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Made Creativision's joystick driver more efficient.
This commit is contained in:
Greg King
parent
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commit
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@ -1,11 +1,11 @@
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;
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; Standard joystick driver for the Creativision.
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;
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; Christian Groessler, 2017-03-08
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; 2017-03-08, Christian Groessler
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; 2021-06-01, Greg King
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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 "creativision.inc"
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@ -13,10 +13,12 @@
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.macpack module
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buttons := tmp2
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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module_header _creativisionstd_joy
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module_header _creativisionstd_joy
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; Driver signature
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@ -39,16 +41,14 @@
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JOY_COUNT = 2 ; Number of joysticks we support
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; Symbolic names for joystick masks (similar names like the defines in joystick.h, but not related to them)
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; Symbolic names for joystick masks (similar names to the macros in joystick.h,
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; with the same values as the masks in creativision.h)
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JOY_UP = $10
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JOY_DOWN = $04
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JOY_LEFT = $20
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JOY_RIGHT = $08
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; ------------------------------------------------------------------------
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; Code
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.code
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; ------------------------------------------------------------------------
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@ -59,7 +59,7 @@ JOY_RIGHT = $08
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;
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INSTALL: lda #JOY_ERR_OK
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ldx #0
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ldx #>$0000
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; rts ; Fall through
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; ------------------------------------------------------------------------
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@ -82,14 +82,14 @@ COUNT: lda #<JOY_COUNT
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; READ: Read a particular joystick passed in A.
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;
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READJOY: and #1 ; fix joystick number
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bne READJOY_1 ; read right joystick
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READJOY: lsr a ; Get joystick number
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bcs READJOY_1 ; Read right joystick
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; Read left joystick
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ldx ZP_JOY0_DIR
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lda ZP_JOY0_BUTTONS
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jmp convert ; convert joystick state to cc65 values
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bcc convert ; Convert joystick state to cc65 values
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; Read right joystick
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@ -97,11 +97,11 @@ READJOY_1: ldx ZP_JOY1_DIR
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lda ZP_JOY1_BUTTONS
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lsr a
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lsr a
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;jmp convert ; convert joystick state to cc65 values
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; fall thru...
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;jmp convert ; Convert joystick state to cc65 values
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; Fall thru...
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; ------------------------------------------------------------------------
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; convert: make runtime lib compatible values
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; convert: make runtime lib-compatible values
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; inputs:
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; A - buttons
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; X - direction
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@ -111,24 +111,24 @@ convert:
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; ------
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; buttons:
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; Port values are for the left hand joystick (right hand joystick
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; Port values are for the left-hand joystick (right-hand joystick
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; values were shifted to the right to be identical).
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; Why are there two bits indicating a pressed trigger?
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; According to the "Second book of programs for the Dick Smith Wizard"
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; (pg. 88ff), the left hand button gives the value of
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; %00010001 and the right hand button gives %00100010
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; (pg. 88ff), the left-hand button gives the value of
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; %00010001 and the right-hand button gives %00100010
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; Why two bits? Can there be cases that just one of those bits is set?
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; Until these questions have been answered, we only use the lower two
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; bits and ignore the upper ones...
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; Until those questions have been answered, we only use the lower two
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; bits, and ignore the upper ones.
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and #%00000011 ; button status came in in A, strip high bits
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sta retval ; initialize 'retval' with button status
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and #%00000011 ; Button status came in A, strip high bits
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sta buttons
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; ------
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; direction:
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; CV has a 16-direction joystick
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; CV has a 16-direction joystick.
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;
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; port values: (compass points)
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; Port values: (compass points)
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; N - $49 - %01001001
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; NNE - $48 - %01001000
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; NE - $47 - %01000111
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@ -147,55 +147,51 @@ convert:
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; NNW - $4A - %01001010
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; center - $00 - %00000000
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;
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; mapping to cc65 definitions (4-direction joystick with 8 possible directions thru combinations)
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; Mapping to cc65 definitions (4-direction joystick with 8 possible directions thru combinations):
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; N, E, S, W -> JOY_UP, JOY_RIGHT, JOY_DOWN, JOY_LEFT
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; NE, SE, SW, NW -> (JOY_UP | JOY_RIGHT), (JOY_DOWN | JOY_RIGHT), (JOY_DOWN | JOY_LEFT), (JOY_UP | JOY_LEFT)
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; NNE, ENE, ESE, SSE, SSW, WSW, WNW, NNW:
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; toggle between straight and diagonal direction for every call, e.g.
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; toggle between the straight and diagonal directions for each call, e.g.,
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; NNE:
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; call to READJOY: return JOY_UP | JOY_RIGHT
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; call to READJOY: return JOY_UP
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; call to READJOY: return JOY_UP | JOY_RIGHT
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; call to READJOY: return JOY_UP
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; call to READJOY: return JOY_UP | JOY_RIGHT
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; etc...
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; etc.
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txa ; move direction status into A
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beq done ; center position (no bits are set), nothing to do
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txa ; Move direction status into A
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beq done ; Center position (no bits are set), nothing to do
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and #$0F ; get rid of the "$40" bit
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bit bit0 ; is it a "three letter" direction (NNE, ENE, etc.)?
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beq special ; yes (bit #0 is zero)
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and #$0F ; Get rid of the "$40" bit
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lsr a ; Is it "three-letter" direction (NNE, ENE, etc.)?
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tax ; Create index into table
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bcc special ; Yes (bit #0 was zero)
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lsr a ; create index into table
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tax
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lda dirtable,x
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done: ora retval ; include "button" bits
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ldx #0
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done: ora buttons ; Include button bits
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ldx #>$0000
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rts
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; NNE, ENE, ESE, SSE, SSW, WSW, WNW, NNW
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special: lsr a
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tax
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lda toggler ; toggle the toggler
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special: lda toggle ; Toggle the flag
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eor #$01
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sta toggler
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bne spec_1 ; toggler is 1, use spectable_1 entry
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sta toggle
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bne spec_1 ; Flag is 1, use spectable_1 entry
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lda spectable_0,x ; toggler is 0, use spectable_0 entry
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bne done ; jump always
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lda spectable_0,x
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bne done ; Jump always
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spec_1: lda spectable_1,x
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bne done ; jump always
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bne done ; Jump always
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; ------------------------------------------------------------------------
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;
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.rodata
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; a mapping table of "port values" to "cc65 values"
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; port value had been shifted one bit to the right (range 0..7)
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; A mapping table of "port values" to "cc65 values"
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; Port value had been shifted one bit to the right (range 0..7)
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dirtable: .byte JOY_DOWN ; S
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.byte JOY_DOWN | JOY_RIGHT ; SE
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.byte JOY_RIGHT ; E
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@ -205,12 +201,12 @@ dirtable: .byte JOY_DOWN ; S
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.byte JOY_LEFT ; W
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.byte JOY_DOWN | JOY_LEFT ; SW
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; two "special" mapping tables for three-letter directions (NNE, etc.)
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; Two "special" mapping tables for three-letter directions (NNE, etc.)
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spectable_0: .byte JOY_DOWN ; SSW
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.byte JOY_DOWN ; SSE
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.byte JOY_RIGHT ; ESE
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.byte JOY_RIGHT ; ENE
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.byte JOY_RIGHT ; NNE
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.byte JOY_UP ; NNE
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.byte JOY_UP ; NNW
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.byte JOY_LEFT ; WNW
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.byte JOY_LEFT ; WSW
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@ -224,14 +220,10 @@ spectable_1: .byte JOY_DOWN | JOY_LEFT ; SSW
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.byte JOY_UP | JOY_LEFT ; WNW
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.byte JOY_DOWN | JOY_LEFT ; WSW
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; ------------------------------------------------------------------------
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;
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bit0: .byte $01
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; ------------------------------------------------------------------------
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;
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.bss
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toggler: .res 1
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retval: .res 1
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toggle: .res 1
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.end
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