X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Futil.h;h=a1f4bd740226fd899591003eb77afc27fe196200;hb=9d232a6d578e1283c543b0a40f5915e39813ac21;hp=57527fcc686edbfcedcf5149ecf369a69e123758;hpb=ebc56baa41db060b8783051e67b6fcbc148ebd60;p=openvswitch

diff --git a/lib/util.h b/lib/util.h
index 57527fcc..a1f4bd74 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -17,6 +17,7 @@
 #ifndef UTIL_H
 #define UTIL_H 1
 
+#include <limits.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -103,6 +104,14 @@ rightmost_1bit(uintmax_t x)
     return x & -x;
 }
 
+/* Returns 'x' with its rightmost 1-bit changed to a zero (e.g. 01011000 =>
+ * 01010000), or 0 if 'x' is 0. */
+static inline uintmax_t
+zero_rightmost_1bit(uintmax_t x)
+{
+    return x & (x - 1);
+}
+
 #ifndef MIN
 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
 #endif
@@ -233,9 +242,33 @@ char *xreadlink(const char *filename);
 char *follow_symlinks(const char *filename);
 
 void ignore(bool x OVS_UNUSED);
+
+/* Returns the number of trailing 0-bits in 'n'.  Undefined if 'n' == 0.
+ *
+ * This compiles to a single machine instruction ("bsf") with GCC on x86. */
+#if !defined(UINT_MAX) || !defined(UINT32_MAX)
+#error "Someone screwed up the #includes."
+#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
+static inline int
+raw_ctz(uint32_t n)
+{
+    return __builtin_ctz(n);
+}
+#else
+/* Defined in util.c. */
+int raw_ctz(uint32_t n);
+#endif
+
+/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
+static inline int
+ctz(uint32_t n)
+{
+    return n ? raw_ctz(n) : 32;
+}
+
 int log_2_floor(uint32_t);
 int log_2_ceil(uint32_t);
-int ctz(uint32_t);
+int popcount(uint32_t);
 
 bool is_all_zeros(const uint8_t *, size_t);
 bool is_all_ones(const uint8_t *, size_t);