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66 lines
1.1 KiB
ArmAsm
66 lines
1.1 KiB
ArmAsm
;
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; Karri Kaksonen, 2022-03-25
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;
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; unsigned char get_tv (void)
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;
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.include "atari7800.inc"
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.include "get_tv.inc"
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.export _get_tv
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.export _paldetected
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.segment "DATA"
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_paldetected:
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.byte $FF
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; ---------------------------------------------------------------
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; unsigned char get_tv (void)
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; ---------------------------------------------------------------
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.segment "CODE"
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.proc _get_tv: near
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.segment "CODE"
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ldx #$00
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lda #$FF
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cmp _paldetected
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bne L8
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L1: lda MSTAT
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and #$80
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bne L1
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L2: lda MSTAT
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and #$80
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beq L2
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L3: lda MSTAT
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and #$80
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bne L3
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lda #$00
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sta M0001
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jmp L5
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L4: sta MWSYNC
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sta MWSYNC
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dec M0001
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L5: lda MSTAT
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and #$80
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beq L4
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lda M0001
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cmp #$78
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bcc L6
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lda #TV::NTSC
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jmp L7
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L6: lda #TV::PAL
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L7: sta _paldetected
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ldx #$00
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L8: lda _paldetected
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rts
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.segment "BSS"
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M0001:
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.res 1,$00
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.endproc
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