From 3d4557343fbc5ca281b621efa79e63287e38e25b Mon Sep 17 00:00:00 2001
From: Garritt McCune <glmccune@gmail.com>
Date: Fri, 8 May 2020 10:16:41 -0500
Subject: [PATCH] Added an I/O port driver and made it callable from C.

---
 includes/io.h |  4 ++++
 kernel/io.s   | 11 +++++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 includes/io.h
 create mode 100644 kernel/io.s

diff --git a/includes/io.h b/includes/io.h
new file mode 100644
index 0000000..cc1c42e
--- /dev/null
+++ b/includes/io.h
@@ -0,0 +1,4 @@
+#ifndef IO_H
+#define IO_H
+void outb(unsigned short port, unsigned char data);
+#endif
diff --git a/kernel/io.s b/kernel/io.s
new file mode 100644
index 0000000..1c963c1
--- /dev/null
+++ b/kernel/io.s
@@ -0,0 +1,11 @@
+global outb
+
+; outb - Send a byte to an I/O port.
+; stack: [esp + 8] The data byte
+; 		 [esp + 4] The I/O port
+;		 [esp	 ] Return address
+outb:
+	mov al, [esp + 8] ; Move the data to send into the AL register
+	mov dx, [esp + 4] ; Move the address of the I/O port into the DX register
+	out dx, al		  ; Send the data to the I/O port
+	ret				  ; Return