/* Unnamed semaphores and pthreads. */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

#include <pthread.h>
#include <sys/types.h>
#include <synch.h>

#include "array.h"

#define massert( cond, msg )                                                  \
   if( cond ) {                                                               \
      perror( msg );                                                          \
      exit(-1);                                                               \
   }

char buf[] = "abcdefghijklmnopqrstuvwsyz";
sema_t sem_main, sem_inv, sem_rev;

void *inv( void *data ) {
   int len = strlen(buf);
   while( 1 ) {
      sema_wait( &sem_inv );
         inverse(buf, len);
      sema_post( &sem_main);
   }
}
void *rev( void* data ) {
   int len = strlen(buf);
   while( 1 ) {
      sema_wait( &sem_rev );
         reverse(buf, len);
      sema_post( &sem_main);
   }
}  

int main( int argc, char* argv[] ) {
   
   pthread_t inv_pthread, rev_pthread;

   massert(pthread_create( &inv_pthread, NULL, inv, NULL ), "pthread" );
   massert(pthread_create( &rev_pthread, NULL, rev, NULL ), "pthread" );
   
   massert(sema_init( &sem_main, 0, USYNC_THREAD, NULL), "sema_init" );
   massert(sema_init( &sem_inv , 0, USYNC_THREAD, NULL), "sema_init" );
   massert(sema_init( &sem_rev , 0, USYNC_THREAD, NULL), "sema_init" );

   while(1) {
      sema_post( &sem_inv );
      sema_wait( &sem_main );
         puts(buf);
         sleep(1);
      sema_post( &sem_rev );
      sema_wait( &sem_main );
         puts(buf);
         sleep(1);
   }
   pthread_exit(NULL); 
   return 0;
}