initial changes

cmake/arch.cmake

@@ -0,0 +1,16 @@
+if("${CMAKE_SIZEOF_VOID_P}" EQUAL "4")
+  message(FATAL_ERROR "32-bit compilation is not supported")
+endif()
+
+if(CMAKE_SYSTEM_PROCESSOR MATCHES "^(aarch64.*|AARCH64.*|arm64.*|ARM64.*)")
+  set(IS_ARM_SYSTEM 1)
+endif()
+
+if(PROJECT_IS_ARM64 AND NOT IS_ARM_SYSTEM AND NOT PROJECT_REQUIRE_ALPINE)
+  message(FATAL_ERROR "aarch64 cross-compile is not supported")
+endif()
+
+string(REPLACE "_" "-" PROJECT_MARCH ${PROJECT_BUILD_ARCH})
+if("${PROJECT_BUILD_ARCH}" STREQUAL "aarch64")
+  set(PROJECT_MARCH armv8-a)
+endif()