X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=ld45_start_nothing;a=blobdiff_plain;f=src%2Fintr.asm;fp=src%2Fintr.asm;h=1bbf3197e6e470a5714485fa55c50665cc0d483c;hp=0000000000000000000000000000000000000000;hb=6bbbb04131204b22367677209d7de8c3f906d0e2;hpb=8a43487117b23806e478603f3c8ab72e37cd1882

diff --git a/src/intr.asm b/src/intr.asm
new file mode 100644
index 0000000..1bbf319
--- /dev/null
+++ b/src/intr.asm
@@ -0,0 +1,60 @@
+; vi:filetype=nasm ts=8 sts=8 sw=8:
+	section .text
+
+%include "intr.inc"
+
+	global init_intr
+init_intr:
+	call init_pic
+	ret
+
+	global set_intr
+set_intr:
+	ret
+
+PIC1_CMD equ 20h
+PIC1_DATA equ 21h
+PIC2_CMD equ 0a0h
+PIC2_DATA equ 0a1h
+
+; PIC initialization command word 1 bits
+ICW1_ICW4_NEEDED	equ 01h
+ICW1_SINGLE		equ 02h
+ICW1_INTERVAL4		equ 04h
+ICW1_LEVEL		equ 08h
+ICW1_INIT		equ 10h
+; PIC initialization command word 4 bits
+ICW4_8086		equ 01h
+ICW4_AUTO_EOI		equ 02h
+ICW4_BUF_SLAVE		equ 08h
+ICW4_BUF_MASTER		equ 0ch
+ICW4_SPECIAL		equ 10h
+; PIC operation command word 2 bits
+OCW2_EOI		equ 20h
+
+init_pic:
+	; send ICW1 saying we'll follow with ICW4 later on
+	mov al, ICW1_INIT | ICW1_ICW4_NEEDED
+	out PIC1_CMD, al
+	out PIC2_CMD, al
+	; send ICW2 with IRQ remapping
+	mov al, IRQ_OFFSET
+	out PIC1_DATA, al
+	add al, 8
+	out PIC2_DATA, al
+	; send ICW3 to setup the master/slave relationship
+	; ... set bit3 = 3rd interrupt input has a slave
+	mov al, 4
+	out PIC1_DATA, al
+	; ... set slave ID to 2
+	mov al, 2
+	out PIC2_DATA, al
+	; send ICW4 to set 8086 mode (no calls generated)
+	mov al, ICW4_8086
+	out PIC1_DATA, al
+	out PIC2_DATA, al
+	; done, reset the data port to 0
+	xor al, al
+	out PIC1_DATA, al
+	out PIC2_DATA, al
+	ret