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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.
135 lines
3.3 KiB
ArmAsm
135 lines
3.3 KiB
ArmAsm
;
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; IJK joystick driver for the Atmos
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; Can be used multiple times when statically linked to the application.
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;
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; 2002-12-20, Based on Ullrich von Bassewitz's code.
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; 2017-11-01, Stefan Haubenthal
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;
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.include "joy-kernel.inc"
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.include "joy-error.inc"
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.include "atmos.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 _atmos_ijk_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 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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.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 #%11000000
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sta VIA::DDRA
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sta VIA::PRA
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lda VIA::PRA
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and #%00100000
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bne ijkPresent
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lda #<JOY_ERR_NO_DEVICE
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.byte $2C ; Skip next opcode
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ijkPresent:
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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:
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bne right
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; Ensure Printer Strobe is set to Output
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lda #%10110111
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sta VIA::DDRB
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; Set Strobe Low
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lda #%00000000
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sta VIA::PRB
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; Set Top two bits of PortA to Output and rest as Input
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lda #%11000000
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sta VIA::DDRA
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; Select Left Joystick
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lda #%01111111
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sta VIA::PRA
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; Read back Left Joystick state
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lda VIA::PRA
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; Mask out unused bits
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and #%00011111
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; Invert Bits
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eor #%00011111
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; Index table to conform to Generic Format
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tax
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lda GenericIJKBits,X
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bne L1
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right:
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; Select Right Joystick
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lda #%10111111
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sta VIA::PRA
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; Read back Right Joystick state and rejig bits
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lda VIA::PRA
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and #%00011111
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eor #%00011111
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tax
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lda GenericIJKBits,X
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; Restore VIA PortA state
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L1: ldx #%11111111
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stx VIA::DDRA
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inx ; x=0
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rts
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.rodata
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GenericIJKBits:
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.byte 0,2,1,3,32,34,33,0,8,10,9,0,40,42,41,0
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.byte 16,18,17,0,48,50,49,0,0,0,0,0,0,0,0,0
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