Headers

kernel/io.c

@@ -1,3 +1,4 @@
+// Function to read a byte from port
 unsigned char port_byte_in(unsigned short port) {
 	unsigned char res;
 	__asm__("in %%dx, %%al" : "=a" (res) : "d" (port));
@@ -5,6 +6,21 @@ unsigned char port_byte_in(unsigned short port) {
 	return res;
 }
 
+// to write a byte to port
 void port_byte_out(unsigned short port, unsigned char data) {
+	__asm__("out %%al, %%dx" : :"a" (data), "d" (port));	
+}
+
+
+// Read word from port
+unsigned short port_word_in(unsigned short port) {
+	unsigned short res;
+	__asm__("in %%dx, %%ax" : "=a" (res) : "d" (port));
+
+	return res;
+}
 
+// write word to port
+void port_word_out(unsigned short port, unsigned short data) {
+	__asm__("out %%ax, %%dx" : :"a" (data), "d" (port));
 }

kernel/io.h

@@ -0,0 +1,5 @@
+unsigned char port_byte_in();
+void port_byte_out();
+
+unsigned short port_word_in();
+void port_word_out();