Circular Buffer in Qt

Question

What is the best way to create a circular buffer in Qt? I would just do something like this:

vidoudpsocket.h

typedef struct
{
    CircularBuffer *before
    quint16 *data;
    CircularBuffer *next;
} CircularBuffer;

videoudpsocket.cpp

VideoUDPSocket::VideoUDPSocket(QObject *parent)
    : QObject(parent)
{
    CircularBuffer buffer0, buffer1, buffer2, buffer3, buffer4, buffer5, buffer6, buffer7;
    buffer0.before = buffer7;
    buffer0.data = (quint16 *) malloc(16384*16384);
    buffer0.next = buffer1;
    //...
}

Is this a good way to implement it in Qt or is there a better?

Thank you!

Edit:

My first try do not even seems to work, the compiler does not know what to do with CircularBuffer inside the structure.

I now try to use QVector but i alwas get the Error allocating memory for data[i]-Debug-Message (at i > 7809).

#define MAXNUMBERRANGEBINS 8192
QVector<quint8**> ringBuffer;
ringBuffer.resize(8);
foreach(quint8** data, ringBuffer)
{
    data = (quint8**) malloc(MAXNUMBERRANGEBINS*2*sizeof( quint8* ));
    if(data == NULL)
        qDebug() << "Error allocating memory for data";
    for(int i = 0; i < MAXNUMBERRANGEBINS*2; i++)
    {
        data[i] = (quint8*) malloc(MAXNUMBERRANGEBINS*2);
        if(data[i] == NULL)
            qDebug() << "Error allocating memory for data[" << i << "]";
    }
}

Edit2 If I calculated right, my array is about 270MB big per buffer, that should explain the memory allocation error, am I right?

wouldn't an array (or list or vector) be a better than buffer0, buffer1, buffer 2 etc. ? — Michael Vincent, Oct 02 '15 at 08:29
It may worth a note that Qt has its own QCircularBuffer since Qt 5.5 but it is in Qt3D: http://doc.qt.io/qt-5/qt3d-qcircularbuffer.html#details — demonplus, Oct 02 '15 at 10:17
You can use the private `QRingBuffer`. See an example [here](http://stackoverflow.com/a/32317276/1329652). — Kuba hasn't forgotten Monica, Oct 02 '15 at 14:22

score 0 · Answer 1 · edited Feb 07 '19 at 09:45

0

Don't use selfmade linked lists. Direct access is easier to understand and easier to debug.

     QVector<uint16_t*>(8) ringBuffer;
     foreach(uint16_t* data, ringBuffer){
       data = new(1024);
     }

     size_t index = 0;

     //Access 
     while(true)
     {

       memcpy(ringBuffer[index],yourSource, 1024);
       index = (index +1) % 8;
     }

edited Feb 07 '19 at 09:45

Vincent Beltman

2,064
13
27

answered Oct 02 '15 at 08:34

znoopy2k

58
5

Thank you, I will try that! – honiahaka10 Oct 02 '15 at 11:19
I added my new code to my question but it does not seem to work, i always get an memory-allocation-error. – honiahaka10 Oct 02 '15 at 11:57

Circular Buffer in Qt

Edit:

1 Answers1