#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

#define FALSE	0 
#define TRUE	1 
#define N	2		/* number of processes */

int Tc[]={5000000,100000000};	/* time for each proc. in critical region */
int Tn[]={1000000,10000000};	/* time for each proc. in noncritical region */

int turn=0;			/* whose turn is it? */ 

void compute(int T)		/* compute for some time */ 
{
  int i;
  for(i=0;i<T;i++);
}

void critical_region(int process)	/* print PID and compute a while */
{
  int i;
  for(i=0;i<10;i++) {
    /* printf("%d",process); */
    fprintf(stdout,"%d",process); fflush(stdout);
    compute(Tc[process]);
  } 
}

void noncritical_region(int process)	/* print PID and compute a while */
{
  int i;
  for(i=0;i<10;i++) {
    /* printf("%c",(int)'a'+process); */
    fprintf(stdout,"%c",(int)'a'+process); fflush(stdout);
    compute(Tn[process]);
  } 
}

void *one_thread(void *tid)
{
  int i,j,process;

  process = (int)tid;

  if (process==0) {
    while(TRUE) {
      while(turn!=1) ;		/* loop */
      critical_region(process);
      turn=0;
      noncritical_region(process);
    }
  }
  else if (process==1) {
    while(TRUE) {
      while(turn!=0) ;		/* loop */
      critical_region(process);
      turn=1;
      noncritical_region(process);
    }
  }
  pthread_exit(NULL);
}

int main(int argc, char *argv[])
{
  pthread_t threads[N];
  int status, i;

  /* We use threads instead of processes in this example */
  for(i=0;i<N;i++) {
    printf("Main: creating thread %d\n",i);
    status = pthread_create(&threads[i],NULL,one_thread,(void *)i);
    if(status != 0) {
      printf("pthread_create returned error code %d\n",status);
      exit(-1);
    }
  }
  sleep(60);			/* Let threads run for a while */
}