69 lines
1.1 KiB
ArmAsm
69 lines
1.1 KiB
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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#if CONFIG_MEMORY_MODEL_60K
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install_ram_routines:
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// Copy routines into place
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ldx #__ram_routines_end-__ram_routines_start-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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php
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// Offset of arg of lda ($00),y
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stx peek_under_roms+pa-peek_under_roms_routine+1
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jsr memmap_allram
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pa: lda ($00),y
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jsr memmap_normal
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plp
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rts
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poke_under_roms_routine:
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php
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// Offset of arg of lda ($00),y
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stx poke_under_roms+pb-poke_under_roms_routine+1
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jsr memmap_allram
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pb: sta ($00),y
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jsr memmap_normal
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plp
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rts
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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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rts
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memmap_allram_routine:
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sei
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pha
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lda #$04
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sta $01
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pla
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rts
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__ram_routines_end:
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#endif // CONFIG_MEMORY_MODEL_60K
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