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141 lines
3.4 KiB
ArmAsm
141 lines
3.4 KiB
ArmAsm
;
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; Standard joystick driver for the Commodore 510 (aka P500). May be used
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; multiple times when linked to the statically application.
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;
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; Ullrich von Bassewitz, 2003-02-16
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;
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.include "zeropage.inc"
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.include "extzp.inc"
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.include "joy-kernel.inc"
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.include "joy-error.inc"
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.include "cbm510.inc"
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.include "extzp.inc"
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.macpack generic
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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.segment "JUMPTABLE"
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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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; Button state masks (8 values)
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.byte $01 ; JOY_UP
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.byte $02 ; JOY_DOWN
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.byte $04 ; JOY_LEFT
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.byte $08 ; JOY_RIGHT
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.byte $10 ; JOY_FIRE
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.byte $00 ; Future expansion
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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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.word INSTALL
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.word UNINSTALL
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.word COUNT
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.word 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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; ------------------------------------------------------------------------
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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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;
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READ: ldx #$0F ; Switch to the system bank
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stx IndReg
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tax ; Save joystick number
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; Get the direction bits
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ldy #CIA::PRB
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lda (cia2),y ; Read joystick inputs
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sta tmp1
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; Get the fire bits
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ldy #CIA::PRA
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lda (cia2),y
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; Make the result value
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cpx #$00 ; Joystick 0?
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bne @L1 ; Jump if no
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; Joystick 1, fire is in bit 6, direction in bit 0-3
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asl a
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jmp @L2
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; Joystick 2, fire is in bit 7, direction in bit 5-7
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@L1: ldx #$00 ; High byte of return value
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lsr tmp1
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lsr tmp1
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lsr tmp1
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lsr tmp1
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; Mask the relavant bits, get the fire bit
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@L2: asl a ; Fire bit into carry
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lda tmp1
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and #$0F
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bcc @L3
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ora #$10
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@L3: eor #$1F ; All bits are inverted
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; Switch back to the execution bank and return the joystick mask in a/x
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ldy ExecReg
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sty IndReg
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rts
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