mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-11-28 08:50:22 +00:00
93 lines
1.8 KiB
Plaintext
93 lines
1.8 KiB
Plaintext
|
|
USE_INTERRUPTOR = 0
|
|
|
|
.segment "DATA"
|
|
|
|
StartDlist: .word NullDlist-1
|
|
NextDlist: .word NullDlist-1
|
|
|
|
.segment "CODE"
|
|
|
|
.global ___dlist_setup
|
|
.global DLIST_IRQ_NEXT
|
|
.global DLIST_IRQ_RESTART
|
|
.if USE_INTERRUPTOR
|
|
.interruptor DLIST_IRQ
|
|
.endif
|
|
|
|
___dlist_setup:
|
|
SEI ; set interrupt bit, make the CPU ignore interrupt requests
|
|
|
|
sta StartDlist+0 ; save XA as pointer to start of dlist
|
|
stx StartDlist+1
|
|
|
|
LDA #%01111111 ; switch off interrupt signals from CIA-1
|
|
STA $DC0D
|
|
|
|
AND $D011 ; clear most significant bit of VIC's raster register
|
|
STA $D011
|
|
|
|
LDA $DC0D ; acknowledge pending interrupts from CIA-1
|
|
LDA $DD0D ; acknowledge pending interrupts from CIA-2
|
|
|
|
LDA #252 ; set rasterline where interrupt shall occur
|
|
STA $D012
|
|
|
|
.if !USE_INTERRUPTOR
|
|
LDA #<DLIST_IRQ ; set interrupt vectors, pointing to interrupt service routine below
|
|
STA $0314
|
|
LDA #>DLIST_IRQ
|
|
STA $0315
|
|
.endif
|
|
|
|
LDA #%00000001 ; enable raster interrupt signals from VIC
|
|
STA $D01A
|
|
cli
|
|
rts
|
|
|
|
DLIST_IRQ:
|
|
DLIST_CALL:
|
|
lda NextDlist+1
|
|
pha
|
|
lda NextDlist+0
|
|
pha
|
|
rts
|
|
|
|
DLIST_IRQ_RESTART:
|
|
sta $d012
|
|
lda StartDlist+0
|
|
sta NextDlist+0
|
|
lda StartDlist+1
|
|
sta NextDlist+1
|
|
bne DLIST_ACK
|
|
|
|
DLIST_IRQ_STOP:
|
|
lda #0 ; disable raster interrupt signals from VIC
|
|
sta $D01A
|
|
bne DLIST_ACK
|
|
|
|
DLIST_IRQ_NEXT:
|
|
sta $d012
|
|
pla
|
|
sta NextDlist+0
|
|
pla
|
|
sta NextDlist+1
|
|
DLIST_ACK:
|
|
ASL $D019 ; acknowledge the interrupt by clearing the VIC's interrupt flag
|
|
.if USE_INTERRUPTOR
|
|
clc
|
|
rts
|
|
.else
|
|
pla
|
|
tay
|
|
pla
|
|
tax
|
|
pla
|
|
rti ; return from interrupt
|
|
; JMP $EA31 ; jump into KERNAL's standard interrupt service routine to handle keyboard scan, cursor display etc.
|
|
.endif
|
|
|
|
NullDlist:
|
|
lda #252
|
|
jmp DLIST_IRQ_RESTART
|