Add console, klog, and writef modules.

They are not complete, but adding to checkpoint progress.

src/hulk/klog.d

@@ -0,0 +1,76 @@
+/**
+ * HULK Kernel Log buffer.
+ */
+module hulk.klog;
+
+import core.stdc.stdarg;
+import hulk.console;
+static import hulk.writef;
+
+/**
+ * Kernel buffer size log.
+ * 16 gives a kernel buffer size of 64KB.
+ */
+enum size_t KLOG_SIZE_LOG = 16u;
+
+/** Kernel buffer size.  */
+enum size_t KLOG_SIZE = 1u << KLOG_SIZE_LOG;
+
+/** Kernel log buffer. */
+private __gshared align(4096) char[KLOG_SIZE] klog_buffer;
+
+/** Write index in the kernel log buffer. */
+private __gshared size_t klog_index;
+
+/** Pointer to the console to use for kernel log output. */
+private __gshared Console * console;
+
+/**
+ * Initialize the klog module.
+ *
+ * @param console Pointer to the Console to use for kernel output.
+ */
+void initialize(Console * console)
+{
+    .console = console;
+}
+
+/**
+ * Write a formatted string to the kernel log.
+ *
+ * @param s Format string.
+ * @param args Variable arguments structure.
+ */
+void writef(string s, va_list args)
+{
+    hulk.writef.writef(s, args, function void(ubyte ch) {
+                console.write(ch);
+            });
+}
+
+/**
+ * Write a formatted string to the kernel log.
+ *
+ * @param s Format string.
+ */
+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 console.
+ *
+ * @param s Format string.
+ */
+extern (C) void writefln(string s, ...)
+{
+    va_list args;
+    va_start(args, s);
+    writef(s, args);
+    writef("\n", args);
+    va_end(args);
+}