Fix Menu Driven Program for OS Scheduling Algorithms (in C)

[roerohan]

Miscellaneous/C/Operating Systems/Scheduling_Algorithms.c

Lines 1 to 359 in 956b202

	#include<stdio.h>
	#include<stdlib.h>
	typedef struct process {
	char name[5];
	int bt;
	int at;
	int prt;
	int wt, ta;
	int flag;
	}
	processes;
	void bubble_sort(processes proc[], int n) {
	processes t;
	int i, j;
	for (i = 1; i < n; i++)
	for (j = 0; j < n - i; j++) {
	if (proc[j].at > proc[j + 1].at) {
	t = proc[j];
	proc[j] = proc[j + 1];
	proc[j + 1] = t;
	}
	}
	}
	int get_Processes(processes P[]) {
	int i, n;
	printf("\n Enter total no. of processes : ");
	scanf("%d", & n);
	for (i = 0; i < n; i++) {
	printf("\n PROCESS [%d]", i + 1);
	printf(" Enter process name : ");
	scanf("%s", & P[i].name);
	printf(" Enter burst time : ");
	scanf("%d", & P[i].bt);
	printf(" Enter arrival time : ");
	scanf("%d", & P[i].at);
	printf(" Enter priority : ");
	scanf("%d", & P[i].prt);
	}
	printf("\n PROC.\tB.T.\tA.T.\tPRIORITY");
	for (i = 0; i < n; i++)
	printf("\n %s\t%d\t%d\t%d", P[i].name, P[i].bt, P[i].at, P[i].prt);
	return n;
	}
	// FCFS Algorithm
	void FCFS(processes P[], int n) {
	processes proc[10];
	int sumw = 0, sumt = 0;
	int x = 0;
	float avgwt = 0.0, avgta = 0.0;
	int i, j;
	for (i = 0; i < n; i++)
	proc[i] = P[i];
	bubble_sort(proc, n);
	printf("\n\n PROC.\tB.T.\tA.T.");
	for (i = 0; i < n; i++)
	printf("\n %s\t%d\t%d", proc[i].name, proc[i].bt, proc[i].at);
	sumw = proc[0].wt = 0;
	sumt = proc[0].ta = proc[0].bt - proc[0].at;
	for (i = 1; i < n; i++) {
	proc[i].wt = (proc[i - 1].bt + proc[i - 1].at + proc[i - 1].wt) - proc[i].at;;
	proc[i].ta = (proc[i].wt + proc[i].bt);
	sumw += proc[i].wt;
	sumt += proc[i].ta;
	}
	avgwt = (float) sumw / n;
	avgta = (float) sumt / n;
	printf("\n\n PROC.\tB.T.\tA.T.\tW.T\tT.A.T");
	for (i = 0; i < n; i++)
	printf("\n %s\t%d\t%d\t%d\t%d", proc[i].name, proc[i].bt, proc[i].at, proc[i].wt, proc[i].ta);
	printf("0\t");
	for (i = 1; i <= n; i++) {
	x += proc[i - 1].bt;
	printf("%d ", x);
	}
	printf("\n\n Average waiting time = %0.2f\n Average turn-around = %0.2f.", avgwt, avgta);
	}
	//Shortest Job First - Pre-emptive
	void SJF_P(processes P[], int n) {
	int i, t_total = 0, tcurr, b[10], min_at, j, x, min_bt;
	int sumw = 0, sumt = 0;
	float avgwt = 0.0, avgta = 0.0;
	processes proc[10], t;
	for (i = 0; i < n; i++) {
	proc[i] = P[i];
	t_total += P[i].bt;
	}
	bubble_sort(proc, n);
	for (i = 0; i < n; i++)
	b[i] = proc[i].bt;
	i = j = 0;
	avgwt = (float) sumw / n;
	avgta = (float) sumt / n;
	printf("\n\n Average waiting time = %0.2f\n Average turn-around = %0.2f.", avgwt, avgta);
	}
	//SJF Non Pre-emptive
	void SJF_NP(processes P[], int n) {
	processes proc[10];
	processes t;
	int sumw = 0, sumt = 0;
	int x = 0;
	float avgwt = 0.0, avgta = 0.0;
	int i, j;
	for (i = 0; i < n; i++)
	proc[i] = P[i];
	bubble_sort(proc, n);
	for (i = 2; i < n; i++)
	for (j = 1; j < n - i + 1; j++) {
	if (proc[j].bt > proc[j + 1].bt) {
	t = proc[j];
	proc[j] = proc[j + 1];
	proc[j + 1] = t;
	}
	}
	printf("\n\n PROC.\tB.T.\tA.T.");
	for (i = 0; i < n; i++)
	printf("\n %s\t%d\t%d", proc[i].name, proc[i].bt, proc[i].at);
	sumw = proc[0].wt = 0;
	sumt = proc[0].ta = proc[0].bt - proc[0].at;
	for (i = 1; i < n; i++) {
	proc[i].wt = (proc[i - 1].bt + proc[i - 1].at + proc[i - 1].wt) - proc[i].at;;
	proc[i].ta = (proc[i].wt + proc[i].bt);
	sumw += proc[i].wt;
	sumt += proc[i].ta;
	}
	avgwt = (float) sumw / n;
	avgta = (float) sumt / n;
	printf("\n\n PROC.\tB.T.\tA.T.\tW.T\tT.A.T");
	for (i = 0; i < n; i++)
	printf("\n %s\t%d\t%d\t%d\t%d", proc[i].name, proc[i].bt, proc[i].at, proc[i].wt, proc[i].ta);
	printf("0\t");
	for (i = 1; i <= n; i++) {
	x += proc[i - 1].bt;
	printf("%d ", x);
	}
	printf("\n\n Average waiting time = %0.2f\n Average turn-around = %0.2f.", avgwt, avgta);
	}
	// Priority - Preemptive
	void Priority_P(processes P[], int n) {
	int i, t_total = 0, tcurr, b[10], j, x, min_pr;
	int sumw = 0, sumt = 0;
	float avgwt = 0.0, avgta = 0.0;
	processes proc[10], t;
	for (i = 0; i < n; i++) {
	proc[i] = P[i];
	t_total += P[i].bt;
	}
	bubble_sort(proc, n);
	for (i = 0; i < n; i++)
	b[i] = proc[i].bt;
	i = j = 0;
	printf(" %d", tcurr);
	avgwt = (float) sumw / n;
	avgta = (float) sumt / n;
	printf("\n\n Average waiting time = %0.2f\n Average turn-around = %0.2f.", avgwt, avgta);
	}
	//Priority Non Pre-emptive
	void Priority_NP(processes P[], int n) {
	processes proc[10];
	processes t;
	int sumw = 0, sumt = 0;
	float avgwt = 0.0, avgta = 0.0;
	int i, j;
	int x = 0;
	for (i = 0; i < n; i++)
	proc[i] = P[i];
	bubble_sort(proc, n);
	for (i = 2; i < n; i++)
	for (j = 1; j < n - i + 1; j++) {
	if (proc[j].prt > proc[j + 1].prt) {
	t = proc[j];
	proc[j] = proc[j + 1];
	proc[j + 1] = t;
	}
	}
	printf("\n\n PROC.\tB.T.\tA.T.");
	for (i = 0; i < n; i++)
	printf("\n %s\t%d\t%d", proc[i].name, proc[i].bt, proc[i].at);
	sumw = proc[0].wt = 0;
	sumt = proc[0].ta = proc[0].bt - proc[0].at;
	for (i = 1; i < n; i++) {
	proc[i].wt = (proc[i - 1].bt + proc[i - 1].at + proc[i - 1].wt) - proc[i].at;;
	proc[i].ta = (proc[i].wt + proc[i].bt);
	sumw += proc[i].wt;
	sumt += proc[i].ta;
	}
	avgwt = (float) sumw / n;
	avgta = (float) sumt / n;
	printf("\n\n PROC.\tB.T.\tA.T.\tW.T\tT.A.T");
	for (i = 0; i < n; i++)
	printf("\n %s\t%d\t%d\t%d\t%d", proc[i].name, proc[i].bt, proc[i].at, proc[i].wt, proc[i].ta);
	printf("0\t");
	for (i = 1; i <= n; i++) {
	x += proc[i - 1].bt;
	printf("%d ", x);
	}
	printf("\n\n Average waiting time = %0.2f\n Average turn-around = %0.2f.", avgwt, avgta);
	}
	//Round Robin Scheduling
	void RR(processes P[], int n) {
	int pflag = 0, t, tcurr = 0, k, i, Q = 0;
	int sumw = 0, sumt = 0;
	float avgwt = 0.0, avgta = 0.0;
	processes proc1[10], proc2[10];
	for (i = 0; i < n; i++)
	proc1[i] = P[i];
	bubble_sort(proc1, n);
	for (i = 0; i < n; i++)
	proc2[i] = proc1[i];
	printf("\n Enter quantum time : ");
	scanf("%d", & Q);
	for (k = 0;; k++) {
	if (k > n - 1)
	k = 0;
	if (proc1[k].bt > 0)
	printf(" %d %s", tcurr, proc1[k].name);
	t = 0;
	while (t < Q && proc1[k].bt > 0) {
	t++;
	tcurr++;
	proc1[k].bt--;
	}
	if (proc1[k].bt <= 0 && proc1[k].flag != 1) {
	proc1[k].wt = tcurr - proc2[k].bt - proc1[k].at;
	proc1[k].ta = tcurr - proc1[k].at;
	pflag++;
	proc1[k].flag = 1;
	sumw += proc1[k].wt;
	sumt += proc1[k].ta;
	}
	if (pflag == n)
	break;
	}
	printf(" %d", tcurr);
	avgwt = (float) sumw / n;
	avgta = (float) sumt / n;
	printf("\n\n Average waiting time = %0.2f\n Average turn-around = %0.2f.", avgwt, avgta);
	}
	int main() {
	processes P[10];
	int ch, n;
	do {
	printf("\n\n SIMULATION OF CPU SCHEDULING ALGORITHMS\n");
	printf("\n Options:");
	printf("\n 0. Enter process data.");
	printf("\n 1. FCFS");
	printf("\n 2. SJF (Pre-emptive)");
	printf("\n 3. SJF (Non Pre-emptive)");
	printf("\n 4. Priority Scheduling (Pre-emptive)");
	printf("\n 5. Priority Scheduling (Non Pre-emptive)");
	printf("\n 6. Round Robin");
	printf("\n 7. Exit\n Select : ");
	scanf("%d", & ch);
	switch (ch) {
	case 0:
	n = get_Processes(P);
	break;
	case 1:
	FCFS(P, n);
	break;
	case 2:
	SJF_P(P, n);
	break;
	case 3:
	SJF_NP(P, n);
	break;
	case 4:
	Priority_P(P, n);
	break;
	case 5:
	Priority_NP(P, n);
	break;
	case 6:
	RR(P, n);
	break;
	case 7:
	exit(0);
	}
	} while (ch != 7);
	return 0;
	}

The program has some errors, which needs to be fixed.

P.S. Do not upload the compiled object file with the fixed code.

[fonkamloic]

Can I add multi-threading support?

[roerohan]

Sure @fonkamloic

[fonkamloic]

Hi @roerohan! Please review my pull request. So that I can move on to implement the logic of queuing and synchronizing threads.