include(ProcessorCount)

ProcessorCount(processor_count)
message("processor_count='${processor_count}'")

if(NOT processor_count MATCHES "^[0-9]+$")
  message(FATAL_ERROR "ProcessorCount function returned a non-integer")
endif()

if(processor_count EQUAL 0)
  message(FATAL_ERROR "could not determine number of processors
- Additional code for this platform needed in ProcessorCount.cmake?")
endif()