Add output module for console output routines

src/hel/hel.d

@@ -1,11 +1,16 @@
 import uefi;
+import output;
+
+__gshared EFI_SYSTEM_TABLE * g_st;
 
 extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
 {
+    g_st = st;
+
     st.ConOut.ClearScreen(st.ConOut);
 
-    st.ConOut.OutputString(st.ConOut, cast(CHAR16 *)"HOS EFI loader\r\n"w);
-    st.ConOut.OutputString(st.ConOut, cast(CHAR16 *)"Press any key...\r\n"w);
+    writeln("HOS EFI loader");
+    writeln("Press any key...");
 
     st.ConIn.Reset(st.ConIn, FALSE);
     EFI_INPUT_KEY key;

src/hel/output.d

@@ -0,0 +1,21 @@
+import uefi;
+import hel;
+
+void write(string s)
+{
+    __gshared static CHAR16[256] s16;
+    size_t i = 0u;
+    while (i < s.length)
+    {
+        s16[i] = s[i];
+        i++;
+    }
+    s16[i++] = 0u;
+    g_st.ConOut.OutputString(g_st.ConOut, &s16[0]);
+}
+
+void writeln(string s)
+{
+    write(s);
+    write("\r\n");
+}