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Diffstat (limited to 'pd/portmidi/pm_test/midithread.c')
| -rw-r--r-- | pd/portmidi/pm_test/midithread.c | 327 |
1 files changed, 0 insertions, 327 deletions
diff --git a/pd/portmidi/pm_test/midithread.c b/pd/portmidi/pm_test/midithread.c deleted file mode 100644 index 861b347c..00000000 --- a/pd/portmidi/pm_test/midithread.c +++ /dev/null @@ -1,327 +0,0 @@ -/* midithread.c -- example program showing how to do midi processing
- in a preemptive thread
-
- Notes: if you handle midi I/O from your main program, there will be
- some delay before handling midi messages whenever the program is
- doing something like file I/O, graphical interface updates, etc.
-
- To handle midi with minimal delay, you should do all midi processing
- in a separate, high priority thread. A convenient way to get a high
- priority thread in windows is to use the timer callback provided by
- the PortTime library. That is what we show here.
-
- If the high priority thread writes to a file, prints to the console,
- or does just about anything other than midi processing, this may
- create delays, so all this processing should be off-loaded to the
- "main" process or thread. Communication between threads can be tricky.
- If one thread is writing at the same time the other is reading, very
- tricky race conditions can arise, causing programs to behave
- incorrectly, but only under certain timing conditions -- a terrible
- thing to debug. Advanced programmers know this as a synchronization
- problem. See any operating systems textbook for the complete story.
-
- To avoid synchronization problems, a simple, reliable approach is
- to communicate via messages. PortMidi offers a message queue as a
- datatype, and operations to insert and remove messages. Use two
- queues as follows: midi_to_main transfers messages from the midi
- thread to the main thread, and main_to_midi transfers messages from
- the main thread to the midi thread. Queues are safe for use between
- threads as long as ONE thread writes and ONE thread reads. You must
- NEVER allow two threads to write to the same queue.
-
- This program transposes incoming midi data by an amount controlled
- by the main program. To change the transposition, type an integer
- followed by return. The main program sends this via a message queue
- to the midi thread. To quit, type 'q' followed by return.
-
- The midi thread can also send a pitch to the main program on request.
- Type 'm' followed by return to wait for the next midi message and
- print the pitch.
-
- This program illustrates:
- Midi processing in a high-priority thread.
- Communication with a main process via message queues.
-
- */
-
-#include "stdio.h"
-#include "stdlib.h"
-#include "string.h"
-#include "assert.h"
-#include "portmidi.h"
-#include "pmutil.h"
-#include "porttime.h"
-
-/* if INPUT_BUFFER_SIZE is 0, PortMidi uses a default value */
-#define INPUT_BUFFER_SIZE 0
-
-#define OUTPUT_BUFFER_SIZE 100
-#define DRIVER_INFO NULL
-#define TIME_PROC NULL
-#define TIME_INFO NULL
-/* use zero latency because we want output to be immediate */
-#define LATENCY 0
-
-#define STRING_MAX 80
-
-/**********************************/
-/* DATA USED ONLY BY process_midi */
-/* (except during initialization) */
-/**********************************/
-
-int active = FALSE;
-int monitor = FALSE;
-int midi_thru = TRUE;
-
-long transpose;
-PmStream *midi_in;
-PmStream *midi_out;
-
-/****************************/
-/* END OF process_midi DATA */
-/****************************/
-
-/* shared queues */
-PmQueue *midi_to_main;
-PmQueue *main_to_midi;
-
-#define QUIT_MSG 1000
-#define MONITOR_MSG 1001
-#define THRU_MSG 1002
-
-/* timer interrupt for processing midi data */
-void process_midi(PtTimestamp timestamp, void *userData)
-{
- PmError result;
- PmEvent buffer; /* just one message at a time */
- long msg;
-
- /* do nothing until initialization completes */
- if (!active)
- return;
-
- /* check for messages */
- do {
- result = Pm_Dequeue(main_to_midi, &msg);
- if (result) {
- if (msg >= -127 && msg <= 127)
- transpose = msg;
- else if (msg == QUIT_MSG) {
- /* acknowledge receipt of quit message */
- Pm_Enqueue(midi_to_main, &msg);
- active = FALSE;
- return;
- } else if (msg == MONITOR_MSG) {
- /* main has requested a pitch. monitor is a flag that
- * records the request:
- */
- monitor = TRUE;
- } else if (msg == THRU_MSG) {
- /* toggle Thru on or off */
- midi_thru = !midi_thru;
- }
- }
- } while (result);
-
- /* see if there is any midi input to process */
- do {
- result = Pm_Poll(midi_in);
- if (result) {
- long status, data1, data2;
- if (Pm_Read(midi_in, &buffer, 1) == pmBufferOverflow)
- continue;
- if (midi_thru)
- Pm_Write(midi_out, &buffer, 1);
- /* unless there was overflow, we should have a message now */
- status = Pm_MessageStatus(buffer.message);
- data1 = Pm_MessageData1(buffer.message);
- data2 = Pm_MessageData2(buffer.message);
- if ((status & 0xF0) == 0x90 ||
- (status & 0xF0) == 0x80) {
-
- /* this is a note-on or note-off, so transpose and send */
- data1 += transpose;
-
- /* keep within midi pitch range, keep proper pitch class */
- while (data1 > 127)
- data1 -= 12;
- while (data1 < 0)
- data1 += 12;
-
- /* send the message */
- buffer.message = Pm_Message(status, data1, data2);
- Pm_Write(midi_out, &buffer, 1);
-
- /* if monitor is set, send the pitch to the main thread */
- if (monitor) {
- Pm_Enqueue(midi_to_main, &data1);
- monitor = FALSE; /* only send one pitch per request */
- }
- }
- }
- } while (result);
-}
-
-void exit_with_message(char *msg)
-{
- char line[STRING_MAX];
- printf("%s\n", msg);
- fgets(line, STRING_MAX, stdin);
- exit(1);
-}
-
-int main()
-{
- int id;
- long n;
- const PmDeviceInfo *info;
- char line[STRING_MAX];
- int spin;
- int done = FALSE;
-
- /* determine what type of test to run */
- printf("begin PortMidi multithread test...\n");
-
- /* note that it is safe to call PortMidi from the main thread for
- initialization and opening devices. You should not make any
- calls to PortMidi from this thread once the midi thread begins.
- to make PortMidi calls.
- */
-
- /* make the message queues */
- /* messages can be of any size and any type, but all messages in
- * a given queue must have the same size. We'll just use long's
- * for our messages in this simple example
- */
- midi_to_main = Pm_QueueCreate(32, sizeof(long));
- assert(midi_to_main != NULL);
- main_to_midi = Pm_QueueCreate(32, sizeof(long));
- assert(main_to_midi != NULL);
-
- /* a little test of enqueue and dequeue operations. Ordinarily,
- * you would call Pm_Enqueue from one thread and Pm_Dequeue from
- * the other. Since the midi thread is not running, this is safe.
- */
- n = 1234567890;
- Pm_Enqueue(midi_to_main, &n);
- n = 987654321;
- Pm_Enqueue(midi_to_main, &n);
- Pm_Dequeue(midi_to_main, &n);
- if (n != 1234567890) {
- exit_with_message("Pm_Dequeue produced unexpected result.");
- }
- Pm_Dequeue(midi_to_main, &n);
- if(n != 987654321) {
- exit_with_message("Pm_Dequeue produced unexpected result.");
- }
-
- /* always start the timer before you start midi */
- Pt_Start(1, &process_midi, 0); /* start a timer with millisecond accuracy */
- /* the timer will call our function, process_midi() every millisecond */
-
- Pm_Initialize();
-
- id = Pm_GetDefaultOutputDeviceID();
- info = Pm_GetDeviceInfo(id);
- if (info == NULL) {
- printf("Could not open default output device (%d).", id);
- exit_with_message("");
- }
- printf("Opening output device %s %s\n", info->interf, info->name);
-
- /* use zero latency because we want output to be immediate */
- Pm_OpenOutput(&midi_out,
- id,
- DRIVER_INFO,
- OUTPUT_BUFFER_SIZE,
- TIME_PROC,
- TIME_INFO,
- LATENCY);
-
- id = Pm_GetDefaultInputDeviceID();
- info = Pm_GetDeviceInfo(id);
- if (info == NULL) {
- printf("Could not open default input device (%d).", id);
- exit_with_message("");
- }
- printf("Opening input device %s %s\n", info->interf, info->name);
- Pm_OpenInput(&midi_in,
- id,
- DRIVER_INFO,
- INPUT_BUFFER_SIZE,
- TIME_PROC,
- TIME_INFO);
-
- active = TRUE; /* enable processing in the midi thread -- yes, this
- is a shared variable without synchronization, but
- this simple assignment is safe */
-
- printf("Enter midi input; it will be transformed as specified by...\n");
- printf("%s\n%s\n%s\n",
- "Type 'q' to quit, 'm' to monitor next pitch, t to toggle thru or",
- "type a number to specify transposition.",
- "Must terminate with [ENTER]");
-
- while (!done) {
- long msg;
- int len;
- fgets(line, STRING_MAX, stdin);
- /* remove the newline: */
- len = strlen(line);
- if (len > 0) line[len - 1] = 0; /* overwrite the newline char */
- if (strcmp(line, "q") == 0) {
- msg = QUIT_MSG;
- Pm_Enqueue(main_to_midi, &msg);
- /* wait for acknowlegement */
- do {
- spin = Pm_Dequeue(midi_to_main, &msg);
- } while (spin == 0); /* spin */ ;
- done = TRUE; /* leave the command loop and wrap up */
- } else if (strcmp(line, "m") == 0) {
- msg = MONITOR_MSG;
- Pm_Enqueue(main_to_midi, &msg);
- printf("Waiting for note...\n");
- do {
- spin = Pm_Dequeue(midi_to_main, &msg);
- } while (spin == 0); /* spin */ ;
- printf("... pitch is %ld\n", msg);
- } else if (strcmp(line, "t") == 0) {
- /* reading midi_thru asynchronously could give incorrect results,
- e.g. if you type "t" twice before the midi thread responds to
- the first one, but we'll do it this way anyway. Perhaps a more
- correct way would be to wait for an acknowledgement message
- containing the new state. */
- printf("Setting THRU %s\n", (midi_thru ? "off" : "on"));
- msg = THRU_MSG;
- Pm_Enqueue(main_to_midi, &msg);
- } else if (sscanf(line, "%ld", &msg) == 1) {
- if (msg >= -127 && msg <= 127) {
- /* send transposition value */
- printf("Transposing by %ld\n", msg);
- Pm_Enqueue(main_to_midi, &msg);
- } else {
- printf("Transposition must be within -127...127\n");
- }
- } else {
- printf("%s\n%s\n%s\n",
- "Type 'q' to quit, 'm' to monitor next pitch, or",
- "type a number to specify transposition.",
- "Must terminate with [ENTER]");
- }
- }
-
- /* at this point, midi thread is inactive and we need to shut down
- * the midi input and output
- */
- Pt_Stop(); /* stop the timer */
- Pm_QueueDestroy(midi_to_main);
- Pm_QueueDestroy(main_to_midi);
-
- /* Belinda! if close fails here, some memory is deleted, right??? */
- Pm_Close(midi_in);
- Pm_Close(midi_out);
-
- printf("finished portMidi multithread test...enter any character to quit [RETURN]...");
- fgets(line, STRING_MAX, stdin);
- return 0;
-}
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