timer.s

国内一位牛人自己开发的操作系统

TIME_LENGTH	=	1190
.global setup_timer
setup_timer:

/*	init 8259 for interruption */

	movb $(0x11),%al
	outb %al,$(0x20)
	movb $(0x20),%al
	outb %al,$(0x21)
	movb $(0x04),%al
	outb %al,$(0x21)
	movb $(0x03),%al
	outb %al,$(0x21)

	movb $(0xfe),%al
	outb %al,$(0x21)

	
	movb $(0x11),%al
	outb %al,$(0xa0)
	movb $(0x70),%al
	outb %al,$(0xa1)
	movb $(0x02),%al
	outb %al,$(0xa1)
	movb $(0x01),%al
	outb %al,$(0xa1)
	
	movb $(0x04),%al
	outb %al,$(0xa1)

/*	init 8259 end 	*/


/*	init 8254 for timer ,thus for time-sharing */

	movb $(0x34),%al
	outb %al,$(0x43)

	movl $(TIME_LENGTH),%eax
	outb %al,$(0x40)
	movb %ah,%al
	outb %al,$(0x40)

/*	init 8254 end  */

	ret