QWinEventNotifier alternative on Linux and Qt Embedded (Is there one?)

[chesterx]

Hi there Folks.
I'm implementing a QIODevice derived class for use with the FTDI232 API (ftd2xx.h) wich is Win-Mac-Linux API. FTDI makes Serial over USB chips.
The API is kind enough to provide me a function for setting up events, but not kind enough to provide me a function based callback mechanism for getting notified over characters received or transmitted.
So in my quest to making it adhere to QIODevice standards (actually talking about being able to emit the bytesWritten() and the readyReady() signals without spawning another thread) I've found:

*On Windows*

The way I was doing it before writing a nice QIODevice was, in another thread:

HANDLE hEvtRead = ::CreateEventA(NULL, FALSE, FALSE, "");   //From the Windows API
FT_SetEventNotification(ftHandle,FT_EVENT_RXCHAR,hEvtRead); // From the FTDI API        
 
WaitForSingleObject(hEvtRead,INFINITE);
//Handle the event..

HANDLE hEvtRead = ::CreateEventA(NULL, FALSE, FALSE, "");   //From the Windows API
FT_SetEventNotification(ftHandle,FT_EVENT_RXCHAR,hEvtRead); // From the FTDI API        

WaitForSingleObject(hEvtRead,INFINITE);
//Handle the event..

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But I don't want to do it on another thread, I want to keep it as simple as possible like being able to use my Serial Port on a single threaded application like one can with QTcpSockets, so I can't go Waiting for Single Objects on my code in the main thread. I have to find a way to insert the hEvtRead in the events that QCoreApplication's event loop is waiting for.
And the I've found a very nice solution for this on the QProcess source code. It's a class called QWinEventNotifier that does in mere 3 lines, everything i want:

//Inside my QIODevice derived class constructor:
HANDLE hEvtRead = ::CreateEventA(NULL, FALSE, FALSE, "");   //From the Windows API
FT_SetEventNotification(ftHandle,FT_EVENT_RXCHAR,hEvtRead); // From the FTDI API    
 
charReceivedNotifier = new QWinEventNotifier(hEvtRead, this);
QObject::connect(charReceivedNotifier, SIGNAL(activated(HANDLE)), this, SIGNAL(readyRead()));
charReceivedNotifier->setEnabled(true);

//Inside my QIODevice derived class constructor:
HANDLE hEvtRead = ::CreateEventA(NULL, FALSE, FALSE, "");   //From the Windows API
FT_SetEventNotification(ftHandle,FT_EVENT_RXCHAR,hEvtRead); // From the FTDI API    

charReceivedNotifier = new QWinEventNotifier(hEvtRead, this);
QObject::connect(charReceivedNotifier, SIGNAL(activated(HANDLE)), this, SIGNAL(readyRead()));
charReceivedNotifier->setEnabled(true);

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Ok, ok I know I'll have to keep an eye on <qwineventnotifier_p.h> for it's a private class inside <QtCore/private>.

*On Linux (glib and qt embedded)*

The way I was doing it before writing a nice QIODevice for it was, in another thread:

typedef struct _EVENT_HANDLE{
 pthread_cond_t eCondVar;
 pthread_mutex_t eMutex;
 int iVar;
} EVENT_HANDLE;
 
//QThread's run() code:
EVENT_HANDLE eh;
 
pthread_mutex_init(&eh.eMutex, NULL);
pthread_cond_init(&eh.eCondVar, NULL);
 
FT_SetEventNotification(ftHandle, FT_EVENT_RXCHAR, (void*)&eh);
 
pthread_mutex_lock(&eh.eMutex);
pthread_cond_wait(&eh.eCondVar, &eh.eMutex);
pthread_mutex_unlock(&eh.eMutex);
 
//Handle event

typedef struct _EVENT_HANDLE{
 pthread_cond_t eCondVar;
 pthread_mutex_t eMutex;
 int iVar;
} EVENT_HANDLE;

//QThread's run() code:
EVENT_HANDLE eh;

pthread_mutex_init(&eh.eMutex, NULL);
pthread_cond_init(&eh.eCondVar, NULL);

FT_SetEventNotification(ftHandle, FT_EVENT_RXCHAR, (void*)&eh);

pthread_mutex_lock(&eh.eMutex);
pthread_cond_wait(&eh.eCondVar, &eh.eMutex);
pthread_mutex_unlock(&eh.eMutex);

//Handle event

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But I just couldn't find a solution like QWinEventNotifier. I've found solutions that are close to it but are specific to socket descriptors.
Has anyone run into this problem? Am I the first one trying this? I know it's a pain that the FTDI API doesn't provide me a function callback mechanism; it would be really simple..
If you guys have a tip it'll be appreciated.

Thanks
Hernan

[kuzulis]

Hi chesterx!

I decided a similar problem. Chip FTDI232 for any operating system looks like a serial port. Right? Therefore, in the *nix for the events of the reading / writing data can be used QSocketNotifier.

[offtop]But the only bad thing is that the class QWinEventNotifier (in Windows) Private![/offtop]

I wrote a library QSerialDevice to work with serial port. It works like QAbstractSocket.
If you are interested in implementation - then look here: http://gitorious.org/qserialdevice

[chesterx]

Tks kuzulis,
I'll take a look as soon I get back to work next week.

I know it's a private class, but all we have to do, if you want to keep your class up to date, is keep track of the QWinEventNotifier class.

Happy New Year

[chesterx]

Hi kuzulis.
I just learned how to (well in a basic level) use github/gitorious and bitbucket with mercurial or git. I cloned qserialdevice and i'm going to help you with it. I don't want to reinvent the wheel .

[kuzulis]

Hi.

Help is needed only to branches 2.0
main areas are:

- Symbian
1. Implement a notification mechanism for tracking errors, data availability for read, empty of the transmit buffer.
2. Implement a mechanism to track errors parity and frame
3. Implement a policy of reading (IgnorePolicy, PassZeroPolicy and etc).
4. Test on real device

-WinCE
1. Test on real device

- Win32
1. Test on real device

-*nix
1. Implement a mechanism to track errors parity and frame
2. Implement a policy of reading (IgnorePolicy, PassZeroPolicy and etc).
3. Test on real device

Choose any of them.

Ok. I'll wait for bug fixes