#include <stdint.h>

#include "kernel.h"

#include "ioport.h"

#include "pic.h"
#include "interrupt.h"

/* ioports */
#define MCMD 0x20
#define SCMD 0xA0
#define MDATA 0x21
#define SDATA 0xA1

#define IRR 0x0A
#define ISR 0x0B

#define EOI 0x20
#define ICW1_ICW4  0x01
#define CMD_INIT  0x10
#define MODE_8086  0x01

static uint16_t readregister(uint8_t ocw3) {
	outport8(MCMD, ocw3);
	outport8(SCMD, ocw3);
	return inport8(MCMD) | inport8(SCMD) << 8;
}

static uint16_t readirr() {
	return readregister(IRR);
}

static uint16_t readisr() {
	return readregister(ISR);
}

static void reprogram() {
	outport8(MCMD, CMD_INIT | ICW1_ICW4);
	outport8(SCMD, CMD_INIT | ICW1_ICW4);
	outport8(MDATA, IRQ0);
	outport8(SDATA, IRQ8);
	outport8(MDATA, 0x04); /* Slave PIC at IRQ2 */
	outport8(SDATA, 0x02); /* Cascade Identity */
	outport8(MDATA, MODE_8086);
	outport8(SDATA, MODE_8086);
	/* masks */
	outport8(MDATA, 0);
	outport8(SDATA, 0);
}

static void deprogram() {
	outport8(MCMD, CMD_INIT | ICW1_ICW4);
	outport8(SCMD, CMD_INIT | ICW1_ICW4);
	outport8(MDATA, 0x08);
	outport8(SDATA, 0x70);
	outport8(MDATA, 0x04); /* Slave PIC at IRQ2 */
	outport8(SDATA, 0x02); /* Cascade Identity */
	outport8(MDATA, MODE_8086);
	outport8(SDATA, MODE_8086);
	outport8(MDATA, 0);
	outport8(SDATA, 0);
}

static void sendmastereoi() {
	outport8(MCMD, EOI);
}

static void sendslaveeoi() {
	outport8(SCMD, EOI);
}

static void sendeoi(unsigned int irq) {
	if (irq >= 8) {
		sendslaveeoi();
	}
	sendmastereoi();
}

struct pic pic;

void pic_init() {
	pic.eoi = sendeoi;
	pic.mastereoi = sendmastereoi;
	pic.readirr = readirr;
	pic.readisr = readisr;
	pic.reprogram = reprogram;
	pic.deprogram = deprogram;
}