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cc65/libsrc/rp6502/irq.s
2023-11-17 11:08:51 -08:00

51 lines
498 B
ArmAsm

;
; 2023, Rumbledethumps
;
; Enables the C IRQ tools
.export initirq, doneirq
.import callirq, _exit
.include "rp6502.inc"
.segment "ONCE"
initirq:
lda #<handler
ldx #>handler
sei
sta $FFFE
stx $FFFF
cli
rts
.code
doneirq:
sei
rts
.segment "LOWCODE"
handler:
cld
phx
tsx
pha
inx
inx
lda $100,X
and #$10
bne break
phy
jsr callirq
ply
pla
plx
rti
break:
lda #$FF
sta RIA_A
jmp _exit