(svn r2685) -Codechange: Split the music/sound/video drivers into separate files and move them into subfolders.

This results in shorter and hopefully easier to maintain files.
Note: I had to change paths in #include statements of some unrelated files, because I added the ottd base directory to the include path (-I.)

music/extmidi.c

@@ -0,0 +1,112 @@
+#ifndef __BEOS__
+#ifndef __MORPHOS__
+#include "stdafx.h"
+
+#include "openttd.h"
+#include "music/extmidi.h"
+#include "sound.h"
+#include "string.h"
+#include "variables.h"
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <errno.h>
+
+static struct {
+	char song[MAX_PATH];
+	int pid;
+} _midi;
+
+static void DoPlay(void);
+static void DoStop(void);
+
+static const char* ExtMidiStart(const char* const * parm)
+{
+	_midi.song[0] = '\0';
+	_midi.pid = -1;
+	return NULL;
+}
+
+static void ExtMidiStop(void)
+{
+	_midi.song[0] = '\0';
+	DoStop();
+}
+
+static void ExtMidiPlaySong(const char* filename)
+{
+	ttd_strlcpy(_midi.song, filename, lengthof(_midi.song));
+	DoStop();
+}
+
+static void ExtMidiStopSong(void)
+{
+	_midi.song[0] = '\0';
+	DoStop();
+}
+
+static bool ExtMidiIsPlaying(void)
+{
+	if (_midi.pid != -1 && waitpid(_midi.pid, NULL, WNOHANG) == _midi.pid)
+		_midi.pid = -1;
+	if (_midi.pid == -1 && _midi.song[0] != '\0') DoPlay();
+	return _midi.pid != -1;
+}
+
+static void ExtMidiSetVolume(byte vol)
+{
+	fprintf(stderr, "extmidi: set volume not implemented\n");
+}
+
+static void DoPlay(void)
+{
+	_midi.pid = fork();
+	switch (_midi.pid) {
+		case 0: {
+			int d;
+
+			close(0);
+			close(1);
+			close(2);
+			d = open("/dev/null", O_RDONLY);
+			if (d != -1) {
+				if (dup2(d, 1) != -1 && dup2(d, 2) != -1) {
+					#if defined(MIDI_ARG)
+						execlp(msf.extmidi, "extmidi", MIDI_ARG, _midi.song, NULL);
+					#else
+						execlp(msf.extmidi, "extmidi", _midi.song, NULL);
+					#endif
+				}
+			}
+			exit(1);
+		}
+
+		case -1:
+			fprintf(stderr, "extmidi: couldn't fork: %s\n", strerror(errno));
+			/* FALLTHROUGH */
+
+		default:
+			_midi.song[0] = '\0';
+			break;
+	}
+}
+
+static void DoStop(void)
+{
+	if (_midi.pid != -1) kill(_midi.pid, SIGTERM);
+}
+
+const HalMusicDriver _extmidi_music_driver = {
+	ExtMidiStart,
+	ExtMidiStop,
+	ExtMidiPlaySong,
+	ExtMidiStopSong,
+	ExtMidiIsPlaying,
+	ExtMidiSetVolume,
+};
+
+#endif /* __MORPHOS__ */
+#endif /* __BEOS__ */