Example embedded

embedded/crosscompile_random_forest/CMake/Autodownload.cmake

@@ -0,0 +1,49 @@
+## This function auto-downloads mlpack dependencies.
+## You need to pass the LINK to download from, the name of
+## the dependency, and the name of the compressed package such as
+## armadillo.tar.gz
+## At each download, this module sets a GENERIC_INCLUDE_DIR path,
+## which means that you need to set the main path for the include
+## directories for each package.
+## Note that, the package should be compressed only as .tar.gz
+
+macro(get_deps LINK DEPS_NAME PACKAGE)
+  if (NOT EXISTS "${CMAKE_BINARY_DIR}/deps/${PACKAGE}")
+    file(DOWNLOAD ${LINK}
+           "${CMAKE_BINARY_DIR}/deps/${PACKAGE}"
+            STATUS DOWNLOAD_STATUS_LIST LOG DOWNLOAD_LOG
+            SHOW_PROGRESS)
+    list(GET DOWNLOAD_STATUS_LIST 0 DOWNLOAD_STATUS)
+    if (DOWNLOAD_STATUS EQUAL 0)
+      execute_process(COMMAND ${CMAKE_COMMAND} -E
+          tar xf "${CMAKE_BINARY_DIR}/deps/${PACKAGE}"
+          WORKING_DIRECTORY "${CMAKE_BINARY_DIR}/deps/")
+    else ()
+      list(GET DOWNLOAD_STATUS_LIST 1 DOWNLOAD_ERROR)
+      message(FATAL_ERROR
+          "Could not download ${DEPS_NAME}! Error code ${DOWNLOAD_STATUS}: ${DOWNLOAD_ERROR}!  Error log: ${DOWNLOAD_LOG}")
+    endif()
+  endif()
+  # Get the name of the directory.
+  file (GLOB DIRECTORIES RELATIVE "${CMAKE_BINARY_DIR}/deps/"
+      "${CMAKE_BINARY_DIR}/deps/${DEPS_NAME}*.*")
+  if(${DEPS_NAME} MATCHES "stb")
+    file (GLOB DIRECTORIES RELATIVE "${CMAKE_BINARY_DIR}/deps/"
+        "${CMAKE_BINARY_DIR}/deps/${DEPS_NAME}")
+  endif()
+  # list(FILTER) is not available on 3.5 or older, but try to keep
+  # configuring without filtering the list anyway 
+  # (it works only if the file is present as .tar.gz).
+  if (${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.6.0")
+    list(FILTER DIRECTORIES EXCLUDE REGEX ".*\.tar\.gz")
+  endif ()
+  list(LENGTH DIRECTORIES DIRECTORIES_LEN)
+  if (DIRECTORIES_LEN GREATER 0)
+    list(GET DIRECTORIES 0 DEPENDENCY_DIR)
+    set(GENERIC_INCLUDE_DIR "${CMAKE_BINARY_DIR}/deps/${DEPENDENCY_DIR}/include")
+    install(DIRECTORY "${GENERIC_INCLUDE_DIR}/" DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
+  else ()
+    message(FATAL_ERROR
+            "Problem unpacking ${DEPS_NAME}! Expected only one directory ${DEPS_NAME};. Try to remove the directory ${CMAKE_BINARY_DIR}/deps and reconfigure.")
+  endif ()
+endmacro()

embedded/crosscompile_random_forest/CMake/ConfigureCrossCompile.cmake

@@ -0,0 +1,45 @@
+# This file adds the necessary configurations to cross compile
+# mlpack for embedded systems. You need to set the following variables
+# from the command line: CMAKE_SYSROOT and TOOLCHAIN_PREFIX.
+# This file will compile OpenBLAS if it is downloaded and it is not
+# available on your system in order to find the BLAS library.  If OpenBLAS will
+# be compiled, the OPENBLAS_TARGET variable must be set.  This can be done
+# by, e.g., setting BOARD_NAME (which will set OPENBLAS_TARGET in
+# `board/flags-config.cmake`).
+
+if (CMAKE_CROSSCOMPILING)
+  include(board/flags-config.cmake)
+  if (NOT CMAKE_SYSROOT AND (NOT TOOLCHAIN_PREFIX))
+    message(FATAL_ERROR "Neither CMAKE_SYSROOT nor TOOLCHAIN_PREFIX are set; please set both of them and try again.")
+  elseif(NOT CMAKE_SYSROOT)
+    message(FATAL_ERROR "Cannot configure: CMAKE_SYSROOT must be set when performing cross-compiling!")
+  elseif(NOT TOOLCHAIN_PREFIX)
+    message(FATAL_ERROR "Cannot configure: TOOLCHAIN_PREFIX must be set when performing cross-compiling!")
+  endif()
+endif()
+
+macro(search_openblas version)
+  set(BLA_STATIC ON)
+  find_package(BLAS)
+  if (NOT BLAS_FOUND OR (NOT BLAS_LIBRARIES))
+    if(NOT OPENBLAS_TARGET)
+      message(FATAL_ERROR "Cannot compile OpenBLAS: OPENBLAS_TARGET is not set.  Either set that variable, or set BOARD_NAME correctly!")
+    endif()
+    get_deps(https://github.com/xianyi/OpenBLAS/releases/download/v${version}/OpenBLAS-${version}.tar.gz OpenBLAS OpenBLAS-${version}.tar.gz)
+    if (NOT MSVC)
+      if (NOT EXISTS "${CMAKE_BINARY_DIR}/deps/OpenBLAS-${version}/libopenblas.a")
+        set(ENV{COMMON_OPT} "${CMAKE_OPENBLAS_FLAGS}") # Pass our flags to OpenBLAS
+        execute_process(COMMAND make TARGET=${OPENBLAS_TARGET} BINARY=${OPENBLAS_BINARY} HOSTCC=gcc CC=${CMAKE_C_COMPILER} FC=${CMAKE_FORTRAN_COMPILER} NO_SHARED=1
+                        WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/deps/OpenBLAS-${version})
+      endif()
+      file(GLOB OPENBLAS_LIBRARIES "${CMAKE_BINARY_DIR}/deps/OpenBLAS-${version}/libopenblas.a")
+      set(BLAS_openblas_LIBRARY ${OPENBLAS_LIBRARIES})
+      set(LAPACK_openblas_LIBRARY ${OPENBLAS_LIBRARIES}) 
+      set(BLA_VENDOR OpenBLAS)
+      set(BLAS_FOUND ON)
+    endif()
+  endif()
+  find_library(GFORTRAN NAMES libgfortran.a)
+  find_library(PTHREAD NAMES libpthread.a)
+  set(CROSS_COMPILE_SUPPORT_LIBRARIES ${GFORTRAN} ${PTHREAD})
+endmacro()

embedded/crosscompile_random_forest/CMakeLists.txt

@@ -0,0 +1,79 @@
+cmake_minimum_required(VERSION 3.6)
+project(RandomForest)
+
+include(CMake/Autodownload.cmake)
+include(CMake/ConfigureCrossCompile.cmake)
+
+option(USE_OPENMP "If available, use OpenMP for parallelization." ON)
+
+# Set required standard to C++17.
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# If we're using gcc, then we need to link against pthreads to use std::thread,
+# which we do in the tests.
+if (CMAKE_COMPILER_IS_GNUCC)
+  find_package(Threads)
+  set(MLPACK_LIBRARIES ${MLPACK_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT})
+endif()
+
+search_openblas(0.3.26)
+
+get_deps(https://files.mlpack.org/armadillo-12.6.5.tar.gz armadillo armadillo-12.6.5.tar.gz)
+set(ARMADILLO_INCLUDE_DIR ${GENERIC_INCLUDE_DIR})
+find_package(Armadillo REQUIRED)
+# Include directories for the previous dependencies.
+set(MLPACK_INCLUDE_DIRS ${MLPACK_INCLUDE_DIRS} ${ARMADILLO_INCLUDE_DIRS})
+set(MLPACK_LIBRARIES ${MLPACK_LIBRARIES} ${ARMADILLO_LIBRARIES})
+
+# Find stb_image.h and stb_image_write.h.
+get_deps(https://mlpack.org/files/stb.tar.gz stb stb.tar.gz)
+set(STB_IMAGE_INCLUDE_DIR ${GENERIC_INCLUDE_DIR})
+set(MLPACK_INCLUDE_DIRS ${MLPACK_INCLUDE_DIRS} "${STB_IMAGE_INCLUDE_DIR}")
+
+# Find ensmallen.
+get_deps(https://www.ensmallen.org/files/ensmallen-latest.tar.gz ensmallen ensmallen-latest.tar.gz)
+set(ENSMALLEN_INCLUDE_DIR ${GENERIC_INCLUDE_DIR})
+set(MLPACK_INCLUDE_DIRS ${MLPACK_INCLUDE_DIRS} "${ENSMALLEN_INCLUDE_DIR}")
+
+# Find cereal.
+get_deps(https://github.com/USCiLab/cereal/archive/refs/tags/v1.3.0.tar.gz cereal cereal-1.3.0.tar.gz)
+set(CEREAL_INCLUDE_DIR ${GENERIC_INCLUDE_DIR})
+set(MLPACK_INCLUDE_DIRS ${MLPACK_INCLUDE_DIRS} ${CEREAL_INCLUDE_DIR})
+
+# Detect OpenMP support in a compiler. If the compiler supports OpenMP, flags
+# to compile with OpenMP are returned and added.  Note that MSVC does not
+# support a new-enough version of OpenMP to be useful.
+if (USE_OPENMP)
+  find_package(OpenMP)
+endif ()
+
+if (OpenMP_FOUND AND OpenMP_CXX_VERSION VERSION_GREATER_EQUAL 3.0.0)
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
+  set(MLPACK_LIBRARIES ${MLPACK_LIBRARIES} ${OpenMP_CXX_LIBRARIES})
+else ()
+  # Disable warnings for all the unknown OpenMP pragmas.
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unknown-pragmas")
+  set(OpenMP_CXX_FLAGS "")
+endif ()
+
+include_directories(BEFORE ${MLPACK_INCLUDE_DIRS})
+include_directories(BEFORE ${CMAKE_CURRENT_SOURCE_DIR}/src/)
+
+# Finally, add any cross-compilation support libraries (they may need to come
+# last).  If we are not cross-compiling, no changes will happen here.
+set(MLPACK_LIBRARIES ${MLPACK_LIBRARIES} ${CROSS_COMPILE_SUPPORT_LIBRARIES})
+
+add_executable(RandomForest main.cpp ${SOURCES_FILES})
+target_sources(RandomForest PRIVATE ${SOURCE_FILES})
+
+target_include_directories(RandomForest PRIVATE
+  ${MLPACK_INCLUDE_DIRS}
+  /meta/mlpack/src/
+)
+
+target_link_libraries(RandomForest PRIVATE -static
+  ${MLPACK_LIBRARIES}
+)
+

embedded/crosscompile_random_forest/board/crosscompile-toolchain.cmake

@@ -0,0 +1,40 @@
+## This file handles cross-compilation configurations for aarch64,
+## known as arm64. The objective of this file is to find and assign
+## cross-compiler and the entire toolchain.
+##
+## This configuration works best with the buildroot toolchain.  When using this
+## file, be sure to set the TOOLCHAIN_PREFIX and CMAKE_SYSROOT variables,
+## preferably via the CMake configuration command (e.g. `-DCMAKE_SYSROOT=<...>`).
+##
+## Currently, we recommend using buildroot toolchain for
+## cross-compilation. Here is the link to download the toolchains:
+## https://toolchains.bootlin.com/
+
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSROOT)
+set(TOOLCHAIN_PREFIX "" CACHE STRING "Path for toolchain for cross compiler and other compilation tools.")
+
+# Ensure that CMake tries to build static libraries when testing the compiler.
+set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+
+set(CMAKE_AR "${TOOLCHAIN_PREFIX}gcc-ar" CACHE FILEPATH "" FORCE)
+set(CMAKE_C_COMPILER ${TOOLCHAIN_PREFIX}gcc)
+set(CMAKE_CXX_COMPILER ${TOOLCHAIN_PREFIX}g++)
+set(CMAKE_LINKER ${TOOLCHAIN_PREFIX}ld)
+set(CMAKE_C_ARCHIVE_CREATE "<CMAKE_AR> qcs <TARGET> <LINK_FLAGS> <OBJECTS>")
+set(CMAKE_C_ARCHIVE_FINISH  true)
+set(CMAKE_FORTRAN_COMPILER ${TOOLCHAIN_PREFIX}gfortran)
+set(CMAKE_ASM_COMPILER ${CMAKE_C_COMPILER})
+set(CMAKE_OBJCOPY ${TOOLCHAIN_PREFIX}objcopy CACHE INTERNAL "objcopy tool")
+set(CMAKE_SIZE_UTIL ${TOOLCHAIN_PREFIX}size CACHE INTERNAL "size tool")
+
+## Here are the standard ROOT_PATH if you are using the standard toolchain
+## if you are using a different toolchain you have to specify that too.
+set(CMAKE_FIND_ROOT_PATH "${CMAKE_SYSROOT}")
+
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} --sysroot=${CMAKE_SYSROOT}" CACHE INTERNAL "" FORCE)
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

embedded/crosscompile_random_forest/board/flags-config.cmake

@@ -0,0 +1,95 @@
+# This function provides a set of specific flags for each supported board
+# depending on the processor type. The objective is to optimize for size.
+# Thus, all of the following flags are chosen carefully to reduce binary 
+# footprints.
+
+# Set generic minimization flags for all platforms.
+# These flags are the same for all cross-compilation cases and they are
+# mainly to reduce the binary footprint.
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Os -s -fdata-sections -ffunction-sections")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fomit-frame-pointer -fno-unwind-tables")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-asynchronous-unwind-tables -fvisibility=hidden")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fshort-enums -finline-small-functions")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -findirect-inlining -fno-common")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fmerge-all-constants -fno-ident")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-unroll-loops -fno-math-errno")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-stack-protector")
+set(CMAKE_OPENBLAS_FLAGS "${CMAKE_CXX_FLAGS}") # OpenBLAS does not supoport flto
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto")
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--hash-style=gnu -Wl,--build-id=none")
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-z,norelro")
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--gc-sections")
+## Keep the following flag in comment, it will be relevant in the case of MCU's
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wl,-nmagic,-Bsymbolic -nostartfiles")
+
+set(BOARD_NAME "" CACHE STRING "Specify Board name to optimize for.")
+string(TOUPPER ${BOARD_NAME} BOARD)
+
+# Set specific platforms CMAKE CXX flags.
+if(BOARD MATCHES "RPI0" OR BOARD MATCHES "RPI1" OR BOARD MATCHES "ARM11")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=arm1176jzf-s")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mcpu=arm1176jzf-s -mfloat-abi=hard -mfpu=vfp")
+  set(OPENBLAS_TARGET "ARMV6")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD MATCHES "RPI2" OR BOARD MATCHES "CORTEXA7")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=cortex-a7")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfloat-abi=hard -mfpu=neon-vfpv4")
+  set(OPENBLAS_TARGET "ARMV7")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD MATCHES "CORTEXA8")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=cortex-a8")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfloat-abi=hard -mfpu=neon")
+  set(OPENBLAS_TARGET "ARMV7")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD MATCHES "CORTEXA9")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=cortex-a9")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfloat-abi=hard -mfpu=neon")
+  set(OPENBLAS_TARGET "CORTEXA9")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD MATCHES "CORTEXA15")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=cortex-a15")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfloat-abi=hard -mfpu=neon")
+  set(OPENBLAS_TARGET "CORTEXA15")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD MATCHES "RPI3" OR BOARD MATCHES "CORTEXA53")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=cortex-a53 -mfloat-abi=hard")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon-fp-armv8 -mneon-for-64bit")
+  set(OPENBLAS_TARGET "CORTEXA53")
+  set(OPENBLAS_BINARY "64")
+elseif(BOARD MATCHES "RPI4" OR BOARD MATCHES "CORTEXA72")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=cortex-a72 -mfloat-abi=hard")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon-fp-armv8 -mneon-for-64bit")
+  set(OPENBLAS_TARGET "CORTEXA72")
+  set(OPENBLAS_BINARY "64")
+elseif(BOARD MATCHES "JETSONAGX" OR BOARD MATCHES "CORTEXA76")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=cortex-a76 -mfloat-abi=hard")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon-fp-armv8 -mneon-for-64bit")
+  set(OPENBLAS_TARGET "CORTEXA76")
+  set(OPENBLAS_BINARY "64")
+elseif(BOARD MATCHES "BV")
+  set(OPENBLAS_TARGET "RISCV64_GENERIC")
+  set(OPENBLAS_BINARY "64")
+elseif(BOARD MATCHES "C906")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=thead-c906")
+  set(OPENBLAS_TARGET "RISCV64_GENERIC")
+  set(OPENBLAS_BINARY "64")
+elseif(BOARD MATCHES "x280")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mtune=sifive-x280")
+  set(OPENBLAS_TARGET "x280")
+  set(OPENBLAS_BINARY "64")
+elseif(BOARD MATCHES "KATAMI")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=pentium3")
+  set(OPENBLAS_TARGET "KATAMI")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD MATCHES "COPPERMINE")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=pentium3")
+  set(OPENBLAS_TARGET "COPPERMINE")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD MATCHES "NORTHWOOD")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=pentium4")
+  set(OPENBLAS_TARGET "NORTHWOOD")
+  set(OPENBLAS_BINARY "32")
+elseif(BOARD)
+  ## TODO: update documentation with a list of the supported boards.
+  message(FATAL_ERROR "Given BOARD_NAME is not known; please choose a supported board from the list")
+endif()

embedded/crosscompile_random_forest/main.cpp

@@ -0,0 +1,35 @@
+#include <mlpack.hpp>
+
+using namespace mlpack;
+
+int main(int argc, char** argv)
+{
+  arma::mat dataset;
+  data::Load("../../data/covertype-small.csv", dataset);
+
+  // Labels are the last row.\n",
+  // The dataset stores labels from 1 through 7, but we need 0 through 6\n",
+  // (in mlpack labels are zero-indexed), so we subtract 1.\n",
+  arma::Row<size_t> labels = arma::conv_to<arma::Row<size_t>>::from(dataset.row(dataset.n_rows - 1)) - 1;
+  dataset.shed_row(dataset.n_rows - 1);
+
+  arma::mat trainSet, testSet;
+  arma::Row<size_t> trainLabels, testLabels;
+
+  // Split dataset randomly into training set and test set.\n",
+  data::Split(dataset, labels, trainSet, testSet, trainLabels, testLabels, 0.3
+      /* Percentage of dataset to use for test set. */);
+
+  RandomForest<> rf(trainSet, trainLabels, 7 /* Number of classes in dataset */, 10 /* 10 trees */);
+  // Predict the labels of the test points.,
+  arma::Row<size_t> output;
+  rf.Classify(testSet, output);
+  // Now print the accuracy. The 'probabilities' output could also be used to\n",
+  // generate an ROC curve.\n",
+  const size_t correct = arma::accu(output == testLabels);
+  std::cout << correct
+            << " correct out of "
+            << testLabels.n_elem << "\n"
+            << 100.0 * correct / testLabels.n_elem
+            << "%)." << std::endl;
+}

embedded/mlpack_embedded_cmake/CMake/Autodownload.cmake

@@ -0,0 +1,49 @@
+## This function auto-downloads mlpack dependencies.
+## You need to pass the LINK to download from, the name of
+## the dependency, and the name of the compressed package such as
+## armadillo.tar.gz
+## At each download, this module sets a GENERIC_INCLUDE_DIR path,
+## which means that you need to set the main path for the include
+## directories for each package.
+## Note that, the package should be compressed only as .tar.gz
+
+macro(get_deps LINK DEPS_NAME PACKAGE)
+  if (NOT EXISTS "${CMAKE_BINARY_DIR}/deps/${PACKAGE}")
+    file(DOWNLOAD ${LINK}
+           "${CMAKE_BINARY_DIR}/deps/${PACKAGE}"
+            STATUS DOWNLOAD_STATUS_LIST LOG DOWNLOAD_LOG
+            SHOW_PROGRESS)
+    list(GET DOWNLOAD_STATUS_LIST 0 DOWNLOAD_STATUS)
+    if (DOWNLOAD_STATUS EQUAL 0)
+      execute_process(COMMAND ${CMAKE_COMMAND} -E
+          tar xf "${CMAKE_BINARY_DIR}/deps/${PACKAGE}"
+          WORKING_DIRECTORY "${CMAKE_BINARY_DIR}/deps/")
+    else ()
+      list(GET DOWNLOAD_STATUS_LIST 1 DOWNLOAD_ERROR)
+      message(FATAL_ERROR
+          "Could not download ${DEPS_NAME}! Error code ${DOWNLOAD_STATUS}: ${DOWNLOAD_ERROR}!  Error log: ${DOWNLOAD_LOG}")
+    endif()
+  endif()
+  # Get the name of the directory.
+  file (GLOB DIRECTORIES RELATIVE "${CMAKE_BINARY_DIR}/deps/"
+      "${CMAKE_BINARY_DIR}/deps/${DEPS_NAME}*.*")
+  if(${DEPS_NAME} MATCHES "stb")
+    file (GLOB DIRECTORIES RELATIVE "${CMAKE_BINARY_DIR}/deps/"
+        "${CMAKE_BINARY_DIR}/deps/${DEPS_NAME}")
+  endif()
+  # list(FILTER) is not available on 3.5 or older, but try to keep
+  # configuring without filtering the list anyway 
+  # (it works only if the file is present as .tar.gz).
+  if (${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.6.0")
+    list(FILTER DIRECTORIES EXCLUDE REGEX ".*\.tar\.gz")
+  endif ()
+  list(LENGTH DIRECTORIES DIRECTORIES_LEN)
+  if (DIRECTORIES_LEN GREATER 0)
+    list(GET DIRECTORIES 0 DEPENDENCY_DIR)
+    set(GENERIC_INCLUDE_DIR "${CMAKE_BINARY_DIR}/deps/${DEPENDENCY_DIR}/include")
+    install(DIRECTORY "${GENERIC_INCLUDE_DIR}/" DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
+  else ()
+    message(FATAL_ERROR
+            "Problem unpacking ${DEPS_NAME}! Expected only one directory ${DEPS_NAME};. Try to remove the directory ${CMAKE_BINARY_DIR}/deps and reconfigure.")
+  endif ()
+endmacro()