[Qemu-devel] [PATCH v2] utils: Add pow2ceil()

[Alexey Kardashevskiy <aik@ozlabs.ru>]

This adds a helper to get closest bigger power-of-two value.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v2:
* s/up_pow_of_two/pow2ceil/
---
 include/qemu-common.h | 2 ++
 util/cutils.c         | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/qemu-common.h b/include/qemu-common.h
index 644b46d..ae29748 100644
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@@ -417,6 +417,8 @@ static inline bool is_power_of_2(uint64_t value)
 
 /* round down to the nearest power of 2*/
 int64_t pow2floor(int64_t value);
+/* round up to the nearest power of 2*/
+int64_t pow2ceil(int64_t value);
 
 #include "qemu/module.h"
 
diff --git a/util/cutils.c b/util/cutils.c
index dbe7412..ecaa440 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -483,6 +483,15 @@ int64_t pow2floor(int64_t value)
     return value;
 }
 
+/* round up to the nearest power of 2*/
+int64_t pow2ceil(int64_t value)
+{
+    if (!is_power_of_2(value)) {
+        value = 0x8000000000000000ULL >> (clz64(value) - 1);
+    }
+    return value;
+}
+
 /*
  * Implementation of  ULEB128 (http://en.wikipedia.org/wiki/LEB128)
  * Input is limited to 14-bit numbers
-- 
2.0.0