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Receive data with UDP protocol



  • hello,
    i want all received data to be stored in bytearray but in bytearray only last bunch of data are stored,is ther any way to store all the data in a array
    This is my UDP receive progrm:-
    connect(mSocket,&QUdpSocket::readyRead,&{
    if(mSocket->hasPendingDatagrams())
    {
    QByteArray data1 ;
    datagram1.resize(mSocket->pendingDatagramSize());
    QDataStream str(&datagram1, QIODevice::ReadOnly);
    mSocket->readDatagram(datagram1.data(),datagram1.size() );
    ui->textEdit->append(QString(datagram1.toHex()));

    }
    });



  • @swansorter
    This appends whatever it receives as hex to the text edit. How many times is it called? Why are you using UDP? If you use UDP, there is no guarantee all data will arrive, that's the point of UDP.

    QDataStream str(&datagram1, QIODevice::ReadOnly);
    

    This line does not seem to do anything, so maybe remove it.

    Your lambda only does one datagram read per each readyRead(); but at least in principle you could receive a stream of datagrams for one readyRead(), and it won't activate readRead() again if you fail to read all of them.. I think you should change your if to a while?



  • @JonB I am using udp to read image sensor values
    i want receive 2014080bytes



  • @swansorter
    Your comment does not address what I have said. And the fact remains that you may miss some UDP datagrams. Did you try the code change I mentioned?



  • @JonB sir i changed the if to while and i am able to recieve all the data





  • @JonB how to store incommming data



  • @swansorter
    Which direction "incoming"? Assuming you mean as per the code you already have, you need to stop using a local variable QByteArray data1 and instead use, say, a class variable one, so that you can append all the data arriving to it, like you do with your text edit.



  • @swansorter said in Receive data with UDP protocol:

    This is my UDP receive progrm:-
    connect(mSocket,&QUdpSocket::readyRead,&{
    if(mSocket->hasPendingDatagrams())
    {
    QByteArray data1 ;
    datagram1.resize(mSocket->pendingDatagramSize());
    QDataStream str(&datagram1, QIODevice::ReadOnly);
    mSocket->readDatagram(datagram1.data(),datagram1.size() );
    ui->textEdit->append(QString(datagram1.toHex()));
    }
    });

    This can not work!
    a. you have to change the if statement into while, to ensure you will handle all received datagram
    b. you copy the data bunch into a local variable, which will be lost after if statement, you have to define a class member to store the different payloads

    For example like this:

    connect(mSocket,&QUdpSocket::readyRead, [this]() {
        while(mSocket->hasPendingDatagrams())
        {
            QByteArray datagram(mSocket->pendingDatagramSize(), 0);
            mSocket->readDatagram(datagram.data(), datagram.size() );
            ui->textEdit->append(QString(datagram.toHex()));
    
            // I suppose the class contains a member mPayload which is a QByteArray
            mPayload.append(datagram);
         }
    });
    

    Now you have to know when data is completely received ;)



  • modules:composer.user_said_in, @KroMignon, Receive data with UDP protocol

    mPayload

    mPayload will give segmentation fault if i use out side



  • @swansorter said in Receive data with UDP protocol:

    mPayload will give segmentation fault if i use out side

    Can you give more details about what you are doing and the debugger backtrace?



  • @KroMignon
    1.i want to receive 2014080 bytes
    2.Receiving it bunch by bunch
    3.problem is each time i receive data the datagram1(bytearry )updated with new bunch of data and qstring also,so at last i only get last bunch of data.
    4. i tried using global variable qstring it receives all the data but giving (SEGMENTATION FAULT).
    is there any other way to do it .

    this is my udp receive program
    void MainWindow::readPendingDatagrams()
    {
    while(mSocket->hasPendingDatagrams())
    {
    QString received_data_x;
    QByteArray datagram1;
    datagram1.resize(mSocket->pendingDatagramSize());
    mSocket->readDatagram(datagram1.data(),datagram1.size() );
    received_data_x.append(datagram1.toHex());

    }

    }



  • @swansorter if i use class member global variable it gives me a segmentation fault

    void MainWindow::on_pushButton_2_pressed()
    {
    //if iuse class member or global variable;
    QString test= received_data//class member;
    int width = 2098, height = 240;
    int bufpo0 = 0, bufpo1 = 1, bufpo2 = 2, bufpo3 = 3;
    QImage img(width, height, QImage::Format_RGB888);
    QByteArray cmd= QByteArray::fromHex(test.replace("\r\n","").toLatin1());

       for (int packet = 0; packet < cmd.length(); packet++)
       {
    

    //in this loop am getting segmentation fault*///
    Auto_image_RGBdata[packet] = static_cast<quint8>(cmd.data()[bufpo0]) | static_cast<quint8>(cmd.data()[bufpo1]) << 8 | static_cast<quint8>(cmd.data()[bufpo2]) << 16 | static_cast<quint8>(cmd.data()[bufpo3])<< 24;

           bufpo0 = bufpo0 + 4;
           bufpo1 = bufpo1 + 4;
           bufpo2 = bufpo2 + 4;
           bufpo3 = bufpo3 + 4;
       }
    
    
    
       for (int y = 0; y < height; y++)
       {
           for (int x = 0; x < width; x++)
           {
                QRgb value = qRgb((Auto_image_RGBdata[x] >> 22 & 0x000000ff),   Auto_image_RGBdata[x] >> 12 & 0x000000ff), (Auto_image_RGBdata[x]>>2  & 0x000003ff));
               img.setPixel(x,y,value);
           }
       }
       ui->port->setPixmap(QPixmap::fromImage(img.scaled(541,301,Qt::KeepAspectRatio)));
    

    ui->port->setScaledContents(true); QPixmap::fromImage(img.scaled(width/4,height*2,Qt::KeepAspectRatio)).save("image2.jpg","JPG");

    }



  • @swansorter said in Receive data with UDP protocol:

    this is my udp receive program
    void MainWindow::readPendingDatagrams()
    {
    while(mSocket->hasPendingDatagrams())
    {
    QString received_data_x;
    QByteArray datagram1;
    datagram1.resize(mSocket->pendingDatagramSize());
    mSocket->readDatagram(datagram1.data(),datagram1.size() );
    received_data_x.append(datagram1.toHex());
    }
    }

    once again received_data_x is a local variable not a class member!



  • @KroMignon if i use received_data_x as class member i am getting segmentation fault



  • @KroMignon
    28621 [1] {
    0x55555562d82c 55 push %rbp
    0x55555562d82d <+0x0001> 48 89 e5 mov %rsp,%rbp
    0x55555562d830 <+0x0004> 53 push %rbx
    0x55555562d831 <+0x0005> 48 81 ec d8 00 00 00 sub $0xd8,%rsp
    0x55555562d838 <+0x000c> 48 89 bd 28 ff ff ff mov %rdi,-0xd8(%rbp)
    0x55555562d83f <+0x0013> 64 48 8b 04 25 28 00 00 00 mov %fs:0x28,%rax
    0x55555562d848 <+0x001c> 48 89 45 e8 mov %rax,-0x18(%rbp)
    0x55555562d84c <+0x0020> 31 c0 xor %eax,%eax
    28635 [1] QString test= x_member;
    0x55555562d84e <+0x0022> 48 8b 85 28 ff ff ff mov -0xd8(%rbp),%rax
    0x55555562d855 <+0x0029> 48 8d 90 88 02 00 00 lea 0x288(%rax),%rdx
    0x55555562d85c <+0x0030> 48 8d 85 68 ff ff ff lea -0x98(%rbp),%rax
    0x55555562d863 <+0x0037> 48 89 d6 mov %rdx,%rsi
    0x55555562d866 <+0x003a> 48 89 c7 mov %rax,%rdi
    0x55555562d869 <+0x003d> e8 26 52 00 00 callq 0x555555632a94 <QString::QString(QString const&)>
    28636 [1] int width = 2098, height = 240;
    0x55555562d86e <+0x0042> c7 85 5c ff ff ff 32 08 00 00 movl $0x832,-0xa4(%rbp)
    0x55555562d878 <+0x004c> c7 85 60 ff ff ff f0 00 00 00 movl $0xf0,-0xa0(%rbp)
    28637 [1] int bufpo0 = 0, bufpo1 = 1, bufpo2 = 2, bufpo3 = 3;
    0x55555562d882 <+0x0056> c7 85 40 ff ff ff 00 00 00 00 movl $0x0,-0xc0(%rbp)
    0x55555562d88c <+0x0060> c7 85 44 ff ff ff 01 00 00 00 movl $0x1,-0xbc(%rbp)
    0x55555562d896 <+0x006a> c7 85 48 ff ff ff 02 00 00 00 movl $0x2,-0xb8(%rbp)
    0x55555562d8a0 <+0x0074> c7 85 4c ff ff ff 03 00 00 00 movl $0x3,-0xb4(%rbp)
    28638 [1] QImage img(width, height, QImage::Format_RGB888);
    0x55555562d8aa <+0x007e> 8b 95 60 ff ff ff mov -0xa0(%rbp),%edx
    0x55555562d8b0 <+0x0084> 8b b5 5c ff ff ff mov -0xa4(%rbp),%esi
    0x55555562d8b6 <+0x008a> 48 8d 45 80 lea -0x80(%rbp),%rax
    0x55555562d8ba <+0x008e> b9 0d 00 00 00 mov $0xd,%ecx
    0x55555562d8bf <+0x0093> 48 89 c7 mov %rax,%rdi
    0x55555562d8c2 <+0x0096> e8 19 f4 f2 ff callq 0x55555555cce0 _ZN6QImageC1EiiNS_6FormatE@plt
    28639 [1] QByteArray cmd= QByteArray::fromHex(test.replace("\r\n","").toLatin1());
    0x55555562d8c7 <+0x009b> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562d8cb <+0x009f> 48 8d 35 06 05 0d 00 lea 0xd0506(%rip),%rsi # 0x5555556fddd8
    0x55555562d8d2 <+0x00a6> 48 89 c7 mov %rax,%rdi
    0x55555562d8d5 <+0x00a9> e8 be 4e 00 00 callq 0x555555632798 <QString::QString(char const*)>
    0x55555562d8da <+0x00ae> 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax
    0x55555562d8e1 <+0x00b5> 48 8d 35 c8 7e 0d 00 lea 0xd7ec8(%rip),%rsi # 0x5555557057b0
    0x55555562d8e8 <+0x00bc> 48 89 c7 mov %rax,%rdi
    0x55555562d8eb <+0x00bf> e8 a8 4e 00 00 callq 0x555555632798 <QString::QString(char const*)>
    0x55555562d8f0 <+0x00c4> 48 8d 55 a0 lea -0x60(%rbp),%rdx
    0x55555562d8f4 <+0x00c8> 48 8d b5 78 ff ff ff lea -0x88(%rbp),%rsi
    0x55555562d8fb <+0x00cf> 48 8d 85 68 ff ff ff lea -0x98(%rbp),%rax
    0x55555562d902 <+0x00d6> b9 01 00 00 00 mov $0x1,%ecx
    0x55555562d907 <+0x00db> 48 89 c7 mov %rax,%rdi
    0x55555562d90a <+0x00de> e8 b1 fc f2 ff callq 0x55555555d5c0 _ZN7QString7replaceERKS_S1_N2Qt15CaseSensitivityE@plt
    0x55555562d90f <+0x00e3> 48 89 c2 mov %rax,%rdx
    0x55555562d912 <+0x00e6> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562d916 <+0x00ea> 48 89 d6 mov %rdx,%rsi
    0x55555562d919 <+0x00ed> 48 89 c7 mov %rax,%rdi
    0x55555562d91c <+0x00f0> e8 83 4c 00 00 callq 0x5555556325a4 <QString::toLatin1() const &>
    0x55555562d921 <+0x00f5> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562d928 <+0x00fc> 48 8d 55 c0 lea -0x40(%rbp),%rdx
    0x55555562d92c <+0x0100> 48 89 d6 mov %rdx,%rsi
    0x55555562d92f <+0x0103> 48 89 c7 mov %rax,%rdi
    0x55555562d932 <+0x0106> e8 39 f4 f2 ff callq 0x55555555cd70 _ZN10QByteArray7fromHexERKS_@plt
    0x55555562d937 <+0x010b> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562d93b <+0x010f> 48 89 c7 mov %rax,%rdi
    0x55555562d93e <+0x0112> e8 11 00 f3 ff callq 0x55555555d954 QByteArray::~QByteArray()
    0x55555562d943 <+0x0117> 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax
    0x55555562d94a <+0x011e> 48 89 c7 mov %rax,%rdi
    0x55555562d94d <+0x0121> e8 b8 51 00 00 callq 0x555555632b0a QString::~QString()
    0x55555562d952 <+0x0126> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562d956 <+0x012a> 48 89 c7 mov %rax,%rdi
    0x55555562d959 <+0x012d> e8 ac 51 00 00 callq 0x555555632b0a QString::~QString()
    28643 [1] for (int packet = 0; packet < cmd.length(); packet++)//2098100(lines)=540000packets
    0x55555562d95e <+0x0132> c7 85 50 ff ff ff 00 00 00 00 movl $0x0,-0xb0(%rbp)
    0x55555562d968 <+0x013c> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562d96f <+0x0143> 48 89 c7 mov %rax,%rdi
    0x55555562d972 <+0x0146> e8 71 49 00 00 callq 0x5555556322e8 <QByteArray::length() const>
    0x55555562d977 <+0x014b> 39 85 50 ff ff ff cmp %eax,-0xb0(%rbp)
    0x55555562d97d <+0x0151> 0f 9c c0 setl %al
    0x55555562d980 <+0x0154> 84 c0 test %al,%al
    0x55555562d982 <+0x0156> 0f 84 d8 00 00 00 je 0x55555562da60 MainWindow::on_pushButton_2_pressed()+564
    28648 [1] Auto_image_RGBdata[packet] = static_cast<quint8>(cmd.data()[bufpo0]) | static_cast<quint8>(cmd.data()[bufpo1]) << 8 | static_cast<quint8>(cmd.data()[bufpo2]) << 16 | static_cast<quint8>(cmd.data()[bufpo3])<< 24;
    0x55555562d988 <+0x015c> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562d98f <+0x0163> 48 89 c7 mov %rax,%rdi
    0x55555562d992 <+0x0166> e8 97 49 00 00 callq 0x55555563232e QByteArray::data()
    0x55555562d997 <+0x016b> 48 89 c2 mov %rax,%rdx
    0x55555562d99a <+0x016e> 8b 85 40 ff ff ff mov -0xc0(%rbp),%eax
    0x55555562d9a0 <+0x0174> 48 98 cltq
    0x55555562d9a2 <+0x0176> 48 01 d0 add %rdx,%rax
    0x55555562d9a5 <+0x0179> 0f b6 00 movzbl (%rax),%eax
    0x55555562d9a8 <+0x017c> 0f b6 d8 movzbl %al,%ebx
    0x55555562d9ab <+0x017f> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562d9b2 <+0x0186> 48 89 c7 mov %rax,%rdi
    0x55555562d9b5 <+0x0189> e8 74 49 00 00 callq 0x55555563232e QByteArray::data()
    0x55555562d9ba <+0x018e> 48 89 c2 mov %rax,%rdx
    0x55555562d9bd <+0x0191> 8b 85 44 ff ff ff mov -0xbc(%rbp),%eax
    0x55555562d9c3 <+0x0197> 48 98 cltq
    0x55555562d9c5 <+0x0199> 48 01 d0 add %rdx,%rax
    0x55555562d9c8 <+0x019c> 0f b6 00 movzbl (%rax),%eax
    0x55555562d9cb <+0x019f> 0f b6 c0 movzbl %al,%eax
    0x55555562d9ce <+0x01a2> c1 e0 08 shl $0x8,%eax
    0x55555562d9d1 <+0x01a5> 09 c3 or %eax,%ebx
    0x55555562d9d3 <+0x01a7> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562d9da <+0x01ae> 48 89 c7 mov %rax,%rdi
    0x55555562d9dd <+0x01b1> e8 4c 49 00 00 callq 0x55555563232e QByteArray::data()
    0x55555562d9e2 <+0x01b6> 48 89 c2 mov %rax,%rdx
    0x55555562d9e5 <+0x01b9> 8b 85 48 ff ff ff mov -0xb8(%rbp),%eax
    0x55555562d9eb <+0x01bf> 48 98 cltq
    0x55555562d9ed <+0x01c1> 48 01 d0 add %rdx,%rax
    0x55555562d9f0 <+0x01c4> 0f b6 00 movzbl (%rax),%eax
    0x55555562d9f3 <+0x01c7> 0f b6 c0 movzbl %al,%eax
    0x55555562d9f6 <+0x01ca> c1 e0 10 shl $0x10,%eax
    0x55555562d9f9 <+0x01cd> 09 c3 or %eax,%ebx
    0x55555562d9fb <+0x01cf> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562da02 <+0x01d6> 48 89 c7 mov %rax,%rdi
    0x55555562da05 <+0x01d9> e8 24 49 00 00 callq 0x55555563232e QByteArray::data()
    0x55555562da0a <+0x01de> 48 89 c2 mov %rax,%rdx
    0x55555562da0d <+0x01e1> 8b 85 4c ff ff ff mov -0xb4(%rbp),%eax
    0x55555562da13 <+0x01e7> 48 98 cltq
    0x55555562da15 <+0x01e9> 48 01 d0 add %rdx,%rax
    0x55555562da18 <+0x01ec> 0f b6 00 movzbl (%rax),%eax
    0x55555562da1b <+0x01ef> 0f b6 c0 movzbl %al,%eax
    0x55555562da1e <+0x01f2> c1 e0 18 shl $0x18,%eax
    0x55555562da21 <+0x01f5> 89 d9 mov %ebx,%ecx
    0x55555562da23 <+0x01f7> 09 c1 or %eax,%ecx
    0x55555562da25 <+0x01f9> 48 8d 05 74 a5 3a 00 lea 0x3aa574(%rip),%rax # 0x5555559d7fa0 <Auto_image_RGBdata>
    0x55555562da2c <+0x0200> 8b 95 50 ff ff ff mov -0xb0(%rbp),%edx
    0x55555562da32 <+0x0206> 48 63 d2 movslq %edx,%rdx
    0x55555562da35 <+0x0209> 89 0c 90 mov %ecx,(%rax,%rdx,4)
    28658 [1] bufpo0 = bufpo0 + 4;
    0x55555562da38 <+0x020c> 83 85 40 ff ff ff 04 addl $0x4,-0xc0(%rbp)
    28659 [1] bufpo1 = bufpo1 + 4;
    0x55555562da3f <+0x0213> 83 85 44 ff ff ff 04 addl $0x4,-0xbc(%rbp)
    28660 [1] bufpo2 = bufpo2 + 4;
    0x55555562da46 <+0x021a> 83 85 48 ff ff ff 04 addl $0x4,-0xb8(%rbp)
    28661 [1] bufpo3 = bufpo3 + 4;
    0x55555562da4d <+0x0221> 83 85 4c ff ff ff 04 addl $0x4,-0xb4(%rbp)
    28643 [2] for (int packet = 0; packet < cmd.length(); packet++)//2098
    100(lines)=540000packets
    0x55555562da54 <+0x0228> 83 85 50 ff ff ff 01 addl $0x1,-0xb0(%rbp)
    0x55555562da5b <+0x022f> e9 08 ff ff ff jmpq 0x55555562d968 MainWindow::on_pushButton_2_pressed()+316
    28666 [1] for (int y = 0; y < height; y++)
    0x55555562da60 <+0x0234> c7 85 54 ff ff ff 00 00 00 00 movl $0x0,-0xac(%rbp)
    0x55555562da6a <+0x023e> 8b 85 54 ff ff ff mov -0xac(%rbp),%eax
    0x55555562da70 <+0x0244> 3b 85 60 ff ff ff cmp -0xa0(%rbp),%eax
    0x55555562da76 <+0x024a> 0f 8d b2 00 00 00 jge 0x55555562db2e MainWindow::on_pushButton_2_pressed()+770
    28669 [1] for (int x = 0; x < width; x++)
    0x55555562da7c <+0x0250> c7 85 58 ff ff ff 00 00 00 00 movl $0x0,-0xa8(%rbp)
    0x55555562da86 <+0x025a> 8b 85 58 ff ff ff mov -0xa8(%rbp),%eax
    0x55555562da8c <+0x0260> 3b 85 5c ff ff ff cmp -0xa4(%rbp),%eax
    0x55555562da92 <+0x0266> 0f 8d 8a 00 00 00 jge 0x55555562db22 MainWindow::on_pushButton_2_pressed()+758


    0x55555562da98 <+0x026c> 48 8d 05 01 a5 3a 00 lea 0x3aa501(%rip),%rax # 0x5555559d7fa0 <Auto_image_RGBdata>
    0x55555562da9f <+0x0273> 8b 95 58 ff ff ff mov -0xa8(%rbp),%edx
    0x55555562daa5 <+0x0279> 48 63 d2 movslq %edx,%rdx
    0x55555562daa8 <+0x027c> 8b 04 90 mov (%rax,%rdx,4),%eax
    0x55555562daab <+0x027f> c1 f8 02 sar $0x2,%eax
    0x55555562daae <+0x0282> 25 ff 03 00 00 and $0x3ff,%eax
    0x55555562dab3 <+0x0287> 89 c6 mov %eax,%esi
    0x55555562dab5 <+0x0289> 48 8d 05 e4 a4 3a 00 lea 0x3aa4e4(%rip),%rax # 0x5555559d7fa0 <Auto_image_RGBdata>
    0x55555562dabc <+0x0290> 8b 95 58 ff ff ff mov -0xa8(%rbp),%edx
    0x55555562dac2 <+0x0296> 48 63 d2 movslq %edx,%rdx
    0x55555562dac5 <+0x0299> 8b 04 90 mov (%rax,%rdx,4),%eax
    0x55555562dac8 <+0x029c> c1 f8 0c sar $0xc,%eax
    0x55555562dacb <+0x029f> 0f b6 c8 movzbl %al,%ecx
    0x55555562dace <+0x02a2> 48 8d 05 cb a4 3a 00 lea 0x3aa4cb(%rip),%rax # 0x5555559d7fa0 <Auto_image_RGBdata>
    0x55555562dad5 <+0x02a9> 8b 95 58 ff ff ff mov -0xa8(%rbp),%edx
    0x55555562dadb <+0x02af> 48 63 d2 movslq %edx,%rdx
    0x55555562dade <+0x02b2> 8b 04 90 mov (%rax,%rdx,4),%eax
    0x55555562dae1 <+0x02b5> c1 f8 16 sar $0x16,%eax
    0x55555562dae4 <+0x02b8> 0f b6 c0 movzbl %al,%eax
    0x55555562dae7 <+0x02bb> 89 f2 mov %esi,%edx
    0x55555562dae9 <+0x02bd> 89 ce mov %ecx,%esi
    0x55555562daeb <+0x02bf> 89 c7 mov %eax,%edi
    0x55555562daed <+0x02c1> e8 ff 56 00 00 callq 0x5555556331f1 <qRgb(int, int, int)>
    0x55555562daf2 <+0x02c6> 89 85 64 ff ff ff mov %eax,-0x9c(%rbp)
    28672 [1] img.setPixel(x,y,value);
    0x55555562daf8 <+0x02cc> 8b 8d 64 ff ff ff mov -0x9c(%rbp),%ecx
    0x55555562dafe <+0x02d2> 8b 95 54 ff ff ff mov -0xac(%rbp),%edx
    0x55555562db04 <+0x02d8> 8b b5 58 ff ff ff mov -0xa8(%rbp),%esi
    0x55555562db0a <+0x02de> 48 8d 45 80 lea -0x80(%rbp),%rax
    0x55555562db0e <+0x02e2> 48 89 c7 mov %rax,%rdi
    0x55555562db11 <+0x02e5> e8 aa f0 f2 ff callq 0x55555555cbc0 _ZN6QImage8setPixelEiij@plt
    28669 [2] for (int x = 0; x < width; x++)
    0x55555562db16 <+0x02ea> 83 85 58 ff ff ff 01 addl $0x1,-0xa8(%rbp)
    0x55555562db1d <+0x02f1> e9 64 ff ff ff jmpq 0x55555562da86 MainWindow::on_pushButton_2_pressed()+602
    28666 [2] for (int y = 0; y < height; y++)
    0x55555562db22 <+0x02f6> 83 85 54 ff ff ff 01 addl $0x1,-0xac(%rbp)
    0x55555562db29 <+0x02fd> e9 3c ff ff ff jmpq 0x55555562da6a MainWindow::on_pushButton_2_pressed()+574
    28676 [1] ui->port->setPixmap(QPixmap::fromImage(img.scaled(541,301,Qt::KeepAspectRatio)));
    0x55555562db2e <+0x0302> 48 8b 85 28 ff ff ff mov -0xd8(%rbp),%rax
    0x55555562db35 <+0x0309> 48 8b 80 20 02 00 00 mov 0x220(%rax),%rax
    0x55555562db3c <+0x0310> 48 8b 98 90 00 00 00 mov 0x90(%rax),%rbx
    0x55555562db43 <+0x0317> 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax
    0x55555562db4a <+0x031e> be 00 00 00 00 mov $0x0,%esi
    0x55555562db4f <+0x0323> 48 89 c7 mov %rax,%rdi
    0x55555562db52 <+0x0326> e8 8d 44 00 00 callq 0x555555631fe4 <QFlagsQt::ImageConversionFlag::QFlags(Qt::ImageConversionFlag)>
    0x55555562db57 <+0x032b> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562db5b <+0x032f> 48 8d 75 80 lea -0x80(%rbp),%rsi
    0x55555562db5f <+0x0333> 41 b9 00 00 00 00 mov $0x0,%r9d
    0x55555562db65 <+0x0339> 41 b8 01 00 00 00 mov $0x1,%r8d
    0x55555562db6b <+0x033f> b9 2d 01 00 00 mov $0x12d,%ecx
    0x55555562db70 <+0x0344> ba 1d 02 00 00 mov $0x21d,%edx
    0x55555562db75 <+0x0349> 48 89 c7 mov %rax,%rdi
    0x55555562db78 <+0x034c> e8 9d 57 00 00 callq 0x55555563331a <QImage::scaled(int, int, Qt::AspectRatioMode, Qt::TransformationMode) const>
    0x55555562db7d <+0x0351> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562db81 <+0x0355> 8b 95 78 ff ff ff mov -0x88(%rbp),%edx
    0x55555562db87 <+0x035b> 48 8d 4d a0 lea -0x60(%rbp),%rcx
    0x55555562db8b <+0x035f> 48 89 ce mov %rcx,%rsi
    0x55555562db8e <+0x0362> 48 89 c7 mov %rax,%rdi
    0x55555562db91 <+0x0365> e8 fc 57 00 00 callq 0x555555633392 <QPixmap::fromImage(QImage&&, QFlagsQt::ImageConversionFlag)>
    0x55555562db96 <+0x036a> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562db9a <+0x036e> 48 89 c6 mov %rax,%rsi
    0x55555562db9d <+0x0371> 48 89 df mov %rbx,%rdi
    0x55555562dba0 <+0x0374> e8 6b f3 f2 ff callq 0x55555555cf10 _ZN6QLabel9setPixmapERK7QPixmap@plt
    0x55555562dba5 <+0x0379> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562dba9 <+0x037d> 48 89 c7 mov %rax,%rdi
    0x55555562dbac <+0x0380> e8 3f ec f2 ff callq 0x55555555c7f0 _ZN7QPixmapD1Ev@plt
    0x55555562dbb1 <+0x0385> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562dbb5 <+0x0389> 48 89 c7 mov %rax,%rdi
    0x55555562dbb8 <+0x038c> e8 33 f1 f2 ff callq 0x55555555ccf0 _ZN6QImageD1Ev@plt
    28677 [1] ui->port->setScaledContents(true);
    0x55555562dbbd <+0x0391> 48 8b 85 28 ff ff ff mov -0xd8(%rbp),%rax
    0x55555562dbc4 <+0x0398> 48 8b 80 20 02 00 00 mov 0x220(%rax),%rax
    0x55555562dbcb <+0x039f> 48 8b 80 90 00 00 00 mov 0x90(%rax),%rax
    0x55555562dbd2 <+0x03a6> be 01 00 00 00 mov $0x1,%esi
    0x55555562dbd7 <+0x03ab> 48 89 c7 mov %rax,%rdi
    0x55555562dbda <+0x03ae> e8 41 f1 f2 ff callq 0x55555555cd20 _ZN6QLabel17setScaledContentsEb@plt
    28679 [1] QPixmap::fromImage(img.scaled(width/4,height2,Qt::KeepAspectRatio)).save("image2.jpg","JPG");
    0x55555562dbdf <+0x03b3> 48 8d 85 3c ff ff ff lea -0xc4(%rbp),%rax
    0x55555562dbe6 <+0x03ba> be 00 00 00 00 mov $0x0,%esi
    0x55555562dbeb <+0x03bf> 48 89 c7 mov %rax,%rdi
    0x55555562dbee <+0x03c2> e8 f1 43 00 00 callq 0x555555631fe4 <QFlagsQt::ImageConversionFlag::QFlags(Qt::ImageConversionFlag)>
    0x55555562dbf3 <+0x03c7> 8b 85 60 ff ff ff mov -0xa0(%rbp),%eax
    0x55555562dbf9 <+0x03cd> 8d 14 00 lea (%rax,%rax,1),%edx
    0x55555562dbfc <+0x03d0> 8b 85 5c ff ff ff mov -0xa4(%rbp),%eax
    0x55555562dc02 <+0x03d6> 8d 48 03 lea 0x3(%rax),%ecx
    0x55555562dc05 <+0x03d9> 85 c0 test %eax,%eax
    0x55555562dc07 <+0x03db> 0f 48 c1 cmovs %ecx,%eax
    0x55555562dc0a <+0x03de> c1 f8 02 sar $0x2,%eax
    0x55555562dc0d <+0x03e1> 89 c7 mov %eax,%edi
    0x55555562dc0f <+0x03e3> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562dc13 <+0x03e7> 48 8d 75 80 lea -0x80(%rbp),%rsi
    0x55555562dc17 <+0x03eb> 41 b9 00 00 00 00 mov $0x0,%r9d
    0x55555562dc1d <+0x03f1> 41 b8 01 00 00 00 mov $0x1,%r8d
    0x55555562dc23 <+0x03f7> 89 d1 mov %edx,%ecx
    0x55555562dc25 <+0x03f9> 89 fa mov %edi,%edx
    0x55555562dc27 <+0x03fb> 48 89 c7 mov %rax,%rdi
    0x55555562dc2a <+0x03fe> e8 eb 56 00 00 callq 0x55555563331a <QImage::scaled(int, int, Qt::AspectRatioMode, Qt::TransformationMode) const>
    0x55555562dc2f <+0x0403> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562dc33 <+0x0407> 8b 95 3c ff ff ff mov -0xc4(%rbp),%edx
    0x55555562dc39 <+0x040d> 48 8d 4d a0 lea -0x60(%rbp),%rcx
    0x55555562dc3d <+0x0411> 48 89 ce mov %rcx,%rsi
    0x55555562dc40 <+0x0414> 48 89 c7 mov %rax,%rdi
    0x55555562dc43 <+0x0417> e8 4a 57 00 00 callq 0x555555633392 <QPixmap::fromImage(QImage&&, QFlagsQt::ImageConversionFlag)>
    0x55555562dc48 <+0x041c> 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax
    0x55555562dc4f <+0x0423> 48 8d 35 5d 7b 0d 00 lea 0xd7b5d(%rip),%rsi # 0x5555557057b3
    0x55555562dc56 <+0x042a> 48 89 c7 mov %rax,%rdi
    0x55555562dc59 <+0x042d> e8 3a 4b 00 00 callq 0x555555632798 <QString::QString(char const
    )>
    0x55555562dc5e <+0x0432> 48 8d b5 78 ff ff ff lea -0x88(%rbp),%rsi
    0x55555562dc65 <+0x0439> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562dc69 <+0x043d> b9 ff ff ff ff mov $0xffffffff,%ecx
    0x55555562dc6e <+0x0442> 48 8d 15 49 7b 0d 00 lea 0xd7b49(%rip),%rdx # 0x5555557057be
    0x55555562dc75 <+0x0449> 48 89 c7 mov %rax,%rdi
    0x55555562dc78 <+0x044c> e8 43 f6 f2 ff callq 0x55555555d2c0 _ZNK7QPixmap4saveERK7QStringPKci@plt
    0x55555562dc7d <+0x0451> 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax
    0x55555562dc84 <+0x0458> 48 89 c7 mov %rax,%rdi
    0x55555562dc87 <+0x045b> e8 7e 4e 00 00 callq 0x555555632b0a QString::~QString()
    0x55555562dc8c <+0x0460> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562dc90 <+0x0464> 48 89 c7 mov %rax,%rdi
    0x55555562dc93 <+0x0467> e8 58 eb f2 ff callq 0x55555555c7f0 _ZN7QPixmapD1Ev@plt
    0x55555562dc98 <+0x046c> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562dc9c <+0x0470> 48 89 c7 mov %rax,%rdi
    0x55555562dc9f <+0x0473> e8 4c f0 f2 ff callq 0x55555555ccf0 _ZN6QImageD1Ev@plt
    28639 [2] QByteArray cmd= QByteArray::fromHex(test.replace("\r\n","").toLatin1());
    0x55555562dca4 <+0x0478> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562dcab <+0x047f> 48 89 c7 mov %rax,%rdi
    0x55555562dcae <+0x0482> e8 a1 fc f2 ff callq 0x55555555d954 QByteArray::~QByteArray()
    28638 [2] QImage img(width, height, QImage::Format_RGB888);
    0x55555562dcb3 <+0x0487> 48 8d 45 80 lea -0x80(%rbp),%rax
    0x55555562dcb7 <+0x048b> 48 89 c7 mov %rax,%rdi
    0x55555562dcba <+0x048e> e8 31 f0 f2 ff callq 0x55555555ccf0 _ZN6QImageD1Ev@plt
    28635 [2] QString test= x_member;
    0x55555562dcbf <+0x0493> 48 8d 85 68 ff ff ff lea -0x98(%rbp),%rax
    0x55555562dcc6 <+0x049a> 48 89 c7 mov %rax,%rdi
    0x55555562dcc9 <+0x049d> e8 3c 4e 00 00 callq 0x555555632b0a QString::~QString()
    28683 [1] }
    0x55555562dcce <+0x04a2> 90 nop
    0x55555562dccf <+0x04a3> 48 8b 45 e8 mov -0x18(%rbp),%rax
    0x55555562dcd3 <+0x04a7> 64 48 33 04 25 28 00 00 00 xor %fs:0x28,%rax
    0x55555562dcdc <+0x04b0> 0f 84 da 00 00 00 je 0x55555562ddbc MainWindow::on_pushButton_2_pressed()+1424
    0x55555562dce2 <+0x04b6> e9 d0 00 00 00 jmpq 0x55555562ddb7 MainWindow::on_pushButton_2_pressed()+1419
    0x55555562dce7 <+0x04bb> 48 89 c3 mov %rax,%rbx
    0x55555562dcea <+0x04be> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562dcee <+0x04c2> 48 89 c7 mov %rax,%rdi
    0x55555562dcf1 <+0x04c5> e8 5e fc f2 ff callq 0x55555555d954 QByteArray::~QByteArray()
    0x55555562dcf6 <+0x04ca> eb 03 jmp 0x55555562dcfb MainWindow::on_pushButton_2_pressed()+1231
    0x55555562dcf8 <+0x04cc> 48 89 c3 mov %rax,%rbx
    0x55555562dcfb <+0x04cf> 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax
    0x55555562dd02 <+0x04d6> 48 89 c7 mov %rax,%rdi
    0x55555562dd05 <+0x04d9> e8 00 4e 00 00 callq 0x555555632b0a QString::~QString()
    0x55555562dd0a <+0x04de> eb 03 jmp 0x55555562dd0f MainWindow::on_pushButton_2_pressed()+1251
    0x55555562dd0c <+0x04e0> 48 89 c3 mov %rax,%rbx
    0x55555562dd0f <+0x04e3> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562dd13 <+0x04e7> 48 89 c7 mov %rax,%rdi
    0x55555562dd16 <+0x04ea> e8 ef 4d 00 00 callq 0x555555632b0a QString::~QString()
    0x55555562dd1b <+0x04ef> eb 6f jmp 0x55555562dd8c MainWindow::on_pushButton_2_pressed()+1376
    0x55555562dd1d <+0x04f1> 48 89 c3 mov %rax,%rbx
    28676 [2] ui->port->setPixmap(QPixmap::fromImage(img.scaled(541,301,Qt::KeepAspectRatio)));
    0x55555562dd20 <+0x04f4> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562dd24 <+0x04f8> 48 89 c7 mov %rax,%rdi
    0x55555562dd27 <+0x04fb> e8 c4 ea f2 ff callq 0x55555555c7f0 _ZN7QPixmapD1Ev@plt
    0x55555562dd2c <+0x0500> eb 03 jmp 0x55555562dd31 MainWindow::on_pushButton_2_pressed()+1285
    0x55555562dd2e <+0x0502> 48 89 c3 mov %rax,%rbx
    0x55555562dd31 <+0x0505> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562dd35 <+0x0509> 48 89 c7 mov %rax,%rdi
    0x55555562dd38 <+0x050c> e8 b3 ef f2 ff callq 0x55555555ccf0 _ZN6QImageD1Ev@plt
    0x55555562dd3d <+0x0511> eb 39 jmp 0x55555562dd78 MainWindow::on_pushButton_2_pressed()+1356
    0x55555562dd3f <+0x0513> 48 89 c3 mov %rax,%rbx
    28679 [2] QPixmap::fromImage(img.scaled(width/4,height*2,Qt::KeepAspectRatio)).save("image2.jpg","JPG");
    0x55555562dd42 <+0x0516> 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax
    0x55555562dd49 <+0x051d> 48 89 c7 mov %rax,%rdi
    0x55555562dd4c <+0x0520> e8 b9 4d 00 00 callq 0x555555632b0a QString::~QString()
    0x55555562dd51 <+0x0525> eb 03 jmp 0x55555562dd56 MainWindow::on_pushButton_2_pressed()+1322
    0x55555562dd53 <+0x0527> 48 89 c3 mov %rax,%rbx
    0x55555562dd56 <+0x052a> 48 8d 45 c0 lea -0x40(%rbp),%rax
    0x55555562dd5a <+0x052e> 48 89 c7 mov %rax,%rdi
    0x55555562dd5d <+0x0531> e8 8e ea f2 ff callq 0x55555555c7f0 _ZN7QPixmapD1Ev@plt
    0x55555562dd62 <+0x0536> eb 03 jmp 0x55555562dd67 MainWindow::on_pushButton_2_pressed()+1339
    0x55555562dd64 <+0x0538> 48 89 c3 mov %rax,%rbx
    0x55555562dd67 <+0x053b> 48 8d 45 a0 lea -0x60(%rbp),%rax
    0x55555562dd6b <+0x053f> 48 89 c7 mov %rax,%rdi
    0x55555562dd6e <+0x0542> e8 7d ef f2 ff callq 0x55555555ccf0 _ZN6QImageD1Ev@plt
    0x55555562dd73 <+0x0547> eb 03 jmp 0x55555562dd78 MainWindow::on_pushButton_2_pressed()+1356
    0x55555562dd75 <+0x0549> 48 89 c3 mov %rax,%rbx
    28639 [3] QByteArray cmd= QByteArray::fromHex(test.replace("\r\n","").toLatin1());
    0x55555562dd78 <+0x054c> 48 8d 85 70 ff ff ff lea -0x90(%rbp),%rax
    0x55555562dd7f <+0x0553> 48 89 c7 mov %rax,%rdi
    0x55555562dd82 <+0x0556> e8 cd fb f2 ff callq 0x55555555d954 QByteArray::~QByteArray()
    0x55555562dd87 <+0x055b> eb 03 jmp 0x55555562dd8c MainWindow::on_pushButton_2_pressed()+1376
    0x55555562dd89 <+0x055d> 48 89 c3 mov %rax,%rbx
    28638 [3] QImage img(width, height, QImage::Format_RGB888);
    0x55555562dd8c <+0x0560> 48 8d 45 80 lea -0x80(%rbp),%rax
    0x55555562dd90 <+0x0564> 48 89 c7 mov %rax,%rdi
    0x55555562dd93 <+0x0567> e8 58 ef f2 ff callq 0x55555555ccf0 _ZN6QImageD1Ev@plt
    0x55555562dd98 <+0x056c> eb 03 jmp 0x55555562dd9d MainWindow::on_pushButton_2_pressed()+1393
    0x55555562dd9a <+0x056e> 48 89 c3 mov %rax,%rbx
    28635 [3] QString test= x_member;
    0x55555562dd9d <+0x0571> 48 8d 85 68 ff ff ff lea -0x98(%rbp),%rax
    0x55555562dda4 <+0x0578> 48 89 c7 mov %rax,%rdi
    0x55555562dda7 <+0x057b> e8 5e 4d 00 00 callq 0x555555632b0a QString::~QString()
    0x55555562ddac <+0x0580> 48 89 d8 mov %rbx,%rax
    0x55555562ddaf <+0x0583> 48 89 c7 mov %rax,%rdi
    0x55555562ddb2 <+0x0586> e8 39 ee f2 ff callq 0x55555555cbf0 _Unwind_Resume@plt
    28683 [2] }
    0x55555562ddb7 <+0x058b> e8 14 ec f2 ff callq 0x55555555c9d0 __stack_chk_fail@plt
    0x55555562ddbc <+0x0590> 48 81 c4 d8 00 00 00 add $0xd8,%rsp
    0x55555562ddc3 <+0x0597> 5b pop %rbx
    0x55555562ddc4 <+0x0598> 5d pop %rbp
    0x55555562ddc5 <+0x0599> c3 retq



  • @swansorter said in Receive data with UDP protocol:

    if i use received_data_x as class member i am getting segmentation fault

    I don't understand this, I do this in many application running on Windows, Linux and Android and I never got a segmentation fault!

    class MainWindow : public QMainWindow
    {
        Q_OBJECT
    
    ...
       QUdpSoccket *mSocket;
       QByteArray mPayload;
    ...
    
    private slots:
        void readPendingDatagrams();
    }
    

    and then

    void MainWindow::readPendingDatagrams()
    {
        while(mSocket->hasPendingDatagrams())
        {
            QByteArray datagram1;
            datagram1.resize(mSocket->pendingDatagramSize());
            mSocket->readDatagram(datagram1.data(),datagram1.size() );
            mPayload.append(datagram1.toHex());
        }
    }
    

    And this works fine.



  • @KroMignon
    void MainWindow::on_pushButton_2_pressed()
    {
    //if iuse class member or global variable;
    QString test= mPayLoad//class member;
    int bufpo0 = 0, bufpo1 = 1, bufpo2 = 2, bufpo3 = 3;
    QByteArray cmd= QByteArray::fromHex(test.replace("\r\n","").toLatin1());

    for (int packet = 0; packet < cmd.length(); packet++)
    {
    //in this loop am getting segmentation fault*///
    Auto_image_RGBdata[packet] = static_cast<quint8>(cmd.data()[bufpo0]) | static_cast<quint8>(cmd.data()[bufpo1]) << 8 | static_cast<quint8>(cmd.data()[bufpo2]) << 16 | static_cast<quint8>(cmd.data()[bufpo3])<< 24;

       bufpo0 = bufpo0 + 4;
       bufpo1 = bufpo1 + 4;
       bufpo2 = bufpo2 + 4;
       bufpo3 = bufpo3 + 4;
    

    }



  • @swansorter in the above code i am getting segmentation fault



  • @swansorter said in Receive data with UDP protocol:

    in the above code i am getting segmentation fault

    First, if you are expecting QByteArray, then store it as QByteArray in the readPendingDatagrams() slot, so don't have to convert from QByteArray to hexstring and back:

    void MainWindow::readPendingDatagrams()
    {
        while(mSocket->hasPendingDatagrams())
        {
            QByteArray datagram1;
            datagram1.resize(mSocket->pendingDatagramSize());
            mSocket->readDatagram(datagram1.data(),datagram1.size() );
            mPayload.append(datagram1);
        }
    }
    

    Then how did you declare Auto_image_RGBdata?



  • @KroMignon
    class MainWindow : public QMainWindow
    {
    Q_OBJECT
    QByteArray mPayload;
    QUdpSocket *mSocket;
    QUdpSocket *socket;
    qint32 Auto_image_RGBdata[2014080]={0};
    private slots:
    void readPendingDatagrams();
    }



  • @swansorter Your code is not very clear to understand, I do my best.

    I suppose you want to read 32 bit words from the stream, in big endian byte order.

    So I would to it with QDataStream, like this:

    QByteArray data = mPayLoad; // made local copy to avoid changes by slot
    QDataStream stream(&data, QIODevice::ReadOnly);
    // default byte order for QDataStream is big endian
    ///stream.setByteOrder(QDataStream::LittleEndian); // if you want to change byte order
    
    // to be sure we are not trying to read more than possible!!
    int maxCount = qMin(data.size() / 4, sizeof(Auto_image_RGBdata)/sizeof(Auto_image_RGBdata[0]));
    
    for(int i = 0; i < maxCount; ++i)
       stream >> Auto_image_RGBdata[i];
    

    That's it.



  • @KroMignon
    sir

    1. i wan to receive 2014080 bytes (from udp)
      2.then i have to re arrange received data

    for (int packet = 0; packet < cmd.length(); packet++)
    {
    //in this loop am getting segmentation fault*///
    Auto_image_RGBdata[packet] = static_cast<quint8>(mPayload.data()[bufpo0]) | static_cast<quint8>(mPayload.data()[bufpo1]) << 8 | static_cast<quint8>(mPayload.data()[bufpo2]) << 16 | static_cast<quint8>(mPayload.data()[bufpo3])<< 24;

    bufpo0 = bufpo0 + 4;
    bufpo1 = bufpo1 + 4;
    bufpo2 = bufpo2 + 4;
    bufpo3 = bufpo3 + 4;

    }
    3.then ill convert Auto_image_RGBdata to image using pix map



  • @swansorter said in Receive data with UDP protocol:

    1.i wan to receive 2014080 bytes (from udp)

    How do you know which is the first datagram?

    2.then i have to re arrange received data

    Have you tried out the code in my previous post?

    3.then ill convert Auto_image_RGBdata to image using pix map

    To convert your image to QPixmap, if you receive a pixel buffer, you could do it like this:

    // be careful, (image_width*image_height*4) must be lower or equal to mPayLoad.size()
    QPixmap pixmap = QPixmap::fromImage(
        QImage(
         mPayLoad.constData(), 
         image_width,
         image_height,
         QImage::Format_ARGB32// take a look a QImage documentation to choose the right format
        ) 
    ); 
    


  • @KroMignon solved thank you very much


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