Hi,
I am working on MCB2300 (with LPC2378 processor). I have written a small function that will read the values into a matrix. But when the control comes to fread it completely hangs up, nothing can be done. Below is the my function which is giving problem
void loadImage(FILE* arq, unsigned char** Matrix){ int i,j; unsigned char tmp; long pos = 51; fseek(arq,0,0); for (i=0; i<300; i++){ for (j=0; j<400; j++){ pos+= 3; fseek(arq,pos,0); fread(&tmp,3,1,arq); Matrix[i][j] = tmp; } } }
Its working fine in GNU C. But when I have tried to use the same code in Keil uVision4, its is not working. Please let me know how to sort this problem
Stop fooling around. 320*200*3 = 64000*3.
The processor don't have enough internal RAM to handle it.
The processor doesn't even have RAM memory regions that are neighbour to each other to allow a single memory allocation of the full size, since the 64kB of main RAM is not neighbour to USB or Ethernet RAM or to the two 64kB external memory banks. And the two 64kB external memory banks are not neighbour either.
Do you have external RAM connected? How much? If yes - how have you convinced the RTL to place 128kB heap in external RAM and 64kB heap in internal RAM?
In fact, you seem to ignore all responses from all posters!
"Compilation is done but I could n't run it"
There you go again - a meaningless statement!
Why couldn't you run it?
What, exactly, prevented you from running it?
What debugging have you done to find the problem?
My IRAM1 settings are default (IRAM1: 0x40000000 Size: 0x8000)
OK, this is the 3rd time I'm asking this: how much RAM do you have? This is important for your application, as you should have realized by now. You indicated that you have 32 Kbytes of RAM. Obviously, this is too little.
My default heap size in startup file is Heap_Size EQU 0x00000800.
I have increased the heap size step by step and tested on images with different sizes. When I have set the heap size to 0x 00007000 , the final image that worked is of size 26.3 KB (109 x 82 x 3). But if I change heap value further it is not working. But my required image size is much larger. What things I need to do so that I can change heap value further and ensure it works with large images?
Once done I have compiled it. Compilation is done but I could n't run it. Nothing is printed
You keep ignoring my suggestions. What's the point in posting about your problems when you ignore the responses? How much RAM do you have? Do you have enough of it to hold your bitmap? If you define a variable at function scope (a so-called automatic variable), memory for it will be allocated on the stack. I am certain that your stack is not large enough to hold a variable that is 75 Kbytes in size. Hence, the program will not work.
I have defined a matrix like below
unsigned char bitmap[320][240]
After that I allocated the some elements into that matrix before reading pixel values to make sure whether all elements in the matrix are initialised in the following manner
for (i=0;i<320;i++){ for (j=0;i<240;j++){ bitmap[i][j]=j; } }
After this I am trying to print the values read in to the matrix using printf statement inthe following manner
for (i=0;i<320;i++){ for (j=0;i<240;j++){ printf(" %d ", bitmap[i][j]); } }
I have already tried previously by allocating one big chunk of memory for a three-dimensionsl array:
unsigned char bitmap[height][width][3]
So it's actually 320 x 240 x3 = 675K
Again, that's meaningless!
You need to state precisely what did happen - and why you consider that to be "not working"!
What, exactly, failed?
How did it fail?
What debugging have you done to find the cause of the failure?
If height and width are very small values like 10,10 then it is working. But not for larger values
How much RAM do you have allocated for the heap? Do you have enough RAM for this? 320x240x3 = 225 Kbytes.
So what goes wrong with your allocation? Does it exit after a failure? Or does it return
It exits after failure.
sizeof(RGB) in my code is 3 bytes. In my application I am trying to read an image with 320 x 240 size. In my startup code heap is set as Heap_Size EQU 0x00000800 and if I try to change these values .\Obj\Memory.axf: Error: L6406W: No space in execution regions with .ANY selector matching Section
If I am taking an image with 10x8 dimensions it is working but beyond that it does n't.
How have you verified that your height and width really have the values you think they have?
Yes I have have verified. They have actual values (I mean height and width of input image)
The type RGB is 3 bytes, but the compiler could add padding when working with arrays of RGB (sizeof(RGB) == 4). So this could increase memory usage to 4 bytes per one instance of RGB.
I have verified the sizeof(RGB) when memory is allocated by giving a printf statement. Always it is showing as 3 bytes only. So here no padding is done by compiler.
I have already tried previously by allocating one big chunk of memory for a three-dimensionsl array: unsigned char bitmap[height][width][3]. Even it did n't worked. In my application height and width are 320 and 240. But matrix with these values in not working. If height and width are very small values like 10,10 then it is working. But not for larger values
So the original code you posted with "tmp" variable wasn't really real code, since tmp was a char while your _real_ tmp was RGB? Never show "almost" real code.
So what goes wrong with your allocation? Does it exit after a failure? Or does it return, but you are unhappy with contents of Matrix? This time too, you don't seem to show full code. No return type shown. And you don't show how the function hands over Matrix at the end.
Do you get an error printout?
Note that exit() isn't a perfect function to use in an embedded application, since there are no operating system to return to. There are neither a desktop nor a command line. Depending on tools, you might get the code stuck in an infinite loop somewhere. Or maybe the application restarts by calling main again. Or maybe you get a watchdog reset. exit() may not even give the processor time to print any pending error message.
Note that RGB contains 3 bytes, but what is sizeof(RGB) with your compiler?
How much memory do you need? How much memory have you set up as heap? How far do you get in the allocation before it fails? How have you verified that your height and width really have the values you think they have?
What changes do I need to make here to ensure matrix with required size is created?
Perhaps you don't have enough heap. Try increasing heap size. It should be specified in your startup code. Besides, the way you allocate memory for your bitmap appears inefficient: 1) The type RGB is 3 bytes, but the compiler could add padding when working with arrays of RGB (sizeof(RGB) == 4). So this could increase memory usage to 4 bytes per one instance of RGB. 2) A bitmap is essentially a two-dimensional array. Yet you allocate memory for it row-by-row, storing pointers to rows in another array. This way the number of heap allocations is Nrows+1, which adds to memory usage since each heap allocation wastes some memory on bookkeeping. Instead, you should allocate one big chunk of memory for one two-dimensional array. Or even a three-dimensionsl array: unsigned char bitmap[height][width][3].
Thanks very much for your reply.
First, you need to determine what the problem actually is!
My apologies for not determining problem properly.
I am trying to read a 24 bit map file where each pixel is represented with 24 bits (i mean 3 bytes) so I am reading 3 bytes. Let me also explain about tmp. In my code I am using a structure as below
typedef struct { unsigned char RGB[3]; }RGB;
The declaration for tmp and Matrix are as below
RGB **Matrix; RGB tmp;
All the pixels of the matrix are read perfectly. I have inserted a printf statement after read in the above code and all the image values are printed in right way. But problem comes when I am trying to store in the matrix. Infact I was unable to allocate memory for the matrix with required size. So I was unable to store. Here is the code for allocating matrix
createMatrix(){ RGB** Matrix; int i; Matrix = (RGB **) malloc (sizeof (RGB*) * height); if (Matrix == NULL){ printf("Memory is not available"); exit(0); } for (i=0;i<height;i++){ Matrix[i] = (RGB *) malloc (sizeof(RGB) * width); if (Matrix[i] == NULL){ printf("Memory is not available"); exit(0); } } }
Thanks in advance
fseek() and fread() does return results, but you never check them. So most probably, you don't check the result of your memory allocations either.
By the way - why do you think you need to perform a seek between each read? Isn't your fread call moving the file pointer forward the required amount?
But then again - why do you do a seek specifying the value 0 when your first read is 51+3 bytes into the file?
And since you are skipping the image header - how do you even know that the image have 3 bytes for each pixel?
And tmp is a unsigned character, having size 1. So why do you try to read 3 bytes in your fread? Where do you want to place the remaining two bytes? Haven't you considered the result of reading more data than tmp can store? What may happen to other data stored directly after tmp on the stack? Would that be good? Would that even make your program work as expected?
You say the code works with GNU C. But haven't you considered what happens if a different compiler moves some variables into registers, instead of keeping them on the stack? Are C programs built using different compilers really expected to behave identically when you do buffer overflow attacks on the variables?
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