set(IMAGE_TARGET ${CMAKE_CURRENT_BINARY_DIR}/raw.img)

if (CMAKE_HOST_APPLE)
set(IMAGE_GEN_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/mkimg_macos.sh)
elseif (CMAKE_HOST_UNIX)
set(IMAGE_GEN_SCRIPT ${CMAKE_CURRENT_SOURCE_DIR}/mkimg_linux.sh)
endif (CMAKE_HOST_APPLE)

add_custom_target(raw_img COMMAND sh ${IMAGE_GEN_SCRIPT} ${IMAGE_TARGET} BYPRODUCTS ${IMAGE_TARGET})