How do i integrate my embedded C source codes (for my embedded linux board) with Qt GUI together?

[embdev]

@jsulm yes it is, the source file containing the function definition SAMPLE_VDEC_VhdH264() is added physically into the project file.

[jsulm]

@embdev You should check the complete "Compile Output" to see whether that file was really built and linked to your executable.
Don't forget that you should always execute qmake again (and do a rebuild) if you change the .pro file!

[embdev]

@jsulm I did a clean, followed by build again in Qt Creator IDE environment but still receiving the error:
In the .pro file, my source file containing the SAMPLE_VDEC_VhdH264() is also included under SOURCES +=

This is an output from the compile tab:

5:39:36: Running steps for project vdec_test...
15:39:36: Configuration unchanged, skipping qmake step.
15:39:36: Starting: "/usr/bin/make" 
arm-hisiv400-linux-g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I../../v1_QtEmbedded-4.8.6/mkspecs/qws/linux-hisiv400-arm-g++ -I../vdec_test -I../../v1_QtEmbedded-4.8.6/include/QtCore -I../../v1_QtEmbedded-4.8.6/include/QtNetwork -I../../v1_QtEmbedded-4.8.6/include/QtGui -I../../v1_QtEmbedded-4.8.6/include -I../../mpp_single/sample/common -I../../mpp_single/include -I../../mpp_single/extdrv/tlv320aic31 -I../../v1_QtEmbedded-4.8.6/examples/multimedia/videographicsitem -I../../mpp_single/lib -I../../mpp_single/include -I../../mpp_single/include -I../../mpp_single/include -I../../mpp_single/include -I../../mpp_single/include -I../../mpp_single/include -I. -I. -I../vdec_test -I. -o mainwindow.o ../vdec_test/mainwindow.cpp
arm-hisiv400-linux-g++ -Wl,-O1 -Wl,-rpath,/home/aa/Hi3536_SDK_V2.0.4.0/v1_QtEmbedded-4.8.6/lib -o vdec_test main.o mainwindow.o sample_comm_audio.o sample_comm_ivs.o sample_comm_sys.o sample_comm_vda.o sample_comm_vdec.o sample_comm_venc.o sample_comm_vi.o sample_comm_vo.o sample_comm_vpss.o sample_vdec.o moc_mainwindow.o    -L/home/aa/Hi3536_SDK_V2.0.4.0/v1_QtEmbedded-4.8.6/lib -L/home/aa/Hi3536_SDK_V2.0.4.0/Working\ folder/vdec_test/../../mpp_single/lib/ -ldnvqe -lhdmi -lmpi -ljpeg -lupvqe -lVoiceEngine -lQtGui -L/home/aa/Hi3536_SDK_V2.0.4.0/v1_QtEmbedded-4.8.6/lib -lQtNetwork -lQtCore -lm -ldl -lrt -lpthread 
mainwindow.o: In function `MainWindow::on_pushButton_clicked()':
mainwindow.cpp:(.text+0xbc): undefined reference to `SAMPLE_VDEC_VdhH264()'
mainwindow.o: In function `MainWindow::on_pushButton_2_clicked()':
mainwindow.cpp:(.text+0xc0): undefined reference to `SAMPLE_VDEC_VdhH265()'
collect2: error: ld returned 1 exit status
Makefile:125: recipe for target 'vdec_test' failed
make: *** [vdec_test] Error 1
15:39:37: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project vdec_test (kit: HI3536 Qt4.8)
When executing step "Make"
15:39:37: Elapsed time: 00:01.

[jsulm]

@embdev To me it doesn't look like a complete rebuild as in the second compiler call object files, which were not compiled before, are already linked:

arm-hisiv400-linux-g++ -Wl,-O1 -Wl,-rpath,/home/aa/Hi3536_SDK_V2.0.4.0/v1_QtEmbedded-4.8.6/lib -o vdec_test main.o mainwindow.o sample_comm_audio.o sample_comm_ivs.o sample_comm_sys.o sample_comm_vda.o sample_comm_vdec.o sample_comm_venc.o sample_comm_vi.o sample_comm_vo.o sample_comm_vpss.o sample_vdec.o moc_mainwindow.o    -L/home/aa/Hi3536_SDK_V2.0.4.0/v1_QtEmbedded-4.8.6/lib -L/home/aa/Hi3536_SDK_V2.0.4.0/Working\ folder/vdec_test/../../mpp_single/lib/ -ldnvqe -lhdmi -lmpi -ljpeg -lupvqe -lVoiceEngine -lQtGui -L/home/aa/Hi3536_SDK_V2.0.4.0/v1_QtEmbedded-4.8.6/lib -lQtNetwork -lQtCore -lm -ldl -lrt -lpthread

Please do a rebuild.
In which file is SAMPLE_VDEC_VhdH264() defined?

[embdev]

@jsulm I've deleted the object files away in my build-release folder. I think could be due to datatype declaration of my function, when it's invoked as HI_32 SAMPLE_VDEC_VdhH264(); in the main.cpp, then the project can be compiled, i.e.:

** in main.cpp **

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "hi3536mainfx.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_pushButton_clicked()
{

  HI_S32 SAMPLE_VDEC_VdhH264();

}

[jsulm]

@embdev Now you are declaring a function with same name, you are not calling it.
Functions are not called like this in C/C++.
You should really check your project configuration and sources.

[embdev]

@jsulm I see, project configurations meaning the .pro file?

[jsulm]

@embdev yes

[mrjj]

@jsulm
Hi
I wonder if
extern "c" {
#include "hi3536mainfx.h"
}

is needed?

[jsulm]

@mrjj said in How do i integrate my embedded C source codes (for my embedded linux board) with Qt GUI together?:

extern "c"

I think it is needed as it is a C header

[mrjj]

@jsulm
Well im not sure. Just realized I never tried a .c file with mingw and see if it will cpp compile it or
it does in fact need extern "c". :)

[kshegunov]

@mrjj said in How do i integrate my embedded C source codes (for my embedded linux board) with Qt GUI together?:

Well im not sure.

It is absolutely needed. C++ supports overloading (which C obviously doesn't) and that ABI-wise is realized by decorating the symbols. So to be able to link properly, you need to tell the compiler that you're actually expecting C-linkage for the functions.

[mrjj]

@kshegunov
Thank you. The reason for my doubts is that my old compiler compiles all as cpp and
hence never needs it. And using Mingw so far, all files been cpp so was not sure if extension .c
would actually trigger different compile. And it does - so that's a key thing for c-files.

[embdev]

@jsulm @mrjj wow, that's really good advice for appending extern "C" { #..... }
After adding this line, my source is able to compile successfully and boot into my embedded target Linux. Of course it's not fully up because my target source code have other issues but I guess on Qt side, it's resolved!

Thank you very much folks!