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cc65/libsrc/plus4/joy/plus4-stdjoy.s
Oliver Schmidt 7f52a770d9 Removed joy_masks array.
So far the joy_masks array allowed several joystick drivers for a single target to each have different joy_read return values. However this meant that every call to joy_read implied an additional joy_masks lookup to post-process the return value.

Given that almost all targets only come with a single joystick driver this seems an inappropriate overhead. Therefore now the target header files contain constants matching the return value of the joy_read of the joystick driver(s) on that target.

If there indeed are several joystick drivers for a single target they must agree on a common return value for joy_read. In some cases this was alredy the case as there's a "natural" return value for joy_read. However a few joystick drivers need to be adjusted. This may cause some overhead inside the driver. But that is for sure smaller than the overhead introduced by the joy_masks lookup before.

!!! ToDo !!!

The following three joystick drivers become broken with this commit and need to be adjusted:
- atrmj8.s
- c64-numpad.s
- vic20-stdjoy.s
2017-08-19 19:11:28 +02:00

105 lines
2.7 KiB
ArmAsm

;
; Standard joystick driver for the Plus/4 and C16.
; May be used multiple times when linked statically to an application.
;
; 2002-12-21, Ullrich von Bassewitz
; 2016-06-18, Greg King
;
.include "joy-kernel.inc"
.include "joy-error.inc"
.include "plus4.inc"
.macpack module
; ------------------------------------------------------------------------
; Header. Includes jump table
.if .xmatch ("MODULE_LABEL", .string(MODULE_LABEL))
module_header _plus4_stdjoy_joy
.else
module_header MODULE_LABEL
.endif
; Driver signature
.byte $6A, $6F, $79 ; ASCII "joy"
.byte JOY_API_VERSION ; Driver API version number
; Library reference
.addr $0000
; Jump table.
.addr INSTALL
.addr UNINSTALL
.addr COUNT
.addr READ
.addr 0 ; IRQ entry unused
; ------------------------------------------------------------------------
; Constants
JOY_COUNT = 2 ; Number of joysticks we support
; ------------------------------------------------------------------------
; Data.
.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 #>JOY_ERR_OK
; 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 #>JOY_COUNT
rts
; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in A.
;
READ: ldy #%11111011 ; Load index for joystick #1
tax ; Test joystick number
beq @L1
ldy #%11111101 ; Load index for joystick #2
ldx #>$0000 ; (Return unsigned int)
@L1: sei
sty TED_KBD ; Read a joystick ...
lda TED_KBD ; ... and some keys -- it's unavoidable
cli
eor #%11111111
; The push buttons are in bits 6 and 7. Both of them cannot be %1 together.
; Therefore, bit 6 can be merged with bit 7.
clc
adc #%01000000
rts