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66 lines
1.4 KiB
ArmAsm
66 lines
1.4 KiB
ArmAsm
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;
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; Maciej 'YTM/Elysium' Witkowiak
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;
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; 10.09.2001
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; unsigned char get_ostype (void);
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; unsigned char get_tv (void);
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.export _get_ostype
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.export _get_tv
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.importzp tmp1
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.include "../inc/const.inc"
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.include "../inc/geossym.inc"
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.include "../inc/geossym2.inc"
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_get_ostype:
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ldx #0
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lda version
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and #%11110000
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cmp #$10
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beq geos10
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lda c128Flag ; we're on at least 2.0
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ora version
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rts
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geos10:
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lda version
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rts
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_get_tv:
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jsr _get_ostype
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bpl only40 ; C64 with 40 columns only
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lda graphMode
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bpl only40 ; C128 but currently on 40 columns
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ldx #1 ; COLUMNS80
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bne tvmode
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only40: ldx #0 ; COLUMNS40
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tvmode: ; PAL/NTSC check here, result in A
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php
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sei ; disable interrupts
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lda CPU_DATA ; this is for C64
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pha
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lda #IO_IN ; enable access to I/O
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sta CPU_DATA
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bit rasreg
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bpl tvmode ; wait for rasterline 127<x<256
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lda #24 ; (rasterline now >=256!)
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modelp: cmp rasreg ; wait for rasterline = 24 (or 280 on PAL)
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bne modelp
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lda grcntrl1 ; 24 or 280 ?
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bpl ntsc
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lda #0 ; PAL
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beq modeend
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ntsc: lda #$80 ; NTSC
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modeend: stx tmp1
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ora tmp1
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sta tmp1
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ldx #0
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pla
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sta CPU_DATA ; restore memory config
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plp ; restore interrupt state
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lda tmp1
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rts
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