#include <kernel/serial.h>
#include <kernel/io.h>
#include <kernel/kernel.h>

uint8_t serial_port_init(int port) {
    // Test port by seeing if scratch register can store a value
    uint8_t old_scratch = inb(port + 7);
    outb(port + 7, old_scratch + 1);
    if (inb(port + 7) != old_scratch + 1)
	return 0;
    outb(port + 7, old_scratch);

    outb(port + 1, 0x00);    // Disable all interrupts
    outb(port + 3, 0x80);    // Enable DLAB (set baud rate divisor)
    outb(port + 0, 0x03);    // Set divisor to 3 (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)
    if(inb(port + 0) != 0xAE)
	return 0;

    // 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);
    return 1;
}

void serial_putc(int port, const char c) {
    // Poll until transmit is empty
    while(!IS_TRANSMIT_EMPTY(port)) cpu_relax;
    outb(port, c);
}

void serial_puts(int port, const char *str) {
    while (*str) {
	serial_putc(port, str[0]); 
	str++;
    }
}