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163 lines
4.1 KiB
ArmAsm
163 lines
4.1 KiB
ArmAsm
;
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; Standard joystick driver for the Atari 7800.
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; This version tries to use 7800 and 2600 joysticks.
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; But assumes that both joysticks are of same type.
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;
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; Modified by Karri Kaksonen, 2022-03-31
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; Ullrich von Bassewitz, 2002-12-20
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; Using code from Steve Schmidtke
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;
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.include "zeropage.inc"
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.include "joy-kernel.inc"
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.include "joy-error.inc"
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.include "atari7800.inc"
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.macpack generic
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.macpack module
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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module_header _atari7800_stdjoy_joy
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; Driver signature
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.byte $6A, $6F, $79 ; "joy"
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.byte JOY_API_VERSION ; Driver API version number
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; Library reference
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.addr $0000
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; Jump table.
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.addr INSTALL
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.addr UNINSTALL
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.addr COUNT
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.addr READ
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; ------------------------------------------------------------------------
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; Constants
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JOY_COUNT = 2 ; Number of joysticks we support
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.code
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; ------------------------------------------------------------------------
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; INSTALL routine. Is called after the driver is loaded into memory. If
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; possible, check if the hardware is present and determine the amount of
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; memory available.
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; Must return an JOY_ERR_xx code in a/x.
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;
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INSTALL:
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; Assume 7800 2-button controller, can change
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; to 2600 1-button later
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lda #$14
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sta CTLSWB ; enable 2-button 7800 controller 1: set pin 6 to output
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ldy #$00
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sty SWCHB ; enable 2-button 7800 controller 2: pull pin 6 (INPT4) high
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reset:
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lda #JOY_ERR_OK
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.assert JOY_ERR_OK = 0, error
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tax
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; rts ; Run into UNINSTALL instead
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; ------------------------------------------------------------------------
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; UNINSTALL routine. Is called before the driver is removed from memory.
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; Can do cleanup or whatever. Must not return anything.
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;
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UNINSTALL:
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rts
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; ------------------------------------------------------------------------
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; COUNT: Return the total number of available joysticks in a/x.
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;
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COUNT:
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lda #<JOY_COUNT
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ldx #>JOY_COUNT
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rts
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; ------------------------------------------------------------------------
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; READ: Read a particular joystick passed in A for 2 fire buttons.
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readbuttons:
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; Y has joystick of interest 0/1
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; return value:
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; $00: no button,
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; $01: left/B button,
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; $02: right/A button,
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; $03: both buttons
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; preserves X
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tya
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beq L5
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; Joystick 1 processing
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; 7800 joystick 1 buttons
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ldy #0 ; ........
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bit INPT2 ; Check for right button
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bpl L1
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ldy #2 ; ......2.
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L1: bit INPT3 ;Check for left button
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bpl L2
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iny ; ......21
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L2: tya
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bne L4 ; 7800 mode joystick worked
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; 2600 Joystick 1
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bit INPT5
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bmi L4
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L3: iny ; .......1
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lda #0 ; Fallback to 2600 joystick mode
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sta CTLSWB
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L4: tya ; ......21
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rts
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L5: ; Joystick 0 processing
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; 7800 joystick 0 buttons
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ldy #0 ; ........
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bit INPT0 ; Check for right button
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bpl L6
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ldy #2 ; ......2.
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L6: bit INPT1 ;Check for left button
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bpl L7
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iny ; ......21
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L7: tya
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bne L4 ; 7800 mode joystick worked
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; 2600 Joystick 0
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bit INPT4
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bmi L4
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bpl L3
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READ:
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tay ; Store joystick 0/1 in Y
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beq L8
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lda SWCHA ; Read directions of joystick 1
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rol ; ...RLDU.
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rol ; ..RLDU..
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rol ; .RLDU... - joystick 1
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jmp L9
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L8: lda SWCHA ; Read directions of joystick 0
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ror ; .RLDU... - joystick 0
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L9: tax
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jsr readbuttons ; A = ......21, X = .RLDU...
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ror ; A = .......2 1
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tay ; Y = .......2
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txa ; A = .RLDU...
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ror ; A = 1.RLDU..
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tax ; X = 1.RLDU..
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tya ; A = .......2
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ror ; A = ........ 2
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txa ; A = 1.RLDU..
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rol ; A = .RLDU..2 1
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rol ; A = RLDU..21
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eor #$F0 ; The direction buttons were inversed
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and #$F3
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rts
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