k-chow/k/pic.c

#include "idt.h"
#include "io.h"
#include "pic.h"
#include "stdio.h"

static void send_icw1(void)
{
    outb(MASTER_PIC_A, ICW1);
    outb(SLAVE_PIC_A, ICW1);
}

static void send_icw2(void)
{
    outb(MASTER_PIC_B, IDT_RESERVED_ENTRIES);
    outb(SLAVE_PIC_B, IDT_RESERVED_ENTRIES + 8);
}

static void send_icw3(void)
{
    outb(MASTER_PIC_B, 0x4);
    outb(SLAVE_PIC_B, 0x2);
}


static void send_icw4(void)
{
    outb(MASTER_PIC_B, 0x1);
    outb(SLAVE_PIC_B, 0x1);
}

static void mask_irqs(void)
{
    outb(MASTER_PIC_B, 0xff ^ 0x2);
    outb(SLAVE_PIC_B, 0xff);
}

void init_pic(void)
{
    send_icw1();
    send_icw2();
    send_icw3();
    send_icw4();
    mask_irqs();
    asm volatile("sti");
}

void acknowledge(uint32_t int_vector)
{
    printf("acknowledging %d\r\n", int_vector);
    uint8_t ocw2 = 0x20;
    if (int_vector >= IDT_RESERVED_ENTRIES + 8)
        outb(SLAVE_PIC_A, ocw2);
    outb(MASTER_PIC_A, ocw2);
}