Add beginning basic serial driver

src/kernel/serial.cpp

@@ -0,0 +1,31 @@
+#include "io.h"
+#include "serial.h"
+
+serial_port g_com1;
+
+
+serial_port::serial_port() :
+	m_port(0)
+{
+}
+
+serial_port::serial_port(uint16_t port) :
+	m_port(port)
+{
+}
+
+bool serial_port::read_ready() { return (inb(m_port + 5) & 0x01) != 0; }
+bool serial_port::write_ready() { return (inb(m_port + 5) & 0x20) != 0; }
+
+char
+serial_port::read() {
+	while (!read_ready());
+	return inb(m_port);
+}
+
+void
+serial_port::write(char c) {
+	while (!write_ready());
+	outb(m_port, c);
+}
+