SEMAPHORES TO IMPLEMENT PRODUCER CONSUMER PROBLEM

#include<sys/sem.h>
#include<fcntl.h>
#include<unistd.h>
#include<sys/types.h>
#include<stdio.h>
#include<sys/ipc.h>
void up(int);
void down(int);
union value
{
int val;
struct semid_ds *buf;
unsigned short *array;
struct seminto *_buf;
}
main()
{
int mutex,full,empty,pid,i,key,j,k;
union value arg;
key=ftok("",'a');
mutex=semget(key,1,0660|IPC_CREAT);
arg.val=0;
semctl(full,0,SETVAL,arg);
key=ftok("",'c');
empty=semget(key,1,0660|IPC_CREAT);
arg.val=4;
semctl(empty,0,SETVAL,arg);
pid=fork();
switch(pid)
{
case -1:
printf("Error");
case 0:
sleep(13);
printf("\n");
printf("Consumer consuming items\n");
for(i=0;i<5;i++)
{
down(full);
down(mutex);
for(j=4-i;j>=1;j--)
printf("*");
for(k=0;k<=i;k++)
printf("_");
printf("\n");
fflush(stdout);
up(mutex);
up(empty);
sleep(1);
}
printf("Buffer empty\n");
break;
default:
printf("Producer producing items\n");
for(i=0;i<5;i++)
{
down(full);
down(mutex);
//printf("producer is producing %dth item\n",i);
for(j=4-i;j>=1;j--)
printf("_");
for(k=0;k<=i;k++)
printf("*");
printf("\n");
fflush(stdout);
up(mutex);
up(full);
sleep(1);
}
printf("Buffer full\n");
break;
}}
void down(int id)
{
struct sembuf sb={0,-1,0};
semop(id,&sb,1);
}
void up(int id)
{
struct sembuf sb={0,1,0};
semop(id,&sb,1);
}

Posted in: UNIX PROGRAMS