Add comment about log2().

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@5408

diff --git a/coregrind/m_libcbase.c b/coregrind/m_libcbase.c
index 4a530952278b4e909de571aecbf33fe56c10d355..cd620cc9730ad6eef8aeb13c4e24b49cd3677dd6 100644 (file)
--- a/coregrind/m_libcbase.c
+++ b/coregrind/m_libcbase.c
@@ -413,6 +413,7 @@ Int VG_(memcmp) ( const void* s1, const void* s2, SizeT n )
    Misc useful functions
    ------------------------------------------------------------------ */
 
+/* Returns the base-2 logarithm of x.  Returns -1 if x is not a power of two. */
 Int VG_(log2) ( Int x ) 
 {
    Int i;

diff --git a/include/pub_tool_libcbase.h b/include/pub_tool_libcbase.h
index cc1a55e371a9407cfd1ba4bd90fbf465630c17fb..f9d0eeec5f9af27afc55d627019d8b8456c950c3 100644 (file)
--- a/include/pub_tool_libcbase.h
+++ b/include/pub_tool_libcbase.h
@@ -111,7 +111,7 @@ extern Int   VG_(memcmp) ( const void* s1, const void* s2, SizeT n );
 extern void VG_(ssort)( void* base, SizeT nmemb, SizeT size,
                         Int (*compar)(void*, void*) );
 
-/* Returns the base-2 logarithm of x. */
+/* Returns the base-2 logarithm of x.  Returns -1 if x is not a power of two. */
 extern Int VG_(log2) ( Int x );
 
 // A pseudo-random number generator returning a random UInt.  If pSeed