Hinge loop to rotate the matrix

Question

I am trying to write a function to rotate an image matrix using a looping technique. However, I am encountering some problems to make it work correctly.

EDIT: Here is my updated code that works, but only when n is a multiple of the block size. How will I handle different matrix sizes? Right now, I'm just using square blocks, and it works great for these square blocks. How would I decide to change this to use rectangular blocks depending on the size of the array I am giving. In particular, if I have been given an nxn array, how can I select the rectangular dimensions of the block to divide it by?

  //Block size to tune
  int block = 20;
  int i1, j1, k1,  i, j, k;

  for(i1 = 0; i1 < n; i1 += block) {
    for(j1 = 0; j1< n; j1 += block) {
            for(i = i1; i < i1 + block; i++){
                for(j = j1; j < j1 + block; j++){
                    dest[getInd(j, i, n)] = src[getInd(i, n - 1 - j, n)]; 

                }
            }
        }
    }

}

Answer 1

:

  for(i1 = 0; i1 < n/block; i1 += block) {
    for(j1 = 0; j1< n/block; j1 += block) {

:

  for(i1 = 0; i1 < n; i1 += block) {
    for(j1 = 0; j1 < n; j1 += block) {

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