mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-10-24 23:25:28 +00:00
mockingboard: add interrupt handlre for parts w/o cycle count
This commit is contained in:
parent
4f5b214f60
commit
4767e7e5c5
@ -108,8 +108,60 @@ reset_ay_right:
|
|||||||
sta MB_VALUE
|
sta MB_VALUE
|
||||||
jsr write_ay_both
|
jsr write_ay_both
|
||||||
|
|
||||||
|
;=========================
|
||||||
|
; Setup Interrupt Handler
|
||||||
|
;=========================
|
||||||
|
; Vector address goes to 0x3fe/0x3ff
|
||||||
|
; FIXME: should chain any existing handler
|
||||||
|
|
||||||
|
lda #<interrupt_handler
|
||||||
|
sta $03fe
|
||||||
|
lda #>interrupt_handler
|
||||||
|
sta $03ff
|
||||||
|
|
||||||
|
;============================
|
||||||
|
; Enable 50Hz clock on 6522
|
||||||
|
;============================
|
||||||
|
|
||||||
|
sei ; disable interrupts just in case
|
||||||
|
|
||||||
|
lda #$40 ; Continuous interrupts, don't touch PB7
|
||||||
|
sta $C40B ; ACR register
|
||||||
|
lda #$7F ; clear all interrupt flags
|
||||||
|
sta $C40E ; IER register (interrupt enable)
|
||||||
|
|
||||||
|
lda #$C0
|
||||||
|
sta $C40D ; IFR: 1100, enable interrupt on timer one oflow
|
||||||
|
sta $C40E ; IER: 1100, enable timer one interrupt
|
||||||
|
|
||||||
|
lda #$1A
|
||||||
|
sta $C404 ; write into low-order latch
|
||||||
|
lda #$41
|
||||||
|
sta $C405 ; write into high-order latch,
|
||||||
|
; load both values into counter
|
||||||
|
; clear interrupt and start counting
|
||||||
|
|
||||||
|
; 4fe7 / 1e6 = .020s, 50Hz
|
||||||
|
; 411a / 1e6 = .016s, 60Hz
|
||||||
|
|
||||||
rts
|
rts
|
||||||
|
|
||||||
|
interrupt_handler:
|
||||||
|
; A saved by firmware in $45
|
||||||
|
txa
|
||||||
|
pha ; save X
|
||||||
|
tya
|
||||||
|
pha ; save Y
|
||||||
|
|
||||||
|
jsr play_music
|
||||||
|
|
||||||
|
pla
|
||||||
|
tay ; restore Y
|
||||||
|
pla
|
||||||
|
tax ; restore X
|
||||||
|
lda $45 ; restore A
|
||||||
|
|
||||||
|
rti ; return from interrupt ; 6
|
||||||
|
|
||||||
|
|
||||||
;=========================================
|
;=========================================
|
||||||
|
Loading…
Reference in New Issue
Block a user