Switch main wz::crc to using crc-32 model with a slicing-by-8 algorithm

For a substantial performance improvement on most systems

lib/framework/CMakeLists.txt

@@ -31,3 +31,30 @@ endif()
 if (APPLE)
 	target_link_libraries(framework PUBLIC "-framework ApplicationServices" "-framework AppKit")
 endif (APPLE)
+
+# Detect endianness (for crc.cpp)
+if (NOT DEFINED CMAKE_CXX_BYTE_ORDER AND CMAKE_VERSION VERSION_LESS 3.20)
+	# CMake < 3.20 does not have CMAKE_<LANG>_BYTE_ORDER
+	# Instead, use the older TestBigEndian module (although this may not work for cross-compilation)
+	if (NOT CMAKE_CROSSCOMPILING)
+		include(TestBigEndian)
+		test_big_endian(IS_BIGENDIAN)
+		if (IS_BIGENDIAN)
+			set(CMAKE_CXX_BYTE_ORDER "BIG_ENDIAN")
+		else()
+			set(CMAKE_CXX_BYTE_ORDER "LITTLE_ENDIAN")
+		endif()
+	else()
+		message(WARNING "Unable to determine endianness for target architecture. Either upgrade to CMake 3.20+ or manually set the CMAKE_CXX_BYTE_ORDER cache variable to \"LITTLE_ENDIAN\" or \"BIG_ENDIAN\". Otherwise, will attempt preprocessor endian detection on compile.")
+	endif()
+endif()
+if (DEFINED CMAKE_CXX_BYTE_ORDER AND NOT CMAKE_CXX_BYTE_ORDER STREQUAL "")
+	message(STATUS "CMAKE_CXX_BYTE_ORDER: ${CMAKE_CXX_BYTE_ORDER}")
+	if (CMAKE_CXX_BYTE_ORDER STREQUAL "LITTLE_ENDIAN")
+		set_property(SOURCE "${CMAKE_CURRENT_SOURCE_DIR}/crc.cpp" APPEND PROPERTY COMPILE_DEFINITIONS WZ_IS_BIG_ENDIAN=0)
+	elseif (CMAKE_CXX_BYTE_ORDER STREQUAL "BIG_ENDIAN")
+		set_property(SOURCE "${CMAKE_CURRENT_SOURCE_DIR}/crc.cpp" APPEND PROPERTY COMPILE_DEFINITIONS WZ_IS_BIG_ENDIAN=1)
+	else()
+		message(FATAL_ERROR "Unsupported / unexpected endianness? (CMAKE_CXX_BYTE_ORDER: \"${CMAKE_CXX_BYTE_ORDER}\")")
+	endif()
+endif()