Apple's MIDI Manager

By Don Veca, San Jose, CA

Introduction

The MIDI Manager is Apple’s new standard MIDI tool set. It enables developers to cleanly transfer MIDI data to and from synthesizers and other concurrently running applications. It supplies a complete MIDI tool set which is as powerful as any existing implementation, yet strictly adheres to system guidelines. Included with the MIDI Manager are the Apple MIDI Driver and PatchBay.

The Apple MIDI Driver interprets all incoming and out going MIDI messages and handles all serial port I/O. This includes various modes of time code generation and concurrent asynchronous serial port communication. PatchBay is Apple’s graphical user interface for the MIDI Manager. Supplied as a utility application and a Desk Accessory, PatchBay enables users to intuitively route MIDI data and time code to and from the Apple MIDI Driver as well as throughout multiple applications running under Multifinder. The MIDI Manager proper, however, supplies all internal communications and supplies a thorough and very powerful MIDI tool set.

Main Concepts

From the music software developer’s point of view, the main components of the MIDI Manager are clients and ports. A client is any program that uses the MIDI Manager’s facilities. Although an application usually needs only one client, it can actually have several. Each client can, and usually does, create multiple ports which are basically unidirectional streams of MIDI information. Each port can be either a time port, which provides the MIDI Manager’s timing facilities, or a data port, which is used to read or write MIDI packets. The data ports are further divided into input and output ports. A client’s ports can be connected to one of its own ports or to any other client’s ports; however, input ports can only be connected to output ports (and vice versa). Time ports enable port synchronization: when a time port’s clock ticks, all clocks of all ports connected to it tick synchronously. Data ports send and receive MIDI data such as note-on/note-off or system exclusive messages. Input and output ports respectively receive and send MIDI data to the ports of MIDI drivers or other MIDI Manager compatible applications running concurrently under Multifinder. We will now illustrate the proper use of the MIDI Manager through the explanation of a sample application called MIDIArp.

The MIDIArp Demo Application

MIDIArp is a simple arpeggiator program [tone generator for those who are not blessed with a huge vocabulary like Don’s. -ed] that illustrates the use of the MIDI Manager’s data and timing facilities. MIDIArp simply reads in note-on data and arpeggiates it until corresponding note-off data is received. The basic flow of MIDIArp is quite simple: after MIDIArp initializes the various Macintosh Managers, it signs into the MIDI Manager, calls a routine to set up its time, input, and output ports, pops up its main dialog box, and cycles through its main event loop. The main event loop simply checks for user (console) input, and adjusts its arpeggio direction and speed parameters accordingly. Once the quit button is selected, MIDIArp signs out from the MIDI Manager and terminates. During the main event loop, however, MIDIArp continually arpeggiates its MIDI input at interrupt level via its readHook and timeProc routines.

MIDIArp.h

MIDIArp includes a header file, MIDIArp.h, which contains its main data structures and symbolic constants. In addition to the standard user interface constants for menu and dialog resource ID’s, constants are defined to identify our own resource of type ‘port’. We define three such ‘port’ resources: one for each MIDI Manager port we intend to use. This is necessary in order to save the state of our patch between each launch of the application. For readability, several MIDIArp constants are defined followed by several constants local to the MIDI Manager itself. Specifically, we define our client and ‘ICN#’ resource ID, both of which are used to sign in to the MIDI Manager. The client ID is a four-byte OSType (and by convention, although not by necessity, our client ID is used as our application signature). We then define our port ID’s which are also of type OSType. The actual ports will be displayed by PatchBay from top to bottom in ascending alphabetical order. (It is recommended that time ports be displayed above the data ports that are synchronized to them, and that an application’s input and output ports be displayed in the reverse order of that used by the Apple MIDI Driver.)

After several MIDI Manager parameters are symbolically defined, we define our main data structures. The first data structure that we will need is a NoteInfo record which contains fields to store the MIDI channel, key number, and key velocity of each incoming note-on message. The NoteInfo record is itself an individual field of the main MIDIArp data structure ArpParams. The ArpParams structure contains various fields of information concerning the current state of the MIDIArp client. In particular, it contains a field called Locked, which is used to prevent the structure from being modified while it is in use. Incoming MIDI data (notes that MIDIArp is currently arpeggiating) are stored in an array of NoteInfo records called NoteTbl. Other fields hold information about things such as tempo and current arpeggiation pattern (e.g., whether we are currently going up or down, etc.). NextNoteOn is a field used to keep track of the exact time the next note is to be played. Finally, the ArpParams structure allows the storage of each port’s reference number.

MIDIArp.c

The main source file for MIDIArp is MIDIArp.c. Here we first define several global variables, including an ArpParams record called ArpGlobals, a variable to hold our current arpeggiation speed ID, and a flag (GManualPatch) to indicate whether the current port configuration (patch) has been set up by a (previously saved) PatchBay patch or needs to be reconfigured by MIDIArp itself (based on its last configuration). The main() routine of MIDIArp calls InitThings() to initialize the Macintosh Managers, ArpInit() which signs-in to the MIDI Manager and sets up our ports, StartDialog() to bring up the main dialog box with default settings, and then RunDialog() to handle events. When the Quit button is finally hit, ArpClose() is called to sign-out from the MIDI Manager, and the main dialog box is shut down through a call to StopDialog(). InitThings(), in addition to initializing the various managers of the Macintosh, sets up a standard menu bar and seeds the random number generator for random arpeggiation. ArpInit(), on the other hand, completely sets up MIDIArp’s MIDI Manager environment. In order to use the MIDI Manager we must first make sure that it is currently installed. This is achieved through a call to SndDispVersion() (sound dispatch version). Given the constant midiToolNum, SndDispVersion() returns the version of the currently installed MIDI Manager or zero if the MIDI Manager is not installed. Once we have concluded that the MIDI Manager is installed, we must sign in to the MIDI Manager (before we make any other calls) by calling MIDISignIn(). We pass as arguments to MIDISignIn() our client ID, our client reference constant, a handle to our ‘ICN#’ resource, and our client name string. The client ID is used for future MIDI Manager calls and allows other clients, such as patchers, to get information about us. The client reference constant, or refCon, is a general purpose parameter that is only really needed by certain types of applications (such as device drivers). The handle to the ‘ICN#’ resource and the client name string are passed to allow PatchBay (or any other clients) to display them via MIDIGetClientIcon() and MIDIGetClientName(), respectively.

The next thing we do in ArpInit() is add our time, input, and output ports via MIDIAddPort() and connect them accordingly. The tricky part is determining whether the ports will automatically be connected via a saved PatchBay patch, or whether we must connect them ourselves. Therefore, we set the global flag GManualPatch to true before we add any ports allowing us to determine by the return value of MIDIAddPort() whether or not we need to connect the ports ourselves. If MIDIAddPort() returns midiVConnectMade (virtual connection resolved), then we know that the ports were virtually connected by someone else via MIDIConnectTime() or MIDIConnectData(). In this case we simply set GManualPatch to false indicating that we do not have to manually patch together the ports. If GManualPatch is still true after all ports have been added, then we will call PatchPorts() to do our own patching.

The first port we add in ArpInit() is our time port or time base. We do this by calling MIDIAddPort(). This call will create a new port with attributes as described in an InitParams data structure; therefore, we must first set one up. The init record contains various information including items such as the port ID, the port type (time, input, output, invisible time) the port’s readHook, the time format, port name, etc., and a port reference constant (refCon). If the port’s readHook routine is to be called at interrupt level, then the refCon can be used to store the contents of the application’s A5 register for global variable access. The same basic strategy is used for creating the input and output ports; however, MIDIArp by default wants its data ports to be sync’d to its time port. So before we actually add the port, we set the timeBase field of the InitParams record to our time port’s reference number (previously obtained when we added our time port).

Now that all the ports have been added, we check GManualPatch, and, if it’s still true, we call PatchPorts() to patch the ports as they were when we last quit. To reconfigure our port connections, we must read in the ‘port’ resource of each port. The port resource is nothing more than the saved result of MIDIGetPortInfo() from our last session. MIDIGetPortInfo() returns a handle to a record containing the port type, time base of the port, and a list of all its connections.

To reconfigure our time port, we first check its port info record (of its ‘port’ resource) to see if we should be sync’d to another client’s time base. If so, we call MIDIConnectTime(), connecting the external time port to our time port (slaving us to it). If the result of MIDIConnectTime() is midiVConnectErr, then the external port’s owner is not currently signed in; otherwise, we must set our sync mode to externalSync. Next, we check to see if we are supposed to be the time base of one or more external ports. If so, we connect our time port to each.

It’s a little less complicated to reconfigure our input and output ports. All we have to do is connect our input and output port to each of the ports listed in the PortInfo record contained in the corresponding ‘port’ resource. The last thing we need to do in ArpInit() is start our time port’s clock by calling MIDIStartTime(). Now that everything is set up, we simply cycle through our main event loop, waiting for the MIDI Manager to call our readHook routine with incoming MIDI data.

In addition to handling user events, the main event loop periodically checks to see if an external time base has suddenly been connected to us. This is achieved by first detecting that “something in MIDI Manager world has changed,” and then by checking our time port’s info record to see if the MIDI Manager reports that we currently have an external time base. This situation arises if another client attempts to connect themselves to us or if a user of a patcher program (such as Patchbay) manually connects an external time port to ours. We check for either event in our main event loop by calling MIDIWorldChanged(). If MIDIWorldChanged() returns true, then we know that something in the current world has changed; however, this could be caused by a client signing in or out, a port being added or removed, or a connection being made or removed. Therefore, we must call MIDIGetPortInfo() on our time port and check whether the returned port information record reports that we currently have an external time base. If so, we then set our time port to external sync via MIDISetSync(); otherwise, we set it back to midiInternalSync (in the case that we were currently in external sync mode). The only thing left now is to get and process incoming MIDI data; this operation is handled at interrupt level through use of a readHook and a timeProc routine.

Before jumping into the details, a general explanation of the interrupt level control flow of MIDIArp’s readHook and timeProc is needed. The readHook is called by the MIDI Manager whenever an incoming message becomes “current.” When the first note of an input sequence is sent to MIDIArp’s input port, the MIDI Manager calls MIDIArp’s readHook which then copies it into the application’s note table buffer and calls the timeProc to take care of the output. When called, the timeProc determines the next note in the note table to be played, writes out the selected note, and then tells the MIDI Manager exactly when to call the timeProc for the next output. In other words, the only time the MIDIArp application calls its timeProc is from within its readHook, and this is done only when it receives the first note of an input sequence. After that, the timeProc itself is responsible for setting up its next wake-up.

As summarized above, MIDIArp’s readHook ArpReader() reads all incoming data, and starts a series of timeProc wake-ups which create the arpeggiation effect. As you may recall, the refCon field of the initialization record of each port was set to point to our application’s global variables and passed as an argument to MIDIAddPort() when the port was originally created; additionally, the readHook field of the input port’s initialization record was set to the address of ArpReader(). When the MIDI Manager calls a port’s readHook, it passes two parameters: the next “current” MIDIPacket, and the port’s refCon value. Because the MIDI Manager calls ArpReader() at interrupt level, the readHook first sets up our A5 world. This is achieved by calling the System routine SetA5() with the refCon parameter. Since we will be modifying the note table in the ArpGlobals record, we must check whether any other routine is currently reading it by checking the Locked field. If it is locked, we simply return midiKeepPacket, which tells the MIDI Manager to save the new packet -- we’ll get it later. The packet is of interest to MIDIArp only if it is does not contain a MIDI Manager system specific message (indicated in the message type field of the flags byte), and does contain a note-on message. If these conditions are satisfied, then we set the return value to midiMorePacket, telling the MIDI Manager that we now have this packet and that we want the next one.

Before we actually return, however, we process the current packet. If the status byte in the packet indicates a note-on message, then we copy it into our note table and increment our current note count. If our note count is now equal to 1 (i.e., this is the first note of an arpeggio), then we call ArpTimeProc() to initiate an arpeggiation. (ArpTimeProc() is the routine that actually writes out the MIDI data.) If the status byte in the packet is a note-off message, however, we locate the matching note in the note table; and, if it’s still a valid note (it didn’t get “stolen”), then we simply delete it from the note table and decrement the table’s current note count NumNotes. (A note can get “stolen” if there are 32 notes in our note table and a new note that is lower than the highest note is inserted.) Finally, we restore the system’s A5 world and return.

As mentioned above, we call our timeProc ArpTimeProc() from our readHook ArpReader() when we get the first note of an arpeggiation series. However, it is quite common for the MIDI Manager to call a timeProc at interrupt level (per an application scheduled event that will be illustrated below). This can be set up by calling the MIDI Manager routine MIDIWakeUp() with several arguments which include the reference number of a specific time port, a time, a period, and a pointer to the timeProc. In this case, the MIDI Manager calls the timeProc with the time port’s current time and refCon.

When our readHook ArpReader() calls our timeProc ArpTimeProc(), however, it passes it the time stamp of the current MIDI packet (which in this case is not used) and the refCon parameter that was passed to ArpReader(). (The refCon of each port points to MIDIArp’s global variables.) Once in control, the timeProc again sets up MIDIArp’s A5 world via its refCon parameter (because it may be called by the MIDI Manager as well as from within the readHook). We then lock the ArpGlobals structure so that ArpReader() won’t disturb it. If at this time there are no notes in our note table, then we simply cancel any pending wake-ups and return. Otherwise, we bump the note table index to the next note to be played. However, we must avoid the special case where the first note of an arpeggio may unintentionally be played twice in a row. (For example, the arpeggiation pattern is “Up,” two notes are struck “at same time,” and the first note received is higher than the second note. The first note received gets index 0, noteTbleIndex is set to 0, and the note is played. When the next note is received, the previous note is moved to index 1, the new note is inserted into index 0, and the noteTblIndex is bumped to index 1, which is the note that gets played. This means that the first note will be perceived to be played twice!) To avoid this sequence of events, if the note that we played the last time the ArpTimeProc() was called (LastNote) is the same note as our new one, then we bump the note index once more. Now we can finally write out a note-on message by calling MIDIWritePacket(). And, because we know the duration of the note, we we can write out its corresponding note-off by simply adjusting the time stamp and calling MIDIWritePacket() again with the same packet. The MIDI Manager will make sure that the packet is actually written out at the specified time.

The last thing we do in ArpTimeProc() is schedule the time that the MIDI Manager should call ArpTimeProc() to write out the next note (this is what creates the arpeggio effect). We first set NextNoteOnTime to itself plus the value of Tempo; however, we want the ArpTimeProc() to be called (and write out the packet) soon enough before NextNoteOnTime such that the next call to MIDIWritePacket() will be before the packet’s time stamp expires. Although we call MIDIWritePacket() with an accurately time-stamped packet, we call it early to avoid the chance of the note being received late due to processing time. The basic rule of thumb is to always write early, making sure that the time stamp (which is some time in the future) is accurate. Finally, we unlock the ArpGlobals structure, restore the system’s A5 world, and return.

And that’s it! The readHook continues reading incoming MIDI data, and the timeProc continues scheduling it to be written out. This continues until the user hits the Quit button. When this happens, we call ArpClose() to save our current patch configuration into the applications ‘port’ resource and sign-out from the MIDI Manager.

How to Put It All Together

Before running MIDIArp, however, the MIDI Manager must be installed. Installation consists of nothing more than moving the MIDI Manager and Apple MIDI Driver files into the System folder and restarting the Macintosh. Once the MIDI Manager is installed, PatchBay and any other MIDI Applications can be launched.

Under single Finder, use the PatchBay DA to connect a single application to and from the Apple MIDI Driver; under MultiFinder however, use the PatchBay application. Once PatchBay and one or more MIDI-Manager-compatible applications or drivers are up and running, the input, output, and time ports of the applications or drivers can be connected to themselves, other applications, and to the Apple MIDI Driver in any proper configuration.

When a MIDI instrument is connected to the Macintosh and MIDIArp is launched, the mouse can be used used to connect MIDIArp’s output port to the Apple MIDI Driver’s input port, and to connect the MIDI Driver’s output port to MIDIArp’s input port. (The MIDI Driver’s input port can be thought of as the Macintosh’s output port and visa versa). In this configuration, MIDIArp will continue to arpeggiate (in various patterns and at various tempos) the note data output of one or more interfaced MIDI instruments or any other MIDI-Manager-compatible applications, desk accessories, or drivers.

Where to Get the MIDI Manager

The MIDI manager is currently available to developers through APDA and may possibly be shipped with future System Disks. The MIDIArp sample application (and several other samples) are included on the APDA disk as well. Although there are no MIDI-Manager-compatible third party applications available at the time of this writing, various Macintosh MIDI developers are currently working toward MIDI Manager compatibility, and it is likely that many third party application packages will become available in the near future.

[The full listing is not included due to licensing concerns; you may however get the MIDI manger and PatchBay on the source code disk for this issue, #50. -ed]

/*
 For commented, properly  
 formatted, and complete 
 source code, please refer 
 to the MacTutor source
 listing disk for this issue.
*/
/*** MIDIArp.h ***/
#define mainDialogID 2000
#define quitID   1
#define patternPromptID   2
#define patternUpID3
#define patternDownID4
#define patternUpDownID   5
#define patternDownUpID   6
#define patternRandomID   7
#define speedPromptID8
#define speedVeryFastID   9
#define speedFastID10
#define speedMediumID11
#define speedSlowID12
#define speedVerySlowID   13
#define arpAlertBoxID12345
#define arpAboutAlertID   13554
#define portResType‘port’
#define timePortResInfoID 128 
#define inputPortResInfoID129 
#define outputPortResInfoID 130  
#define noteTblSize32
#define goingUp  1
#define goingDown0
#define speedVeryFast50   
#define speedFast100
#define speedMedium200
#define speedSlow300
#define speedVerySlow500
#define noteDuration  (ArpGlobals.Tempo * 0.95)
#define arpClientID‘MArp’
#define arpIcon  128
#define timePortID ‘Atim’
#define inputPortID‘Bin ‘
#define outputPortID ‘Cout’
#define keyOnOffPacketSize9
#define stdPacketFlags    0
#define flagsTimeStampMask0x7F
#define noTimeBaseRefNum  0
#define noClient ‘    ‘
#define noReadHook 0L
#define noTimeProc 0L
#define zeroTime 0L
#define zeroPeriod 0L
#define refCon0  0L
#define timePortBuffSize  0L
#define inputPortBuffSize 2048
#define outputPortBuffSize0L
 
typedef struct 
{unsigned char Channel;
 unsigned char Note;
 unsigned char Velocity;
 unsigned char Dummy;
} NoteInfo;
typedef struct 
{short  Locked;
 NoteInfo NoteTbl[noteTblSize];
 long   NoteIndex;
 short  NumNotes;
 NoteInfo LastNote;
 short  ArpPattern;
 short  ArpDirection;
 long   Tempo;
 long   NextNoteOnTime;
 short  InputRefNum;
 short  OutputRefNum;
 short  TimeRefNum;
} ArpParams;

/************* 
 MIDIArp.c
*************/
 // Include Standard Mac Headers
#include <MIDI.h>
#include “MIDIDefs.h”
#include “MIDIArp.h”

DialogPtr GMainDialog;  
ArpParams ArpGlobals;
short   GCurSpeedID; 
Boolean GManualPatch;
Boolean GDone = false;  
char    GMIDIMgrVerStr[256]; 

main() 
{
 InitThings(); 
 ArpInit(); 
 StartDialog();  
 RunDialog();  
 ArpClose();
 StopDialog(); 
}
  
void InitThings(void)
{
 FlushEvents(everyEvent, 0);
 InitGraf(&qd.thePort);   
 InitFonts();    
 InitWindows();  
 InitMenus();    
 TEInit();
 InitDialogs(NULL);
 InitCursor();   
 
 { 
 Handle MenuBar = GetNewMBar(menuBar); 
 SetMenuBar(MenuBar);
 DisposHandle(MenuBar);
 AddResMenu(GetMHandle(appleMenu), ‘DRVR’);  
 DrawMenuBar();
 }
 
 Seed(); // Rand Num Generator
}

void ArpInit(void)
{
 MIDIPortParams  Init;  
 Handle TheIconHndl;
 OSErr  TheErr;
 long   MIDIMgrVerNum;  
 char   CStrBuf1[256];
 
 MIDIMgrVerNum = SndDispVersion(midiToolNum);
 if (MIDIMgrVerNum == 0)
 {
 ArpAlert(“The MIDI Manage is not installed!  
 Aborting...”);
 ExitToShell();
 }
 else
 { 
 StdMacVerNumToStr(MIDIMgrVerNum, GMIDIMgrVerStr);
 sprintf(CStrBuf1,”MIDI Manager Version %s”, 
 GMIDIMgrVerStr);
 ArpAlert(CStrBuf1);
 }
 
 TheIconHndl = GetResource(‘ICN#’, arpIcon);
 TheErr = MIDISignIn(arpClientID, refCon0, 
 TheIconHndl, “\pMIDIArp”);
 if (TheErr) 
 {
 ArpAlert(“Trouble signing MIDIArp into MIDI
 Manager!  Aborting...”);
 ExitToShell();
 }
 
 GManualPatch = true;
 
 Init.portID = timePortID;
 Init.portType = midiPortTypeTime;
 Init.timeBase = noTimeBaseRefNum;
 Init.readHook = noReadHook;
 Init.initClock.sync = midiInternalSync;
 Init.initClock.curTime = zeroTime;
 Init.initClock.format =  midiFormatMSec;
 Init.refCon = SetCurrentA5();
 C2PStrCpy(“TimeBase”,Init.name);
 TheErr = MIDIAddPort(arpClientID, timePortBuffSize, 
 &(ArpGlobals.TimeRefNum), &Init);
 
 if (TheErr == midiVConnectMade) 
 {
 GManualPatch = false;
 }
 else if (TheErr == memFullErr)
 {
 ArpAlert(“Not enough room in 
 heap zone to add time 
 port!  Aborting...”);
 MIDISignOut(arpClientID);
 ExitToShell();
 }
 
 Init.portID = inputPortID;
 Init.portType = midiPortTypeInput;
 Init.timeBase = ArpGlobals.TimeRefNum;
 Init.offsetTime = midiGetCurrent;
 Init.readHook = (Ptr) ArpReader;
 Init.refCon = SetCurrentA5();
 C2PStrCpy(“InputPort”, Init.name);
 TheErr = MIDIAddPort(arpClientID, inputPortBuffSize, 
 &(ArpGlobals.InputRefNum), &Init);
 
 if (TheErr == midiVConnectMade) 
 {
 GManualPatch = false;
 }
 else if (TheErr == memFullErr)
 {
 ArpAlert(“Not enough room in heap zone to add input 
 port!  Aborting...”);
 MIDISignOut(arpClientID);
 ExitToShell();
 }
 
 Init.portID = outputPortID;
 Init.portType = midiPortTypeOutput;
 Init.timeBase = ArpGlobals.TimeRefNum;
 Init.offsetTime = midiGetCurrent;
 Init.readHook = NULL;
 Init.refCon = &ArpGlobals;
 C2PStrCpy(“OutputPort”, Init.name);
 TheErr = MIDIAddPort(arpClientID, outputPortBuffSize, 
 &(ArpGlobals.OutputRefNum), &Init);
 
 if (TheErr == midiVConnectMade)   {
 GManualPatch = false;
 }
 else if (TheErr == memFullErr)
 {
 ArpAlert(“Not enough room in heap zone to add output
 port!  Aborting...”);
 MIDISignOut(arpClientID);
 ExitToShell();  
 }
 
 if (GManualPatch)
 {
 PatchPorts();
 }
 
 ArpGlobals.Locked = false;
 ArpGlobals.NumNotes = 0;
 ArpGlobals.ArpPattern = patternUpDownID;
 ArpGlobals.Tempo = speedMedium;
 GCurSpeedID = speedMediumID;
 
 MIDIStartTime(ArpGlobals.TimeRefNum); 
}

void StartDialog(void)
{
 GMainDialog = GetNewDialog(mainDialogID, 
 NULL, (WindowPtr) -1);
 SetPort(GMainDialog);
 
 ChangeState(GMainDialog, ArpGlobals.ArpPattern == 
 patternUpID, patternUpID);
 ChangeState(GMainDialog, ArpGlobals.ArpPattern == 
 patternDownID, patternDownID);
 ChangeState(GMainDialog, ArpGlobals.ArpPattern == 
 patternUpDownID, patternUpDownID);
 ChangeState(GMainDialog, ArpGlobals.ArpPattern == 
 patternDownUpID, patternDownUpID);
 ChangeState(GMainDialog, ArpGlobals.ArpPattern == 
 patternRandomID, patternRandomID);
 
 ChangeState(GMainDialog, GCurSpeedID == 
 speedVeryFastID, speedVeryFastID);
 ChangeState(GMainDialog, GCurSpeedID == speedFastID, 
 speedFastID);
 ChangeState(GMainDialog, GCurSpeedID ==
 speedMediumID, speedMediumID);
 ChangeState(GMainDialog, GCurSpeedID == speedSlowID, 
 speedSlowID);
 ChangeState(GMainDialog, GCurSpeedID == 
 speedVerySlowID, speedVerySlowID);
 
 ShowWindow(GMainDialog);
 StdAdjustDLOGLocation(GMainDialog);
}

void RunDialog(void)
{
 OSErr  TheErr = noErr;
 short  ItemHit;
 EventRecordAnEvent;
 WindowPtrWhichWindow;
 Rect   Boundry;
 MIDIPortInfoHdl PortInfoH;
 GrafPtrSavePort;

 while (!GDone) {
 if (MIDIWorldChanged(arpClientID))
 {
 PortInfoH = MIDIGetPortInfo(arpClientID, timePortID);
 if ((**PortInfoH).timeBase.clientID != noClient)
 {
 MIDISetSync(ArpGlobals.TimeRefNum, midiExternalSync);
 }
 else
 {
 MIDISetSync(ArpGlobals.TimeRefNum, midiInternalSync);
 }
 DisposHandle((Handle) PortInfoH);
 }
 
 if (WaitNextEvent(everyEvent,&AnEvent, updatePeriod,NULL)) 
 {
 
 if ((AnEvent.what == keyDown) && (AnEvent.modifiers
 & cmdKey)) 
 {
 AdjustMenus();
 DoMenuCommand(MenuKey(AnEvent.message & charCodeMask) 
 );
 }
 
 if (IsDialogEvent(&AnEvent)) 
 {
 if (AnEvent.what == updateEvt)
 {
 GetPort(&SavePort);
 SetPort((GrafPtr) AnEvent.message);
 StdHiliteButton(GMainDialog, quitID); 
 SetPort(SavePort);
 }
 
 if (AnEvent.what == keyDown && 
 ((AnEvent.message & charCodeMask) 
 == charEnterKey)) 
 {
 GDone = true;
 }
 else if (
 DialogSelect(&AnEvent, &GMainDialog, &ItemHit)) 
 {
 switch (ItemHit)
 {
 case quitID:
 GDone = true;
 break;
 
 case 
 patternUpID:
 case 
 patternDownID:
 case 
 patternUpDownID:
 case   
 patternDownUpID:
 case 
 patternRandomID:
 SwitchRadio(GMainDialog, &(ArpGlobals.ArpPattern), 
 ItemHit);
 break;
 
 case 
 speedVeryFastID:
 ArpGlobals.Tempo = speedVeryFast;
 SwitchRadio(GMainDialog, &GCurSpeedID, ItemHit);
 break;
 
 case
  speedFastID:
 ArpGlobals.Tempo = speedFast;
 SwitchRadio(GMainDialog,&GCurSpeedID, ItemHit);
 break;
 
 case
  speedMediumID: 
 ArpGlobals.Tempo = speedMedium;
 SwitchRadio(GMainDialog, &GCurSpeedID, ItemHit);
 break;
 
 case 
 speedSlowID:
 ArpGlobals.Tempo = speedSlow;
 SwitchRadio(GMainDialog, &GCurSpeedID, ItemHit);
 break;
 
 case
  speedVerySlowID:
 ArpGlobals.Tempo = speedVerySlow;
 SwitchRadio(GMainDialog, &GCurSpeedID, ItemHit);
 break;
 
 default:
 SysBeep(2);
 break;
 } 
 } 
 } 
 else {
 switch (AnEvent.what) 
 {
 case mouseDown:
 switch(FindWindow(AnEvent.where, 
 &WhichWindow) ) 
 {
 case 
 inMenuBar:
 AdjustMenus();
 DoMenuCommand( 
 MenuSelect(AnEvent.where));
 break;

 case 
 inSysWindow:
 SystemClick(&AnEvent, WhichWindow);

 break;
 case 
 inContent:
 if (WhichWindow != FrontWindow()) 
 {
 SelectWindow(WhichWindow);
 AdjustMenus();
 } 
 break;
 case 
 inGoAway:
 if (TrackGoAway(WhichWindow,AnEvent.where)) 
 {
 GDone = true;
 }
 break;
 case 
 inDrag:
 SetRect(&Boundry, 4, 24, 
 qd.screenBits.bounds.right - 4,
 qd.screenBits.bounds.bottom - 4);
 
 DragWindow(WhichWindow,AnEvent.where,&Boundry);
 break;
 default:
 break;
 }
 break;
 
 default:
 break;
 } 
 }
 } 
 }  
}

void ArpClose(void)
{
 if (GManualPatch)
 {
 SavePatch(timePortID, timePortResInfoID, “timePortInfo”);

 SavePatch(inputPortID, inputPortResInfoID,
 “inputPortInfo”);

 SavePatch(outputPortID, outputPortResInfoID, 
 “outputPortInfo”);
 }
 MIDISignOut(arpClientID);
}

void StopDialog(void)
{
 StdSaveDLOGLocation(GMainDialog, mainDialogID);
 HideWindow(GMainDialog);
 DisposDialog(GMainDialog);
}

pascal short 
ArpReader(MIDIPacket *ThePacketPtr, long TheRefCon)
{
 long SysA5 = SetA5(TheRefCon);
 short  RetVal = midiMorePacket, i, j;
 
 if(ArpGlobals.Locked) 
 {
 RetVal = midiKeepPacket; 
 }
 else if ( ThePacketPtr->flags == stdPacketFlags 
 && ((ThePacketPtr->data[0] & statusMask) 
 == keyOn || (ThePacketPtr->data[0]
   & statusMask) == keyOff))
 {
 RetVal = midiMorePacket;
 if ((ThePacketPtr->data[0] & statusMask) 
 == keyOn && ThePacketPtr->data[2] != zeroVelo)
 {
 for (i=0; i<ArpGlobals.NumNotes; i++)
 {
 if   (ThePacketPtr->data[1] <= 
 ArpGlobals.NoteTbl[i].Note) 
 {
 break; 
 }
 }
 for(j=ArpGlobals.NumNotes; j>i; j--)
 {
 ArpGlobals.
 NoteTbl[j].Channel = ArpGlobals.NoteTbl[j-1].Channel;
 ArpGlobals.
 NoteTbl[j].Note = ArpGlobals.NoteTbl[j-1].Note;
 ArpGlobals.
 NoteTbl[j].Velocity = ArpGlobals.NoteTbl[j-1].
 Velocity;
 }
 ArpGlobals.NoteTbl[i].Channel = ThePacketPtr->data[0]
 & channelMask;
 ArpGlobals.NoteTbl[i].Note = ThePacketPtr->data[1];
 ArpGlobals.NoteTbl[i].Velocity = ThePacketPtr->data[2];
 
 if(ArpGlobals.NumNotes < noteTblSize) 
 {
 ArpGlobals.NumNotes++;
 }
 if(ArpGlobals.NumNotes == 1) 
 {
 ArpGlobals.NextNoteOnTime = ThePacketPtr->tStamp;
 ArpTimeProc(ThePacketPtr->tStamp, TheRefCon);                 }
 } 
 else if ((ThePacketPtr->data[0] & 
 statusMask) == keyOff || (ThePacketPtr->data[0] & 
 statusMask) == keyOn)
 {
 for (i=0; i< ArpGlobals.NumNotes; i++)
 {
 if((ArpGlobals.NoteTbl[i].Channel == 
 (ThePacketPtr->data[0] & channelMask)) 
 && (ArpGlobals.NoteTbl[i].Note == ThePacketPtr->data[1]))
 {
 break; 
 }
 }
 
 if (i < ArpGlobals.NumNotes)
 {
 
 for (/*i=i*/; i<ArpGlobals.NumNotes-1; i++)
 { 
 ArpGlobals.NoteTbl[i].Channel = 
 ArpGlobals.NoteTbl[i+1].Channel;
 ArpGlobals.NoteTbl[i].Note = 
 ArpGlobals.NoteTbl[i+1].Note;
 ArpGlobals.NoteTbl[i].Velocity = 
 ArpGlobals.NoteTbl[i+1].Velocity;
 }
 ArpGlobals.NumNotes--;
 }
 }
 }
 
 SetA5(SysA5);
 return(RetVal);
}

pascal void ArpTimeProc(long , long TheRefCon)
{
 long SysA5 = SetA5(TheRefCon); 
 int    i;
 MIDIPacket TheMIDIPacket;
 
 ArpGlobals.Locked = 1;

 if (ArpGlobals.NumNotes == 0) 
 {
 MIDIWakeUp(ArpGlobals.TimeRefNum, zeroTime, 
 zeroPeriod, noTimeProc);
 } 
 else
 { 
 BumpNoteTableIndex();
 if (ArpGlobals.NoteTbl [ArpGlobals.NoteIndex] 
 == ArpGlobals.LastNote)
 { 
 BumpNoteTableIndex();
 }
 ArpGlobals.LastNote = ArpGlobals.NoteTbl[
 ArpGlobals.NoteIndex];
 
 TheMIDIPacket.flags = stdPacketFlags; 
 TheMIDIPacket.len = keyOnOffPacketSize;
 
 i = ArpGlobals.NoteIndex;
 TheMIDIPacket.tStamp = ArpGlobals.NextNoteOnTime;
 TheMIDIPacket.data[0] = ArpGlobals.NoteTbl[i].
 Channel | keyOn;
 TheMIDIPacket.data[1] = ArpGlobals.NoteTbl[i].Note;
 TheMIDIPacket.data[2] = ArpGlobals.NoteTbl[i].Velocity;
 MIDIWritePacket(ArpGlobals.OutputRefNum, &TheMIDIPacket);
 
 TheMIDIPacket.tStamp += noteDuration;
 TheMIDIPacket.data[0] -= 0x10;  
 MIDIWritePacket(ArpGlobals.OutputRefNum, &TheMIDIPacket);
 
 ArpGlobals.NextNoteOnTime += ArpGlobals.Tempo;          
 MIDIWakeUp(ArpGlobals.TimeRefNum, 
 ArpGlobals.NextNoteOnTime - ArpGlobals.Tempo/2,
 zeroPeriod, (ProcPtr) ArpTimeProc);
 }
 ArpGlobals.Locked = false;
 
 SetA5(SysA5);
}

void BumpNoteTableIndex(void)
{
 if (ArpGlobals.NumNotes == 1)
 {
 ArpGlobals.NoteIndex = 0;
 }
 else
 { 
 switch(ArpGlobals.ArpPattern)
 {
 case patternUpID:
 if (ArpGlobals.NoteIndex >= ArpGlobals.
 NumNotes-1) 
 { 
 ArpGlobals.NoteIndex = 0;
 }
 else 
 { 
 ArpGlobals.NoteIndex++;
 }
 break;
 
 case patternUpDownID:    
 case patternDownUpID:
 if (ArpGlobals.ArpDirection == goingUp)
 {
 
 if (ArpGlobals.NoteIndex > 
 ArpGlobals.NumNotes-1) 
 {
 ArpGlobals.NoteIndex = ArpGlobals.NumNotes-1;
 ArpGlobals.ArpDirection = goingDown;
 }
 else if (ArpGlobals.NoteIndex == 
 ArpGlobals.NumNotes-1)
 {
 ArpGlobals.NoteIndex--;
 ArpGlobals.ArpDirection = goingDown;
 }
 else
 {
 ArpGlobals.NoteIndex++;
 }
 }
 else
 { 
 if (ArpGlobals.NoteIndex < 0)
 {
 ArpGlobals.NoteIndex = 0;
 ArpGlobals.ArpDirection = goingUp;
 }
 else if (ArpGlobals.NoteIndex == 0)
 {
 ArpGlobals.NoteIndex++;
 ArpGlobals.ArpDirection = goingUp;
 }
 else
 {
 ArpGlobals.NoteIndex--;
 }
 }
 break;
 
 case patternDownID:
 if (ArpGlobals.NoteIndex <= 0) 
 {
 ArpGlobals.NoteIndex = ArpGlobals.
 NumNotes-1;
 }
 else
 {
 ArpGlobals.NoteIndex--;
 }
 break;
 
 case patternRandomID:
 ArpGlobals.NoteIndex
 = Choose(ArpGlobals.NumNotes);
 break;
 }
 }
}

void PatchPorts(void)
{
 MIDIPortInfoHdl PortInfoH; 
 MIDIPortInfoPtr PortInfoP; 
 short  i, TheErr;
 
 PortInfoH = (MIDIPortInfoHdl) 
 GetResource(portResType, timePortResInfoID);
 if (PortInfoH == NULL)
 {
 ReportResError(“GetResource(portResType, 
 timePortResInfoID)”);
 }
 HLock((Handle) PortInfoH);
 PortInfoP = *PortInfoH;
 if (GetHandleSize((Handle) PortInfoH) != 0)
 {
 if (PortInfoP->timeBase.clientID != noClient)
 { 
 TheErr = MIDIConnectTime(PortInfoP->
 timeBase.clientID, PortInfoP->
 timeBase.portID, arpClientID, timePortID);
 if (TheErr != midiVConnectErr) 
 { 
 
 MIDISetSync(ArpGlobals.TimeRefNum, 
 midiExternalSync);
 }
 }
 
 for (i=0; i<PortInfoP->numConnects; i++)
 {
 MIDIConnectTime(arpClientID, timePortID, 
 PortInfoP->cList[i].clientID, 
 PortInfoP->cList[i].portID);
 }
 }
 HUnlock((Handle) PortInfoH);
 ReleaseResource((Handle) PortInfoH);
 ReportResError(“PatchPorts/ReleaseResource()”);
 
 PortInfoH = (MIDIPortInfoHdl)
 GetResource(portResType,inputPortResInfoID);
 if (PortInfoH == NULL)
 {
 ReportResError(“PatchPorts/GetResource()”);
 }
 HLock((Handle) PortInfoH);
 PortInfoP = *PortInfoH;
 if (GetHandleSize((Handle) PortInfoH) != 0)
 {
 for (i=0; i<PortInfoP->numConnects; i++)
 {
 MIDIConnectData(arpClientID, inputPortID, 
 PortInfoP->cList[i].clientID, 
 PortInfoP->cList[i].portID);
 }
 }
 HUnlock((Handle) PortInfoH);
 ReleaseResource((Handle) PortInfoH);
 ReportResError(“PatchPorts/GetResource()”);
 
 PortInfoH = (MIDIPortInfoHdl)
 GetResource(portResType, outputPortResInfoID);
 if (PortInfoH == NULL)
 { 
 ReportResError(“PatchPorts/GetResource()”);
 }
 HLock((Handle) PortInfoH);
 PortInfoP = *PortInfoH;
 if (GetHandleSize((Handle) PortInfoH) != 0)
 {
 for(i=0; i<PortInfoP->numConnects; i++)
 {
 MIDIConnectData(arpClientID, outputPortID,
 PortInfoP->cList[i].clientID, 
 PortInfoP->cList[i].portID);
 }
 }
 HUnlock((Handle) PortInfoH);
 ReleaseResource((Handle)  PortInfoH);
 ReportResError(“PatchPorts/ReleaseResource()”);
}

void SavePatch(OSType PortID, short PortInfoResID, char *PortInfoResName)
{
 Handle PortResH;
 CursHandle WatchCurs;  
 
 WatchCurs = GetCursor(watchCursor);
 HLock((Handle) WatchCurs);
 SetCursor(*WatchCurs);
 HUnlock((Handle) WatchCurs);

 PortResH = GetResource(portResType,
  PortInfoResID);
 ReportResError(“SavePatch/GetResource()”);
 RmveResource(PortResH);
 ReportResError(“SavePatch/RmveResource()
  (make sure disk is  unlocked)” );
 DisposHandle(PortResH);
 UpdateResFile(CurResFile());
 ReportResError(“SavePatch/UpdateResFile() 
 (make sure disk is unlocked)”);
 
 PortResH = (Handle) MIDIGetPortInfo(
 arpClientID, PortID);
 
 addresource(PortResH, portResType, PortInfoResID,
  PortInfoResName);
 ReportResError(“SavePatch/addresource()”);
 WriteResource(PortResH);
 ReportResError(“SavePatch/WriteResource()
  (make sure disk is unlocked)”);
 UpdateResFile(CurResFile());
 ReportResError(“SavePatch/UpdateResFile() 
 (make sure disk is unlocked)”);
 ReleaseResource(PortResH);
 ReportResError(“SavePatch/ReleaseResource() 
 (make sure disk is unlocked)”);
 InitCursor();
}

void Terminate(void)
{
 MIDISignOut(arpClientID);
 StopDialog();
 ExitToShell();
}