[systemd-devel] [PATCH 20/26] util: add log2u, log2u_round_up

[Michal Schmidt]

two's logarithms for unsigned.
---
 src/shared/util.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/shared/util.h b/src/shared/util.h
index 21a90a4..dfb4341 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -829,6 +829,21 @@ static inline int log2i(int x) {
         return __SIZEOF_INT__ * 8 - __builtin_clz(x) - 1;
 }
 
+static inline unsigned log2u(unsigned x) {
+        assert(x > 0);
+
+        return sizeof(unsigned) * 8 - __builtin_clz(x) - 1;
+}
+
+static inline unsigned log2u_round_up(unsigned x) {
+        assert(x > 0);
+
+        if (x == 1)
+                return 0;
+
+        return log2u(x - 1) + 1;
+}
+
 static inline bool logind_running(void) {
         return access("/run/systemd/seats/", F_OK) >= 0;
 }
-- 
2.1.0