/**
 * One final C program coverying a huge amount of ground
 * @author gtowell
 * Created: May 9, 2021
 * **/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

//Formatting for data output
#define  CCOLUMN "%2d  %9ld %8.3f\n"

#ifndef NULL
#define NULL (void *)0
#endif

//function pointer typedef
typedef void(*funs)(long);
//array of function pointers
funs funarray[4];

/**
 * First worker function
 * Just do standard array stuff
 * @param cnt the amount of work to do.
 * **/
void work1(long cnt)
{
    long arr[cnt];
    for (int i = 0; i < cnt; i++) {
        for (int j = 0; j < cnt; j++) {
            arr[i] += j;
        }
    }
}

/**
 * First worker function. Half way to full pointer bliss
 * Just do standard array stuff
 * @param cnt the amount of work to do.
 * **/
void work1b(long cnt)
{
    long arr[cnt];
    for (int i = 0; i < cnt; i++) {
        int *p = (int *)arr;
        for (int j = 0; j < cnt; j++) {
            *(p++) += j;
        }
    }
}

/**
 * Second worker function
 * Just do stuff very similar to worker1, but do it all with pointers
 * @param cnt the amount of work to do.
 * **/
void work2(long cnt) {
    long *arr = malloc(cnt * sizeof(long));
    long *last = arr + cnt;
    for (int i = 0; i < cnt; i++)
    {
        long *p = arr;
        while (1) {
            *(p++) += i;
            if (p==last)
                break;
        }
    }
    free(arr);
}

typedef struct ll {
    int val;
    struct ll *next;
} ll;

/**
 * Third worker function
 * Again, similar to work1, but in linkedlist style
 * @param cnt the amout of work to do
 * **/
void work3(long cnt)
{
    ll *head = NULL;

    for (int i = 0; i < cnt; i++) {
        if (i==0) {
            //In the first  loop, set of the linked list
            head = malloc(1 * sizeof(ll));
            ll *this = head;
            for (int j = 0; j < cnt; j++) {
                this->next = malloc(1 * sizeof(ll));
                this->val = i;
                this = this->next;
                this->next = NULL;
            }
        } else {
           ll *this = head;
            for (int j = 0; j < cnt; j++) {
                this->val += j;
                this = this->next;
            }
        }
    }
    while (head != NULL)
    {
        ll *nxt = head->next;
        free(head);
        head = nxt;
    }
}

int main(int argc, char const *argv[]) {
    funarray[0] = work1;
    funarray[1] = work1b;
    funarray[2] = work2;
    funarray[3] = work3;
    clock_t start, end;
    start = clock();
    int funsel = atoi(argv[1]);
    int funwork = atol(argv[2]);
    funarray[funsel](funwork);
    end = clock();
    float cpu_time_used = ((float) (end - start)) / CLOCKS_PER_SEC;
    printf(CCOLUMN, funsel, funwork, cpu_time_used );
    return 0;
}