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37107174c6
The implementation is a bit tricky as it requires to take different code paths for the //e, the //c and the IIgs. Additionally the //c only provides a VBL IRQ flag supposed to be used by an IRQ handler to determine what triggered the IRQ. However, masking IRQs on the CPU, activating the VBL IRQ, clearing any pending VBL IRQs and then polling for the IRQ flag does the trick.
71 lines
2.0 KiB
ArmAsm
71 lines
2.0 KiB
ArmAsm
;
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; Oliver Schmidt, 04.01.2005
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;
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; unsigned char get_ostype (void)
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;
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.constructor initostype, 9
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.export _get_ostype
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; Identify machine according to:
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; Apple II Miscellaneous TechNote #7, Apple II Family Identification
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.segment "ONCE"
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initostype:
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sec
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jsr $FE1F
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bcs nogs
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tya
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ora #$80
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done: sta ostype
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rts
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nogs: ldx #$FF
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next: inx
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lda value,x
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ldy index,x
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beq done ; $00 is no valid index
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cmp $FB00,y
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beq next
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: inx
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ldy index,x
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bne :-
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beq next ; Branch always
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index: .byte $B3, $00 ; Apple ][
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.byte $B3, $1E, $00 ; Apple ][+
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.byte $B3, $1E, $00 ; Apple /// (emulation)
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.byte $B3, $C0, $00 ; Apple //e
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.byte $B3, $C0, $DD, $00 ; Apple //e Option Card
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.byte $B3, $C0, $00 ; Apple //e (enhanced)
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.byte $B3, $C0, $BF, $00 ; Apple //c
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.byte $B3, $C0, $BF, $00 ; Apple //c (3.5 ROM)
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.byte $B3, $C0, $BF, $00 ; Apple //c (Mem. Exp.)
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.byte $B3, $C0, $BF, $00 ; Apple //c (Rev. Mem. Exp.)
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.byte $B3, $C0, $BF, $00 ; Apple //c Plus
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.byte $00
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value: .byte $38, $10 ; Apple ][
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.byte $EA, $AD, $11 ; Apple ][+
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.byte $EA, $8A, $20 ; Apple /// (emulation)
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.byte $06, $EA, $30 ; Apple //e
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.byte $06, $E0, $02, $32 ; Apple //e Option Card
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.byte $06, $E0, $31 ; Apple //e (enhanced)
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.byte $06, $00, $FF, $40 ; Apple //c
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.byte $06, $00, $00, $41 ; Apple //c (3.5 ROM)
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.byte $06, $00, $03, $43 ; Apple //c (Mem. Exp.)
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.byte $06, $00, $04, $44 ; Apple //c (Rev. Mem. Exp.)
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.byte $06, $00, $05, $45 ; Apple //c Plus
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.byte $00
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.code
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_get_ostype:
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lda ostype
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ldx #$00
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rts
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.segment "INIT"
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ostype: .res 1
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