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https://github.com/MiSTer-devel/CDi_MiSTer.git
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0fc841c7ea
Ensures a consistent stream of CD data from HPS, even when MiSTer Main stumbles once. Request of sector data is decoupled from sector ticks. This will still not allow screenshots being performed, as MiSTer Main will hang for a second.
65 lines
961 B
NASM
65 lines
961 B
NASM
section .text
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org $400000
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vector:
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dc.l $1234
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dc.l main
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main:
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move.l #cdicirq,$200
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move #$2000,SR
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move.w #$2480,$303FFC ; IRQ vector
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move.w #$0023,$303C00 ; Command Register = Reset Mode 1
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move.w #$8000,$303FFE ; Data buffer
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move.w #$2480,$303FFC ; Interrupt Vector
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move.w #$0029,$303C00 ; Read Mode 1
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move.l #$0021600,$303C02 ; Time Register
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move.w #$C000,$303FFE ; Start the Read
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move.l #$2000,A3
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move.b #'A',$80002019
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jsr waitforirq
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move.b #'B',$80002019
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jsr waitforirq
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move.b #'C',$80002019
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move.w #$0000,$303FFE ; Stop the Read
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move.w #$C000,$303FFE ; Start the Read
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jsr waitforirq
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jsr waitforirq
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endless:
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bra endless
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wait:
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add #-1,d0
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bne wait
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rts
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waitforirq:
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move #0,d0
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waitforirqloop:
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cmp #0,d0
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beq waitforirqloop
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move.b #'O',$80002019
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rts
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cdicirq:
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move.b #'I',$80002019
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move.w $303FF4,d0 ; clear flags on ABUFD
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move.w $303FF6,d0 ; clear flags on XBUF
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;move.b #$92,$80004005
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move #1,d0
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rte
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