A2osX/SYS/KERNEL.S.IRQ.txt
2020-12-15 14:23:22 +01:00

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NEW
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
*--------------------------------------
MSLOT .EQ $7f8
*--------------------------------------
*IRQ.BRK jmp IRQ.6
*--------------------------------------
IRQ.Handler cld
sta IRQ.6+1
pla
pha
and #$10 BRK?
* bne IRQ.BRK
bne *
stx IRQ.5+1
sty IRQ.4+1
lda RDPAGE2
pha
sta CLRPAGE2
lda RD80STORE
pha
sta CLR80STORE
lda RDREADAUX
pha
sta CLRREADAUX Make sure we can access FD.Table
lda RDWRITEAUX
pha
sta CLRWRITEAUX Driver may R/W in screen holes
lda MSLOT Save MSLOT
pha
lda RDCXROM C100-C7ff state
pha
sta CLRCXROM Enable access to slot C100-C7ff space
IRQ.JSR jsr CORE.IRQ.DEV SELF MODIFIED
ldx #CLRCXROM
pla Get CXROM State
bpl .3
inx X = SETCXROM
.3 sta $C000,x
pla Get back MSLOT
sta MSLOT
sta IRQ.2+2
and #$F0
eor #$C0 ....mmm...not looking like Cn....
bne IRQ.3
sta CLRC8ROM Release $C800
IRQ.2 lda $ff00 SELF MODIFIED
IRQ.3 pla Must keep Carry
bpl .1
sta SETWRITEAUX
clv coming for AUX.....cancel switch
.1 pla
bpl .2
sta SETREADAUX
clv coming for AUX.....cancel switch
.2 pla
bpl .3
sta SET80STORE
.3 pla
bpl .30
sta SETPAGE2
.30 bvc IRQ.4 if not V, skip task switching
tsx Check Stack if before "dec IRQ.InKernel"
cpx #$fc $1ff-PChi-PClo-P = $1fc
bcs .8 in CORE.Run or CORE.Dispatch
lda $103,x
cmp /A2osX.SYSCALL
bcs .8 we are in kernel GP or LC
php
php make room for 2 additional bytes
tsx
lda $104,x get RTI PC LO
bne .4
dec $105,x adjust RTI PC HI
.4 dec $104,x back one byte, to make it a "RTS" return adddress
lda $103,x get IRQ pushed P
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 $103,x
.8 clc
IRQ.4 ldy #$ff Self Modified
IRQ.5 ldx #$ff Self Modified
IRQ.6 lda #$ff Self Modified
bcc IRQ.8
dec IRQ.Skip Make regular ProDOS IRQ manager skip A2osX
IRQ.JMP jmp $FFFF SELF MODIFIED Not handled, pass to ProDOS
IRQ.8 rti
*--------------------------------------
MAN
SAVE usr/src/sys/kernel.s.irq
LOAD usr/src/sys/kernel.s
ASM