 RedSon  5,000
Recognized Expert Expert
I'm doing a bit of bluetooth programming and I am writing some middleware to make developing applications easier. The BT driver is implemented as a simple serial driver so its like OpenFile and WriteFile and ReadFile. So I get a notification from the module that there is a phone that wishes to make a hands free profile connection to my device. It also give me a big byte array with some information about the phone that is requesting to connect. So from this point my middleware needs to pass the byte array along to the application for processing. But here is the problem, I can't just pass a pointer to the byte array because as soon as the middleware leaves the function that byte array will be deleted from the stack. So I figured I could make a copy of it in the heap and pass that. But now I run into the issue of who does the deleting of that heap memory? I don't think the application should do it because that kind of defeats the purpose of the middleware, but the middleware can't just delete it willy-nilly because the application might still be using the data. So how do I do it?
The Data path is like this... Message with data comes in from the BT circuit board, it goes to the driver, the driver gives it to the middleware, the middleware needs to give it to the application, the application acts on the data, the application calls into the middleware to respond to the message, the middleware takes the information that the application sent it and makes a BT packet, the middleware passes that response back to the driver and finally the driver sends it out.
Questions? Answers?
4 2112   Savage 1,764
Recognized Expert Top Contributor
I'm doing a bit of bluetooth programming and I am writing some middleware to make developing applications easier. The BT driver is implemented as a simple serial driver so its like OpenFile and WriteFile and ReadFile. So I get a notification from the module that there is a phone that wishes to make a hands free profile connection to my device. It also give me a big byte array with some information about the phone that is requesting to connect. So from this point my middleware needs to pass the byte array along to the application for processing. But here is the problem, I can't just pass a pointer to the byte array because as soon as the middleware leaves the function that byte array will be deleted from the stack. So I figured I could make a copy of it in the heap and pass that. But now I run into the issue of who does the deleting of that heap memory? I don't think the application should do it because that kind of defeats the purpose of the middleware, but the middleware can't just delete it willy-nilly because the application might still be using the data. So how do I do it?
The Data path is like this... Message with data comes in from the BT circuit board, it goes to the driver, the driver gives it to the middleware, the middleware needs to give it to the application, the application acts on the data, the application calls into the middleware to respond to the message, the middleware takes the information that the application sent it and makes a BT packet, the middleware passes that response back to the driver and finally the driver sends it out.
Questions? Answers?
Have you created a class for this?
If so you might try adding a class member that will hold the array.After you have finished all the "dirty jobs" you delete the class(I suppose you will get rid of memory in destructor).
Savage
RedSon 5,000
Recognized Expert Expert
Have you created a class for this?
If so you might try adding a class member that will hold the array.After you have finished all the "dirty jobs" you delete the class(I suppose you will get rid of memory in destructor).
Savage
Thats a good idea, but the problem is that there are over 150 messages that send byte arrays that mean different types. Part of the design decision is to use the windows messaging to post messages to the applications that have subscribed as listeners. Implementing >150 different member fields and structs for this middleware is not considered a valuable activity to pursue.
RedSon 5,000
Recognized Expert Expert
Use the WM_COPYDATA message.
Ahh good idea, I forgot about that one. I'll do some more research on it and let you know what happens.
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