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https://github.com/mgcaret/of816.git
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52 lines
1.7 KiB
ArmAsm
52 lines
1.7 KiB
ArmAsm
; This is a stub ROM for the GoSXB emulator that will jump to $200000 upon
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; reset, NMI, or BRK.
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; For every other kind of interrupt, it causes GoSXB to exit. If it happens
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; to be running on real hardware, it will hang instead of exit.
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; The purpose of this stub is to execute OF816 in ROM in bank $20.
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.p816
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.a16
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.i16
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.include "macros.inc"
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.segment "ROMBOOT"
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.proc romboot
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jml f:$200000
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.endproc
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.proc emuirq
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pha
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lda 2,s
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and #%00100000
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bne romboot ; if BRK, handle like we reset.
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pla ; in case we want to RTI or something in the future
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; fall-through
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.endproc
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.proc die
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wdm $FF ; GoSXB will exit
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hang: bra hang ; Anything else will hang
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.endproc
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.segment "VECTORS"
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.proc vectors
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; native mode vectors
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.word $FFFF ; FFE0 - reserved
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.word $FFFF ; FFE2 - reserved
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.word .loword(die) ; FFE4 - COP
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.word .loword(romboot) ; FFE6 - BRK
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.word .loword(die) ; FFE8 - ABORT
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.word .loword(romboot) ; FFEA - NMI
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.word $FFFF ; FFEC - reserved
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.word .loword(die) ; FFEE - IRQ
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; emulation mode vectors
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.word $FFFF ; FFF0 - reserved
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.word $FFFF ; FFF2 - reserved
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.word .loword(die) ; FFF4 - COP
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.word $FFFF ; FFF6 - reserved
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.word .loword(die) ; FFF8 - ABORT
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.word .loword(romboot) ; FFFA - NMI
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.word .loword(romboot) ; FFFC - RESET
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.word .loword(emuirq) ; FFFE - IRQ/BRK
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.endproc
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