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6637e28831
remove redundant code and add jmp to the common sequence two more bytes could be saved at the expense of longer sequence with interrupts disabled by moving sei/cli
111 lines
2.4 KiB
ArmAsm
111 lines
2.4 KiB
ArmAsm
;
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; Standard joystick driver for the C64. 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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;
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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 "c64.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 _c64_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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; 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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; ------------------------------------------------------------------------
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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: tax ; Joystick number into X
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bne joy2
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; Read joystick 1
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joy1: lda #$7F
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sei
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sta CIA1_PRA
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lda CIA1_PRB
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cli
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jmp end
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; Read joystick 2
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joy2: ldx #0
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lda #$E0
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ldy #$FF
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sei
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sta CIA1_DDRA
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lda CIA1_PRA
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sty CIA1_DDRA
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cli
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end: and #$1F
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eor #$1F
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rts
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