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cc65/libsrc/nes/joy/nes-stdjoy.s
Oliver Schmidt 1976d6cd32 Removed IRQ support from joystick drivers.
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.
2018-02-01 22:38:36 +01:00

102 lines
2.3 KiB
ArmAsm

;
; Standard joypad driver for the NES. May be used multiple times when
; linked to the statically application.
;
; Ullrich von Bassewitz, 2003-05-02
; Stefan Haubenthal, 2004-10-05
;
.include "zeropage.inc"
.include "joy-kernel.inc"
.include "joy-error.inc"
.include "nes.inc"
.macpack module
; ------------------------------------------------------------------------
; Header. Includes jump table
module_header _nes_stdjoy_joy
; Driver signature
.byte $6A, $6F, $79 ; "joy"
.byte JOY_API_VERSION ; Driver API version number
; Library reference
.addr $0000
; Jump table.
.addr INSTALL
.addr UNINSTALL
.addr COUNT
.addr READJOY
; ------------------------------------------------------------------------
; Constants
JOY_COUNT = 2 ; Number of joysticks we support
.code
; ------------------------------------------------------------------------
; INSTALL routine. Is called after the driver is loaded into memory. If
; possible, check if the hardware is present and determine the amount of
; memory available.
; Must return an JOY_ERR_xx code in a/x.
;
INSTALL:
lda #JOY_ERR_OK
ldx #0
; rts ; Run into UNINSTALL instead
; ------------------------------------------------------------------------
; UNINSTALL routine. Is called before the driver is removed from memory.
; Can do cleanup or whatever. Must not return anything.
;
UNINSTALL:
rts
; ------------------------------------------------------------------------
; COUNT: Return the total number of available joysticks in a/x.
;
COUNT:
lda #JOY_COUNT
ldx #0
rts
; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in A.
;
READJOY:
and #$01 ; Fix joystick number
tay ; Joystick number (0,1) into Y
lda #1
sta APU_PAD1
lda #0
sta APU_PAD1
; Read joystick
ldx #8
@Loop: lda APU_PAD1,y
ror a
ror tmp1
dex
bne @Loop
lda tmp1
; ldx #$00 ; X implicitly fixed
rts