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Vector type compatibility issue

user123random (32)
How do I go around the following Vector type compatibility error ?

phung@UbuntuHW15:~/Documents/taylor$ g++ -g host.cpp -o host `pk
g-config --cflags --libs opencv`
host.cpp: In function ‘int main(int, char**)’:
host.cpp:52:13: error: cannot convert ‘std::vector<unsigned char>’ to ‘packet*’ in assignment
     tologic = vector<uint8_t>(sizeof(struct packet) * N * N, 0);  // lena.tiff 
             ^
host.cpp:123:15: error: cannot convert ‘std::vector<packet>’ to ‘packet*’ in assignment
     fromlogic = vector<packet>(sizeof(struct packet) * N * N);
               ^
phung@UbuntuHW15:~/Documents/taylor$ 



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// g++ -g host.cpp -o host `pkg-config --cflags --libs opencv`

#include <opencv2/core/core.hpp>
#include <opencv2/imgcodecs/imgcodecs.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <unistd.h>
#include <fcntl.h>
#include <iostream>
#include <fstream>      // std::ifstream, std::ofstream
#include <string>
#include <sys/wait.h>
#include <errno.h>

using namespace cv;
using namespace std;


#define N 512

struct packet{
  uint8_t r,g,b;
};


int main(int argc, char *argv[]) {

  int fdr, fdw, rc, donebytes;
  char *buf;
  pid_t pid;
  struct packet *tologic, *fromlogic;
  int i;
  float a, da;

  fdr = open("/dev/stdin", O_RDONLY);
  fdw = open("/dev/stdout", O_WRONLY);

  if ((fdr < 0) || (fdw < 0)) {
    perror("Failed to open Xillybus device file(s)");
    exit(1);
  }

  pid = fork();

  if (pid < 0) {
    perror("Failed to fork()");
    exit(1);
  }

  if (pid) {
    close(fdr);

    tologic = vector<uint8_t>(sizeof(struct packet) * N * N, 0);  // lena.tiff is sized as 512*512*3
    if (!tologic) {
      fprintf(stderr, "Failed to allocate memory\n");
      exit(1);
    }

	// READ in an image file

    String imageName( "lena512color.tiff" ); // by default

    if( argc > 1)
    {
        imageName = argv[1];
    }

    Mat image;

    image = imread( imageName, IMREAD_COLOR ); // Read the file
    if( image.empty() )                      // Check for invalid input
    {
        cout <<  "Could not open or find the image" << std::endl ;
        return -1;
    }

	 namedWindow( "Original Image", CV_WINDOW_AUTOSIZE );
	 imshow( "Original Image", image );
	 
	 Mat rgbchannel[3];
	 // The actual splitting.
	 split(image, rgbchannel);
	 
	 namedWindow("Blue",CV_WINDOW_AUTOSIZE);
	 imshow("Red", rgbchannel[0]);
	 
	 namedWindow("Green",CV_WINDOW_AUTOSIZE);
	 imshow("Green", rgbchannel[1]);
	 
	 namedWindow("Red",CV_WINDOW_AUTOSIZE);
	 imshow("Blue", rgbchannel[2]);

	tologic->r = *(rgbchannel[0].data);
	tologic->g = *(rgbchannel[1].data);
	tologic->b = *(rgbchannel[2].data);

    buf = (char *) tologic;
    donebytes = 0;

	while (donebytes < sizeof(struct packet) * N) {
	  rc = write(fdw, buf + donebytes, sizeof(struct packet) * N - donebytes);

	  if ((rc < 0) && (errno == EINTR))
		continue;

	  if (rc <= 0) {
		perror("write() failed");
		exit(1);
	  }

	  donebytes += rc;
	}

	sleep(1); // Let debug output drain (if used)

	close(fdw);

	return 0;
  } 

  else {
    close(fdw);

    fromlogic = vector<packet>(sizeof(struct packet) * N * N);
    if (!fromlogic) {
      fprintf(stderr, "Failed to allocate memory\n");
      exit(1);
    }

    buf = (char *) fromlogic;
    donebytes = 0;

    while (donebytes < sizeof(struct packet) * N) {
      rc = read(fdr, buf + donebytes, sizeof(struct packet) * N - donebytes);

      if ((rc < 0) && (errno == EINTR))
		continue;

      if (rc < 0) {
		perror("read() failed");
		exit(1);
      }

      if (rc == 0) {
		fprintf(stderr, "Reached read EOF!? Should never happen.\n");
		exit(0);
      }

      donebytes += rc;
    }

   // for (i=0; i<N; i++)
      printf("R:%d G:%d B:%d \n", fromlogic[0].r, fromlogic[0].g, fromlogic[0].b);
      printf("R:%d G:%d B:%d \n", fromlogic[68499].r, fromlogic[68499].g, fromlogic[68499].b);
    sleep(1); // Let debug output drain (if used)

    close(fdr);

    return 0;
  }
}
Last edited on
tpb (1495)
A vector is a vector. It's not a pointer of any kind so it can't be assigned to one.
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vector<packet> vTo(sizeof(packet) * N * N, 0);
vector<packet> vFrom(sizeof(packet) * N * N);

If you need to pass a raw packet* C-style array, you can use:
 
 
vFrom.data()

But maybe you don't really want to use a vector. I'm not sure if there's any advantage here since the main advantage of a vector is that it can change size dynamically.

You're using open and printf so you seem to be more of a C programmer. Are you trying to rewrite this in C++?
Last edited on
user123random (32)
Yes, I am helping to rewrite this piece of code in C++.

I am still trying to understand the logic designed by the previous c code author.

By the way, thanks for the vFrom.data() tips.
user123random (32)
sleep(1); // Let debug output drain (if used)

What do you have in mind regarding this line of code ?
tpb (1495)
If it needs the sleep it needs the sleep.

Why are you rewriting this in C++? I don't see the point.
user123random (32)
@tpb

because openCV C API is no longer being maintained by its developers.

By the way, how to go around the following error ?


phung@UbuntuHW15:~/Documents/taylor$ g++ -g host.cpp -o host `pkg-config --cflags --
libs opencv`
host.cpp: In function ‘YUV_packet* rgb2yuv(RGB_packet)’:
host.cpp:32:26: error: expected primary-expression before ‘.’ token
  uint8_t red = RGB_packet.R;
                          ^
host.cpp:33:28: error: expected primary-expression before ‘.’ token
  uint8_t green = RGB_packet.G;
                            ^
host.cpp:34:27: error: expected primary-expression before ‘.’ token
  uint8_t blue = RGB_packet.B;
                           ^
phung@UbuntuHW15:~/Documents/taylor$ 




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// g++ -g host.cpp -o host `pkg-config --cflags --libs opencv`

#include <opencv2/core/core.hpp>
#include <opencv2/imgcodecs/imgcodecs.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <unistd.h>
#include <fcntl.h>
#include <iostream>
#include <fstream>      // std::ifstream, std::ofstream
#include <string>
#include <sys/wait.h>
#include <errno.h>
#include <cmath>

using namespace cv;
using namespace std;


#define N 512

struct RGB_packet{
  uint8_t R,G,B;
};

struct YUV_packet{
  uint8_t Y,U,V;
};


struct YUV_packet* rgb2yuv(struct RGB_packet)  // convert rgb to yuv
{  
	uint8_t red = RGB_packet.R;
	uint8_t green = RGB_packet.G;
	uint8_t blue = RGB_packet.B;

	struct YUV_packet *yuv_result;

	uint8_t Y = yuv_result->Y;
	uint8_t U = yuv_result->U;
	uint8_t V = yuv_result->V;

	// https://www.pcmag.com/encyclopedia/term/55166/yuv-rgb-conversion-formulas
    Y = (uint8_t)(0.299*red + 0.587*green + 0.114*blue);
    U = (uint8_t)(0.492*(blue-Y));
    V = (uint8_t)(0.877*(red-Y));

	return yuv_result;
}

int main(int argc, char *argv[]) {

  int fdr, fdw, rc, donebytes;
  char *buf;
  pid_t pid;
  struct RGB_packet *tologic;
  struct YUV_packet *fromlogic;

  fdr = open("/dev/stdin", O_RDONLY);  // will change to /dev/xillybus_read_128
  fdw = open("/dev/stdout", O_WRONLY); // will change to /dev/xillybus_write_128

  if ((fdr < 0) || (fdw < 0)) {
    perror("Failed to open Xillybus device file(s)");
    exit(1);
  }

  pid = fork();

  if (pid < 0) {
    perror("Failed to fork()");
    exit(1);
  }

  if (pid) {
	close(fdr);

	vector<RGB_packet> vTo(sizeof(struct RGB_packet) * N * N);  // lena.tiff is sized as 512*512*3

    tologic = vTo.data();

    if (!tologic) {
      fprintf(stderr, "Failed to allocate memory\n");
      exit(1);
    }

	// READ in an image file

    String imageName( "lena512color.tiff" ); // by default

    if( argc > 1)
    {
        imageName = argv[1];
    }

    Mat image;

    image = imread( imageName, IMREAD_COLOR ); // Read the file
    if( image.empty() )                      // Check for invalid input
    {
        cout <<  "Could not open or find the image" << std::endl ;
        return -1;
    }

	namedWindow( "Original Image", CV_WINDOW_AUTOSIZE );
	imshow( "Original Image", image );
	 
	Mat rgbchannel[3];
	// The actual splitting.
	split(image, rgbchannel);
	 
	namedWindow("Blue",CV_WINDOW_AUTOSIZE);
	imshow("Red", rgbchannel[0]);
	 
	namedWindow("Green",CV_WINDOW_AUTOSIZE);
	imshow("Green", rgbchannel[1]);
	 
	namedWindow("Red",CV_WINDOW_AUTOSIZE);
	imshow("Blue", rgbchannel[2]);

	waitKey(0);  // see all three split channels before feeding in the channel data to xillybus for hardware computation

	tologic->R = *(rgbchannel[0].data);
	tologic->G = *(rgbchannel[1].data);
	tologic->B = *(rgbchannel[2].data);

    buf = (char *) tologic;
    donebytes = 0;

	while (donebytes < sizeof(struct RGB_packet) * N * N) {
	  rc = write(fdw, buf + donebytes, sizeof(struct RGB_packet) * N * N - donebytes);

	  if ((rc < 0) && (errno == EINTR))
		continue;

	  if (rc <= 0) {
		perror("write() failed");
		exit(1);
	  }

	  donebytes += rc;
	}

	sleep(1); // Let debug output drain (if used)

	close(fdw);

	return 0;
  } 

  else {
    close(fdw);

	vector<YUV_packet> vFrom(sizeof(struct YUV_packet) * N * N);

    fromlogic = vFrom.data();

    if (!fromlogic) {
      fprintf(stderr, "Failed to allocate memory\n");
      exit(1);
    }

    buf = (char *) fromlogic;
    donebytes = 0;

    while (donebytes < sizeof(struct YUV_packet) * N * N) {
      rc = read(fdr, buf + donebytes, sizeof(struct YUV_packet) * N * N - donebytes);

      if ((rc < 0) && (errno == EINTR))
		continue;

      if (rc < 0) {
		perror("read() failed");
		exit(1);
      }

      if (rc == 0) {
		fprintf(stderr, "Reached read EOF!? Should never happen.\n");
		exit(0);
      }

      donebytes += rc;
    }

    for (int i = 0; i < (sizeof(struct RGB_packet) * N * N); i++)  // check the perfomance of hardware with respect to software computation
	{
		if((abs(rgb2yuv(tologic[i])->Y - fromlogic[i].Y) > 1) ||
		   (abs(rgb2yuv(tologic[i])->U - fromlogic[i].U) > 1) ||
		   (abs(rgb2yuv(tologic[i])->V - fromlogic[i].V) > 1)) // rgb2yuv conversion hardware tolerance fails by more than 1 compared to software computation
		{
			printf("R:%d G:%d B:%d \n", tologic[i].R, tologic[i].G, tologic[i].B);
      		printf("Y:%d U:%d V:%d \n", fromlogic[i].Y, fromlogic[i].U, fromlogic[i].V);
		}
	}

    sleep(1); // Let debug output drain (if used)

    close(fdr);

    return 0;
  }
}
megatron 0 (471)
To get around that error you need to define an actual struct, you cannot use the struct name as an object, you have to declare it first:

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// Define an RGB_packet called packet in parameters
YUV_packet rgb2yuv(RGB_packet packet)  // convert rgb to yuv
{  
	uint8_t red = packet.R;
	uint8_t green = packet.G;
	uint8_t blue = packet.B;

	YUV_packet yuv_result; // Declare a YUV_packet called yuv_result

	// https://www.pcmag.com/encyclopedia/term/55166/yuv-rgb-conversion-formulas
    yuv_result.Y = (uint8_t)(0.299*red + 0.587*green + 0.114*blue);
    yuv_result.U = (uint8_t)(0.492*(blue-yuv_result.Y));
    yuv_result.V = (uint8_t)(0.877*(red-yuv_result.Y));

	return yuv_result;
}



Last edited on
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