/*
* returns number of messages actually read, or error code
*/
PMEXPORT int Pm_Read(PortMidiStream *stream, PmEvent *buffer, int32_t length) {
PmInternal *midi = (PmInternal *) stream;
int n = 0;
PmError err = pmNoError;
pm_hosterror = FALSE;
/* arg checking */
if(midi == NULL)
err = pmBadPtr;
else if(!descriptors[midi->device_id].pub.opened)
err = pmBadPtr;
else if(!descriptors[midi->device_id].pub.input)
err = pmBadPtr;
/* First poll for data in the buffer...
* This either simply checks for data, or attempts first to fill the buffer
* with data from the MIDI hardware; this depends on the implementation.
* We could call Pm_Poll here, but that would redo a lot of redundant
* parameter checking, so I copied some code from Pm_Poll to here: */
else err = (*(midi->dictionary->poll))(midi);
if (err != pmNoError) {
if (err == pmHostError) {
midi->dictionary->host_error(midi, pm_hosterror_text,
PM_HOST_ERROR_MSG_LEN);
pm_hosterror = TRUE;
}
return pm_errmsg(err);
}
while (n < length) {
PmError err = Pm_Dequeue(midi->queue, buffer++);
if (err == pmBufferOverflow) {
/* ignore the data we have retreived so far */
return pm_errmsg(pmBufferOverflow);
} else if (err == 0) { /* empty queue */
break;
}
n++;
}
return n;
}
void *Pm_QueuePeek(PmQueue *q)
{
PmQueueRep *queue = (PmQueueRep *) q;
PmError rslt;
long temp;
/* arg checking */
if (!queue)
return NULL;
if (queue->peek_flag) {
return queue->peek;
}
/* this is ugly: if peek_overflow is set, then Pm_Dequeue()
* returns immediately with pmBufferOverflow, but here, we
* want Pm_Dequeue() to really check for data. If data is
* there, we can return it
*/
temp = queue->peek_overflow;
queue->peek_overflow = FALSE;
rslt = Pm_Dequeue(q, queue->peek);
queue->peek_overflow = temp;
if (rslt == 1) {
queue->peek_flag = TRUE;
return queue->peek;
} else if (rslt == pmBufferOverflow) {
/* when overflow is indicated, the queue is empty and the
* first message that was dropped by Enqueue (signalling
* pmBufferOverflow to its caller) would have been the next
* message in the queue. Pm_QueuePeek will return NULL, but
* remember that an overflow occurred. (see Pm_Dequeue)
*/
queue->peek_overflow = TRUE;
}
return NULL;
}
/* 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);
}
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;
}
