mirror of
https://github.com/cc65/cc65.git
synced 2024-07-17 09:29:10 +00:00
64 lines
898 B
ArmAsm
64 lines
898 B
ArmAsm
;
|
|
; Karri Kaksonen, 2022-03-25
|
|
;
|
|
; unsigned char get_tv (void)
|
|
;
|
|
.include "atari7800.inc"
|
|
.export _get_tv
|
|
|
|
.segment "DATA"
|
|
|
|
_paldetected:
|
|
.byte $FF
|
|
|
|
; ---------------------------------------------------------------
|
|
; unsigned char get_tv (void)
|
|
; ---------------------------------------------------------------
|
|
|
|
.segment "CODE"
|
|
|
|
.proc _get_tv: near
|
|
|
|
.segment "CODE"
|
|
|
|
ldx #$00
|
|
lda #$FF
|
|
cmp _paldetected
|
|
bne L8
|
|
L1: lda $0028
|
|
and #$80
|
|
bne L1
|
|
L2: lda $0028
|
|
and #$80
|
|
beq L2
|
|
L3: lda $0028
|
|
and #$80
|
|
bne L3
|
|
lda #$00
|
|
sta M0001
|
|
jmp L5
|
|
L4: sta $0024
|
|
sta $0024
|
|
dec M0001
|
|
L5: lda $0028
|
|
and #$80
|
|
beq L4
|
|
lda M0001
|
|
cmp #$78
|
|
bcc L6
|
|
lda #$00
|
|
jmp L7
|
|
L6: lda #$01
|
|
L7: sta _paldetected
|
|
ldx #$00
|
|
L8: lda _paldetected
|
|
rts
|
|
|
|
.segment "BSS"
|
|
|
|
M0001:
|
|
.res 1,$00
|
|
|
|
.endproc
|
|
|