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cc65/libsrc/telestrat/joy/telestrat.s
2023-02-26 20:03:41 +01:00

116 lines
2.9 KiB
ArmAsm

;
; Telestrat joystick driver
;
; 2002-12-20, Based on Ullrich von Bassewitz's code.
; 2017-11-01, Stefan Haubenthal
; 2020-05-20, Jede
;
.include "joy-kernel.inc"
.include "joy-error.inc"
.include "telestrat.inc"
.macpack module
; ------------------------------------------------------------------------
; Header. Includes jump table
module_header _telestrat_joy
; Driver signature
.byte $6A, $6F, $79 ; "joy"
.byte JOY_API_VERSION ; Driver API version number
; Library reference
.addr $0000
; Jump table.
.addr INSTALL
.addr UNINSTALL
.addr COUNT
.addr READ
; ------------------------------------------------------------------------
; Constants
JOY_COUNT = 2 ; Number of joysticks we support
.code
; ------------------------------------------------------------------------
; INSTALL routine. Is called after the driver is loaded into memory. If
; possible, check if the hardware is present and determine the amount of
; memory available.
; Must return an JOY_ERR_xx code in a/x.
;
INSTALL:
lda #%11000000
sta VIA2::DDRB
sta VIA2::PRB
; We could detect joysticks because with previous command bit0,1,2,3,4 should be set to 1 after
; But if some one press fire or press direction, we could reach others values which could break joystick detection.
lda #JOY_ERR_OK
.assert JOY_ERR_OK = 0, error
tax
; rts ; Run into UNINSTALL instead
; ------------------------------------------------------------------------
; UNINSTALL routine. Is called before the driver is removed from memory.
; Can do cleanup or whatever. Must not return anything.
;
UNINSTALL:
rts
; ------------------------------------------------------------------------
; COUNT: Return the total number of available joysticks in a/x.
;
COUNT:
lda #<JOY_COUNT
ldx #>JOY_COUNT
rts
; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in A.
;
; How telestrat joysticks works
; PB7 and PB6 select right or left port
; When PB7 and PB6 are high, it controls two CA3083 (2 NPN transistors array) bases.
; In that case, PB0 to PB4 are set to high (it means no action are pressed)
; When the user press something then bit will be set to 0.
; Bit 0 is right
; Bit 1 is left
; Bit 2 is fire
; ...
READ:
beq right
lda VIA2::PRB
and #%01111111
ora #%01000000
sta VIA2::PRB
; then read
lda VIA2::PRB
eor #%01011111
rts
right:
lda VIA2::PRB
and #%10111111
ora #%10000000
sta VIA2::PRB
; then read
lda VIA2::PRB
eor #%10011111
rts