#include <iostream>
#include <cstdlib>
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
using namespace std;
int i=0;
pthread_t threads[5];
int x[20];
struct thread_data{
int upper_bound;
int lower_bound;
int *arr;
};
int semid;
void set_sem()
{
semid=semget(12345,1,IPC_CREAT|0666);
perror("semget");
semctl(semid,0,SETVAL,5);
}
int get_sem()
{
return semctl(semid,0,GETVAL,0);
}
void create_thread(int x[20], int first, int last);
sembuf psembuf={0,-1,SEM_UNDO};
sembuf vsembuf={0,1,SEM_UNDO};
void *quicksort(void *threadarg)
{
int getv;
semop(semid,&psembuf,1);
getv=get_sem();
cout<<"semaphore value decrease to "<<getv;
struct thread_data *my_data;
my_data = (struct thread_data *) threadarg;
int first,last;
first=my_data->upper_bound;
last=my_data->lower_bound;
int pivot,j,temp,i;
if(first<last){
pivot=first;
i=first;
j=last;
cout<<"\nbefore done firts loop i = "<<i<<"j="<<j<<endl;
for(int w=first;w<=last;w++) {
cout<<endl<<"x["<<w<<"] ="<< *((my_data->arr) +w)<<endl;
}
while(i<j){
while(*((my_data->arr)+i) <= *((my_data->arr)+pivot) && i<last)
i++;
while(*((my_data->arr)+j) > *((my_data->arr)+pivot) && j>first)
j--;
if(i<j){
temp=*((my_data->arr)+i);
*((my_data->arr)+i)=*((my_data->arr)+j);
*((my_data->arr)+j)=temp;
}
}
cout<<"\ndone firts loop\n"<<endl<<first<<endl<<last<<endl;
temp=*((my_data->arr)+pivot);
*((my_data->arr)+pivot)=*((my_data->arr)+j);
*((my_data->arr)+j)=temp;
for(int t = first;t<=last;t++)
cout<<*((my_data->arr)+t)<<endl;
for(int w=first;w<=last;w++) {
cout<<endl<<"x["<<w<<"] ="<< my_data->arr[w]<<endl;
}
if (first < j-1) {
cout<<"create thread first = "<<first<<"last = "<<j-1<<endl;
create_thread(x,first,j-1);
}
else if (first == j-1 && my_data->arr[first]>my_data->arr[j]) {
temp = my_data->arr[first];
my_data->arr[first] = my_data->arr[j];
my_data->arr[j] = temp;
}
if (j+1<last)
{
cout<<"create thread first = "<<j+1<<"last = "<<last<<endl;
create_thread(x,j+1,last);
}
else if (j+1 == last && my_data->arr[last]< my_data->arr[j])
{
temp = my_data->arr[last];
my_data->arr[last] = my_data->arr[j];
my_data->arr[j] = temp;
}
}
semop(semid,&vsembuf,1);
// pthread_exit(NULL);
}
void create_thread(int x[20],int first, int last)
{
int rc=0;
i++;
pthread_attr_t attr;
void *status;
int getv;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
cout<<" entered create thread" << i <<endl<<"first"<<first<<"last"<<last;
struct thread_data td;
td.upper_bound=first;
td.lower_bound=last;
td.arr=x;
getv=get_sem();
cout<<"semaphore value is "<<getv<<endl;
if(getv < 1 )
{
sleep(5);
}
rc = pthread_create(&threads[i], NULL,
quicksort, (void *)&td);
if (rc){
cout << "Error:unable to create thread," << rc << endl;
exit(-1);
}
pthread_attr_destroy(&attr);
rc = pthread_join(threads[i], &status);
if (rc){
cout << "Error:unable to join," << rc << endl;
exit(-1);
}
cout<<"existing";
}
int main()
{
int size,i;
cout<<"Enter size of the array: ";
cin>>size;
cout<<"Enter elements: ";
for(i=0;i<size;i++)
cin>>x[i];
cout<<" hello "<<endl;
set_sem();
cout<<"semaphore set to "<<get_sem();
create_thread(x,0,size-1);
cout<<"Sorted elements: "<<endl;
for(i=0;i<size;i++)
cout<<x[i]<<" "<<endl;
return 0;
}
