Unduplicate the implementations of next power of two

Qtbase contains four identical implementations of next power of two,
these should be shared and the implementation made available to other
qt modules, as it is also used many places outside of qtbase.

[ChangeLog][QtCore][QtMath] Introduced qNextPowerOfTwo methods.

Change-Id: Id23fbe5ad6bae647b30d5a4212c0330e48a50278
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 2 insertions, 13 deletions

diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp
index 7ca47961c0..52af67c86a 100644
--- a/src/corelib/tools/qbytearray.cpp
+++ b/src/corelib/tools/qbytearray.cpp
@@ -48,6 +48,7 @@
 #include "qlocale_p.h"
 #include "qscopedpointer.h"
 #include <qdatastream.h>
+#include <qmath.h>
 
 #ifndef QT_NO_COMPRESS
 #include <zlib.h>
@@ -72,19 +73,7 @@ int qAllocMore(int alloc, int extra) Q_DECL_NOTHROW
     Q_ASSERT(alloc >= 0 && extra >= 0);
     Q_ASSERT_X(alloc < (1 << 30) - extra, "qAllocMore", "Requested size is too large!");
 
-    unsigned nalloc = alloc + extra;
-
-    // Round up to next power of 2
-
-    // Assuming container is growing, always overshoot
-    //--nalloc;
-
-    nalloc |= nalloc >> 1;
-    nalloc |= nalloc >> 2;
-    nalloc |= nalloc >> 4;
-    nalloc |= nalloc >> 8;
-    nalloc |= nalloc >> 16;
-    ++nalloc;
+    unsigned nalloc = qNextPowerOfTwo(alloc + extra);
 
     Q_ASSERT(nalloc > unsigned(alloc + extra));