip on enhanced //e
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cmp #$EA
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beq + ; test for Fastchip on non-enhanced //e
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jmp ++
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+ ; FASTChip
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fc_lock = $C06A
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fc_enable = $C06B
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fc_config = $C06E
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fc_data = $C06F
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FC_UNLOCK = $6A ; write 4 times
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FC_LOCK = $A6
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FC_SPKR = 2 ; speaker delay register
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FC_HIFI = 4 ; set to 'HIFI'
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FC_JOY = 3 ; joystick delay register
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FC_LONG = 2 ; set to 'LONG'
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lda #FC_UNLOCK
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sta fc_lock
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sta fc_lock
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sta fc_lock
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sta fc_lock
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sta fc_enable
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lda fc_enable ; 00 if no fastchip
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cmp #$80 ; 80 if Fastchip normal
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bne ++ ; A0 if Fastchip disabled
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lda #FC_JOY ; change Fastchip joystick delay setting to 'LONG'
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sta fc_config ; (improves joystick detection)
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lda #FC_LONG
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sta fc_data
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lda #FC_SPKR ; change Fastchip speaker delay setting to 'HIFI'
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sta fc_config ; (improves sound on most games)
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lda #FC_HIFI
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sta fc_data
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lda #FC_LOCK ; (settings revert on power cycle)
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sta fc_lock
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++
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lda #0
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sta @joyX
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sta @joyY
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lda $C070 ; reset analog input timers
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@loop ldx #1
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@1 lda $C064,x ; check timer input
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bpl @beat
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inc @joyX,x ; still high, increment counter
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@nextpdl dex
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bpl @1
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lda $C064
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ora $C065
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bpl @yes ; both inputs low, we're done
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lda @joyX
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ora @joyY
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bpl @loop ; do it again
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@no clc
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+HIDE_NEXT_BYTE
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@yes sec
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rts
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@beat nop
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bpl @nextpdl ; kill time
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@joyX !byte 0
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@joyY !byte 0
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