Arrays in Vex Programming Kit EasyC?

[thegathering]

Originally Posted by sedim

Hi all,
I have tried defining:

int example_array[4]; //Works!
//and
int example_array[55]; //Works!
//but!!!!!!!!
int example_array[56];// Or greater does not work!!!!!!!!

//I get a complier error
"C:\vex\Guidance\Main.c:12:Error [1300] stack frame too large

Any ideas??

Arrays are limited by the amount of memory that can be allocated to them. 1300 blocks of memory for a single array is an extremely large amount, even more so for that little vex bot.

I would suggest if you absolutely have to use an array, you make parallel arrays, perhaps several arrays of 10 or even two dimensional arrays (an array holding references to multiple arrays) to break up the locations that the array can be stored.

If that does not work, then you may just not have enough memory to store large arrays. If that is the case, then you may be out of luck and will have to work around it or trim down your variable usage to free space. :\

Hope that helps somewhat.

[sedim]

Thanks for the Array Clarification. I am only defining 56 locations the moment I define one more it fails as in:
int example_array[55]; //Works!
int another_array[0];//does not work!!!!!!!!

//Still Gives me
"C:\vex\Guidance\Main.c:12:Error [1300] stack frame too large

The error # [1300] as defined in the C 18 Manual is as follows:

"1300: stack frame too large
The size of the stack frame has exceeded the maximum addressable size.
Commonly caused by too many local variables allocated as 'auto' storage
class in a single function."

When I change the "Default Storage Class" to from "Auto to "Overlay" or "Static" using MPLAB IDE, the linker gets me in trouble with the following:

MPLINK 3.90, Linker
Copyright (c) 2004 Microchip Technology Inc.
Error - could not find definition of symbol '__Wait:0' in file 'C:\vex\Guidance\Main.o'.
Errors : 1

So I comment out the Wait function and now the others start giving me the same problem:

as in:

//Wait (1000);
printf("hello all\n");

Error is now :

MPLINK 3.90, Linker
Copyright (c) 2004 Microchip Technology Inc.
Error - could not find definition of symbol '__printf:0' in file 'C:\vex\Guidance\Main.o'.
Errors : 1


Any Ideas folks?

[foobert]

perhaps if you declared the array static you could get it off the stack.

but remember alls you gets is a meager 2k for everything.

[Mark McLeod]

You are running into defined limits on how many bytes of global or local variables are available within any one project file or within any one routine.
It's not your one array of [56], but the sum of all the variables you've declared. For instance, if you have a couple of other variables declared, like so:

int a,b,c;
int example_array[55];

then

// int a,b,c;
int example_array[58];

would work for you.

The magic number is 256 bytes (or 128 int's).

• 256 bytes of global variables (outside any routine or static) in any one project file (block).
• 120 bytes of local variables declared within any single routine (not static)

but you should test the limits as you've been doing.

[sedim]

Thank you all for your contributions. Indeed, Mark McLeod's post is confirmed. I have also found out that we can utilize the "overlay" Storage class which acts as a static class but is initialized upon entry to the function. The maximums achieved are:

int array0[60];
overlay int array1[128];//But there are consequences

in the same function.

Best
Sedim