120 lines
1.7 KiB
ArmAsm
120 lines
1.7 KiB
ArmAsm
.export _init, _nmi_int, _irq_int
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.segment "VECTORS"
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.addr _nmi_int ; NMI vector
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.addr _init ; Reset vector
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.addr _irq_int ; IRQ/BRK vector
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SD_CONTROLLER = $e000
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SD_ARG = SD_CONTROLLER + $4
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SD_RESP = SD_CONTROLLER + $10
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CLK_DIV = $20
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.zeropage
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rca: .res 4
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.code
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_nmi_int:
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_irq_int:
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_init:
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ldx #$ff
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txs
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lda #$00
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sta SD_CONTROLLER
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lda #$aa
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sta SD_ARG
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lda #$01
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sta SD_ARG+1
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lda #$00
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sta SD_ARG+2
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sta SD_ARG+3
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lda #$08
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sta SD_CONTROLLER
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jsr delay
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lda #55
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sta SD_CONTROLLER
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jsr delay
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lda #41
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sta SD_CONTROLLER
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jsr delay
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@acmd41:
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lda #55
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sta SD_CONTROLLER
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jsr delay
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lda #$80
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sta SD_ARG+1
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lda #$ff
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sta SD_ARG+2
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lda #$40
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sta SD_ARG+3
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lda #41
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sta SD_CONTROLLER
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jsr delay
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lda SD_RESP+3
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bmi card_ready
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ldx #$10
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@loop: dex
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bne @loop
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bra @acmd41
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card_ready:
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lda #2
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sta SD_CONTROLLER
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jsr delay
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lda #3
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sta SD_CONTROLLER
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jsr delay
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lda SD_RESP
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sta rca
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lda SD_RESP+1
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sta rca+1
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lda SD_RESP+2
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sta rca+2
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lda SD_RESP+3
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sta rca+3
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lda rca
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sta SD_ARG
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lda rca+1
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sta SD_ARG+1
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lda rca+2
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sta SD_ARG+2
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lda rca+3
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sta SD_ARG+3
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lda #7
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sta SD_CONTROLLER
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jsr delay
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lda #17
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sta SD_CONTROLLER
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@end: bra @end
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delay:
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nop
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nop
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nop
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nop
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nop
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nop
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nop
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rts |