build(gpio): added CMakeLists.txt for gpio binary

gpio/CMakeLists.txt

@@ -0,0 +1,31 @@
+cmake_minimum_required(VERSION 3.10)
+
+project(gpio VERSION 0.1)
+set(TARGET gpio)
+
+# Have CMake find pthreads library within our toolchain
+set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
+find_package(Threads REQUIRED)
+
+# Source Files
+set(gpio_src
+    gpio.c readall.c
+)
+
+# Add library target
+add_executable (${TARGET} ${gpio_src})
+
+# Add include directory for gpio
+target_include_directories (${TARGET} PUBLIC 
+                            ${CMAKE_CURRENT_SOURCE_DIR}
+                            ${CMAKE_CURRENT_SOURCE_DIR}/../wiringPiDev
+                            ${CMAKE_CURRENT_SOURCE_DIR}/../wiringPi
+                            ${CMAKE_INSTALL_PREFIX}/include)
+
+
+# Add the following required libraries: wiringPi, wiringPiDev, Threads, Math, Crypt, and RealTime
+target_link_directories(${TARGET} PUBLIC ${CMAKE_INSTALL_PREFIX}/lib)
+target_link_libraries(${TARGET} wiringPi wiringPiDev ${CMAKE_THREAD_LIBS_INIT} crypt m rt)
+
+# Add install
+install(TARGETS ${TARGET} DESTINATION bin)