serial output

1 files changed, 37 insertions, 0 deletions

diff --git a/kernel/src/devices/serial.c b/kernel/src/devices/serial.c
new file mode 100644
index 0000000..76bc71a
--- /dev/null
+++ b/kernel/src/devices/serial.c
@@ -0,0 +1,37 @@
+#include <io.h>
+#include <serial.h>
+
+void init_serial()
+{
+	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
+}
+
+uint8_t serial_received()
+{
+	return inb(PORT + 5) & 1;
+}
+
+char read_serial()
+{
+	while (serial_received() == 0);
+
+	return (char)inb(PORT);
+}
+
+uint8_t is_transmit_empty()
+{
+	return inb(PORT + 5) & 0x20;
+}
+
+void write_serial(char c)
+{
+	while (is_transmit_empty() == 0);
+
+	outb(PORT, (uint8_t)c);
+}