.286

_TEXT	segment	byte public 'CODE'
DGROUP	group	_DATA,_BSS
	assume	cs:_TEXT,ds:DGROUP,ss:DGROUP
_TEXT	ends

_DATA	segment word public 'DATA'
_DATA	ends
_BSS	segment word public 'BSS'
_irq_vector	label	word
	dw	offset _DummyHandler
	dw	offset _DummyHandler
	dw	offset _DummyHandler
	dw	offset _DummyHandler
	dw	offset _DummyHandler
	dw	offset _DummyHandler
	dw	offset _DummyHandler
	dw	offset _DummyHandler
_BSS	ends

_TEXT   segment byte public 'CODE'
_DummyHandler	proc near
	push	ax
	in	al, 0b6h
	nop
	nop
	out	0b6h, al
	pop	ax
	iret
_DummyHandler	endp

Interrupt0	proc near	; Divide by zero
	push	ax
	pop	ax
	iret
Interrupt0	endp
Interrupt1	proc near	; Single step
	iret
Interrupt1	endp
Interrupt2	proc near	; NMI
	iret
Interrupt2	endp
Interrupt3	proc near	; Breakpoint
	iret
Interrupt3	endp
Interrupt4	proc near	; Overflow
	iret
Interrupt4	endp
Interrupt5	proc near	; PrintScreen
	iret
Interrupt5	endp

IntrTransmit	proc near
	cli
	push	ax
	push	si
	mov	si, offset DGROUP:_irq_vector
	call	word ptr [si]
	mov	al, 1
	out	0b6h, al
	pop	si
	pop	ax
	sti
	iret
IntrTransmit	endp

IntrKeyPush	proc near
	cli
	push	ax
	push	si
	mov	si, offset DGROUP:_irq_vector + 2
	call	word ptr [si]
	mov	al, 2
	out	0b6h, al
	pop	si
	pop	ax
	sti
	iret
IntrKeyPush	endp

IntrRTCAlarm	proc near
	cli
	push	ax
	push	si
	mov	si, offset DGROUP:_irq_vector + 4
	call	word ptr [si]
	mov	al, 4
	out	0b6h, al
	pop	si
	pop	ax
	sti
	iret
IntrRTCAlarm	endp

IntrReceive	proc near
	cli
	push	ax
	push	si
	mov	si, offset DGROUP:_irq_vector + 6
	call	word ptr [si]
	mov	al, 8
	out	0b6h, al
	pop	si
	pop	ax
	sti
	iret
IntrReceive	endp

IntrDrawLine	proc near
	cli
	push	ax
	push	si
	mov	si, offset DGROUP:_irq_vector + 8
	call	word ptr [si]
	mov	al, 16
	out	0b6h, al
	pop	si
	pop	ax
	sti
	iret
IntrDrawLine	endp

IntrVblankCount	proc near
	cli
	push	ax
	push	si
	mov	si, offset DGROUP:_irq_vector + 10
	call	word ptr [si]
	mov	al, 32
	out	0b6h, al
	pop	si
	pop	ax
	sti
	iret
IntrVblankCount	endp

IntrVblankBegin	proc near
	cli
	push	ax
	push	di
	push	si
	mov	si, offset DGROUP:_irq_vector + 12
	call	word ptr [si]
	mov	al, 64
	out	0b6h, al
	pop	si
	pop	di
	pop	ax
	sti
	iret
IntrVblankBegin	endp

IntrHblankCount	proc near
	cli
	push	ax
	push	di
	push	si
	mov	si, offset DGROUP:_irq_vector + 14
	call	word ptr [si]
	mov	al, 128
	out	0b6h, al
	pop	si
	pop	di
	pop	ax
	sti
	iret
IntrHblankCount	endp

_IRQ_Init	proc near
	cli
	push	ax
	push	bx
	push	dx
	push	ds

	xor	ax,ax
	mov	ds,ax

	mov	bx, 00000h	; Divide by zero
	mov	ax, offset Interrupt0
	mov	dx, seg Interrupt0
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00004h	; Single Step
	mov	ax, offset Interrupt1
	mov	dx, seg Interrupt1
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00008h	; NMI
	mov	ax, offset Interrupt2
	mov	dx, seg Interrupt2
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 0000Ch	; Breakpoint
	mov	ax, offset Interrupt3
	mov	dx, seg Interrupt3
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00010h	; Overflow
	mov	ax, offset Interrupt4
	mov	dx, seg Interrupt4
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00014h	; PrintScreen
	mov	ax, offset Interrupt5
	mov	dx, seg Interrupt5
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	al, 08h		; Interrupt base == 08h
	out	0b0h, al	; Hardware interruppt vector starts at 0x20

	mov	bx, 00020h
	mov	ax, offset IntrTransmit
	mov	dx, seg IntrTransmit
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00024h
	mov	ax, offset IntrKeyPush
	mov	dx, seg    IntrKeyPush
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00028h
	mov	ax, offset IntrRTCAlarm
	mov	dx, seg    IntrRTCAlarm
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 0002Ch
	mov	ax, offset IntrReceive
	mov	dx, seg    IntrReceive
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00030h
	mov	ax, offset IntrDrawLine
	mov	dx, seg    IntrDrawLine
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00034h
	mov	ax, offset IntrVblankCount
	mov	dx, seg    IntrVblankCount
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 00038h
	mov	ax, offset IntrVblankBegin
	mov	dx, seg    IntrVblankBegin
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	mov	bx, 0003Ch
	mov	ax, offset IntrHblankCount
	mov	dx, seg    IntrHblankCount
	mov	ds:[bx], ax
	mov	ds:[bx+2], dx

	pop	ds
	pop	dx
	pop	bx
	pop	ax
	ret
_IRQ_Init	endp

_TEXT   ends
	public	_IRQ_Init
	public	_irq_vector
	public	_DummyHandler
	end