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#include "pic.h"
#include <sys/control.h>
#include <sys/io.h>
#define PIC1 0x20
#define PIC2 0xa0
#define DATA 1
/* initialization */
#define ICW1_INIT 0x10
/* TODO */
#define ICW1_ICW4 0x01
/* 8086/88 mode */
#define ICW4_8086 0x01
void
pic_init()
{
outb(ICW1_INIT | ICW1_ICW4, PIC1);
outb(ICW1_INIT | ICW1_ICW4, PIC2);
outb(0x20, PIC1 + DATA); /* offset 0x20 */
outb(0x28, PIC2 + DATA); /* offset 0x28 */
outb(0x04, PIC1 + DATA); /* tell master pic there is a slave pic */
outb(0x02, PIC2 + DATA); /* tell slave pic its cascade identity */
outb(ICW4_8086, PIC1 + DATA);
outb(ICW4_8086, PIC2 + DATA);
/* PIC masks */
outb(0xff, PIC1 + DATA);
outb(0xff, PIC2 + DATA);
}
static unsigned char
irq_mask(unsigned char irq)
{
unsigned char mask = (unsigned char)~(1u << irq);
return 0xff & mask;
}
void
pic_enable()
{
unsigned char mask1 = 0xff;
unsigned char mask2 = 0xff;
mask1 &= irq_mask(0); /* irq0 timer */
mask1 &= irq_mask(1); /* irq1 keyboard */
mask1 &= irq_mask(2); /* irq2 cascade */
outb(mask1, PIC1 + DATA);
mask2 &= irq_mask(12 - 8); /* irq12 mouse */
outb(mask2, PIC2 + DATA);
enable_interrupts();
}
void
pic_clear(unsigned char irq)
{
outb(0x20, PIC1);
if (irq >= 8) outb(0x20, PIC2);
}
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