1
0
mirror of https://github.com/cc65/cc65.git synced 2024-11-02 18:06:48 +00:00
cc65/libsrc/atari5200/joy/atr5200std.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

122 lines
2.9 KiB
ArmAsm

;
; Standard joystick driver for the Atari 5200.
;
; Christian Groessler, 2014-05-28
;
.include "zeropage.inc"
.include "joy-kernel.inc"
.include "joy-error.inc"
.include "atari5200.inc"
.macpack module
; ------------------------------------------------------------------------
; Header. Includes jump table
module_header _atr5200std_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
.addr 0 ; IRQ entry not used
.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 $FD32 ; check ROM version
cmp #$E8
bne @2port
lda #4
.byte $2C ; bit opcode, eats the next 2 bytes
@2port: lda #2
ldx #0
rts
; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in A.
;
CENTER = 228 / 2
SENSIVITY = 16
READJOY:
and #3 ; put joystick number in range, just in case
tay
asl a
tax ; Joystick number * 2 (0-6) into X, index into ZP shadow registers
lda #0 ; Initialize return value
cmp TRIG0,y
bne @notrg
lda #$10 ; JOY_BTN
; Read joystick
@notrg: ldy PADDL0,x ; get horizontal position
cpy #CENTER-SENSIVITY
bcs @chkleft
ora #4 ; JOY_LEFT
bne @updown
@chkleft:
cpy #CENTER+SENSIVITY
bcc @updown
ora #8 ; JOY_RIGHT
@updown:ldy PADDL0+1,x ; get vertical position
cpy #CENTER-SENSIVITY
bcs @chkdown
ora #1 ; JOY_UP
bne @done
@chkdown:
cpy #CENTER+SENSIVITY
bcc @done
ora #2 ; JOY_DOWN
@done: rts