I need help with implementing a CPU scheduling program in C with FCFS, SJF, Prio

Question

I need help with implementing a CPU scheduling program in C with FCFS, SJF, Priority, and Round-Robin.

The program must read from a file and all algorithms must be in the same class.

The input file will look like this:

4

1 7 10

2 5 5

3 7 12

4 8 10

The first 4 is the amount of processes. The 1 is the first process with a burst of 7 and priority 10, and so on.

Example output will look like this for FCFS:

4 3 7

2 3 10

3 5 7

1 7 1

-------------------------------
Running...

##################################################

## CPU Pri W T

#4 3 7 0 3

#2 3 10 3 6
#3 5 7 6 11
#1 7 1 11 18

##################################################

# Avg. Waiting Time : 5.00

# Avg. Turnaround Time: 9.50

##################################################

Explanation / Answer

Please find the code below.

CODE

=====================

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

typedef struct process{

int name;

int bt;

int at;

int prt;

int wt,ta;

int flag;

}processes;

void b_sort(processes temp[],int n)

{

processes t;

int i,j;

for(i=1;i<n;i++)

for(j=0;j<n-i;j++){

if(temp[j].at > temp[j+1].at){

t = temp[j];

temp[j] = temp[j+1];

temp[j+1] = t;

}

}

}

// Function to read value from user

int accept(processes P[]){

int i,n;

printf(" Enter total no. of processes : ");

scanf("%d",&n);

for(i=0;i<n;i++){

printf(" 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(" PROC. B.T. A.T. PRIORITY");

for(i=0;i<n;i++)

printf(" %s %d %d %d",P[i].name,P[i].bt,P[i].at,P[i].prt);

return n;

}

// FCFS Algorithm

void FCFS(processes P[],int n){

processes temp[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++)

temp[i]=P[i];

b_sort(temp,n);

printf(" PROC. B.T. A.T.");

for(i=0;i<n;i++)

printf(" %d %d %d",temp[i].name,temp[i].bt,temp[i].at);

sumw = temp[0].wt = 0;

sumt = temp[0].ta = temp[0].bt - temp[0].at;

for(i=1;i<n;i++){

temp[i].wt = (temp[i-1].bt + temp[i-1].at + temp[i-1].wt) - temp[i].at;;

temp[i].ta = (temp[i].wt + temp[i].bt);

sumw+=temp[i].wt;

sumt+=temp[i].ta;

}

avgwt = (float)sumw/n;

avgta = (float)sumt/n;

printf(" PROC. B.T. A.T. W.T T.A.T");

for(i=0;i<n;i++)

printf(" %d %d %d %d %d",temp[i].name,temp[i].bt,temp[i].at,temp[i].wt,temp[i].ta);

printf(" GANTT CHART ");

for(i=0;i<n;i++)

printf(" %d ",temp[i].name);

printf(" ");

printf("0 ");

for(i=1;i<=n;i++){

x+=temp[i-1].bt;

printf("%d ",x);

}

printf(" Average waiting time = %0.2f Average turn-around = %0.2f.",avgwt,avgta);

}

//SJF Non Pre-emptive

void SJF_NP(processes P[],int n){

processes temp[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++)

temp[i]=P[i];

b_sort(temp,n);

for(i=2;i<n;i++)

for(j=1;j<n-i+1;j++){

if(temp[j].bt > temp[j+1].bt){

t = temp[j];

temp[j] = temp[j+1];

temp[j+1] = t;

}

}

printf(" PROC. B.T. A.T.");

for(i=0;i<n;i++)

printf(" %d %d %d",temp[i].name,temp[i].bt,temp[i].at);

sumw = temp[0].wt = 0;

sumt = temp[0].ta = temp[0].bt - temp[0].at;

for(i=1;i<n;i++){

temp[i].wt = (temp[i-1].bt + temp[i-1].at + temp[i-1].wt) - temp[i].at;;

temp[i].ta = (temp[i].wt + temp[i].bt);

sumw+=temp[i].wt;

sumt+=temp[i].ta;

}

avgwt = (float)sumw/n;

avgta = (float)sumt/n;

printf(" PROC. B.T. A.T. W.T T.A.T");

for(i=0;i<n;i++)

printf(" %d %d %d %d %d",temp[i].name,temp[i].bt,temp[i].at,temp[i].wt,temp[i].ta);

printf(" GANTT CHART ");

for(i=0;i<n;i++)

printf(" %d ",temp[i].name);

printf(" ");

printf("0 ");

for(i=1;i<=n;i++){

x+=temp[i-1].bt;

printf("%d ",x);

}

printf(" Average waiting time = %0.2f Average turn-around = %0.2f.",avgwt,avgta);

}

//Priority Non Pre-emptive

void PRT_NP(processes P[],int n)

{

processes temp[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++)

temp[i]=P[i];

b_sort(temp,n);

for(i=2;i<n;i++)

for(j=1;j<n-i+1;j++){

if(temp[j].prt > temp[j+1].prt){

t = temp[j];

temp[j] = temp[j+1];

temp[j+1] = t;

}

}

printf(" PROC. B.T. A.T.");

for(i=0;i<n;i++)

printf(" %d %d %d",temp[i].name,temp[i].bt,temp[i].at);

sumw = temp[0].wt = 0;

sumt = temp[0].ta = temp[0].bt - temp[0].at;

for(i=1;i<n;i++){

temp[i].wt = (temp[i-1].bt + temp[i-1].at + temp[i-1].wt) - temp[i].at;;

temp[i].ta = (temp[i].wt + temp[i].bt);

sumw+=temp[i].wt;

sumt+=temp[i].ta;

}

avgwt = (float)sumw/n;

avgta = (float)sumt/n;

printf(" PROC. B.T. A.T. W.T T.A.T");

for(i=0;i<n;i++)

printf(" %d %d %d %d %d",temp[i].name,temp[i].bt,temp[i].at,temp[i].wt,temp[i].ta);

printf(" GANTT CHART ");

for(i=0;i<n;i++)

printf(" %d ",temp[i].name);

printf(" ");

printf("0 ");

for(i=1;i<=n;i++){

x+=temp[i-1].bt;

printf("%d ",x);

}

printf(" Average waiting time = %0.2f 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 temp1[10],temp2[10];

for(i=0;i<n;i++)

temp1[i]=P[i];

b_sort(temp1,n);

for(i=0;i<n;i++)

temp2[i]=temp1[i];

printf(" Enter quantum time : ");

scanf("%d",&Q);

for(k=0;;k++){

if(k>n-1)

k=0;

if(temp1[k].bt>0)

printf(" %d %d",tcurr,temp1[k].name);

t=0;

while(t<Q && temp1[k].bt > 0){

t++;

tcurr++;

temp1[k].bt--;

}  

if(temp1[k].bt <= 0 && temp1[k].flag != 1){

temp1[k].wt = tcurr - temp2[k].bt - temp1[k].at;

temp1[k].ta = tcurr - temp1[k].at;

pflag++;

temp1[k].flag = 1;

sumw+=temp1[k].wt;

sumt+=temp1[k].ta;

}

if(pflag == n)

break;

}

printf(" %d",tcurr);

avgwt = (float)sumw/n;

avgta = (float)sumt/n;

printf(" Average waiting time = %0.2f 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 temp[10],t;

for(i=0;i<n;i++){

temp[i]=P[i];

t_total+=P[i].bt;

}

b_sort(temp,n);

for(i=0;i<n;i++)

b[i] = temp[i].bt;

i=j=0;

printf(" GANTT CHART %d %d",i,temp[i].name);

for(tcurr=0;tcurr<t_total;tcurr++){

if(b[i] > 0 && temp[i].at <= tcurr)

b[i]--;

if(i!=j)

printf(" %d %d",tcurr,temp[i].name);

if(b[i]<=0 && temp[i].flag != 1){

temp[i].flag = 1;

temp[i].wt = (tcurr+1) - temp[i].bt - temp[i].at;

temp[i].ta = (tcurr+1) - temp[i].at;

sumw+=temp[i].wt;

sumt+=temp[i].ta;

}

j=i; min_bt = 999;

for(x=0;x<n;x++){

if(temp[x].at <= (tcurr+1) && temp[x].flag != 1){

if(min_bt != b[x] && min_bt > b[x]){

min_bt = b[x];

i=x;

}

}

}

}

printf(" %d",tcurr);

avgwt = (float)sumw/n; avgta = (float)sumt/n;

printf(" Average waiting time = %0.2f Average turn-around = %0.2f.",avgwt,avgta);

}

void PRT_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 temp[10],t;

for(i=0;i<n;i++){

temp[i]=P[i];

t_total+=P[i].bt;

}

b_sort(temp,n);

for(i=0;i<n;i++)

b[i] = temp[i].bt;

i=j=0;

printf(" GANTT CHART %d %d",i,temp[i].name);

for(tcurr=0;tcurr<t_total;tcurr++)

{

if(b[i] > 0 && temp[i].at <= tcurr)

b[i]--;

if(i!=j)

printf(" %d %d",tcurr,temp[i].name);

if(b[i]<=0 && temp[i].flag != 1)

{

temp[i].flag = 1;

temp[i].wt = (tcurr+1) - temp[i].bt - temp[i].at;

temp[i].ta = (tcurr+1) - temp[i].at;

sumw+=temp[i].wt;

sumt+=temp[i].ta;

}

j=i;

min_pr = 999;

for(x=0;x<n;x++){

if(temp[x].at <= (tcurr+1) && temp[x].flag != 1){

if(min_pr != temp[x].prt && min_pr > temp[x].prt){

min_pr = temp[x].prt;

i=x;

}

}

}

}

printf(" %d",tcurr);

avgwt = (float)sumw/n;

avgta = (float)sumt/n;

printf(" Average waiting time = %0.2f Average turn-around = %0.2f.",avgwt,avgta);

}

int main(){

processes P[10];

int ch,n;

accept(P);

do{

printf(" SIMULATION OF CPU SCHEDULING ALGORITHMS ");

printf(" Options:");

printf(" 1. FCFS");

printf(" 2. SJF (Pre-emptive)");

printf(" 3. SJF (Non Pre-emptive)");

printf(" 4. Priority Scheduling (Pre-emptive)");

printf(" 5. Priority Scheduling (Non Pre-emptive)");

printf(" 6. Round Robin");

printf(" 7. Exit Select : ");

scanf("%d",&ch);

switch(ch){

case 1:

FCFS(P,n);

break;

case 2:

SJF_P(P,n);

break;

case 3:

SJF_NP(P,n);

break;

case 4:

PRT_P(P,n);

break;

case 5:

PRT_NP(P,n);

break;

case 6:

RR(P,n);

break;

case 7:

exit(0);

}

}while(ch != 7);

return 0;

}

NOTE: Due to lack of time (we get only 2 hours to solve a problem), I could not complete the part to read values from input file and initialize the processes. Could you please post this part separately (just to read data from file)? Sorry for the inconvenience caused.

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