#include <stdbool.h>
#include <sys.h>
#include "serial.h"
#include "../panic.h"

#define PORT 0x3f8          // COM1

void serial_init(void) {
	outb(PORT + 1, 0x00);    // Disable all interrupts
	outb(PORT + 3, 0x80);    // Enable DLAB (set baud rate divisor)
	outb(PORT + 0, 0x01);    // Set divisor to 1 (lo byte) 38400 baud
	outb(PORT + 1, 0x00);    //                  (hi byte)
	outb(PORT + 3, 0x03);    // 8 bits, no parity, one stop bit
	outb(PORT + 2, 0xC7);    // Enable FIFO, clear them, with 14-byte threshold
	outb(PORT + 4, 0x0B);    // IRQs enabled, RTS/DSR set
	outb(PORT + 4, 0x1E);    // Set in loopback mode, test the serial chip
	outb(PORT + 0, 0xAE);    // Test serial chip (send byte 0xAE and check if serial returns same byte)

	// Check if serial is faulty (i.e: not same byte as sent)
	uint8_t response = inb(PORT + 0);
	if(response != 0xAE) {
		panic("Serial is faulty: %X\n", response);
	}

	// If serial is not faulty set it in normal operation mode
	// (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
	outb(PORT + 4, 0x0F);
}

void serial_write(uint8_t a) {
	while((inb(PORT + 5) & 0x20) != 0);
	outb(PORT, a);
}

void serial_write_s(const char* str) {
	while(*str != '\0') {
		serial_write(*str++);
	}
}