+/* Allocates and returns a bitmap initialized to all-1-bits. */
+unsigned long *
+bitmap_allocate1(size_t n_bits)
+{
+ size_t n_bytes = bitmap_n_bytes(n_bits);
+ size_t n_longs = bitmap_n_longs(n_bits);
+ unsigned long *bitmap;
+
+ /* Allocate and initialize most of the bitmap. */
+ bitmap = xmalloc(n_bytes);
+ memset(bitmap, 0xff, n_bytes);
+
+ /* Ensure that the last "unsigned long" in the bitmap only has as many
+ * 1-bits as there actually should be. */
+ bitmap[n_longs - 1] = (1UL << (n_bits % BITMAP_ULONG_BITS)) - 1;
+
+ return bitmap;
+}
+