A2osX/SYS/KERNEL.S.IRQ.txt

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NEW
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AUTO 3,1
*--------------------------------------
* called directly by IRQ Vector $FFFE in AuxLC
* Must keep:
* A,X,Y
* SETREADAUX
* if we are here, Aux ZP/Stack already On
* Exit with RTI
* if A2osX Drivers cannot clear IRQ,
* must call regular System Handler
*--------------------------------------
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*MSLOT .EQ $7f8
*--------------------------------------
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*IRQ.BRK jmp IRQ.6
*--------------------------------------
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IRQ.Handler cld
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sta IRQ.6+1
pla
pha
and #$10 BRK?
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* bne IRQ.BRK
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bne *
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stx IRQ.5+1
sty IRQ.4+1
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lda RD80STORE
and RDPAGE2
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pha
sta CLRPAGE2
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lda RDREADAUX
pha
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sta CLRREADAUX Make sure we can access FD.Table
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lda RDWRITEAUX
pha
sta CLRWRITEAUX Driver may R/W in screen holes
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* lda MSLOT Save MSLOT
* pha
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* lda RDCXROM C100-C7ff state
* pha
* sta CLRCXROM Enable access to slot C100-C7ff space
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IRQ.JSR jsr CORE.IRQ.DEV SELF MODIFIED
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* ldx #CLRCXROM
* pla Get CXROM State
* bpl .3
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* inx X = SETCXROM
*.3 sta $C000,x
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* pla Get back MSLOT
* sta MSLOT
* sta IRQ.2+2
* and #$F0
* eor #$C0 ....mmm...not looking like Cn....
* bne IRQ.3
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* sta CLRC8ROM Release $C800
*IRQ.2 lda $ff00 SELF MODIFIED
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IRQ.3 pla Must keep Carry
bpl .1
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sta SETWRITEAUX
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clv coming for AUX.....cancel switch
.1 pla
bpl .2
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sta SETREADAUX
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clv coming for AUX.....cancel switch
.2 pla
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bpl .3
sta SETPAGE2
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.3 bvc IRQ.4 if not V, skip task switching
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tsx Check Stack if before "dec IRQ.InKernel"
cpx #$fc $1ff-PChi-PClo-P = $1fc
bcs .8 in CORE.Run or CORE.Dispatch
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lda $103,x
cmp /A2osX.SYSCALL
bcs .8 we are in kernel GP or LC
php
php make room for 2 additional bytes
tsx
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lda $104,x get RTI PC LO
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bne .4
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dec $105,x adjust RTI PC HI
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.4 dec $104,x back one byte, to make it a "RTS" return adddress
lda $103,x get IRQ pushed P
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sta $101,x down 2 bytes
lda #A2osX.SLEEP make a RTI like "jsr A2osX.SLEEP"
sta $102,x
lda /A2osX.SLEEP with RTS=PC IRQ-1
sta $103,x
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.8 clc
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IRQ.4 ldy #$ff Self Modified
IRQ.5 ldx #$ff Self Modified
IRQ.6 lda #$ff Self Modified
bcc IRQ.8
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dec IRQ.Skip Make regular ProDOS IRQ manager skip A2osX
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IRQ.JMP jmp $FFFF SELF MODIFIED Not handled, pass to ProDOS
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IRQ.8 rti
*--------------------------------------
MAN
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SAVE usr/src/sys/kernel.s.irq
LOAD usr/src/sys/kernel.s
ASM