X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Futil.c;h=e02f59fb0a0af60d4a71b3c66d297badc86aa924;hb=40f280c781639c24176e054abc20bb7270da9e7a;hp=d430a500728df385abd7d76c1d2e11f913e4b144;hpb=c71c6043a7617e6e6c2b8748550014f54476faa7;p=openvswitch

diff --git a/lib/util.c b/lib/util.c
index d430a500..e02f59fb 100644
--- a/lib/util.c
+++ b/lib/util.c
@@ -301,7 +301,7 @@ set_program_name__(const char *argv0, const char *date, const char *time)
 
 /* Returns a pointer to a string describing the program version.  The
  * caller must not modify or free the returned string.
- */ 
+ */
 const char *
 get_program_version(void)
 {
@@ -663,3 +663,65 @@ log_2_floor(uint32_t n)
     }
 #endif
 }
+
+/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
+int
+ctz(uint32_t n)
+{
+    if (!n) {
+        return 32;
+    } else {
+#if !defined(UINT_MAX) || !defined(UINT32_MAX)
+#error "Someone screwed up the #includes."
+#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
+        return __builtin_ctz(n);
+#else
+        unsigned int k;
+        int count = 31;
+
+#define CTZ_STEP(X)                             \
+        k = n << (X);                           \
+        if (k) {                                \
+            count -= X;                         \
+            n = k;                              \
+        }
+        CTZ_STEP(16);
+        CTZ_STEP(8);
+        CTZ_STEP(4);
+        CTZ_STEP(2);
+        CTZ_STEP(1);
+#undef CTZ_STEP
+
+        return count;
+#endif
+    }
+}
+
+/* Returns true if the 'n' bytes starting at 'p' are zeros. */
+bool
+is_all_zeros(const uint8_t *p, size_t n)
+{
+    size_t i;
+
+    for (i = 0; i < n; i++) {
+        if (p[i] != 0x00) {
+            return false;
+        }
+    }
+    return true;
+}
+
+/* Returns true if the 'n' bytes starting at 'p' are 0xff. */
+bool
+is_all_ones(const uint8_t *p, size_t n)
+{
+    size_t i;
+
+    for (i = 0; i < n; i++) {
+        if (p[i] != 0xff) {
+            return false;
+        }
+    }
+    return true;
+}
+