/*
implementing
Preemptive sjf
Preemptive
shortest job first.
*/
/*
processes
are assumed to be in order P0, P1, P2 and so on.
*/
/* Sample input # 1:
Number
of processes : 5
Arrival
Time Burst Time
P0 5 2
P1 1 6
P2 2 2
P3 3 4
P4 1 5
*/
/* Sample input # 2:
Number
of processes : 4
Arrival
Time Burst Time
P0 1 8
P1 2 4
P2 3 2
P3 9 1
*/
void drawGanttChart();
void calculateProcessSequence();
int findAptProcessNumber(int);
#include<stdlib.h>
#include<stdio.h>
int numberOfProcesses,totalCPUBurstTime,*arrivalTime,*CPUBurstTime,*CPUBurstTimeCopy,*processNumber,minimumArrivalTime,*processSequenceForEachSecond,*waitingTime;
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);
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];
}
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,prevProcess,tempCPUBurstTime,counter,prevProcesss;
for(i=minimumArrivalTime;i<totalCPUBurstTime
+ minimumArrivalTime;i++)
{
pNumber=findAptProcessNumber(i);
processSequenceForEachSecond[i-minimumArrivalTime]=pNumber;
CPUBurstTime[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]++;
}
/*
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 i,min=2147483647,pNumber;
for(i=0;i<numberOfProcesses;i++)
if(arrivalTime[i]<=currentTime
&& min>CPUBurstTime[i] && CPUBurstTime[i]!=0)
{
min=CPUBurstTime[i];
pNumber=i;
}
return
pNumber;
}
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);
}
Can you help me to modify the above code for the calculation of waiting time , turnaround time and response time for the processes? Thankyou
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