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cc65/libsrc/atari5200/joy/atr5200std.s
Oliver Schmidt 2c975d3642 Create static drivers directly from source files.
Up to now static drivers were created via co65 from dynamic drivers. However there was an issue with that approach:

The dynamic drivers are "o65 simple files" which obligates that they start with the 'code' segment. However dynamic drivers need to start with the module header - which is written to. For dynamic drivers this isn't more than a conceptual issue because they are always contain a 'data' segment and may therefore only be loaded into writable memory.

However when dynamic drivers are converted to static drivers using co65 then that issue becomes a real problem as then the 'code' segment may end up in non-writable memory - and thus writing to the module header fails.

Instead of changing the way dynamic drivers work I opted to rather make static driver creation totally independent from dynamic drivers. This allows to place the module header in the 'data' segment (see 'module.mac').
2014-06-04 23:50:18 +02:00

133 lines
3.3 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
; Button state masks (8 values)
.byte $01 ; JOY_UP
.byte $02 ; JOY_DOWN
.byte $04 ; JOY_LEFT
.byte $08 ; JOY_RIGHT
.byte $10 ; JOY_FIRE
.byte $20 ; JOY_FIRE2
.byte $00 ; Future expansion
.byte $00 ; Future expansion
; 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_FIRE
; 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