Codechange: Use null pointer literal instead of the NULL macro

11 files changed, 85 insertions, 85 deletions

diff --git a/src/music/allegro_m.cpp b/src/music/allegro_m.cpp
index 906aec84f..959f15611 100644
--- a/src/music/allegro_m.cpp
+++ b/src/music/allegro_m.cpp
@@ -20,7 +20,7 @@
 #include "../safeguards.h"
 
 static FMusicDriver_Allegro iFMusicDriver_Allegro;
-static MIDI *_midi = NULL;
+static MIDI *_midi = nullptr;
 
 /**
  * There are multiple modules that might be using Allegro and
@@ -30,14 +30,14 @@ extern int _allegro_instance_count;
 
 const char *MusicDriver_Allegro::Start(const char * const *param)
 {
-	if (_allegro_instance_count == 0 && install_allegro(SYSTEM_AUTODETECT, &errno, NULL)) {
+	if (_allegro_instance_count == 0 && install_allegro(SYSTEM_AUTODETECT, &errno, nullptr)) {
 		DEBUG(driver, 0, "allegro: install_allegro failed '%s'", allegro_error);
 		return "Failed to set up Allegro";
 	}
 	_allegro_instance_count++;
 
 	/* Initialise the sound */
-	if (install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, NULL) != 0) {
+	if (install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, nullptr) != 0) {
 		DEBUG(driver, 0, "allegro: install_sound failed '%s'", allegro_error);
 		return "Failed to set up Allegro sound";
 	}
@@ -48,13 +48,13 @@ const char *MusicDriver_Allegro::Start(const char * const *param)
 		return "No sound card found";
 	}
 
-	return NULL;
+	return nullptr;
 }
 
 void MusicDriver_Allegro::Stop()
 {
-	if (_midi != NULL) destroy_midi(_midi);
-	_midi = NULL;
+	if (_midi != nullptr) destroy_midi(_midi);
+	_midi = nullptr;
 
 	if (--_allegro_instance_count == 0) allegro_exit();
 }
@@ -63,12 +63,12 @@ void MusicDriver_Allegro::PlaySong(const MusicSongInfo &song)
 {
 	std::string filename = MidiFile::GetSMFFile(song);
 
-	if (_midi != NULL) destroy_midi(_midi);
+	if (_midi != nullptr) destroy_midi(_midi);
 	if (!filename.empty()) {
 		_midi = load_midi(filename.c_str());
 		play_midi(_midi, false);
 	} else {
-		_midi = NULL;
+		_midi = nullptr;
 	}
 }
 
diff --git a/src/music/bemidi.cpp b/src/music/bemidi.cpp
index ff56d787f..090ac0f90 100644
--- a/src/music/bemidi.cpp
+++ b/src/music/bemidi.cpp
@@ -28,7 +28,7 @@ static FMusicDriver_BeMidi iFMusicDriver_BeMidi;
 
 const char *MusicDriver_BeMidi::Start(const char * const *parm)
 {
-	return NULL;
+	return nullptr;
 }
 
 void MusicDriver_BeMidi::Stop()
diff --git a/src/music/cocoa_m.cpp b/src/music/cocoa_m.cpp
index 2416cade0..c27a0a092 100644
--- a/src/music/cocoa_m.cpp
+++ b/src/music/cocoa_m.cpp
@@ -35,8 +35,8 @@
 static FMusicDriver_Cocoa iFMusicDriver_Cocoa;
 
 
-static MusicPlayer    _player = NULL;
-static MusicSequence  _sequence = NULL;
+static MusicPlayer    _player = nullptr;
+static MusicSequence  _sequence = nullptr;
 static MusicTimeStamp _seq_length = 0;
 static bool           _playing = false;
 static byte           _volume = 127;
@@ -45,12 +45,12 @@ static byte           _volume = 127;
 /** Set the volume of the current sequence. */
 static void DoSetVolume()
 {
-	if (_sequence == NULL) return;
+	if (_sequence == nullptr) return;
 
 	AUGraph graph;
 	MusicSequenceGetAUGraph(_sequence, &graph);
 
-	AudioUnit output_unit = NULL;
+	AudioUnit output_unit = nullptr;
 
 	/* Get output audio unit */
 	UInt32 node_count = 0;
@@ -82,7 +82,7 @@ static void DoSetVolume()
 		{
 #if (MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_5)
 			ComponentDescription desc;
-			AUGraphGetNodeInfo(graph, node, &desc, NULL, NULL, &unit);
+			AUGraphGetNodeInfo(graph, node, &desc, nullptr, nullptr, &unit);
 			comp_type = desc.componentType;
 #endif
 		}
@@ -92,7 +92,7 @@ static void DoSetVolume()
 			break;
 		}
 	}
-	if (output_unit == NULL) {
+	if (output_unit == nullptr) {
 		DEBUG(driver, 1, "cocoa_m: Failed to get output node to set volume");
 		return;
 	}
@@ -109,7 +109,7 @@ const char *MusicDriver_Cocoa::Start(const char * const *parm)
 {
 	if (NewMusicPlayer(&_player) != noErr) return "failed to create music player";
 
-	return NULL;
+	return nullptr;
 }
 
 
@@ -131,8 +131,8 @@ bool MusicDriver_Cocoa::IsSongPlaying()
  */
 void MusicDriver_Cocoa::Stop()
 {
-	if (_player != NULL) DisposeMusicPlayer(_player);
-	if (_sequence != NULL) DisposeMusicSequence(_sequence);
+	if (_player != nullptr) DisposeMusicPlayer(_player);
+	if (_sequence != nullptr) DisposeMusicSequence(_sequence);
 }
 
 
@@ -148,9 +148,9 @@ void MusicDriver_Cocoa::PlaySong(const MusicSongInfo &song)
 	DEBUG(driver, 2, "cocoa_m: trying to play '%s'", filename.c_str());
 
 	this->StopSong();
-	if (_sequence != NULL) {
+	if (_sequence != nullptr) {
 		DisposeMusicSequence(_sequence);
-		_sequence = NULL;
+		_sequence = nullptr;
 	}
 
 	if (filename.empty()) return;
@@ -190,7 +190,7 @@ void MusicDriver_Cocoa::PlaySong(const MusicSongInfo &song)
 	CFRelease(url);
 
 	/* Construct audio graph */
-	AUGraph graph = NULL;
+	AUGraph graph = nullptr;
 
 	MusicSequenceGetAUGraph(_sequence, &graph);
 	AUGraphOpen(graph);
@@ -204,7 +204,7 @@ void MusicDriver_Cocoa::PlaySong(const MusicSongInfo &song)
 	MusicSequenceGetTrackCount(_sequence, &num_tracks);
 	_seq_length = 0;
 	for (UInt32 i = 0; i < num_tracks; i++) {
-		MusicTrack     track = NULL;
+		MusicTrack     track = nullptr;
 		MusicTimeStamp track_length = 0;
 		UInt32         prop_size = sizeof(MusicTimeStamp);
 		MusicSequenceGetIndTrack(_sequence, i, &track);
@@ -230,7 +230,7 @@ void MusicDriver_Cocoa::PlaySong(const MusicSongInfo &song)
 void MusicDriver_Cocoa::StopSong()
 {
 	MusicPlayerStop(_player);
-	MusicPlayerSetSequence(_player, NULL);
+	MusicPlayerSetSequence(_player, nullptr);
 	_playing = false;
 }
 
diff --git a/src/music/dmusic.cpp b/src/music/dmusic.cpp
index bf8657ef4..41ccd6102 100644
--- a/src/music/dmusic.cpp
+++ b/src/music/dmusic.cpp
@@ -141,16 +141,16 @@ static struct {
 /** Handle to our worker thread. */
 static std::thread _dmusic_thread;
 /** Event to signal the thread that it should look at a state change. */
-static HANDLE _thread_event = NULL;
+static HANDLE _thread_event = nullptr;
 /** Lock access to playback data that is not thread-safe. */
 static std::mutex _thread_mutex;
 
 /** The direct music object manages buffers and ports. */
-static IDirectMusic *_music = NULL;
+static IDirectMusic *_music = nullptr;
 /** The port object lets us send MIDI data to the synthesizer. */
-static IDirectMusicPort *_port = NULL;
+static IDirectMusicPort *_port = nullptr;
 /** The buffer object collects the data to sent. */
-static IDirectMusicBuffer *_buffer = NULL;
+static IDirectMusicBuffer *_buffer = nullptr;
 /** List of downloaded DLS instruments. */
 static std::vector<IDirectMusicDownload *> _dls_downloads;
 
@@ -438,7 +438,7 @@ bool DLSFile::LoadFile(const TCHAR *file)
 	DEBUG(driver, 2, "DMusic: Try to load DLS file %s", FS2OTTD(file));
 
 	FILE *f = _tfopen(file, _T("rb"));
-	if (f == NULL) return false;
+	if (f == nullptr) return false;
 
 	FileCloser f_scope(f);
 
@@ -879,13 +879,13 @@ static const char *LoadDefaultDLSFile(const char *user_dls)
 	if ((caps.dwFlags & (DMUS_PC_DLS | DMUS_PC_DLS2)) != 0 && (caps.dwFlags & DMUS_PC_GMINHARDWARE) == 0) {
 		DLSFile dls_file;
 
-		if (user_dls == NULL) {
+		if (user_dls == nullptr) {
 			/* Try loading the default GM DLS file stored in the registry. */
 			HKEY hkDM;
 			if (SUCCEEDED(RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("Software\\Microsoft\\DirectMusic"), 0, KEY_READ, &hkDM))) {
 				TCHAR dls_path[MAX_PATH];
 				DWORD buf_size = sizeof(dls_path); // Buffer size as to be given in bytes!
-				if (SUCCEEDED(RegQueryValueEx(hkDM, _T("GMFilePath"), NULL, NULL, (LPBYTE)dls_path, &buf_size))) {
+				if (SUCCEEDED(RegQueryValueEx(hkDM, _T("GMFilePath"), nullptr, nullptr, (LPBYTE)dls_path, &buf_size))) {
 					TCHAR expand_path[MAX_PATH * 2];
 					ExpandEnvironmentStrings(dls_path, expand_path, lengthof(expand_path));
 					if (!dls_file.LoadFile(expand_path)) DEBUG(driver, 1, "Failed to load default GM DLS file from registry");
@@ -906,7 +906,7 @@ static const char *LoadDefaultDLSFile(const char *user_dls)
 		}
 
 		/* Get download port and allocate download IDs. */
-		IDirectMusicPortDownload *download_port = NULL;
+		IDirectMusicPortDownload *download_port = nullptr;
 		if (FAILED(_port->QueryInterface(IID_IDirectMusicPortDownload, (LPVOID *)&download_port))) return "Can't get download port";
 
 		DWORD dlid_wave = 0, dlid_inst = 0;
@@ -920,7 +920,7 @@ static const char *LoadDefaultDLSFile(const char *user_dls)
 
 		/* Download wave data. */
 		for (DWORD i = 0; i < dls_file.waves.size(); i++) {
-			IDirectMusicDownload *dl_wave = NULL;
+			IDirectMusicDownload *dl_wave = nullptr;
 			if (FAILED(download_port->AllocateBuffer((DWORD)(sizeof(WAVE_DOWNLOAD) + dwAppend * dls_file.waves[i].fmt.wf.nBlockAlign + dls_file.waves[i].data.size()), &dl_wave))) {
 				download_port->Release();
 				return "Can't allocate wave download buffer";
@@ -984,7 +984,7 @@ static const char *LoadDefaultDLSFile(const char *user_dls)
 			i_size += offsets * sizeof(ULONG);
 
 			/* Allocate download buffer. */
-			IDirectMusicDownload *dl_inst = NULL;
+			IDirectMusicDownload *dl_inst = nullptr;
 			if (FAILED(download_port->AllocateBuffer((DWORD)i_size, &dl_inst))) {
 				download_port->Release();
 				return "Can't allocate instrument download buffer";
@@ -1085,19 +1085,19 @@ static const char *LoadDefaultDLSFile(const char *user_dls)
 		download_port->Release();
 	}
 
-	return NULL;
+	return nullptr;
 }
 
 
 const char *MusicDriver_DMusic::Start(const char * const *parm)
 {
 	/* Initialize COM */
-	if (FAILED(CoInitializeEx(NULL, COINITBASE_MULTITHREADED))) return "COM initialization failed";
+	if (FAILED(CoInitializeEx(nullptr, COINITBASE_MULTITHREADED))) return "COM initialization failed";
 
 	/* Create the DirectMusic object */
 	if (FAILED(CoCreateInstance(
 				CLSID_DirectMusic,
-				NULL,
+				nullptr,
 				CLSCTX_INPROC,
 				IID_IDirectMusic,
 				(LPVOID*)&_music
@@ -1106,7 +1106,7 @@ const char *MusicDriver_DMusic::Start(const char * const *parm)
 	}
 
 	/* Assign sound output device. */
-	if (FAILED(_music->SetDirectSound(NULL, NULL))) return "Can't set DirectSound interface";
+	if (FAILED(_music->SetDirectSound(nullptr, nullptr))) return "Can't set DirectSound interface";
 
 	/* MIDI events need to be send to the synth in time before their playback time
 	 * has come. By default, we try send any events at least 50 ms before playback. */
@@ -1149,7 +1149,7 @@ const char *MusicDriver_DMusic::Start(const char * const *parm)
 	params.dwSize = sizeof(DMUS_PORTPARAMS);
 	params.dwValidParams = DMUS_PORTPARAMS_CHANNELGROUPS;
 	params.dwChannelGroups = 1;
-	if (FAILED(_music->CreatePort(guidPort, &params, &_port, NULL))) return "Failed to create port";
+	if (FAILED(_music->CreatePort(guidPort, &params, &_port, nullptr))) return "Failed to create port";
 	/* Activate port. */
 	if (FAILED(_port->Activate(TRUE))) return "Failed to activate port";
 
@@ -1159,19 +1159,19 @@ const char *MusicDriver_DMusic::Start(const char * const *parm)
 	desc.dwSize = sizeof(DMUS_BUFFERDESC);
 	desc.guidBufferFormat = KSDATAFORMAT_SUBTYPE_DIRECTMUSIC;
 	desc.cbBuffer = 1024;
-	if (FAILED(_music->CreateMusicBuffer(&desc, &_buffer, NULL))) return "Failed to create music buffer";
+	if (FAILED(_music->CreateMusicBuffer(&desc, &_buffer, nullptr))) return "Failed to create music buffer";
 
 	/* On soft-synths (e.g. the default DirectMusic one), we might need to load a wavetable set to get music. */
 	const char *dls = LoadDefaultDLSFile(GetDriverParam(parm, "dls"));
-	if (dls != NULL) return dls;
+	if (dls != nullptr) return dls;
 
 	/* Create playback thread and synchronization primitives. */
-	_thread_event = CreateEvent(NULL, FALSE, FALSE, NULL);
-	if (_thread_event == NULL) return "Can't create thread shutdown event";
+	_thread_event = CreateEvent(nullptr, FALSE, FALSE, nullptr);
+	if (_thread_event == nullptr) return "Can't create thread shutdown event";
 
 	if (!StartNewThread(&_dmusic_thread, "ottd:dmusic", &MidiThreadProc)) return "Can't create MIDI output thread";
 
-	return NULL;
+	return nullptr;
 }
 
 
@@ -1191,34 +1191,34 @@ void MusicDriver_DMusic::Stop()
 
 	/* Unloaded any instruments we loaded. */
 	if (_dls_downloads.size() > 0) {
-		IDirectMusicPortDownload *download_port = NULL;
+		IDirectMusicPortDownload *download_port = nullptr;
 		_port->QueryInterface(IID_IDirectMusicPortDownload, (LPVOID *)&download_port);
 
 		/* Instruments refer to waves. As the waves are at the beginning of the download list,
 		 * do the unload from the back so that references are cleared properly. */
-		for (std::vector<IDirectMusicDownload *>::reverse_iterator i = _dls_downloads.rbegin(); download_port != NULL && i != _dls_downloads.rend(); i++) {
+		for (std::vector<IDirectMusicDownload *>::reverse_iterator i = _dls_downloads.rbegin(); download_port != nullptr && i != _dls_downloads.rend(); i++) {
 			download_port->Unload(*i);
 			(*i)->Release();
 		}
 		_dls_downloads.clear();
 
-		if (download_port != NULL) download_port->Release();
+		if (download_port != nullptr) download_port->Release();
 	}
 
-	if (_buffer != NULL) {
+	if (_buffer != nullptr) {
 		_buffer->Release();
-		_buffer = NULL;
+		_buffer = nullptr;
 	}
 
-	if (_port != NULL) {
+	if (_port != nullptr) {
 		_port->Activate(FALSE);
 		_port->Release();
-		_port = NULL;
+		_port = nullptr;
 	}
 
-	if (_music != NULL) {
+	if (_music != nullptr) {
 		_music->Release();
-		_music = NULL;
+		_music = nullptr;
 	}
 
 	CloseHandle(_thread_event);
diff --git a/src/music/extmidi.cpp b/src/music/extmidi.cpp
index f7fc454df..b390c42f5 100644
--- a/src/music/extmidi.cpp
+++ b/src/music/extmidi.cpp
@@ -52,7 +52,7 @@ const char *MusicDriver_ExtMidi::Start(const char * const * parm)
 	if (StrEmpty(command)) command = EXTERNAL_PLAYER " " MIDI_ARG;
 #endif
 
-	/* Count number of arguments, but include 3 extra slots: 1st for command, 2nd for song title, and 3rd for terminating NULL. */
+	/* Count number of arguments, but include 3 extra slots: 1st for command, 2nd for song title, and 3rd for terminating nullptr. */
 	uint num_args = 3;
 	for (const char *t = command; *t != '\0'; t++) if (*t == ' ') num_args++;
 
@@ -63,7 +63,7 @@ const char *MusicDriver_ExtMidi::Start(const char * const * parm)
 	uint p = 1;
 	while (true) {
 		this->params[p] = strchr(this->params[p - 1], ' ');
-		if (this->params[p] == NULL) break;
+		if (this->params[p] == nullptr) break;
 
 		this->params[p][0] = '\0';
 		this->params[p]++;
@@ -75,7 +75,7 @@ const char *MusicDriver_ExtMidi::Start(const char * const * parm)
 
 	this->song[0] = '\0';
 	this->pid = -1;
-	return NULL;
+	return nullptr;
 }
 
 void MusicDriver_ExtMidi::Stop()
@@ -103,7 +103,7 @@ void MusicDriver_ExtMidi::StopSong()
 
 bool MusicDriver_ExtMidi::IsSongPlaying()
 {
-	if (this->pid != -1 && waitpid(this->pid, NULL, WNOHANG) == this->pid) {
+	if (this->pid != -1 && waitpid(this->pid, nullptr, WNOHANG) == this->pid) {
 		this->pid = -1;
 	}
 	if (this->pid == -1 && this->song[0] != '\0') this->DoPlay();
@@ -146,7 +146,7 @@ void MusicDriver_ExtMidi::DoStop()
 	 * 5 seconds = 5000 milliseconds, 10 ms per cycle => 500 cycles. */
 	for (int i = 0; i < 500; i++) {
 		kill(this->pid, SIGTERM);
-		if (waitpid(this->pid, NULL, WNOHANG) == this->pid) {
+		if (waitpid(this->pid, nullptr, WNOHANG) == this->pid) {
 			/* It has shut down, so we are done */
 			this->pid = -1;
 			return;
@@ -159,6 +159,6 @@ void MusicDriver_ExtMidi::DoStop()
 	/* Gracefully stopping failed. Do it the hard way
 	 * and wait till the process finally died. */
 	kill(this->pid, SIGKILL);
-	waitpid(this->pid, NULL, 0);
+	waitpid(this->pid, nullptr, 0);
 	this->pid = -1;
 }
diff --git a/src/music/fluidsynth.cpp b/src/music/fluidsynth.cpp
index 49e50eb9e..4623716a4 100644
--- a/src/music/fluidsynth.cpp
+++ b/src/music/fluidsynth.cpp
@@ -39,7 +39,7 @@ static const char *default_sf[] = {
 	"/usr/share/sounds/sf2/TimGM6mb.sf2",
 	"/usr/share/sounds/sf2/FluidR3_GS.sf2",
 
-	NULL
+	nullptr
 };
 
 static void RenderMusicStream(int16 *buffer, size_t samples)
@@ -81,18 +81,18 @@ const char *MusicDriver_FluidSynth::Start(const char * const *param)
 		if (sfont_id == FLUID_FAILED) return "Could not open sound font";
 	}
 
-	_midi.player = NULL;
+	_midi.player = nullptr;
 
 	uint32 samplerate = MxSetMusicSource(RenderMusicStream);
 	fluid_synth_set_sample_rate(_midi.synth, samplerate);
 	DEBUG(driver, 1, "Fluidsynth: samplerate %.0f", (float)samplerate);
 
-	return NULL;
+	return nullptr;
 }
 
 void MusicDriver_FluidSynth::Stop()
 {
-	MxSetMusicSource(NULL);
+	MxSetMusicSource(nullptr);
 	this->StopSong();
 	delete_fluid_synth(_midi.synth);
 	delete_fluid_settings(_midi.settings);
@@ -117,13 +117,13 @@ void MusicDriver_FluidSynth::PlaySong(const MusicSongInfo &song)
 	if (fluid_player_add(_midi.player, filename.c_str()) != FLUID_OK) {
 		DEBUG(driver, 0, "Could not open music file");
 		delete_fluid_player(_midi.player);
-		_midi.player = NULL;
+		_midi.player = nullptr;
 		return;
 	}
 	if (fluid_player_play(_midi.player) != FLUID_OK) {
 		DEBUG(driver, 0, "Could not start midi player");
 		delete_fluid_player(_midi.player);
-		_midi.player = NULL;
+		_midi.player = nullptr;
 		return;
 	}
 }
@@ -138,7 +138,7 @@ void MusicDriver_FluidSynth::StopSong()
 	}
 	delete_fluid_player(_midi.player);
 	fluid_synth_system_reset(_midi.synth);
-	_midi.player = NULL;
+	_midi.player = nullptr;
 }
 
 bool MusicDriver_FluidSynth::IsSongPlaying()
diff --git a/src/music/midifile.cpp b/src/music/midifile.cpp
index 97fb2edf8..3717ad5d3 100644
--- a/src/music/midifile.cpp
+++ b/src/music/midifile.cpp
@@ -24,7 +24,7 @@
 /* SMF reader based on description at: http://www.somascape.org/midi/tech/mfile.html */
 
 
-static MidiFile *_midifile_instance = NULL;
+static MidiFile *_midifile_instance = nullptr;
 
 /**
  * Owning byte buffer readable as a stream.
@@ -426,7 +426,7 @@ bool MidiFile::LoadFile(const char *filename)
 
 	bool success = false;
 	FILE *file = FioFOpenFile(filename, "rb", Subdirectory::BASESET_DIR);
-	if (file == NULL) return false;
+	if (file == nullptr) return false;
 
 	SMFHeader header;
 	if (!ReadSMFHeader(file, header)) goto cleanup;
@@ -815,7 +815,7 @@ bool MidiFile::LoadSong(const MusicSongInfo &song)
 		{
 			size_t songdatalen = 0;
 			byte *songdata = GetMusicCatEntryData(song.filename, song.cat_index, songdatalen);
-			if (songdata != NULL) {
+			if (songdata != nullptr) {
 				bool result = this->LoadMpsData(songdata, songdatalen);
 				free(songdata);
 				return result;
@@ -1024,7 +1024,7 @@ std::string MidiFile::GetSMFFile(const MusicSongInfo &song)
 	char basename[MAX_PATH];
 	{
 		const char *fnstart = strrchr(song.filename, PATHSEPCHAR);
-		if (fnstart == NULL) {
+		if (fnstart == nullptr) {
 			fnstart = song.filename;
 		} else {
 			fnstart++;
@@ -1054,7 +1054,7 @@ std::string MidiFile::GetSMFFile(const MusicSongInfo &song)
 	byte *data;
 	size_t datalen;
 	data = GetMusicCatEntryData(song.filename, song.cat_index, datalen);
-	if (data == NULL) return std::string();
+	if (data == nullptr) return std::string();
 
 	MidiFile midifile;
 	if (!midifile.LoadMpsData(data, datalen)) {
@@ -1082,7 +1082,7 @@ static bool CmdDumpSMF(byte argc, char *argv[])
 		return false;
 	}
 
-	if (_midifile_instance == NULL) {
+	if (_midifile_instance == nullptr) {
 		IConsolePrint(CC_ERROR, "There is no MIDI file loaded currently, make sure music is playing, and you're using a driver that works with raw MIDI.");
 		return false;
 	}
@@ -1120,7 +1120,7 @@ MidiFile::MidiFile()
 MidiFile::~MidiFile()
 {
 	if (_midifile_instance == this) {
-		_midifile_instance = NULL;
+		_midifile_instance = nullptr;
 	}
 }
 
diff --git a/src/music/null_m.h b/src/music/null_m.h
index 837eeb092..8eb7d6792 100644
--- a/src/music/null_m.h
+++ b/src/music/null_m.h
@@ -17,7 +17,7 @@
 /** The music player that does nothing. */
 class MusicDriver_Null : public MusicDriver {
 public:
-	const char *Start(const char * const *param) override { return NULL; }
+	const char *Start(const char * const *param) override { return nullptr; }
 
 	void Stop() override { }
 
diff --git a/src/music/os2_m.cpp b/src/music/os2_m.cpp
index 1689f00a6..92e177f84 100644
--- a/src/music/os2_m.cpp
+++ b/src/music/os2_m.cpp
@@ -45,7 +45,7 @@ static long CDECL MidiSendCommand(const char *cmd, ...)
 	va_start(va, cmd);
 	vseprintf(buf, lastof(buf), cmd, va);
 	va_end(va);
-	return mciSendString(buf, NULL, 0, NULL, 0);
+	return mciSendString(buf, nullptr, 0, nullptr, 0);
 }
 
 /** OS/2's music player's factory. */
@@ -78,7 +78,7 @@ void MusicDriver_OS2::SetVolume(byte vol)
 bool MusicDriver_OS2::IsSongPlaying()
 {
 	char buf[16];
-	mciSendString("status song mode", buf, sizeof(buf), NULL, 0);
+	mciSendString("status song mode", buf, sizeof(buf), nullptr, 0);
 	return strcmp(buf, "playing") == 0 || strcmp(buf, "seeking") == 0;
 }
 
diff --git a/src/music/qtmidi.cpp b/src/music/qtmidi.cpp
index f8ab150e7..f8412a2dc 100644
--- a/src/music/qtmidi.cpp
+++ b/src/music/qtmidi.cpp
@@ -60,7 +60,7 @@ static void SetMIDITypeIfNeeded(const FSRef *ref)
 
 	assert(ref);
 
-	if (noErr != FSGetCatalogInfo(ref, kFSCatInfoNodeFlags | kFSCatInfoFinderInfo, &catalogInfo, NULL, NULL, NULL)) return;
+	if (noErr != FSGetCatalogInfo(ref, kFSCatInfoNodeFlags | kFSCatInfoFinderInfo, &catalogInfo, nullptr, nullptr, nullptr)) return;
 	if (!(catalogInfo.nodeFlags & kFSNodeIsDirectoryMask)) {
 		FileInfo * const info = (FileInfo *) catalogInfo.finderInfo;
 		if (info->fileType != MIDI_TYPE && !(info->finderFlags & kIsAlias)) {
@@ -94,8 +94,8 @@ static bool LoadMovieForMIDIFile(const char *path, Movie *moov)
 	short refnum = 0;
 	short resid  = 0;
 
-	assert(path != NULL);
-	assert(moov != NULL);
+	assert(path != nullptr);
+	assert(moov != nullptr);
 
 	DEBUG(driver, 2, "qtmidi: start loading '%s'...", path);
 
@@ -116,15 +116,15 @@ static bool LoadMovieForMIDIFile(const char *path, Movie *moov)
 		return false;
 	}
 
-	if (noErr != FSPathMakeRef((const UInt8 *) path, &fsref, NULL)) return false;
+	if (noErr != FSPathMakeRef((const UInt8 *) path, &fsref, nullptr)) return false;
 	SetMIDITypeIfNeeded(&fsref);
 
-	if (noErr != FSGetCatalogInfo(&fsref, kFSCatInfoNone, NULL, NULL, &fsspec, NULL)) return false;
+	if (noErr != FSGetCatalogInfo(&fsref, kFSCatInfoNone, nullptr, nullptr, &fsspec, nullptr)) return false;
 	if (OpenMovieFile(&fsspec, &refnum, fsRdPerm) != noErr) return false;
 	DEBUG(driver, 3, "qtmidi: '%s' successfully opened", path);
 
-	if (noErr != NewMovieFromFile(moov, refnum, &resid, NULL,
-				newMovieActive | newMovieDontAskUnresolvedDataRefs, NULL)) {
+	if (noErr != NewMovieFromFile(moov, refnum, &resid, nullptr,
+				newMovieActive | newMovieDontAskUnresolvedDataRefs, nullptr)) {
 		CloseMovieFile(refnum);
 		return false;
 	}
@@ -191,7 +191,7 @@ static int   _quicktime_state  = QT_STATE_IDLE; ///< Current player state.
 const char *MusicDriver_QtMidi::Start(const char * const *parm)
 {
 	InitQuickTimeIfNeeded();
-	return (_quicktime_started) ? NULL : "can't initialize QuickTime";
+	return (_quicktime_started) ? nullptr : "can't initialize QuickTime";
 }
 
 
@@ -215,7 +215,7 @@ bool MusicDriver_QtMidi::IsSongPlaying()
 			MoviesTask(_quicktime_movie, 0);
 			/* Check wether movie ended. */
 			if (IsMovieDone(_quicktime_movie) ||
-					(GetMovieTime(_quicktime_movie, NULL) >=
+					(GetMovieTime(_quicktime_movie, nullptr) >=
 					 GetMovieDuration(_quicktime_movie))) {
 				_quicktime_state = QT_STATE_STOP;
 			}
diff --git a/src/music/win32_m.cpp b/src/music/win32_m.cpp
index bdba202f2..de5facd48 100644
--- a/src/music/win32_m.cpp
+++ b/src/music/win32_m.cpp
@@ -396,7 +396,7 @@ const char *MusicDriver_Win32::Start(const char * const *parm)
 		if (timeBeginPeriod(_midi.time_period) == MMSYSERR_NOERROR) {
 			/* success */
 			DEBUG(driver, 2, "Win32-MIDI: Start: timer resolution is %d", (int)_midi.time_period);
-			return NULL;
+			return nullptr;
 		}
 	}
 	midiOutClose(_midi.midi_out);