+typedef size_t word;
+enum { bits_per_word = sizeof (word) * CHAR_BIT };
+
+static bool
+get_nth_bit (size_t n, word const *bitset)
+{
+ return bitset[n / bits_per_word] >> n % bits_per_word & 1;
+}
+
+static void
+set_nth_bit (size_t n, word *bitset)
+{
+ size_t one = 1;
+ bitset[n / bits_per_word] |= one << n % bits_per_word;
+}
+