diff --git a/public/tier0/commonmacros.h b/public/tier0/commonmacros.h
index 007220a1..33440087 100644
--- a/public/tier0/commonmacros.h
+++ b/public/tier0/commonmacros.h
@@ -28,15 +28,14 @@
 #define STRING_MATCHES_ID( p, id )		( (*((int *)(p)) == (id) ) ? true : false )
 #define ID_TO_STRING( id, p )			( (p)[3] = (((id)>>24) & 0xFF), (p)[2] = (((id)>>16) & 0xFF), (p)[1] = (((id)>>8) & 0xFF), (p)[0] = (((id)>>0) & 0xFF) )
 
-#define Q_ARRAYSIZE(p)		(sizeof(p)/sizeof(p[0]))
-
 #define SETBITS(iBitVector, bits)		((iBitVector) |= (bits))
 #define CLEARBITS(iBitVector, bits)		((iBitVector) &= ~(bits))
 #define FBitSet(iBitVector, bits)		((iBitVector) & (bits))
 
-inline bool IsPowerOfTwo( int value )
+template <typename T>
+inline bool IsPowerOfTwo( T value )
 {
-	return (value & ( value - 1 )) == 0;
+	return (value & ( value - (T)1 )) == (T)0;
 }
 
 #ifndef REFERENCE
@@ -100,7 +99,14 @@ extern "C++" // templates cannot be declared to have 'C' linkage
 template <typename T, size_t N>
 char (*RtlpNumberOf( UNALIGNED T (&)[N] ))[N];
 
+#ifdef _PREFAST_
+// The +0 is so that we can go:
+// size = ARRAYSIZE(array) * sizeof(array[0]) without triggering a /analyze
+// warning about multiplying sizeof.
+#define RTL_NUMBER_OF_V2(A) (sizeof(*RtlpNumberOf(A))+0)
+#else
 #define RTL_NUMBER_OF_V2(A) (sizeof(*RtlpNumberOf(A)))
+#endif
 
 // This does not work with:
 //
@@ -145,5 +151,23 @@ char (*RtlpNumberOf( UNALIGNED T (&)[N] ))[N];
 #define ARRAYSIZE(A)    RTL_NUMBER_OF_V2(A)
 #define _ARRAYSIZE(A)   RTL_NUMBER_OF_V1(A)
 
+#define Q_ARRAYSIZE(p)		ARRAYSIZE(p)
+#define V_ARRAYSIZE(p)		ARRAYSIZE(p)
+
+template< typename IndexType, typename T, unsigned int N >
+IndexType ClampedArrayIndex( const T (&buffer)[N], IndexType index )
+{
+	return clamp( index, 0, (IndexType)N - 1 );
+}
+
+template< typename T, unsigned int N >
+T ClampedArrayElement( const T (&buffer)[N], unsigned int uIndex )
+{
+	// Put index in an unsigned type to halve the clamping.
+	if ( uIndex >= N )
+		uIndex = N - 1;
+	return buffer[ uIndex ];
+}
+
 #endif // COMMONMACROS_H