2d arrays in MIPS

[MoBsTa]

I have a computer assignment that requires me to use 2d arrays and check if the elements are "singleton's" in a double nested for loop. I wrote the loops and singleton function but I am having trouble figuring out what the starting address for a 2d array is.

Here is the formula that I found to find a certain element. Let's call the matrix A:

A[i,j] = A[0,0] + (((i*N) + j)*sizeof(element))

the sizeof(element) I believe is 4, since we're using hexadecimal to represent each value. The input to this function is $a0 = A[9,9].

The problem I am having is I do not know how to represent the beginning of the matrix A[0,0]. Right now I have it as $a0.

 

[eon]

i havent done mips in a while but dont you just use a label for your 2d array which would just be a .space type
so a 3 by 3 array will be represented by a 9 length .space array

to get the starting address just do an la command on the label

 

[rflcptr]

Does your program require dynamic allocation of the array? If so, you should look at syscall 9.

li $v0, 9
move $a0, $t0 # where $t0 contains the size, in bytes, of the memory to allocate
syscall       # allocate the memory and return the base address of it in $v0

If you're instead using the .space directive to create a static array, simply use this command to retrieve and store its base address into $t0:

la $t0, name_of_array