C code to implement the the first fit best fit worst fit algorithm?

Answer 1

#include<stdio.h>

#include<malloc.h>

/*

filename:firstfit.c

description:this program implements first fit algorithm

Author:Anupam Biswas,NIT Allahabad,India

Date:29.08.2011

*/

#define maxp 10 //maxp:maximum no of processes

#define maxmsz 100 //maxmsz:maximum memory size

struct memory{

int bsz;//bsz:block size

int bs;//bs:block start

int be;//be:block end

int ap;//ap:allocated process

int flag;//for allocated or not

struct memory*link;

}*start,*trav,*prev;

int pq[maxp];//pq:process queue

int f=-1,r=-1;

void enqueue(int ps)

{

/*ps:process size*/

if((r+1)%maxp==f)

{

printf("\nqueue is full, no new process can be loaded");

}

else

{

r=(r+1)%maxp;

pq[r]=ps;

}

}

int dequeue()

{

int ps;

if(f==r)

{

printf("queue empty,no process left\n");

return -1;

}

else

{

f=(f+1)%maxp;

ps=pq[f];

return ps;

}

}

void first_fit(int ps,int pid)

{

/*pid:process id*/

struct memory*block;

block=(struct memory*)malloc(sizeof(struct memory));

trav=start;

/*search the memory block large enough*/

while(trav!=NULL)

{

if(trav->flag==0 && trav->bsz>=ps)

{

break;

}

prev=trav;

trav=trav->link;

}

if(trav==NULL)

{

printf("No large enough block is found\n");

}

else /*if enough memory is found*/

{

dequeue();//remove process from queue

block->bsz=ps;

block->bs=trav->bs;

block->be=trav->bs+ps-1; //anus size defininition

block->ap=pid;

block->flag=1;

block->link=trav;

trav->bsz=trav->bsz-ps;

trav->bs=block->be+1;

if(trav==start)/*if first block is large enough*/

{

start=block;

}

else

{

prev->link=block;

}

}

}

void dealocate_memory(int pid)

{

trav=start;

while(trav!=NULL && trav->ap!=pid)

{

trav=trav->link;

}

if(trav==NULL)

{

printf("This process is not in memory at all\n");

}

else

{

if(trav->link->flag==0)

{

trav->bsz=trav->bsz+trav->link->bsz; //anus link definition

trav->be=trav->link->be;

prev=trav->link;

trav->link=prev->link;

prev->link=NULL;

free(prev);

}

trav->ap=-1;

trav->flag=0;

}

}

void show_mem_status()

{

int c=1,free=0,aloc=0;

trav=start;

printf("Memory Status is::\n");

printf("Block BSZ BS BE Flag process\n");

while(trav!=NULL)

{

printf("%d %d %d %d %d %d\n",c++,trav->bsz,trav->bs,trav->be,trav->flag,trav->ap);

if(trav->flag==0)

{

free=free+trav->bsz;

}

else

{

aloc=aloc+trav->bsz;

}

trav=trav->link;

}

printf("Free memory= %d\n",free);

printf("Allocated memory= %d\n",aloc);

}

int main()

{

int ch,ps;

char cc;

/*the size of the total memory size is defined i.e. largest block or hole*/

/*......................................................................*/

start=(struct memory*)malloc(sizeof(struct memory));

start->bsz=maxmsz;

start->bs=0;

start->be=maxmsz;

start->ap=-1;

start->flag=0;

start->link=NULL;

/*......................................................................*/

while(1)

{

printf("\n\t1. Enter process in queue\n");

printf("\t2. Allocate memory to process from queue\n");

printf("\t3. Show memory staus\n");

printf("\t4. Deallocate memory of processor\n");

printf("\t5. Exit\n");

printf("Enter your choice: ");

scanf("%d",&ch);

switch(ch)

{

case 1:

do

{

printf("Enter the size of the process: ");

scanf("%d",&ps);

enqueue(ps);

printf("Do you want to enter another process(y/n)?: ");

scanf("%c",&cc);

scanf("%c",&cc);

}

while(cc=='y');

break;

case 2:

do

{

ps=pq[f+1];

if(ps!=-1)

{

first_fit(ps,f+1);

show_mem_status();

}

printf("Do you want to allocate mem to another process(y/n)?: ");

scanf("%c",&cc);

scanf("%c",&cc);

}

while(cc=='y');

break;

case 3:

show_mem_status();

break;

case 4:

do

{

printf("Enter the process Id: ");

scanf("%d",&ps);

dealocate_memory(ps);

show_mem_status();

printf("Do you want to enter another process(y/n)?: ");

scanf("%c",&cc);

scanf("%c",&cc);

}

while(cc=='y');

break;

case 5:

break;

default:

printf("\nEnter valid choice!!\n");

}

if(ch==5)

break;

}

}