mirror of
https://github.com/cc65/cc65.git
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1976d6cd32
All but one joystick drivers didn't use IRQs. Espsecially when the joystick driver kernel was the only .interruptor this meant quite some unnecessary overhead because it pulled in the whole IRQ infrastructure. I was told that the one driver using IRQs (the DXS/HIT-4 Player joystick driver for the C64) can be reworked to not do it. Until this is done that driver is defunct.
238 lines
8.1 KiB
ArmAsm
238 lines
8.1 KiB
ArmAsm
;
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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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;
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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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.macpack module
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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module_header _creativisionstd_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 READJOY
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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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; Symbolic names for joystick masks (similar names like the defines in joystick.h, but not related to them)
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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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; 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: lda #JOY_ERR_OK
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ldx #0
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; rts ; Fall through
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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: 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: 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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READJOY: and #1 ; fix joystick number
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bne 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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; Read right joystick
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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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; ------------------------------------------------------------------------
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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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;
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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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; 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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; 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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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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; ------
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; direction:
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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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; N - $49 - %01001001
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; NNE - $48 - %01001000
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; NE - $47 - %01000111
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; ENE - $46 - %01000110
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; E - $45 - %01000101
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; ESE - $44 - %01000100
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; SE - $43 - %01000011
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; SSE - $42 - %01000010
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; S - $41 - %01000001
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; SSW - $40 - %01000000
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; SW - $4F - %01001111
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; WSW - $4E - %01001110
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; W - $4D - %01001101
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; WNW - $4C - %01001100
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; NW - $4B - %01001011
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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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; 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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; 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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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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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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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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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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lda spectable_0,x ; toggler is 0, use spectable_0 entry
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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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; ------------------------------------------------------------------------
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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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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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.byte JOY_UP | JOY_RIGHT ; NE
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.byte JOY_UP ; N
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.byte JOY_UP | JOY_LEFT ; NW
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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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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 ; NNW
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.byte JOY_LEFT ; WNW
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.byte JOY_LEFT ; WSW
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spectable_1: .byte JOY_DOWN | JOY_LEFT ; SSW
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.byte JOY_DOWN | JOY_RIGHT ; SSE
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.byte JOY_DOWN | JOY_RIGHT ; ESE
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.byte JOY_UP | JOY_RIGHT ; ENE
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.byte JOY_UP | JOY_RIGHT ; NNE
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.byte JOY_UP | JOY_LEFT ; NNW
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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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.end
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