8259.s

从网上下载的一个自己编写的简单的操作系统源代码,对底层了解很有好处的

;
;  8259 中断控制器
;
;  dis_irq :禁止8259 响应任何中断 


global dis_irq

[bits 16]


dis_irq:
     mov     al,0xFF	     ; mask off all interrupts for now
     out     0x21,al         ; sencond 8259
     dw      0x00eb,0x00eb
     out     0xA1,al         ;master 8259
     ret






     
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
%if 0
; well, that went ok, I hope. Now we have to reprogram the interrupts :-(
; we put them right after the intel-reserved hardware interrupts, at
; int 0x20-0x2F. There they won't mess up anything. Sadly IBM really
; messed this up with the original PC, and they haven't been able to
; rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f,
; which is used for the internal hardware interrupts as well. We just
; have to reprogram the 8259's, and it isn't fun.

	mov	al,0x11		; initialization sequence
	out	0x20,al		; send it to 8259A-1
	dw	0x00eb,0x00eb		; jmp $+2, jmp $+2
	out	0xA0,al		; and to 8259A-2
	dw	0x00eb,0x00eb
	mov	al,0x20		; start of hardware int's (0x20)
	out	0x21,al
	dw	0x00eb,0x00eb
	mov	al,0x28		; start of hardware int's 2 (0x28)
	out	0xA1,al
	dw	0x00eb,0x00eb
	mov	al,0x04		; 8259-1 is master
	out	0x21,al
	dw	0x00eb,0x00eb
	mov	al,0x02		; 8259-2 is slave
	out	0xA1,al
	dw	0x00eb,0x00eb
	mov	al,0x01		; 8086 mode for both
	out	0x21,al
	dw	0x00eb,0x00eb
	out	0xA1,al
	dw	0x00eb,0x00eb
	mov	al,0xFF		; mask off all interrupts for now
	out	0x21,al
	dw	0x00eb,0x00eb
	out	0xA1,al
%endif