#include "keyboard.h"
#include "portio.h"
#include "irq.h"
#include "types.h"
#include "fileobj.h"

#define BUFFER_SIZE 32

char kbd_buffer[BUFFER_SIZE];

char *buf_head, *buf_tail, *buf_start, *buf_end;

int keyboard_read(struct file_object *fo, void *buf, size_t n);

struct fops keyboard_fops = {
	.read = &keyboard_read,
};

struct file_object keyboard_fo;

unsigned char scancode;
unsigned char e0;

void keyb_out_wait() {
	while (inportb(KEYB_STATUS) & KEYB_STATUS_OBF)
		;
}

void keyb_send_byte(unsigned char b) {
	outportb(KEYB_DATA, b);
	keyb_out_wait();
}

void keyb_set_leds(unsigned char leds) {
	keyb_send_byte(KEYB_COMMAND_LEDS);
	keyb_send_byte(leds);
}

void keyboard_init() {
	e0 = 0;

	buf_start = (char *)&kbd_buffer;
	buf_end = (char *)((char *)(&kbd_buffer) + BUFFER_SIZE - 1);
	buf_head = buf_start;
	buf_tail = buf_end;

	fileobj_init(&keyboard_fo);
	keyboard_fo.fops = &keyboard_fops;

	devfs_register_device("kbd", &keyboard_fo);
}

int keyboard_read(struct file_object *fo, void *buf, size_t n) {
	char *p = buf;
	for (; n; n--, p++) {
		while (
			(buf_head == buf_start && buf_tail == buf_end)
			|| (buf_tail == buf_head - 1)
		) {
			kernel_yield();
		}
		*p = *buf_tail++;
		if (buf_tail > buf_end) {
			buf_tail = buf_start;
		}
	}
}

// Keyboard ISR
void interrupt_33() {
	unsigned char b = inportb(KEYB_DATA);

	if (!(
		(buf_head == buf_end && buf_tail == buf_start)
		|| (buf_head == buf_tail - 1)
	)) {
		if (e0) {
//			printf(" KBD: e0 %x\n", b);
			e0 = 0;
		} else if (b == 0xE0) {
			e0 = 1;
		} else {
//			printf(" KBD: %x\n", b);
		}

		*buf_head++ = b;
		if (buf_head > buf_end) {
			buf_head = buf_start;
		}
	} else {
		printf(" KBD: Keyboard buffer full\n");
	}
	
	ACK_MASTER_IRQ;
}