mirror of
https://github.com/cc65/cc65.git
synced 2024-11-18 00:07:21 +00:00
1cc4fa9356
Extendend memory is mapped over the main memory in the 0x4000..0x7FFF area. Many DOSes disable interrupts while extended memory is banked in, but not all (e.g. SpartaDOS-X). This change modifies the initial interrupt handler to map in main memory before chaining to the "worker" handlers. Since the initial interrupt handler uses a data segment to store the trampoline to chain to the original handler, introduce a new "LOWBSS" segment to hold this trampoline. Otherwise the trampoline may end up inside the 0x4000..0x7FFF area. Add a link time warning if "LOWCODE" segment lays within the extended memory window.
81 lines
1.8 KiB
ArmAsm
81 lines
1.8 KiB
ArmAsm
;
|
|
; IRQ handling (ATARI version)
|
|
;
|
|
|
|
.export initirq, doneirq
|
|
.import callirq
|
|
|
|
.include "atari.inc"
|
|
.ifdef __ATARIXL__
|
|
.import __CHARGEN_START__
|
|
.include "romswitch.inc"
|
|
.endif
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
.segment "ONCE"
|
|
|
|
initirq:
|
|
lda #$4C ; JMP opcode
|
|
sta IRQInd
|
|
lda VVBLKD
|
|
ldx VVBLKD+1
|
|
sta IRQInd+1
|
|
stx IRQInd+2
|
|
lda #7
|
|
ldy #<IRQStub
|
|
ldx #>IRQStub
|
|
jmp SETVBV
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
.code
|
|
|
|
doneirq:
|
|
lda #7
|
|
ldy IRQInd+1
|
|
ldx IRQInd+2
|
|
jmp SETVBV
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
.segment "LOWCODE"
|
|
|
|
IRQStub:
|
|
cld ; Just to be sure
|
|
.ifdef __ATARIXL__
|
|
.ifdef CHARGEN_RELOC
|
|
lda CHBAS
|
|
pha
|
|
.endif
|
|
.endif
|
|
lda PORTB
|
|
pha
|
|
.ifdef __ATARIXL__
|
|
and #$FE ; disable ROM
|
|
.endif
|
|
ora #$10 ; map main memory into $4000..$7FFF area
|
|
sta PORTB
|
|
.ifdef __ATARIXL__
|
|
set_chbase >__CHARGEN_START__
|
|
.endif
|
|
jsr callirq ; Call the functions
|
|
pla
|
|
sta PORTB ; restore old memory settings
|
|
.ifdef __ATARIXL__
|
|
.ifdef CHARGEN_RELOC
|
|
pla
|
|
sta CHBAS
|
|
sta CHBASE
|
|
.endif
|
|
.endif
|
|
jmp IRQInd ; Jump to the saved IRQ vector
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
.segment "LOWBSS"
|
|
|
|
IRQInd: .res 3
|
|
|
|
.end
|