feat(serial): add write

Signed-off-by: Julien CLEMENT <julien.clement@epita.fr>

k/serial.c

@@ -22,5 +22,15 @@ void serial_init(void)
 
 int write(const char *buf, size_t count)
 {
-    return 0;
+    int sent;
+
+    for(sent = 0; sent < count; ++sent)
+    {
+        u8 line_status = inb(COM1 + 5);
+        if (!line_status & EMPTY_TRANSMITTER)
+            break;
+        outb(COM1, buf[sent]);
+    }
+
+    return sent;
 }

k/serial.h

@@ -18,6 +18,8 @@
 
 #define DLAB (0x1 << 7)
 
+#define EMPTY_TRANSMITTER (0x1 << 5)
+
 void serial_init(void);
 int write(const char *buf, size_t count);