Multidimensional array of uint16_t in C

Question

I want to write a method in C that gives me a multidimensional array of uint16_t .

I write this:

uint16_t ** GRAPHICS_CreateImage(int width, int height)
{
  int x;
  uint16_t **image = (uint16_t **)malloc(width * sizeof(uint16_t *));

  for(x=0; x < width; x++)
  {
      GUI_DUMY(x * 5, 0, 0x00F0);
      uint16_t *xx = (uint16_t *)malloc(height * sizeof(uint16_t));
      if(xx == NULL)
      {
        GUI_DUMY(0, 30, 0x0000);
      }
      GUI_DUMY(x * 5, 10, 0x000F);
      image[x] = xx;
      GUI_DUMY(x * 5, 20, 0xF000);
  }
  GUI_DUMY(0, 100, 0x0000);

  return image;
}

The program runs on an LCD-Display (I cannot debug code) and I need to do GUI_DUMY to see squares on the screen. So... my problem is that the malloc in the for hangs when x == 55. (I run the method with width 480 and height 320.)

When I have not enough memory, the malloc has to be finished and xx has to be NULL.

But xx is never NULL.

I have read, this problem can arise because of buffer overflow when mallocing, but I don't know if that is my problem?

Answer 1

I am not sure what GUI_DUMY does nor how you intend to use the image array returned by this function, but here are some ideas to investigate:

• you allocate an array of width pointers to arrays of height 16-bit words. You might need to swap these quantities.
• you allocate an array of pointers to arrays, but the caller might expect an actual 2D array, ie an array of arrays, which is a very different type of object.