if(${CMAKE_VERSION} VERSION_LESS "2.8.3")
  message(STATUS "WITH_CUDA flag requires CMake 2.8.3 or newer. CUDA support is disabled.")
  return()
endif()

if (NOT MSVC AND NOT CMAKE_COMPILER_IS_GNUCXX OR MINGW)
  message(STATUS "CUDA compilation was disabled (due to unsuppoted host compiler).")
  return()
endif()

find_package(CUDA 4.1)

if(CUDA_FOUND)
  set(HAVE_CUDA 1)

  if(WITH_CUFFT)
    set(HAVE_CUFFT 1)
  endif()

  if(WITH_CUBLAS)
    set(HAVE_CUBLAS 1)
  endif()

  message(STATUS "CUDA detected: " ${CUDA_VERSION})

  if(${CUDA_VERSION_STRING} VERSION_GREATER "4.1")
    set(CUDA_ARCH_BIN "1.1 1.2 1.3 2.0 2.1(2.0) 3.0" CACHE STRING "Specify 'real' GPU architectures to build binaries for, BIN(PTX) format is supported")
  else()
    set(CUDA_ARCH_BIN "1.1 1.2 1.3 2.0 2.1(2.0)" CACHE STRING "Specify 'real' GPU architectures to build binaries for, BIN(PTX) format is supported")
  endif()

  set(CUDA_ARCH_PTX "2.0" CACHE STRING "Specify 'virtual' PTX architectures to build PTX intermediate code for")

  string(REGEX REPLACE "\\." "" ARCH_BIN_NO_POINTS "${CUDA_ARCH_BIN}")
  string(REGEX REPLACE "\\." "" ARCH_PTX_NO_POINTS "${CUDA_ARCH_PTX}")

  # Ckeck if user specified 1.0 compute capability: we don't support it
  string(REGEX MATCH "1.0" HAS_ARCH_10 "${CUDA_ARCH_BIN} ${CUDA_ARCH_PTX}")
  set(CUDA_ARCH_BIN_OR_PTX_10 0)
  if(NOT ${HAS_ARCH_10} STREQUAL "")
    set(CUDA_ARCH_BIN_OR_PTX_10 1)
  endif()

  # NVCC flags to be set
  set(NVCC_FLAGS_EXTRA "")

  # These vars will be passed into the templates
  set(OPENCV_CUDA_ARCH_BIN "")
  set(OPENCV_CUDA_ARCH_PTX "")
  set(OPENCV_CUDA_ARCH_FEATURES "")

  # Tell NVCC to add binaries for the specified GPUs
  string(REGEX MATCHALL "[0-9()]+" ARCH_LIST "${ARCH_BIN_NO_POINTS}")
  foreach(ARCH IN LISTS ARCH_LIST)
    if(ARCH MATCHES "([0-9]+)\\(([0-9]+)\\)")
      # User explicitly specified PTX for the concrete BIN
      set(NVCC_FLAGS_EXTRA ${NVCC_FLAGS_EXTRA} -gencode arch=compute_${CMAKE_MATCH_2},code=sm_${CMAKE_MATCH_1})
      set(OPENCV_CUDA_ARCH_BIN "${OPENCV_CUDA_ARCH_BIN} ${CMAKE_MATCH_1}")
      set(OPENCV_CUDA_ARCH_FEATURES "${OPENCV_CUDA_ARCH_FEATURES} ${CMAKE_MATCH_2}")
    else()
      # User didn't explicitly specify PTX for the concrete BIN, we assume PTX=BIN
      set(NVCC_FLAGS_EXTRA ${NVCC_FLAGS_EXTRA} -gencode arch=compute_${ARCH},code=sm_${ARCH})
      set(OPENCV_CUDA_ARCH_BIN "${OPENCV_CUDA_ARCH_BIN} ${ARCH}")
      set(OPENCV_CUDA_ARCH_FEATURES "${OPENCV_CUDA_ARCH_FEATURES} ${ARCH}")
    endif()
  endforeach()

  # Tell NVCC to add PTX intermediate code for the specified architectures
  string(REGEX MATCHALL "[0-9]+" ARCH_LIST "${ARCH_PTX_NO_POINTS}")
    foreach(ARCH IN LISTS ARCH_LIST)
      set(NVCC_FLAGS_EXTRA ${NVCC_FLAGS_EXTRA} -gencode arch=compute_${ARCH},code=compute_${ARCH})
      set(OPENCV_CUDA_ARCH_PTX "${OPENCV_CUDA_ARCH_PTX} ${ARCH}")
      set(OPENCV_CUDA_ARCH_FEATURES "${OPENCV_CUDA_ARCH_FEATURES} ${ARCH}")
    endforeach()

  # These vars will be processed in other scripts
  set(CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} ${NVCC_FLAGS_EXTRA})
  set(OpenCV_CUDA_CC "${NVCC_FLAGS_EXTRA}")

  message(STATUS "CUDA NVCC target flags: ${CUDA_NVCC_FLAGS}")
  
  OCV_OPTION(CUDA_FAST_MATH  "Enable --use_fast_math for CUDA compiler " OFF)
  
  if(CUDA_FAST_MATH)
    set(CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} --use_fast_math)    
  endif()
  
  mark_as_advanced(CUDA_BUILD_CUBIN CUDA_BUILD_EMULATION CUDA_VERBOSE_BUILD CUDA_SDK_ROOT_DIR)

  unset(CUDA_npp_LIBRARY CACHE)
  find_cuda_helper_libs(npp)

  macro(ocv_cuda_compile VAR)
    foreach(var CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_RELEASE CMAKE_CXX_FLAGS_DEBUG)
      set(${var}_backup_in_cuda_compile_ "${${var}}")
      
      # we reomove /EHa as it leasd warnings under windows
      string(REPLACE "/EHa" "" ${var} "${${var}}")
      
      # we remove -ggdb3 flag as it leads to preprocessor errors when compiling CUDA files (CUDA 4.1)
      string(REPLACE "-ggdb3" "" ${var} "${${var}}")
    endforeach()
    
    if (BUILD_SHARED_LIBS)
      set(CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} -Xcompiler -DCVAPI_EXPORTS)
    endif()

    if(UNIX OR APPLE)
      set (CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} -Xcompiler -fPIC)
    endif()
    if(APPLE)
      set (CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} -Xcompiler -fno-finite-math-only)
    endif()

    # disabled because of multiple warnings during building nvcc auto generated files
    if(CMAKE_COMPILER_IS_GNUCXX AND CMAKE_GCC_REGEX_VERSION VERSION_GREATER "4.6.0")
      ocv_warnings_disable(CMAKE_CXX_FLAGS -Wunused-but-set-variable)
    endif()

    CUDA_COMPILE(${VAR} ${ARGN})  
    
    foreach(var CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_RELEASE CMAKE_CXX_FLAGS_DEBUG)
      set(${var} "${${var}_backup_in_cuda_compile_}")
      unset(${var}_backup_in_cuda_compile_)
    endforeach()    
  endmacro()
else()
  unset(CUDA_ARCH_BIN CACHE)
  unset(CUDA_ARCH_PTX CACHE)
endif()