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#include <comus/asm.h>
#include "pic.h"
#define PIC1 0x20 /* IO base address for master PIC */
#define PIC2 0xA0 /* IO base address for slave PIC */
#define PIC1_COMMAND PIC1
#define PIC1_DATA (PIC1 + 1)
#define PIC2_COMMAND PIC2
#define PIC2_DATA (PIC2 + 1)
#define PIC_EOI 0x20 /* End-of-interrupt command code */
#define ICW1_ICW4 0x01 /* Indicates that ICW4 will be present */
#define ICW1_SINGLE 0x02 /* Single (cascade) mode */
#define ICW1_INTERVAL4 0x04 /* Call address interval 4 (8) */
#define ICW1_LEVEL 0x08 /* Level triggered (edge) mode */
#define ICW1_INIT 0x10 /* Initialization - required! */
#define ICW4_8086 0x01 /* 8086/88 (MCS-80/85) mode */
#define ICW4_AUTO 0x02 /* Auto (normal) EOI */
#define ICW4_BUF_SLAVE 0x08 /* Buffered mode/slave */
#define ICW4_BUF_MASTER 0x0C /* Buffered mode/master */
#define ICW4_SFNM 0x10 /* Special fully nested (not) */
void pic_remap(void)
{
outb(PIC1_COMMAND,
ICW1_INIT |
ICW1_ICW4); // starts the initialization sequence (in cascade mode)
io_wait();
outb(PIC2_COMMAND, ICW1_INIT | ICW1_ICW4);
io_wait();
outb(PIC1_DATA, PIC_REMAP_OFFSET); // ICW2: Master PIC vector offset
io_wait();
outb(PIC2_DATA, PIC_REMAP_OFFSET + 8); // ICW2: Slave PIC vector offset
io_wait();
outb(
PIC1_DATA,
4); // ICW3: tell Master PIC that there is a slave PIC at IRQ2 (0000 0100)
io_wait();
outb(PIC2_DATA, 2); // ICW3: tell Slave PIC its cascade identity (0000 0010)
io_wait();
outb(PIC1_DATA,
ICW4_8086); // ICW4: have the PICs use 8086 mode (and not 8080 mode)
io_wait();
outb(PIC2_DATA, ICW4_8086);
io_wait();
outb(PIC1_DATA, 0);
outb(PIC2_DATA, 0);
}
void pic_mask(int irq)
{
uint16_t port;
uint8_t mask;
if (irq < 8) {
port = PIC1_DATA;
} else {
port = PIC2_DATA;
irq -= 8;
}
mask = inb(port) | (1 << irq);
outb(port, mask);
}
void pic_unmask(int irq)
{
uint16_t port;
uint8_t mask;
if (irq < 8) {
port = PIC1_DATA;
} else {
irq -= 8;
port = PIC2_DATA;
}
mask = inb(port) & ~(1 << irq);
outb(port, mask);
}
void pic_disable(void)
{
outb(PIC1_DATA, 0xff);
outb(PIC2_DATA, 0xff);
}
void pic_eoi(int irq)
{
if (irq >= 8) {
outb(PIC2_COMMAND, PIC_EOI);
}
outb(PIC1_COMMAND, PIC_EOI);
}
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