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2c975d3642
Up to now static drivers were created via co65 from dynamic drivers. However there was an issue with that approach: The dynamic drivers are "o65 simple files" which obligates that they start with the 'code' segment. However dynamic drivers need to start with the module header - which is written to. For dynamic drivers this isn't more than a conceptual issue because they are always contain a 'data' segment and may therefore only be loaded into writable memory. However when dynamic drivers are converted to static drivers using co65 then that issue becomes a real problem as then the 'code' segment may end up in non-writable memory - and thus writing to the module header fails. Instead of changing the way dynamic drivers work I opted to rather make static driver creation totally independent from dynamic drivers. This allows to place the module header in the 'data' segment (see 'module.mac').
122 lines
3.6 KiB
ArmAsm
122 lines
3.6 KiB
ArmAsm
;
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; Standard joystick driver for the VIC20. May be used multiple times when linked
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; to the statically application.
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;
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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 "vic20.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 _vic20_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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; Button state masks (8 values)
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.byte $02 ; JOY_UP
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.byte $04 ; JOY_DOWN
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.byte $08 ; JOY_LEFT
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.byte $80 ; JOY_RIGHT
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.byte $10 ; JOY_FIRE
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.byte $00 ; JOY_FIRE2 unavailable
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.byte $00 ; Future expansion
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.byte $00 ; Future expansion
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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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.addr 0 ; IRQ entry unused
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; ------------------------------------------------------------------------
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; Constants
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JOY_COUNT = 1 ; Number of joysticks we support
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; ------------------------------------------------------------------------
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; Data.
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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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lda #<JOY_ERR_OK
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ldx #>JOY_ERR_OK
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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.
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; The current implemenation will ignore the joystick number because we do only
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; have one joystick
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READ: lda #$7F ; mask for VIA2 JOYBIT: sw3
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ldx #$C3 ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
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sei ; necessary?
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ldy VIA2_DDRB ; remember the date of DDRB
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sta VIA2_DDRB ; set JOYBITS on this VIA for input
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lda VIA2_JOY ; read JOYBIT: sw3
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sty VIA2_DDRB ; restore the state of DDRB
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asl ; Shift sw3 into carry
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ldy VIA1_DDRA ; remember the state of DDRA
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stx VIA1_DDRA ; set JOYBITS on this VIA for input
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lda VIA1_JOY ; read JOYBITS: sw0,sw1,sw2,sw4
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sty VIA1_DDRA ; restore the state of DDRA
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cli ; necessary?
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ror ; Shift sw3 into bit 7
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and #$9E ; Mask relevant bits
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eor #$9E ; Active states are inverted
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rts
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