mirror of
https://github.com/cc65/cc65.git
synced 2024-11-09 04:08:11 +00:00
92 lines
2.4 KiB
ArmAsm
92 lines
2.4 KiB
ArmAsm
;
|
|
; Oliver Schmidt, 2012-11-17
|
|
;
|
|
; IRQ handling (Apple2 version)
|
|
;
|
|
|
|
.export initirq, doneirq
|
|
.import callirq, __dos_type, _exit
|
|
|
|
.include "apple2.inc"
|
|
|
|
.macpack apple2
|
|
|
|
.segment "ONCE"
|
|
|
|
initirq:
|
|
; Check for ProDOS
|
|
lda __dos_type
|
|
beq prterr
|
|
|
|
; Allocate interrupt vector table entry
|
|
jsr $BF00 ; MLI call entry point
|
|
.byte $40 ; Alloc interrupt
|
|
.addr i_param
|
|
bcs prterr
|
|
|
|
; Enable interrupts, as old ProDOS versions (i.e. 1.1.1)
|
|
; jump to SYS and BIN programs with interrupts disabled.
|
|
cli
|
|
rts
|
|
|
|
; Print error message and exit
|
|
prterr: ldx #msglen-1
|
|
: lda errmsg,x
|
|
jsr $FDED ; COUT
|
|
dex
|
|
bpl :-
|
|
jmp _exit
|
|
|
|
errmsg: .ifdef __APPLE2ENH__
|
|
scrcode $0D, "tpurretni colla ot deliaF", $0D
|
|
.else
|
|
scrcode $0D, "TPURRETNI COLLA OT DELIAF", $0D
|
|
.endif
|
|
|
|
msglen = * - errmsg
|
|
|
|
.code
|
|
|
|
doneirq:
|
|
; Check for valid interrupt vector table entry number which
|
|
; IS necessary as this gets called even if initirq failed.
|
|
lda int_num
|
|
beq :+
|
|
|
|
; Deallocate interrupt vector table entry
|
|
dec i_param ; Adjust parameter count
|
|
jsr $BF00 ; MLI call entry point
|
|
.byte $41 ; Dealloc interrupt
|
|
.addr i_param
|
|
: rts
|
|
|
|
.segment "LOWCODE"
|
|
|
|
intptr:
|
|
; ProDOS TechRefMan, chapter 6.2:
|
|
; "Each installed routine must begin with a CLD instruction."
|
|
cld
|
|
|
|
; Call interruptors and check for success
|
|
jsr callirq
|
|
bcc :+
|
|
|
|
; ProDOS TechRefMan, chapter 6.2:
|
|
; "When the routine that can process the interrupt is called, it
|
|
; should ... return (via an RTS) with the carry flag clear."
|
|
clc
|
|
rts
|
|
|
|
; ProDOS TechRefMan, chapter 6.2:
|
|
; "When a routine that cannot process the interrupt is called,
|
|
; it should return (via an RTS) with the cary flag set ..."
|
|
: sec
|
|
rts
|
|
|
|
.data
|
|
|
|
; MLI parameter list for (de)alloc interrupt
|
|
i_param:.byte $02 ; param_count
|
|
int_num:.byte $00 ; int_num
|
|
.addr intptr ; int_code
|