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https://github.com/A2osX/A2osX.git
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96 lines
1.9 KiB
Plaintext
96 lines
1.9 KiB
Plaintext
NEW
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AUTO 3,1
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*--------------------------------------
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* this routine handles interrupts and is coded to reach 'lreset' precisely at
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* address $FFCB (ROM rts opcode) for rom switching to function.
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* $FF9B
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*--------------------------------------
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IRQ ldx #$FA save 6 bytes of page 0
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.2 lda $00,x
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sta IRQ.ZPSave-$FA,x
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inx
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bne .2
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lda mslot
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sta IRQ.DoneCn+2
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* ldx #0
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.3 lda inttbl+1,x test for a valid routine.
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beq .4 branch if no routine.
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phx
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jsr IRQ.GoX
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plx
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bcc IRQ.Done
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.4 inx
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inx
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cpx #10
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bne .3
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inc IRQ.Cnt allow 255 unclaimed interrupts
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bne IRQ.Done before system death.
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lda #$01 bad irq so
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jsr GP.SysDeath kill the system.
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*--------------------------------------
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.LIST ON
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IRQ.FREE1 .EQ $ffc8-*
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.LIST OFF
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.BS IRQ.FREE1
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IRQ.Reset1 sta RROMBNK2
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.DO *=$FFCB
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* hits ROM rts at $FFCB
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.ELSE
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ERROR
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.FIN
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*--------------------------------------
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IRQ.Done ldx #$FA
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.1 lda IRQ.ZPSave-$FA,x restore the zero page
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sta $00,x
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inx
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bne .1
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lda CLRC8ROM
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IRQ.DoneCn lda $C100 SELF MODIFIED
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lda IRQ.DoneCn+2
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sta mslot
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rti
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*--------------------------------------
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IRQ.GoX jmp (inttbl,x) interrupt routine x
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IRQ.Reset lda /resetv-1
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pha
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lda #resetv-1
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pha
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bra IRQ.Reset1
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IRQ.Cnt .HS 00 # of unclaimed interrupts.
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IRQ.ZPSave .HS 000000000000 6 bytes
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.LIST ON
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IRQ.FREE2 .EQ $fffa-*
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.LIST OFF
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.BS IRQ.FREE2
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.DA nmivect nmi handler
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.DA IRQ.Reset reset handler
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irqv .DA * PATCHED with ROM vector by LDR
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.LIST OFF
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*--------------------------------------
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IRQ.LEN .EQ *-IRQ
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*--------------------------------------
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MAN
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SAVE USR/SRC/PRODOS.FX/PRODOS.S.IRQ
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LOAD USR/SRC/PRODOS.FX/PRODOS.S
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ASM
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