| |
;-------------------------------
; little music player
; 20020905 gpz: some fixes, works much better now
;-------------------------------
STUBPOLL=$ce00+3
*=$c000-2
.word $c000
;-------------------------------
; jumptable
jmp start
jmp stop
;-------------------------------
; patched from host
init: jmp $1000
play: jmp $1003
;-------------------------------
; some variables
border: .byte $00
rastertime: .byte $00
;-------------------------------
; stop playing and switch to dummy irq
stop:
sei
; volume=0
lda #$00
sta rastertime
sta $d418
lda border
sta $d020
lda #$35
sta $01
lda #<irqoff
sta $fffe
sta $0314
lda #>irqoff
sta $ffff
sta $0315
; acknowledge irq
inc $d019
lda $dc0d
sta $dc0d
cli
jmp mlp
;-------------------------------
; init tune and start playing
start:
sei
lda #$35
sta $01
lda #<irq
sta $fffe
sta $0314
lda #>irq
sta $ffff
sta $0315
lda #$7f
sta $dc0d
lda #$01
sta $d01a
lda #$1b
sta $d011
lda #$fc
sta $d012
; init tune
lda #$00
tax
tay
jsr init
lda #$f0
@ww:
cmp $d012
bne @ww
; acknowledge irq
inc $d019
cli
;-------------------------------
; poll debug-stub to be able to do further transfers
mlp:
@l:
lda $d011
and #$80
bne @l
lda #$28+4+3
@lp: cmp $d012
bne @lp
jsr STUBPOLL
jmp mlp
;-------------------------------
irq:
sei
sta irqa
stx irqx
sty irqy
lda #$fc
@lp: cmp $d012
beq @lp
inc $d020
jsr play
inc $d020
ldx border
lda $d012
cmp rastertime
bcc @skp
sta rastertime
@skp:
@lpw:
lda $d011
and #$80
beq @l
lda $d012
cmp rastertime
bcc @lpw
@l:
cmp $d012
beq @l
stx $d020
; acknowledge irq
inc $d019
irqa=*+1
lda #$00
irqx=*+1
ldx #$00
irqy=*+1
ldy #$00
rti
;-------------------------------
; dummy irq
irqoff:
sei
pha
; acknowledge irq
lda $dc0d
sta $dc0d
inc $d019
pla
rti
|
| |