mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-12-27 17:29:49 +00:00
147 lines
2.4 KiB
ArmAsm
147 lines
2.4 KiB
ArmAsm
;================================
|
|
;================================
|
|
; mockingboard interrupt handler
|
|
;================================
|
|
;================================
|
|
; On Apple II/6502 the interrupt handler jumps to address in 0xfffe
|
|
; This is in the ROM, which saves the registers
|
|
; on older IIe it saved A to $45 (which could mess with DISK II)
|
|
; newer IIe doesn't do that.
|
|
; It then calculates if it is a BRK or not (which trashes A)
|
|
; Then it sets up the stack like an interrupt and calls 0x3fe
|
|
|
|
; Note: the IIc is much more complicated
|
|
; its firmware tries to decode the proper source
|
|
; based on various things, including screen hole values
|
|
; we bypass that by switching out ROM and replacing the
|
|
; $fffe vector with this, but that does mean we have
|
|
; to be sure status flag and accumulator set properly
|
|
|
|
interrupt_handler:
|
|
php ; save status flags
|
|
pha ; save A ; 3
|
|
; A is saved in $45 by firmware
|
|
txa
|
|
pha ; save X
|
|
tya
|
|
pha ; save Y
|
|
|
|
|
|
|
|
; inc $0404 ; debug (flashes char onscreen)
|
|
|
|
|
|
.include "pt3_lib_irq_handler.s"
|
|
|
|
jmp exit_interrupt
|
|
|
|
;=================================
|
|
; Finally done with this interrupt
|
|
;=================================
|
|
|
|
quiet_exit:
|
|
stx DONE_PLAYING
|
|
jsr clear_ay_both
|
|
|
|
ldx #$ff ; also mute the channel
|
|
stx AY_REGISTERS+7 ; just in case
|
|
|
|
|
|
exit_interrupt:
|
|
|
|
; update time
|
|
inc ticks
|
|
lda ticks
|
|
cmp #50
|
|
bne no_tick_oflo
|
|
|
|
lda #0
|
|
sta ticks
|
|
inc seconds
|
|
|
|
no_tick_oflo:
|
|
|
|
; if done, no timeout
|
|
lda command
|
|
cmp #DONE
|
|
beq handle_credits
|
|
|
|
; trigger at timeout value
|
|
|
|
lda seconds
|
|
cmp timeout
|
|
bne handle_credits
|
|
|
|
inc trigger
|
|
|
|
lda which
|
|
asl
|
|
tax
|
|
lda todo_list,x
|
|
sta command
|
|
|
|
cmp #DO_CREDITS
|
|
bne itsnot
|
|
|
|
jsr switch_to_credits
|
|
lda command
|
|
|
|
itsnot:
|
|
cmp #DONE
|
|
beq handle_credits
|
|
|
|
lda todo_list+1,x
|
|
sta timeout
|
|
|
|
; point to next
|
|
inc which
|
|
|
|
; reset seconds
|
|
lda #0
|
|
sta seconds
|
|
|
|
; HUGE HACK
|
|
; return to our code instead of BASIC
|
|
|
|
ldx original_stack
|
|
txs
|
|
lda #>command_loop
|
|
pha
|
|
lda #<command_loop
|
|
pha
|
|
|
|
lda #0 ; program status word
|
|
pha
|
|
|
|
rti
|
|
|
|
handle_credits:
|
|
lda command
|
|
cmp #DONE
|
|
bne done_match
|
|
|
|
jsr display_credits
|
|
|
|
done_match:
|
|
pla
|
|
tay ; restore Y
|
|
pla
|
|
tax ; restore X
|
|
pla ; restore a ; 4
|
|
|
|
; on II+/IIe (but not IIc) we need to do this?
|
|
interrupt_smc:
|
|
lda $45 ; restore A
|
|
plp
|
|
|
|
rti ; return from interrupt ; 6
|
|
|
|
;============
|
|
; typical
|
|
; ???? cycles
|
|
|
|
|
|
|
|
seconds: .byte $00
|
|
ticks: .byte $00
|