+ check_ctz32(0, 32);
+ check_ctz64(0, 64);
+}
+
+static void
+check_clz32(uint32_t x, int n)
+{
+ if (clz32(x) != n) {
+ fprintf(stderr, "clz32(%"PRIu32") is %d but should be %d\n",
+ x, clz32(x), n);
+ abort();
+ }
+}
+
+static void
+check_clz64(uint64_t x, int n)
+{
+ if (clz64(x) != n) {
+ fprintf(stderr, "clz64(%"PRIu64") is %d but should be %d\n",
+ x, clz64(x), n);
+ abort();
+ }
+}
+
+static void
+test_clz(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
+{
+ int n;
+
+ for (n = 0; n < 32; n++) {
+ /* Check minimum x such that f(x) == n. */
+ check_clz32((1u << 31) >> n, n);
+
+ /* Check maximum x such that f(x) == n. */
+ check_clz32(UINT32_MAX >> n, n);
+
+ /* Check a random value in the middle. */
+ check_clz32((random_uint32() | 1u << 31) >> n, n);
+ }
+
+ for (n = 0; n < 64; n++) {
+ /* Check minimum x such that f(x) == n. */
+ check_clz64((UINT64_C(1) << 63) >> n, n);
+
+ /* Check maximum x such that f(x) == n. */
+ check_clz64(UINT64_MAX >> n, n);
+
+ /* Check a random value in the middle. */
+ check_clz64((random_uint64() | UINT64_C(1) << 63) >> n, n);
+ }
+
+ /* Check clz(0). */
+ check_clz32(0, 32);
+ check_clz64(0, 64);