--- a/src/os/macosx/macos.mm
+++ b/src/os/macosx/macos.mm
@@ -7,6 +7,8 @@
  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
  */
 
+/** @file macos.mm Code related to MacOSX. */
+
 #include "../../stdafx.h"
 #include "../../core/bitmath_func.hpp"
 #include "../../rev.h"
@@ -57,6 +59,13 @@
 
 #ifdef WITH_SDL
 
+/**
+ * Show the system dialogue message (SDL on MacOSX).
+ *
+ * @param title Window title.
+ * @param message Message text.
+ * @param buttonLabel Button text.
+ */
 void ShowMacDialog(const char *title, const char *message, const char *buttonLabel)
 {
 	NSRunAlertPanel([ NSString stringWithUTF8String:title ], [ NSString stringWithUTF8String:message ], [ NSString stringWithUTF8String:buttonLabel ], nil, nil);
@@ -66,6 +75,13 @@
 
 extern void CocoaDialog(const char *title, const char *message, const char *buttonLabel);
 
+/**
+ * Show the system dialogue message (Cocoa on MacOSX).
+ *
+ * @param title Window title.
+ * @param message Message text.
+ * @param buttonLabel Button text.
+ */
 void ShowMacDialog(const char *title, const char *message, const char *buttonLabel)
 {
 	CocoaDialog(title, message, buttonLabel);
@@ -74,6 +90,13 @@
 
 #else
 
+/**
+ * Show the system dialogue message (console on MacOSX).
+ *
+ * @param title Window title.
+ * @param message Message text.
+ * @param buttonLabel Button text.
+ */
 void ShowMacDialog(const char *title, const char *message, const char *buttonLabel)
 {
 	fprintf(stderr, "%s: %s\n", title, message);
@@ -82,6 +105,12 @@
 #endif
 
 
+/**
+ * Show an error message.
+ *
+ * @param buf error message text.
+ * @param system message text originates from OS.
+ */
 void ShowOSErrorBox(const char *buf, bool system)
 {
 	/* Display the error in the best way possible. */
@@ -93,7 +122,9 @@
 }
 
 
-/** Determine the current user's locale. */
+/**
+ * Determine and return the current user's locale.
+ */
 const char *GetCurrentLocale(const char *)
 {
 	static char retbuf[32] = { '\0' };
@@ -120,6 +151,13 @@
 
 
 #ifdef WITH_COCOA
+/**
+ * Return the contents of the clipboard (COCOA).
+ *
+ * @param buffer Clipboard content..
+ * @param buff_len Length of the clipboard content..
+ * @return Whether clipboard is empty or not.
+ */
 bool GetClipboardContents(char *buffer, size_t buff_len)
 {
 	NSPasteboard *pb = [ NSPasteboard generalPasteboard ];

--- a/src/os/macosx/splash.cpp
+++ b/src/os/macosx/splash.cpp
@@ -23,17 +23,32 @@
 
 #include <png.h>
 
+/**
+ * Handle pnglib error.
+ *
+ * @param png_ptr Pointer to png struct.
+ * @param message Error message text.
+ */
 static void PNGAPI png_my_error(png_structp png_ptr, png_const_charp message)
 {
 	DEBUG(misc, 0, "[libpng] error: %s - %s", message, (char *)png_get_error_ptr(png_ptr));
 	longjmp(png_jmpbuf(png_ptr), 1);
 }
 
+/**
+ * Handle warning in pnglib.
+ *
+ * @param png_ptr Pointer to png struct.
+ * @param message Warning message text.
+ */
 static void PNGAPI png_my_warning(png_structp png_ptr, png_const_charp message)
 {
 	DEBUG(misc, 1, "[libpng] warning: %s - %s", message, (char *)png_get_error_ptr(png_ptr));
 }
 
+/**
+ * Display a splash image shown on startup (WITH_PNG).
+ */
 void DisplaySplashImage()
 {
 	FILE *f = FioFOpenFile(SPLASH_IMAGE_FILE);
@@ -162,6 +177,9 @@
 
 #else /* WITH_PNG */
 
+/**
+ * Empty 'Display a splash image' routine (WITHOUT_PNG).
+ */
 void DisplaySplashImage() {}
 
 #endif /* WITH_PNG */

--- a/src/video/cocoa/cocoa_v.mm
+++ b/src/video/cocoa/cocoa_v.mm
@@ -7,6 +7,8 @@
  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
  */
 
+/** @file cocoa_v.mm Code related to the cocoa video driver(s). */
+
 /******************************************************************************
  *                             Cocoa video driver                             *
  * Known things left to do:                                                   *
@@ -56,9 +58,13 @@
 
 
 
-/* The main class of the application, the application's delegate */
+/**
+ * The main class of the application, the application's delegate.
+ */
 @implementation OTTDMain
-/* Called when the internal event loop has just started running */
+/**
+ * Called when the internal event loop has just started running.
+ */
 - (void) applicationDidFinishLaunching: (NSNotification*) note
 {
 	/* Hand off to main application code */
@@ -68,7 +74,9 @@
 	[ NSApp stop:_ottd_main ];
 }
 
-/* Display the in game quit confirmation dialog */
+/**
+ * Display the in game quit confirmation dialog.
+ */
 - (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication*) sender
 {
 
@@ -78,6 +86,9 @@
 }
 @end
 
+/**
+ * Initialize the application menu shown in top bar.
+ */
 static void setApplicationMenu()
 {
 	NSString *appName = @"OTTD";
@@ -117,7 +128,9 @@
 	[ menuItem release ];
 }
 
-/* Create a window menu */
+/**
+ * Create a window menu.
+ */
 static void setupWindowMenu()
 {
 	NSMenu *windowMenu = [ [ NSMenu alloc ] initWithTitle:@"Window" ];
@@ -138,6 +151,9 @@
 	[ menuItem release ];
 }
 
+/**
+ * Startup the application.
+ */
 static void setupApplication()
 {
 	ProcessSerialNumber psn = { 0, kCurrentProcess };
@@ -167,7 +183,11 @@
 	[ NSApp setDelegate:_ottd_main ];
 }
 
-
+/**
+ * Update the video modus.
+ *
+ * @pre _cocoa_subdriver != NULL
+ */
 static void QZ_UpdateVideoModes()
 {
 	assert(_cocoa_subdriver != NULL);
@@ -183,7 +203,9 @@
 	_num_resolutions = count;
 }
 
-
+/**
+ * Handle a change of the display area.
+ */
 void QZ_GameSizeChanged()
 {
 	if (_cocoa_subdriver == NULL) return;
@@ -200,7 +222,14 @@
 	GameSizeChanged();
 }
 
-
+/**
+ * Find a suitable cocoa window subdriver.
+ *
+ * @param width Width of display area.
+ * @param height Height of display area.
+ * @param bpp Colour depth of display area.
+ * @return Pointer to window subdriver.
+ */
 static CocoaSubdriver *QZ_CreateWindowSubdriver(int width, int height, int bpp)
 {
 #if defined(ENABLE_COCOA_QUARTZ) || defined(ENABLE_COCOA_QUICKDRAW)
@@ -238,7 +267,17 @@
 	return NULL;
 }
 
-
+/**
+ * Find a suitable cocoa subdriver.
+ *
+ * @param width Width of display area.
+ * @param height Height of display area.
+ * @param bpp Colour depth of display area.
+ * @param fullscreen Wether a fullscreen mode is requested.
+ * @param fallback Whether we look for a fallback driver.
+ * @return Pointer to subdriver.
+ * @return Pointer to window subdriver.
+ */
 static CocoaSubdriver *QZ_CreateSubdriver(int width, int height, int bpp, bool fullscreen, bool fallback)
 {
 	CocoaSubdriver *ret = fullscreen ? QZ_CreateFullscreenSubdriver(width, height, bpp) : QZ_CreateWindowSubdriver(width, height, bpp);
@@ -264,6 +303,9 @@
 
 static FVideoDriver_Cocoa iFVideoDriver_Cocoa;
 
+/**
+ * Stop the cocoa video subdriver.
+ */
 void VideoDriver_Cocoa::Stop()
 {
 	if (!_cocoa_video_started) return;
@@ -276,6 +318,9 @@
 	_cocoa_video_started = false;
 }
 
+/**
+ * Initialize a cocoa video subdriver.
+ */
 const char *VideoDriver_Cocoa::Start(const char * const *parm)
 {
 	if (!MacOSVersionIsAtLeast(10, 3, 0)) return "The Cocoa video driver requires Mac OS X 10.3 or later.";
@@ -304,6 +349,14 @@
 	return NULL;
 }
 
+/**
+ * Set dirty a rectangle managed by a cocoa video subdriver.
+ *
+ * @param left Left x cooordinate of the dirty rectangle.
+ * @param top Uppder y coordinate of the dirty rectangle.
+ * @param width Width of the dirty rectangle.
+ * @param height Height of the dirty rectangle.
+ */
 void VideoDriver_Cocoa::MakeDirty(int left, int top, int width, int height)
 {
 	assert(_cocoa_subdriver != NULL);
@@ -311,12 +364,22 @@
 	_cocoa_subdriver->MakeDirty(left, top, width, height);
 }
 
+/**
+ * Start the main programme loop when using a cocoa video driver.
+ */
 void VideoDriver_Cocoa::MainLoop()
 {
 	/* Start the main event loop */
 	[ NSApp run ];
 }
 
+/**
+ * Change the resolution when using a cocoa video driver.
+ *
+ * @param w New window width.
+ * @param h New window height.
+ * @return Whether the video driver was successfully updated.
+ */
 bool VideoDriver_Cocoa::ChangeResolution(int w, int h)
 {
 	assert(_cocoa_subdriver != NULL);
@@ -329,6 +392,12 @@
 	return ret;
 }
 
+/**
+ * Toggle between windowed and full screen mode for cocoa display driver.
+ *
+ * @param full_screen Whether to switch to full screen or not.
+ * @return Whether the mode switch was successful.
+ */
 bool VideoDriver_Cocoa::ToggleFullscreen(bool full_screen)
 {
 	assert(_cocoa_subdriver != NULL);
@@ -355,7 +424,15 @@
 	return _cocoa_subdriver->IsFullscreen() == full_screen;
 }
 
-/* This is needed since sometimes assert is called before the videodriver is initialized */
+/**
+ * Catch asserts prior to initialization of the videodriver.
+ *
+ * @param title Window title.
+ * @param message Message text.
+ * @param buttonLabel Button text.
+ *
+ * @note This is needed since sometimes assert is called before the videodriver is initialized .
+ */
 void CocoaDialog(const char *title, const char *message, const char *buttonLabel)
 {
 	_cocoa_video_dialog = true;
@@ -375,8 +452,11 @@
 	_cocoa_video_dialog = false;
 }
 
-/* This is needed since OS X application bundles do not have a
- * current directory and the data files are 'somewhere' in the bundle */
+/** Set the application's bundle directory.
+ *
+ * This is needed since OS X application bundles do not have a
+ * current directory and the data files are 'somewhere' in the bundle.
+ */
 void cocoaSetApplicationBundleDir()
 {
 	char tmp[MAXPATHLEN];
@@ -391,7 +471,10 @@
 	CFRelease(url);
 }
 
-/* These are called from main() to prevent a _NSAutoreleaseNoPool error when
+/**
+ * Setup autorelease for the application pool.
+ *
+ * These are called from main() to prevent a _NSAutoreleaseNoPool error when
  * exiting before the cocoa video driver has been loaded
  */
 void cocoaSetupAutoreleasePool()
@@ -399,6 +482,9 @@
 	_ottd_autorelease_pool = [ [ NSAutoreleasePool alloc ] init ];
 }
 
+/**
+ * Autorelease the application pool.
+ */
 void cocoaReleaseAutoreleasePool()
 {
 	[ _ottd_autorelease_pool release ];