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Add irq handling, PAL/NTSC detection and clock()

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This commit is contained in:
Karri Kaksonen 2022-03-22 20:02:54 +02:00
parent 220171d0da
commit d6009721d4
1 changed files with 30 additions and 3 deletions
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33
libsrc/atari7800/crt0.s
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@ -1,16 +1,17 @@
.export _zonecounter
.export _paldetected
.export __STARTUP__ : absolute = 1
.export _exit
.import __ROM_START__
.import __RAM3_START__, __RAM3_SIZE__
.import initlib, donelib
.import zerobss, copydata
.import IRQStub
.import push0, _main
.include "atari7800.inc"
.include "zeropage.inc"
INPTCTRL = $01
OFFSET = $38
CTRL = $3c
.segment "STARTUP"
start:
@ -38,6 +39,29 @@ start:
jsr zerobss
jsr initlib
; Examine machine type as we need the info early
vboff: lda MSTAT
bmi vboff
vbon: lda MSTAT
bpl vbon
vboff2: lda MSTAT
bmi vboff2
lda #$00
sta _paldetected
jmp mtsta
count: sta WSYNC
sta WSYNC
dec _paldetected
mtsta: lda MSTAT
bpl count
lda _paldetected
cmp #$78
bcc mtntsc
lda #$01
jmp mtpal
mtntsc: lda #$00
mtpal: sta _paldetected
; Call main program (pass empty command line)
jsr push0 ; argc
jsr push0 ; argv
@ -50,7 +74,7 @@ _exit:
NMIHandler:
inc _zonecounter
rti
jmp IRQStub
IRQHandler:
rti
@ -58,6 +82,9 @@ IRQHandler:
.segment "DATA"
_zonecounter:
.byte 0
_paldetected:
.byte 0 ; 0 = NTSC, 1 = PAL
.segment "ENCRYPTION"
.res 126, $ff ; Reserved for encryption