51 lines
741 B
ArmAsm
51 lines
741 B
ArmAsm
.MACPACK generic
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.autoimport
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.import _enable_irq
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.export _irq_int, _nmi_int
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.export _register_irq
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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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.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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lsr
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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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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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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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