cmake/Modules/TestBigEndian.cmake

# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

#[=======================================================================[.rst:
TestBigEndian
-------------

Define macro to determine endian type

Check if the system is big endian or little endian

::

  TEST_BIG_ENDIAN(VARIABLE)
  VARIABLE - variable to store the result to
#]=======================================================================]

include(CheckTypeSize)

macro(TEST_BIG_ENDIAN VARIABLE)
  if(NOT DEFINED HAVE_${VARIABLE})
    message(STATUS "Check if the system is big endian")
    message(STATUS "Searching 16 bit integer")

    if(CMAKE_C_COMPILER_LOADED)
      set(_test_language "C")
    elseif(CMAKE_CXX_COMPILER_LOADED)
      set(_test_language "CXX")
    else()
      message(FATAL_ERROR "TEST_BIG_ENDIAN needs either C or CXX language enabled")
    endif()

    CHECK_TYPE_SIZE("unsigned short" CMAKE_SIZEOF_UNSIGNED_SHORT LANGUAGE ${_test_language})
    if(CMAKE_SIZEOF_UNSIGNED_SHORT EQUAL 2)
      message(STATUS "Using unsigned short")
      set(CMAKE_16BIT_TYPE "unsigned short")
    else()
      CHECK_TYPE_SIZE("unsigned int"   CMAKE_SIZEOF_UNSIGNED_INT LANGUAGE ${_test_language})
      if(CMAKE_SIZEOF_UNSIGNED_INT)
        message(STATUS "Using unsigned int")
        set(CMAKE_16BIT_TYPE "unsigned int")

      else()

        CHECK_TYPE_SIZE("unsigned long"  CMAKE_SIZEOF_UNSIGNED_LONG LANGUAGE ${_test_language})
        if(CMAKE_SIZEOF_UNSIGNED_LONG)
          message(STATUS "Using unsigned long")
          set(CMAKE_16BIT_TYPE "unsigned long")
        else()
          message(FATAL_ERROR "no suitable type found")
        endif()

      endif()

    endif()

    if(_test_language STREQUAL "CXX")
      set(_test_file "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/TestEndianess.cpp")
    else()
      set(_test_file "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/TestEndianess.c")
    endif()

    configure_file("${CMAKE_ROOT}/Modules/TestEndianess.c.in"
                   ${_test_file}
                   @ONLY)

     file(READ ${_test_file} TEST_ENDIANESS_FILE_CONTENT)

     try_compile(HAVE_${VARIABLE}
      "${CMAKE_BINARY_DIR}"
      ${_test_file}
      OUTPUT_VARIABLE OUTPUT
      COPY_FILE "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/TestEndianess.bin" )

      if(HAVE_${VARIABLE})

        file(STRINGS "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/TestEndianess.bin"
            CMAKE_TEST_ENDIANESS_STRINGS_LE LIMIT_COUNT 1 REGEX "THIS IS LITTLE ENDIAN")

        file(STRINGS "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/TestEndianess.bin"
            CMAKE_TEST_ENDIANESS_STRINGS_BE LIMIT_COUNT 1 REGEX "THIS IS BIG ENDIAN")

        # on mac, if there are universal binaries built both will be true
        # return the result depending on the machine on which cmake runs
        if(CMAKE_TEST_ENDIANESS_STRINGS_BE  AND  CMAKE_TEST_ENDIANESS_STRINGS_LE)
          if(CMAKE_SYSTEM_PROCESSOR MATCHES powerpc)
            set(CMAKE_TEST_ENDIANESS_STRINGS_BE TRUE)
            set(CMAKE_TEST_ENDIANESS_STRINGS_LE FALSE)
          else()
            set(CMAKE_TEST_ENDIANESS_STRINGS_BE FALSE)
            set(CMAKE_TEST_ENDIANESS_STRINGS_LE TRUE)
          endif()
          message(STATUS "TEST_BIG_ENDIAN found different results, consider setting CMAKE_OSX_ARCHITECTURES or CMAKE_TRY_COMPILE_OSX_ARCHITECTURES to one or no architecture !")
        endif()

        if(CMAKE_TEST_ENDIANESS_STRINGS_LE)
          set(${VARIABLE} 0 CACHE INTERNAL "Result of TEST_BIG_ENDIAN" FORCE)
          message(STATUS "Check if the system is big endian - little endian")
        endif()

        if(CMAKE_TEST_ENDIANESS_STRINGS_BE)
          set(${VARIABLE} 1 CACHE INTERNAL "Result of TEST_BIG_ENDIAN" FORCE)
          message(STATUS "Check if the system is big endian - big endian")
        endif()

        if(NOT CMAKE_TEST_ENDIANESS_STRINGS_BE  AND  NOT CMAKE_TEST_ENDIANESS_STRINGS_LE)
          message(SEND_ERROR "TEST_BIG_ENDIAN found no result!")
        endif()

        file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
          "Determining if the system is big endian passed with the following output:\n${OUTPUT}\nTestEndianess.c:\n${TEST_ENDIANESS_FILE_CONTENT}\n\n")

      else()
        message(STATUS "Check if the system is big endian - failed")
        file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
          "Determining if the system is big endian failed with the following output:\n${OUTPUT}\nTestEndianess.c:\n${TEST_ENDIANESS_FILE_CONTENT}\n\n")
        set(${VARIABLE})
      endif()
  endif()
endmacro()