diff options
Diffstat (limited to '3rdparty/portmidi/pm_test/midithread.c')
-rw-r--r-- | 3rdparty/portmidi/pm_test/midithread.c | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/3rdparty/portmidi/pm_test/midithread.c b/3rdparty/portmidi/pm_test/midithread.c new file mode 100644 index 00000000000..fab9794f2da --- /dev/null +++ b/3rdparty/portmidi/pm_test/midithread.c @@ -0,0 +1,329 @@ +/* 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; + +int 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 */ + int32_t 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) { + int 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; + int32_t 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 int32_t's + * for our messages in this simple example + */ + midi_to_main = Pm_QueueCreate(32, sizeof(int32_t)); + assert(midi_to_main != NULL); + main_to_midi = Pm_QueueCreate(32, sizeof(int32_t)); + 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) { + int32_t msg; + int input; + 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 */ ; + // convert int32_t to long for safe printing + printf("... pitch is %ld\n", (long) 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, "%d", &input) == 1) { + if (input >= -127 && input <= 127) { + /* send transposition value, make sur */ + printf("Transposing by %d\n", input); + msg = (int32_t) input; + Pm_Enqueue(main_to_midi, &msg); + } else { + printf("Transposition must be within -127...127\n"); + } + } else { + printf("%s\n%s\n", + "Type 'q[ENTER]' to quit, 'm[ENTER]' to monitor next pitch, or", + "enter a number to specify transposition."); + } + } + + /* 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; +} |