2014-01-14 10:43:34 +00:00
|
|
|
;
|
|
|
|
|
; Atari XL shadow RAM timer IRQ #1 handler
|
|
|
|
|
;
|
|
|
|
|
; Christian Groessler, chris@groessler.org, 2014
|
|
|
|
|
;
|
|
|
|
|
|
|
|
|
|
;DEBUG = 1
|
|
|
|
|
|
|
|
|
|
.ifdef __ATARIXL__
|
|
|
|
|
|
|
|
|
|
SHRAM_HANDLERS = 1
|
|
|
|
|
.include "atari.inc"
|
|
|
|
|
.include "romswitch.inc"
|
2020-10-30 14:01:47 +00:00
|
|
|
.import __CHARGEN_START__
|
2014-01-14 10:43:34 +00:00
|
|
|
.export set_VTIMR1_handler
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
.segment "LOWBSS"
|
|
|
|
|
|
|
|
|
|
VTIMR1_handler: .res 3
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
.segment "BSS"
|
|
|
|
|
|
|
|
|
|
old_VTIMR1_handler:
|
|
|
|
|
.res 2
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
.segment "LOWCODE"
|
|
|
|
|
|
|
|
|
|
; timer interrupt handler:
|
|
|
|
|
; disable ROM, call user handler, enable ROM again
|
|
|
|
|
|
|
|
|
|
my_VTIMR1_handler:
|
|
|
|
|
disable_rom_quick
|
|
|
|
|
jsr VTIMR1_handler
|
|
|
|
|
enable_rom_quick
|
|
|
|
|
pla
|
|
|
|
|
rti
|
|
|
|
|
|
|
|
|
|
.segment "CODE"
|
|
|
|
|
|
|
|
|
|
; install or remove VTIMR1 handler
|
|
|
|
|
; input: CF - 0/1 for remove/install handler
|
|
|
|
|
; AX - pointer to handler (if CF=1)
|
|
|
|
|
; registers destroyed
|
|
|
|
|
|
|
|
|
|
set_VTIMR1_handler:
|
|
|
|
|
|
|
|
|
|
bcc @remove
|
|
|
|
|
|
|
|
|
|
; install vector
|
|
|
|
|
|
|
|
|
|
stx VTIMR1_handler+2
|
|
|
|
|
sta VTIMR1_handler+1 ; save passed vector in low memory
|
|
|
|
|
lda #$4C ; "JMP" opcode
|
|
|
|
|
sta VTIMR1_handler
|
|
|
|
|
|
|
|
|
|
lda VTIMR1
|
|
|
|
|
sta old_VTIMR1_handler
|
|
|
|
|
lda VTIMR1+1
|
|
|
|
|
sta old_VTIMR1_handler+1
|
|
|
|
|
|
|
|
|
|
lda #<my_VTIMR1_handler
|
|
|
|
|
php
|
|
|
|
|
sei
|
|
|
|
|
sta VTIMR1
|
|
|
|
|
lda #>my_VTIMR1_handler
|
|
|
|
|
sta VTIMR1+1
|
|
|
|
|
plp
|
|
|
|
|
rts
|
|
|
|
|
|
|
|
|
|
@remove: php
|
|
|
|
|
sei
|
|
|
|
|
lda old_VTIMR1_handler
|
|
|
|
|
sta VTIMR1
|
|
|
|
|
lda old_VTIMR1_handler+1
|
|
|
|
|
sta VTIMR1+1
|
|
|
|
|
plp
|
|
|
|
|
rts
|
|
|
|
|
|
|
|
|
|
.endif ; .ifdef __ATARIXL__
|
