enable SSE2 intrinsics on GCC 3.3 or later

GNUmakefile

@@ -9,6 +9,12 @@ CXXFLAGS = -g
 ARFLAGS = -cr	# ar needs the dash on OpenBSD
 RANLIB = ranlib
 UNAME = $(shell uname)
+ISX86 = $(shell uname -m | grep -c "i.86")
+GCC33ORLATER = $(shell gcc -v 2>&1 | grep -c "gcc version \(3.[3-9]\|[4-9]\)")
+
+ifeq ($(ISX86) $(GCC33ORLATER),1 1)
+CXXFLAGS += -msse2
+endif
 
 ifeq ($(UNAME),)	# for DJGPP, where uname doesn't exist
 CXXFLAGS += -mbnu210

integer.h

@@ -21,10 +21,17 @@
 	#endif
 #endif
 
+// SSE2 intrinsics work in GCC 3.3 or later
+#if defined(__SSE2__) && (__GNUC_MAJOR__ > 3 || __GNUC_MINOR__ > 2)
+	#define SSE2_INTRINSICS_AVAILABLE
+#endif
+
 NAMESPACE_BEGIN(CryptoPP)
 
 #if defined(SSE2_INTRINSICS_AVAILABLE) || defined(_MSC_VER)
-
+	// Defined this class for MSVC even if processor pack is not installed,
+	// so that the library can be compiled with processor pack, and calling app
+	// compiled without it.
 	template <class T>
 	class AlignedAllocator : public AllocatorBase<T>
 	{
@@ -38,15 +45,16 @@ NAMESPACE_BEGIN(CryptoPP)
 			return StandardReallocate(*this, p, oldSize, newSize, preserve);
 		}
 	};
+
 	template class CRYPTOPP_DLL AlignedAllocator<word>;
 	typedef SecBlock<word, AlignedAllocator<word> > SecAlignedWordBlock;
 
-void CRYPTOPP_DLL DisableSSE2();
-
 #else
 	typedef SecWordBlock SecAlignedWordBlock;
 #endif
 
+void CRYPTOPP_DLL DisableSSE2();
+
 //! multiple precision integer and basic arithmetics
 /*! This class can represent positive and negative integers
 	with absolute value less than (256**sizeof(word)) ** (256**sizeof(int)).