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

pthread_mutex_t current_mutex;
size_t current = 3;
size_t done = 100000;
int n_threads = 4;

char is_prime(size_t cand){
	for(size_t i = 3; i < (cand+1)/2; i += 2)
		if(! (cand % i))
			return 0;
	return 1;
}

void *worker(void* param){
	do {
		// Take assignment
		pthread_mutex_lock(&current_mutex);
		size_t ours = current + 2;
		current += 2;
		pthread_mutex_unlock(&current_mutex);
	
		// Check.  This takes a while, so we should be unlocked
		if(is_prime(ours))
			printf("Found Prime:  %lu\n", ours);
	} while(current < done);
	return 0;
}

int main(int argc, char ** argv){
	if(argc > 2){
		n_threads = atoi(argv[1]);
		done = atoll(argv[2]);
	}
	pthread_t threads[48];
	pthread_mutex_init(&current_mutex, 0);
	for(int i = 0; i < n_threads; i++)
		pthread_create(threads + i, 0, worker, 0);

	for(int i = 0; i < n_threads; i++)
		pthread_join(threads[i], 0);
	return 0;	
}