-// Quiet a warning on Intel compiler
-#if !defined(__SIZEOF_INT__ )
-#define __SIZEOF_INT__ 0
-#endif
-
-// Check for 64 bits for different compilers: Intel, MSVC and gcc
-#if defined(__x86_64) || defined(_M_X64) || defined(_WIN64) || (__SIZEOF_INT__ > 4)
-#define IS_64BIT
-#endif
+//// For Linux configuration is done using Makefile. To get started type "make help".
+////
+//// For windows you need to set the right compiler switches manually:
+////
+//// -DNDEBUG | Disable debugging mode. Use always.
+////
+//// -DIS_64BIT | Compile in 64-bit mode. Use on 64-bit systems.
+////
+//// -DBIGENDIAN | Should not be used on Windows
+////
+//// -DUSE_PREFETCH | Use prefetch asm-instruction. Gives a small speed up,
+//// | but executable won't work on some very old machines.
+////
+//// -DUSE_BSFQ | Use bsfq asm-instruction. Works only in 64-bit mode.
+//// | Works with ICC and GCC, not with MSVC. Gives a small speed up.
+////
+//// -DUSE_POPCNT | Add runtime support for use of popcnt asm-instruction.
+//// | Works only in 64-bit mode. For compiling requires hardware
+//// | with popcnt support. Around 4% speed-up.