O(n) time, O(1) size array rotation

rotate.c

void
rotate(char *first, char *newfirst, char *end)
{
	char	*next;
	
	next = newfirst;
	while (next != first) {
		char	swap;
		
		swap = *first;
		*(first++) = *next;
		*(next++) = swap;
		if (next >= end)
			next = newfirst;
		else if (first >= newfirst)
			newfirst = next;
	}
}