Thread: Turning off While loop in realtime

Hello all,

I'm going to ask a question that involves MIDI, but it actually doesn't have to be MIDI. My questions is on how to turn off the while loop via hardware input. (i.e. keyboard)

I'm trying to write code that begins looping once it receives a MIDI note on message, and turns off when it receives a MIDI note off message. Here's part of the code:

while(1)
{
if(Pm_Poll(stream))
{
length = Pm_Read(stream, event, sizeof(long));

for(i = 0; i < length; i++)
{
status = Pm_MessageStatus(event[i].message);
data1 = Pm_MessageData1(event[i].message);
data2 = Pm_MessageData2(event[i].message);
printf("Status: %d, Data1: %d, Data2: %d\n", status, data1, data2);

}
int time, temp, loop = 0;
while(status==144){
//if(status==144)
//{
time = Pt_Time(NULL);
while(Pt_Time(NULL) - time < 100);
temp = loop;
loop = temp+1;
printf("\n%d\n", loop);
//}
if(status != 144) break;
}
if(status==128 && data1==67) break;
}
What it does now is it just keeps adding 1 to int loop every 100ms once it receives a MIDI note on, which is status 144. (in the second while loop)

The problem is that once the while loop is initiated, it doesn't update the status. In other words, once status == 144 it begins the loop, and it no longer takes in information which would break the while loop.

If someone can tell me how I can turn off the while loop after it's been initiated I would greatly appreciate it. Thanks in advance.

Originally Posted by baikal_m

Is there another way to terminate the while loop by changing the test condition?

You should be able to use a variable instead of 1 in the while loop, then set it to 0 to terminate.

All,

Thanks for the replies. I think there was a confusion with which while loop I was talking about. The following is the only bit of the code we need for this discussion:

Code:

		if(Pm_Poll(stream))
		{
			length = Pm_Read(stream, event, sizeof(long));
			
			for(i = 0; i < length; i++)
			{
				status = Pm_MessageStatus(event[i].message);
				data1 = Pm_MessageData1(event[i].message);
				data2 = Pm_MessageData2(event[i].message);
				printf("Status: %d, Data1: %d, Data2: %d\n", status, data1, data2);
				
			}
			int time, temp, loop = 0;
			while(status==144)
			{
				if(status==144)
				{
					//int time, temp, loop;
					time = Pt_Time(NULL);
					while(Pt_Time(NULL) - time < 100);
					temp = loop;
					loop = temp+1;
					printf("\n%d\nJR", loop); 	
				}			
				else break;
			}
		}

Basically, the top part inside the for loop is happening constantly. When I push on my hardware midi controller, it receives the mssage. If the button I push sends out a midi note, it first receives status 144 when I push down, and status 128 when I let go. This part of the code works perfectly fine, and streams whatever midi data I send to the code.

What I'm trying to do is to start the loop to increment the data int loop within the while loop when status is 144, and stop when status becomes 128. I eventually want to turn this into something that'll repeat a sequence of notes only when I push down on a midi note on the hardware controller.

So that's why I put the while loop there, to loop and increment. status is being changed anytime there's midi input in the for loop just before the while loop, so I thought that by sending a midi note off(status 128) the while loop would terminate. It doesn't. This is where I have a problem.

I took out the 128 & 67 line because it's not important. It was there to break out of the first while loop (that has been taken out here) and it worked perfectly fine.

I would greatly appreciate it if someone is still willing to help!

Originally Posted by baikal_m

All,

Thanks for the replies. I think there was a confusion with which while loop I was talking about. The following is the only bit of the code we need for this discussion:

Basically, the top part inside the for loop is happening constantly. When I push on my hardware midi controller, it receives the mssage. If the button I push sends out a midi note, it first receives status 144 when I push down, and status 128 when I let go. This part of the code works perfectly fine, and streams whatever midi data I send to the code.

What I'm trying to do is to start the loop to increment the data int loop within the while loop when status is 144, and stop when status becomes 128. I eventually want to turn this into something that'll repeat a sequence of notes only when I push down on a midi note on the hardware controller.

So that's why I put the while loop there, to loop and increment. status is being changed anytime there's midi input in the for loop just before the while loop, so I thought that by sending a midi note off(status 128) the while loop would terminate. It doesn't. This is where I have a problem.

I took out the 128 & 67 line because it's not important. It was there to break out of the first while loop (that has been taken out here) and it worked perfectly fine.

I would greatly appreciate it if someone is still willing to help!

My hat of guessing is a little rusty, but I'm guessing you're asking "how come my while loop won't break me out of my for loop?" To which the answer is, hey put it inside the for loop. Definitely if you intend to do something with status, you're going have to do it where status is.

Code:

		if(Pm_Poll(stream))
		{
			length = Pm_Read(stream, event, sizeof(long));
                        int time, temp, loop = 0;			
			for(i = 0; i < length; i++)
			{
				status = Pm_MessageStatus(event[i].message);
				data1 = Pm_MessageData1(event[i].message);
				data2 = Pm_MessageData2(event[i].message);
				printf("Status: %d, Data1: %d, Data2: %d\n", status, data1, data2);
				if(status==144)
				{
					//int time, temp, loop;
					time = Pt_Time(NULL);
					while(Pt_Time(NULL) - time < 100);
					temp = loop;
					loop = temp+1;
					printf("\n%d\nJR", loop); 	
				}			
				else break;
			}

		}

Assuming this is correct and have been confirmed.

Originally Posted by baikal_m

If the button I push sends out a midi note, it first receives status 144 when I push down, and status 128 when I let go. This part of the code works perfectly fine, and streams whatever midi data I send to the code.

Thank you all so much for the suggestions. It seems that I wasn't too clear exactly what I wanted to do... but, I've figured it out and here's the answer to my own question:

Code:

		if(Pm_Poll(stream))//status will only change if it re-Polls
		{
			length = Pm_Read(stream, event, sizeof(long));
			
			for(i = 0; i < length; i++)//if(Pm_Read(data->stream, data->event, sizeof(long)) > 0)
			{
				status = Pm_MessageStatus(event[i].message);
				data1 = Pm_MessageData1(event[i].message);
				data2 = Pm_MessageData2(event[i].message);
				printf("Status: %d, Data1: %d, Data2: %d\n", status, data1, data2);
			}
			
			int time, temp, loop = 0, counter = 0;
			while(status==144)//Enters this while loop if status==144, or noteon
			{	
				if(Pm_Read(stream, event, sizeof(long)) > 0)//Events must be detected within the loop as well. Otherwise there's no way out of this while loop
				{
					status = Pm_MessageStatus(event[i].message);
					data1 = Pm_MessageData1(event[i].message);
					data2 = Pm_MessageData2(event[i].message);
				}

				time = Pt_Time(NULL);
				while (Pt_Time(NULL) - time < 1);// set to 1ms because 100ms is too long for Pm_Poll to notice anything has happened
				counter++;//Every 1ms counter is incremented
				if(counter % 100 == 0)//when it has counted 100ms, (or whatever you set it to)
				{
					loop++;					// it increments loop
					printf("\n%d\ntest\n", loop); 
				}
			}
		}

This code does exactly what I wanted it to do. It increments "loop" every 100ms when it receives a noteon message (status 144) and terminates when it receives a noteoff(status 128).

use 'break'.