58 lines
1001 B
ArmAsm
58 lines
1001 B
ArmAsm
;; IMPORTANT:
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;; These routines lengths cannot be changed without changing
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;; the aliases for peek_under_roms, poke_under_roms etc
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;; in ,aliases.s.
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;; Thus those addresses are expressed using formulae.
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install_ram_routines:
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;; Copy routines into place
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ldx #ram_routines_len-1
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*
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lda ram_routines_start,x
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sta tiny_nmi_handler,x
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dex
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bpl -
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;; Point NMI handler to tiny_nmi_handler
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lda #<tiny_nmi_handler
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sta $FFFE
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lda #>tiny_nmi_handler
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sta $FFFF
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rts
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ram_routines_start:
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tiny_nmi_handler_routine:
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inc missed_nmi_flag
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rti
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peek_under_roms_routine:
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stx peek_under_roms+7 ;Offset of arg of lda ($00),y
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jsr memmap_allram
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lda ($00),y
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jmp memmap_normal
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poke_under_roms_routine:
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stx poke_under_roms+7 ;Offset of arg of lda ($00),y
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jsr memmap_allram
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sta ($00),y
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;; FALL THROUGH
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memmap_normal_routine:
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pha
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lda #$37
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sta $01
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pla
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cli
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rts
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memmap_allram_routine:
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sei
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lda #$04
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sta $01
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rts
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ram_routines_end:
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.alias ram_routines_len ram_routines_end-ram_routines_start
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