From: Michal Schmidt <mschmidt@redhat.com>
Date: Tue, 14 Oct 2014 23:28:54 +0000 (+0200)
Subject: util: add log2u(), log2u_round_up()
X-Git-Tag: v218~652
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=b5de6d984296c9446ba0d2d32fd3248f453208aa

util: add log2u(), log2u_round_up()

Two's logarithms for unsigned.
---

diff --git a/src/shared/util.h b/src/shared/util.h
index aad9eb7fc..e405b02a8 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -830,6 +830,21 @@ 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;
 }