+ return x;
+}
+
+/* An attempt at a useful 1-bit hash function. Has not been analyzed for
+ * quality. */
+static inline uint32_t hash_boolean(bool x, uint32_t basis)
+{
+ enum { P0 = 0xc2b73583 }; /* This is hash_int(1, 0). */
+ enum { P1 = 0xe90f1258 }; /* This is hash_int(2, 0). */
+ return (x ? P0 : P1) ^ HASH_ROT(basis, 1);
+}
+
+static inline uint32_t hash_double(double x, uint32_t basis)
+{
+ BUILD_ASSERT_DECL(sizeof x == 8);
+ return hash_2words((const uint32_t *) &x, basis);
+}
+
+static inline uint32_t hash_pointer(const void *p, uint32_t basis)
+{
+ /* Often pointers are hashed simply by casting to integer type, but that
+ * has pitfalls since the lower bits of a pointer are often all 0 for
+ * alignment reasons. It's hard to guess where the entropy really is, so
+ * we give up here and just use a high-quality hash function.
+ *
+ * The double cast suppresses a warning on 64-bit systems about casting to
+ * an integer to different size. That's OK in this case, since most of the
+ * entropy in the pointer is almost certainly in the lower 32 bits. */
+ return hash_int((uint32_t) (uintptr_t) p, basis);