Add serial module

src/hulk/hulk.d

@@ -21,6 +21,7 @@ import hulk.pic;
 import hulk.acpi;
 import hulk.apic;
 import hulk.rtc;
+import hulk.serial;
 
 extern extern(C) __gshared ubyte _hulk_bss_size;
 
@@ -56,6 +57,7 @@ void hulk_start()
 {
     cli();
     initialize_cpu();
+    Serial.initialize();
     Gdt.initialize();
     Idt.initialize();
     Fb.initialize(cast(uint *)Hurl.HULK_FRAMEBUFFER,

src/hulk/klog.d

@@ -58,7 +58,7 @@ struct Klog
     }
 
     /**
-     * Write a formatted string and newline to the console.
+     * Write a formatted string and newline to the kernel log.
      *
      * @param s Format string.
      */

src/hulk/serial.d

@@ -0,0 +1,74 @@
+/**
+ * Serial port access.
+ */
+module hulk.serial;
+
+import hulk.cpu;
+import core.stdc.stdarg;
+static import hulk.writef;
+
+struct Serial
+{
+    enum BASE_PORT = 0x3F8;
+
+    /**
+     * Initialize the serial module.
+     */
+    static void initialize()
+    {
+    }
+
+    /**
+     * Write a character to the serial port.
+     *
+     * @param ch Character to write.
+     */
+    static void write(ubyte ch)
+    {
+        if (ch == '\n')
+        {
+            out8(BASE_PORT, '\r');
+        }
+        out8(BASE_PORT, ch);
+    }
+
+    /**
+     * Write a formatted string to the serial port.
+     *
+     * @param s Format string.
+     * @param args Variable arguments structure.
+     */
+    public static void writef(string s, va_list args)
+    {
+        hulk.writef.writef(s, args, function void(ubyte ch) {
+                    Serial.write(ch);
+                });
+    }
+
+    /**
+     * Write a formatted string to the serial port.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void writef(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        writef(s, args);
+        va_end(args);
+    }
+
+    /**
+     * Write a formatted string and newline to the serial port.
+     *
+     * @param s Format string.
+     */
+    public static extern (C) void writefln(string s, ...)
+    {
+        va_list args;
+        va_start(args, s);
+        writef(s, args);
+        writef("\n", args);
+        va_end(args);
+    }
+}