/*
implementing Round Robin Scheduling
*/
/*
processes are assumed to be in order P0,
P1, P2 and so on.
*/
/* Sample input #
1:
Number of processes : 4
Time Quantum : 2
Arrival Time Burst Time
P0 0 3
P1 0 6
P2 0 1
P3 0 5
*/
void
drawGanttChart();
void
calculateProcessSequence();
int
findAptProcessNumber(int,int,int);
#include<stdlib.h>
#include<stdio.h>
int
numberOfProcesses,totalCPUBurstTime,*arrivalTime,*CPUBurstTime,*CPUBurstTimeCopy,*processNumber,minimumArrivalTime,*processSequenceForEachSecond,*waitingTime,timeQuantum;
float
averageWaitingTime,averageTurnAroundTime;
float
averageWaitingTime=0;
/*arrays used to
draw Gantt Chart*/
int
*processNumberGantt,*CPUBurstTimeGantt,ganttSize;
int main()
{
int i,j,temp;
printf("Enter the number of processes
: ");
scanf("%d",&numberOfProcesses);
printf("Enter the Time Quantum :
");
scanf("%d",&timeQuantum);
arrivalTime=(int*)malloc(sizeof(int)*numberOfProcesses);
CPUBurstTime=(int*)malloc(sizeof(int)*numberOfProcesses);
CPUBurstTimeCopy=(int*)malloc(sizeof(int)*numberOfProcesses);
processNumber=(int*)malloc(sizeof(int)*numberOfProcesses);
waitingTime=(int*)malloc(sizeof(int)*numberOfProcesses);
minimumArrivalTime=2147483647;
for(i=0;i<numberOfProcesses;i++)
{
waitingTime[i]=0;
processNumber[i]=i;
printf("\nEnter the data for
process number : %d\n",i);
printf("\n");
printf("Arrival Time : ");
scanf("%d",&arrivalTime[i]);
printf("CPU Burst time :
");
scanf("%d",&CPUBurstTime[i]);
CPUBurstTimeCopy[i]=CPUBurstTime[i];
totalCPUBurstTime+=CPUBurstTime[i];
if(minimumArrivalTime>arrivalTime[i])
{
minimumArrivalTime=arrivalTime[i];
}
}
/*
implementing bubble sort algorithm
sorting processes on the basis of
arrival time
*/
for(i=0;i<numberOfProcesses;i++)
{
for(j=0;j<numberOfProcesses-i-1;j++)
{
if(arrivalTime[j]>arrivalTime[j+1])
{
temp=arrivalTime[j];
arrivalTime[j]=arrivalTime[j+1];
arrivalTime[j+1]=temp;
temp=CPUBurstTime[j];
CPUBurstTime[j]=CPUBurstTime[j+1];
CPUBurstTime[j+1]=temp;
temp=processNumber[j];
processNumber[j]=processNumber[j+1];
processNumber[j+1]=temp;
}
}
}
processSequenceForEachSecond=(int*)malloc(sizeof(int)*totalCPUBurstTime);
/* this function calculates the process sequence
for each second. */
calculateProcessSequence();
printf("\nAverage Waiting Time = %f\n",averageWaitingTime);
printf("\nAverage Turn Around Time =
%f\n\n",averageTurnAroundTime);
drawGanttChart();
}
void
calculateProcessSequence()
{
int
i,j,pNumber=processNumber[0],prevProcess,tempCPUBurstTime,counter=0,prevProcesss;
for(i=minimumArrivalTime;i<totalCPUBurstTime
+ minimumArrivalTime;i++)
{
/* here i denotes the current time */
prevProcess=pNumber;
pNumber=findAptProcessNumber(i,pNumber,counter);
if(pNumber==prevProcess)
{
counter++;
}
else
counter=1;
CPUBurstTime[pNumber]--;
processSequenceForEachSecond[i-minimumArrivalTime]=pNumber;
//printf("Lavish
P%d\n",pNumber);
/*
claculating the waiting time of
each process;
*/
for(j=0;j<numberOfProcesses;j++)
if(CPUBurstTime[j]!=0 &&
arrivalTime[j]<=i && j!=pNumber)
waitingTime[j]++;
}
/*
for(i=0;i<totalCPUBurstTime;i++)
printf("Lavish
P%d\n",processSequenceForEachSecond[i]);
*//* claculating the size of gantt chart
arrays*/
ganttSize=1;
prevProcess=processSequenceForEachSecond[0];
for(i=0;i<totalCPUBurstTime;i++)
{
if(prevProcess!=processSequenceForEachSecond[i])
ganttSize++;
prevProcess=processSequenceForEachSecond[i];
}
/* allocating the size of gantt chart
arrays */
processNumberGantt=(int*)malloc(sizeof(int)*ganttSize);
CPUBurstTimeGantt=(int*)malloc(sizeof(int)*ganttSize);
/* assigning the values to Gantt Chart
Arrays */
prevProcess=processSequenceForEachSecond[0];
tempCPUBurstTime=0;
counter=0;
for(i=0;i<totalCPUBurstTime;i++)
{
if(prevProcess!=processSequenceForEachSecond[i])
{
processNumberGantt[counter]=prevProcess;
CPUBurstTimeGantt[counter]=tempCPUBurstTime;
counter++;
tempCPUBurstTime=0;
}
tempCPUBurstTime++;
prevProcess=processSequenceForEachSecond[i];
}
CPUBurstTimeGantt[ganttSize-1]=tempCPUBurstTime;
processNumberGantt[ganttSize-1]=prevProcess;
/* calculating the averageWaitingTime and
averageTurnAroundTime */
averageWaitingTime=0;
averageTurnAroundTime=0;
for(i=0;i<numberOfProcesses;i++)
{
averageWaitingTime+=waitingTime[i];
averageTurnAroundTime+=waitingTime[i]+CPUBurstTimeCopy[i];
}
averageWaitingTime=averageWaitingTime/(float)numberOfProcesses;
averageTurnAroundTime=averageTurnAroundTime/(float)numberOfProcesses;
}
int
findAptProcessNumber(int currentTime,int currentProcess,int time)
{
/* this function returns the process number
that should run on currentTime. */
/* time variable is used to indicate the
time for which a process is being executed */
int i,pNumber,answer;
if(currentTime!=0 &&
(time==timeQuantum || CPUBurstTime[currentProcess]==0))
{
for(i=0;i<numberOfProcesses;i++)
{
if(processNumber[i]==currentProcess)
{
if((currentProcess+1)==numberOfProcesses)
answer=0;
else
answer=currentProcess+1;
while(arrivalTime[answer]>currentTime
|| CPUBurstTime[answer]==0)
answer=(answer+1)%numberOfProcesses;
return answer;
}
}
}
else
return currentProcess;
}
void
drawGanttChart()
{
const int maxWidth=100;
int
scalingFactor,i,counter,tempi,currentTime;
printf("The gantt chart for the given
processes is : \n\n");
scalingFactor=maxWidth/totalCPUBurstTime;
for(i=0;i<scalingFactor*totalCPUBurstTime+2+ganttSize;i++)
printf("-");
printf("\n|");
counter=0,tempi=0;
for(i=0;i<scalingFactor*totalCPUBurstTime;i++)
if(i==CPUBurstTimeGantt[counter]*scalingFactor+tempi)
{
counter++;
tempi=i;
printf("|");
}
else
if(i==(CPUBurstTimeGantt[counter]*scalingFactor)/2+tempi)
printf("P%d",processNumberGantt[counter]);
else
printf(" ");
printf("|");
printf("\n");
for(i=0;i<scalingFactor*totalCPUBurstTime+2+ganttSize;i++)
printf("-");
printf("\n");
/* printing the time labels of the gantt
chart */
counter=0;
tempi=0;
currentTime=minimumArrivalTime;
printf("%d",currentTime);
for(i=0;i<scalingFactor*totalCPUBurstTime;i++)
if(i==CPUBurstTimeGantt[counter]*scalingFactor+tempi)
{
tempi=i;
currentTime+=CPUBurstTimeGantt[counter];
averageWaitingTime+=currentTime;
counter++;
printf("%2d",currentTime);
}
else
{
printf(" ");
}
currentTime+=CPUBurstTimeGantt[counter];
printf("%2d\n\n",currentTime);
}
