packets: Add more utility functions for IPv4 and IPv6 addresses.

We had these functions scattered around the source tree anyway.  packets.h
is a good place to centralize them.

I do plan to introduce some additional callers.

1 files changed, 25 insertions, 6 deletions

diff --git a/tests/test-util.c b/tests/test-util.c
index e9a827a4c..bc4af2356 100644
--- a/tests/test-util.c
+++ b/tests/test-util.c
@@ -17,6 +17,7 @@
 #include <config.h>
 
 #include <inttypes.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -24,7 +25,7 @@
 #include "util.h"
 
 static void
-check(uint32_t x, int n)
+check_log_2_floor(uint32_t x, int n)
 {
     if (log_2_floor(x) != n) {
         fprintf(stderr, "log_2_floor(%"PRIu32") is %d but should be %d\n",
@@ -33,20 +34,38 @@ check(uint32_t x, int n)
     }
 }
 
+static void
+check_ctz(uint32_t x, int n)
+{
+    if (ctz(x) != n) {
+        fprintf(stderr, "ctz(%"PRIu32") is %d but should be %d\n",
+                x, ctz(x), n);
+        abort();
+    }
+}
+
 int
 main(void)
 {
     int n;
 
     for (n = 0; n < 32; n++) {
-        /* Check minimum x that has log2(x) == n. */
-        check(1 << n, n);
+        /* Check minimum x such that f(x) == n. */
+        check_log_2_floor(1 << n, n);
+        check_ctz(1 << n, n);
 
-        /* Check maximum x that has log2(x) == n. */
-        check((1 << n) | ((1 << n) - 1), n);
+        /* Check maximum x such that f(x) == n. */
+        check_log_2_floor((1 << n) | ((1 << n) - 1), n);
+        check_ctz(UINT32_MAX << n, n);
 
         /* Check a random value in the middle. */
-        check((random_uint32() & ((1 << n) - 1)) | (1 << n), n);
+        check_log_2_floor((random_uint32() & ((1 << n) - 1)) | (1 << n), n);
+        check_ctz((random_uint32() | 1) << n, n);
     }
+
+    /* Check ctz(0).
+     * (log_2_floor(0) is undefined.) */
+    check_ctz(0, 32);
+
     return 0;
 }