var current = 0;

function nextImg() {
	current++;
	if (current >= unit_count) {
		current = 0;
	}
	prevImage = current - 1;
	if (prevImage < 0) {
		prevImage = unit_count - 1;
	} else if (prevImage > unit_count) {
		prevImage = 0;
	}
	document.getElementById("unit" + prevImage).style.display = "none";
	document.getElementById("unit" + current).style.display = "block";
}

function prevImg() {
	current--;
	if (current < 0) {
		current = unit_count - 1;
	}
	prevImage = current + 1;
	if (prevImage < 0) {
		prevImage = unit_count - 1;
	} else if (prevImage >= unit_count) {
		prevImage = 0;
	}
	document.getElementById("unit" + prevImage).style.display = "none";
	document.getElementById("unit" + current).style.display = "block";
}

var slideshowInterval;

function startSlideshow() {
	slideshowInterval = setInterval("nextImg()", 5000);
}

function stopSlideshow() {
	clearInterval(slideshowInterval);
}