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I need to make an android program that controls an OTG USB device

I have the device's android library as an *.a (libdevice_api.a) file, and the associated header file (device.h)

The library's documentation is very old and shows a project that uses Android.mk for a sample build, but I would prefer to do this using CMake

How do I include this .a file and the header file in my project using CMake? Currently all my NDK code is in /app/src/main/cpp. As a first sample program, I would ideally like to be able to include the .a file to my project and use the library's getVersion() function to test if it worked. Here is my current CMakeLists.txt file: 

# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html

# Sets the minimum version of CMake required to build the native library.

cmake_minimum_required(VERSION 3.4.1)

#SET ( CMAKE_C_FLAGS_RELEASE "-DCONFIG_RELEASE -O2" )

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.

add_library( # Sets the name of the library.
            mirics-jni

    # Sets the library as a shared library.
            SHARED
            mirics-jni.cpp )

# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
        log-lib

        # Specifies the name of the NDK library that
        # you want CMake to locate.
        log )

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
        mirics-jni

        # Links the target library to the log library
        # included in the NDK.
        ${log-lib} )

include_directories()
user13267
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  • Have you checked other questions on Stack Overflow about using external libraries in Android CMake project? E.g. [this one](https://stackoverflow.com/questions/49781205/linking-external-libraries-using-ndk-gradle-cmake-in-android-studio) or [that](https://stackoverflow.com/questions/52665480/how-to-add-external-library-in-android-studio-with-cmake). Or do you find their answers don't work for your case? – Tsyvarev Jun 03 '20 at 08:20
  • @Tsyvarev thanks for the links I'll have a look at them. I actually tried [this](https://stackoverflow.com/questions/14077611/how-do-i-tell-cmake-to-link-in-a-static-library-in-the-source-directory/4149520) but it results in an error "error adding symbols: File in wrong format" so I'm not sure if I am including it correctly – user13267 Jun 03 '20 at 09:27
  • Your question does not show how you try to use `libdevice_api.a`. The key to this would be `SET_TARGET_PROPERTIES(device_api PROPERTIES IMPORTED_LOCATION …)` (see https://stackoverflow.com/a/31544491/192373). – Alex Cohn Jun 03 '20 at 14:43
  • Thank you @AlexCohn I will have a look at using SET_TARGET_PROPERTIES as well. [This](https://stackoverflow.com/questions/62175986/msi-sdr-device-sample-code-does-not-compile) is the device I am trying to interface with, if you are interested. – user13267 Jun 03 '20 at 15:01
  • @AlexCohn I have tried that, but I am getting an error "error adding symbols: File in wrong format", I am not sure if hte .a file itself is corrupted or not, but since it is an official file from the manufacturer's website I am assuming I am just using it wrong – user13267 Jun 04 '20 at 00:58
  • The problem may be the same as your [other question](https://stackoverflow.com/questions/62175986/msi-sdr-device-sample-code-does-not-compile): you only have a 32-bit ARM library, and Android Studio (via CMake) attempts to build for other architectures. Use `abifilters` to guide it. – Alex Cohn Jun 04 '20 at 09:30

0 Answers0