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

#define ADD 1
#define SUB 2

pthread_mutex_t	libpcp_lock = PTHREAD_MUTEX_INITIALIZER;

int		sum = 100;
int		tmpa;
int		tmpb;

static void *
func(void *arg)
{
    int		op;
    int		i;

    if (strcmp((char *)arg, "add") == 0)
	op = ADD;
    else if (strcmp((char *)arg, "sub") == 0)
	op = SUB;
    else
	pthread_exit("bad arg");

    for (i = 0; i < 10000; i++) {
	int	sts;
	pthread_mutex_lock(&libpcp_lock);
	tmpb = tmpa = sum;
	if (op == ADD) {
	    tmpa++;
	    if ((i % 1000) == 0) wait(&sts);
	    tmpb++;
	}
	else {
	    tmpa--;
	    if ((i % 1000) == 0) wait(&sts);
	    tmpb--;
	}
	if (tmpa == tmpb) sum = tmpa;
	pthread_mutex_unlock(&libpcp_lock);
    }

    pthread_exit(NULL);
}

main()
{
    pthread_t	tid1;
    pthread_t	tid2;
    int		sts;
    char	*msg;

    sts = pthread_create(&tid1, NULL, func, "add");
    if (sts != 0) {
	printf("thread_create: tid1: sts=%d\n", sts);
	exit(1);
    }
    sts = pthread_create(&tid2, NULL, func, "sub");
    if (sts != 0) {
	printf("thread_create: tid2: sts=%d\n", sts);
	exit(1);
    }

    pthread_join(tid1, (void *)&msg);
    if (msg != NULL) printf("tid1: %s\n", msg);
    pthread_join(tid2, (void *)&msg); 
    if (msg != NULL) printf("tid2: %s\n", msg);

    if (sum == 100) {
	printf("Congratulations, you're in a bozo-free zone\n");
	exit(0);
    }
    else {
	printf("Bozo! sum=%d at the end, expecting 100\n", sum);
	exit(1);
    }

    /*NOTREACHED*/
}