77 lines
1.1 KiB
ArmAsm
77 lines
1.1 KiB
ArmAsm
.MACPACK generic
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.autoimport
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.import _enable_irq
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.import _map
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.export irq_int, nmi_int
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.export _register_irq
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.export _init_interrupts
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IRQ_CMD_ADDR = $effc
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IRQ_DAT_ADDR = $effd
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IRQ_CMD_READIRQ = $00
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; void init_interrupts();
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; remap the upper page into ram,
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; then load the new vector addresses.
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.proc _init_interrupts
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; map(001f, f);
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lda #$1f
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jsr pushax
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lda #$f
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jsr _map
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lda #<irq_int
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sta $fffe
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lda #>irq_int
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sta $ffff
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lda #<nmi_int
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sta $fffa
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lda #>nmi_int
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sta $fffb
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rts
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.endproc
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.proc nmi_int
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rti
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.endproc
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; irq_int
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.proc irq_int
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; Load IRQ number
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lda #IRQ_CMD_READIRQ
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sta IRQ_CMD_ADDR
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lda IRQ_DAT_ADDR
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; shift by 2 (oh so only 128 interrupts are supported lol)
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asl
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tax
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jmp (irq_table,x)
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; use that to index jump table
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.endproc
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; void register_irq(void* addr, uint8_t irqn);
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.proc _register_irq
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asl
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tax
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jsr popa
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sta irq_table,x
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jsr popa
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sta irq_table+1,x
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lda #$00
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jsr pusha
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txa
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lsr
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jsr _enable_irq
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rts
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.endproc
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.data
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; interrupt handler jump table
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irq_table: .res 256
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