//
// Created by rick on 28-01-21.
//

#include "serial.h"
#include <types.h>
#include <drivers/ports.h>

int serial_init() {
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_INTERRUPT, 0x00);    // Disable all interrupts
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_LINE_CONTROL, 0x80);    // Enable DLAB (set baud rate divisor)
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DLAB_LSB, 0x03);    // Set divisor to 3 (lo byte) 38400 baud
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DLAB_MSB, 0x00);    //                  (hi byte)
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_LINE_CONTROL, 0x03);    // 8 bits, no parity, one stop bit
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_INTERRUPT_ID_FIFO,
                  0xC7);    // Enable FIFO, clear them, with 14-byte threshold
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_MODEM_CONTROL, 0x0B);    // IRQs enabled, RTS/DSR set
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_MODEM_CONTROL, 0x1E);    // Set in loopback mode, test the serial chip
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DATA,
                  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 (port_byte_in(PORT_SERIAL_0 + PORT_SERIAL_DATA) != 0xAE) {
        return 1;
    }

    // If serial is not faulty set it in normal operation mode
    // (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_MODEM_CONTROL, 0x0F);
    return 0;
}

int is_transmit_empty() {
    return port_byte_in(PORT_SERIAL_0 + PORT_SERIAL_LINE_STATUS) & 0x20;
}

void write_serial(char a) {
    while (is_transmit_empty() == 0);

    port_byte_out(PORT_SERIAL_0 + PORT_SERIAL_DATA, a);
}

void serial_kprint(char *msg) {
    u32 i = 0;
    while (1) {
        char c = msg[i];
        if (c == 0) {
            break;
        }
        if (c == '\n') {
            write_serial('\r');
        }
        write_serial(c);
        i++;
    }
}