Spiral Matrix Program

My Spiral Matrix Program

#include < stdio.h>

#define UP      0
#define LEFT    1
#define DOWN    2
#define RIGHT   3

int getele(int *arr, int x, int y, int size) {

    int pos=(x*size)+y;
    return arr[pos];
}

int setele(int *arr, int x, int y, int data, int size) {
    
    int pos=(x*size)+y;
    arr[pos]=data;
}

void setspiral_worker(int *arr, int x, int y, int data, int size, int dir) {

    if(data==1)
        setele(arr, x, y, data, size);
    else {
        setele(arr, x, y, data, size);
        dir=check_change_dir(arr, x, y, size, dir);
        if (dir == UP) {
            x--;
        } else if (dir == LEFT) {
            y--;
        } else if (dir == DOWN) {
            x++;
        } else if (dir == RIGHT) {
            y++;
        }
        setspiral_worker(arr, x, y, data-1, size, dir);
    }
}

void setspiral_driver(int *arr, int size) {
    
    setspiral_worker(arr, size-1, size-1, size*size, size, UP);
}

int check_change_dir(int *arr, int x, int y, int size, int dir) {
    
    if (dir == UP) {
        x--;
    } else if (dir == LEFT) {
       y--; 
    } else if (dir == DOWN) {
       x++;
    } else if (dir == RIGHT) {
       y++;
    }

    if (x>=0 && x<=size-1 && y>=0 && y<=size-1 
        && getele(arr, x, y, size) == 0)
        return dir;
    else 
        return (dir+1)%4;
}

int main() {
    int oper=UP;
    int size;
    int i,j;

    int *matrix;

    printf("Enter the size:");
    scanf("%d", &size);

    matrix=malloc(size*size);
    
    for(i=0; i < size ;i++)
        for(j=0; j < size;j++)
            setele(matrix, i, j, 0, size);
    setspiral_driver(matrix, size);
    for(i=0; i < size;i++) {
        for(j=0; j < size;j++)
            printf("%4d\t",getele(matrix, i, j, size));
        printf("\n");
    }
    return 0;
}