Transpose, Rotate by +90, Rotate by -90 a matrix.

#include <stdio.h>
#include <stdlib.h>

void displayMatrix(unsigned int const *p, unsigned int row, unsigned int col);
void rotate(unsigned int *pS, unsigned int *pD, unsigned int row, unsigned int col);

int main()
{
    // declarations
    unsigned int image[][4] = {{1,2,3,4}, {5,6,7,8}, {9,10,11,12}};
    unsigned int *pSource;
    unsigned int *pDestination;
    unsigned int m, n;

    // setting initial values and memory allocation
    m = 3, n = 4, pSource = (unsigned int *)image;
    pDestination = (unsigned int *)malloc(sizeof(int)*m*n);

    // process each buffer
    displayMatrix(pSource, m, n);

    rotate(pSource, pDestination, m, n);

    displayMatrix(pDestination, n, m);

    free(pDestination);

    getchar();
    return 0;
}

void displayMatrix(unsigned int const *p, unsigned int r, unsigned int c)
{
    unsigned int row, col;
    printf("\n\n");

    for(row = 0; row < r; row++)
    {
        for(col = 0; col < c; col++)
        {
            printf("%d\t", *(p + row * c + col));
        }
        printf("\n");
    }

    printf("\n\n");
}

void rotate(unsigned int *pS, unsigned int *pD, unsigned int row, unsigned int col)
{
    unsigned int r, c;
    for(r = 0; r < row; r++)
    {
        for(c = 0; c < col; c++)
        {
            //*(pD + (col-c-1)*row + r) = *(pS + r * col + c);    //rotate by -90
     
          // *(pD + c*row+ (row-r-1)) = *(pS + r * col + c);   //rotate by +90
       
          *(pD + c*row+ r) = *(pS + r * col + c);                  //transpose
        }
    }
}