1 Building native code applications and libraries 2 3 STEP 1 4 Building an application. 5 -------- 6 7 0) set the environment variable PREBUILT to point to the Android prebuilt directory 8 export PREBUILT=<path_to_android_src>/prebuilt/<platform> 9 10 where you type in the actual path to the android source in place of <path_to_android_src> 11 and the platform you are using instead of <platform>: either linux-x86 or darwin-x86 12 13 1) Test the pndk install by building the hello world sample application: 14 15 cd <your_pndk_base>/samples/sample 16 make clean 17 make 18 19 The sample application uses hello.c to construct the hello binary, which you 20 can load and run on the ARM device. To achieve proper runtime behavior, verify 21 that: 22 * crtbegin_dynamic.o is the first linked object file 23 * crtend_android.o is last linked object. 24 Both are set by the config.mk file in pndk/config. 25 26 2) Test that this works correctly by attaching your ARM-based device to the USB 27 port and installing the application (hello) you just made by (in the commands 28 below # is the ARM device's shell prompt): 29 30 NOTE: need a development build so remount opens system permissions 31 32 adb remount 33 adb push hello system/app 34 adb shell 35 # cd system/app 36 # ./hello 37 Hello from the NDK; no user libraries. 38 # exit 39 40 3) You may also build the c++ binary hello_cpp.cpp into an application: 41 42 make -f Makefile.hello_cpp clean 43 make -f Makefile.hello_cpp hello_cpp 44 45 This uses the hello_cpp.cpp and hello_cpp.h files to construct the hello_cpp 46 binary application, which you can load and run on the ARM device. Note that 47 we do not provide for C++ exceptions thus you must use the -fno-exceptions flag 48 when compiling. 49 50 adb push hello_cpp system/app 51 adb shell 52 # cd system/app 53 # ./hello_cpp 54 C++ example printing message: Hello world! 55 # exit 56 57 58 STEP 2 59 Building and using a library 60 ------- 61 62 Makefile.lib in pndk/sample shows how to make either a shared library or a 63 static library from the hellolibrary.c source. The example makes the libraries 64 libhello-shared.so and libhello-static.a . 65 66 Makefile.uselib then shows how to make an application that links against either 67 a shared or a static library. They examples shows how to build the two 68 applications use_hellolibrary-so and use-hellolibrary-a from the source 69 use_hellolibrary.c. 70 71 1) To make a shared library and an application that uses it: 72 73 make -f Makefile.lib clean 74 make -f Makefile.lib sharedlib 75 make -f Makefile.uselib clean 76 make -f Makefile.uselib use_hellolibrary-so 77 78 2) Copy the shared library libhello-shared.so to /system/lib (or the location 79 in which shared libraries are found by the kernel on your ARM-based device.) 80 81 adb push libhello-shared.so system/lib 82 83 You would not typically use the -shared or -static extensions in the filename, 84 but the distinction is important in the case where a static and shared library 85 are made in the same directory. Giving the files different names allows you to 86 override the link defaults that default to a static library of the same name. 87 88 3) The application, use_hellolibrary-so, can now be tested by loading and 89 running on the ARM device. 90 91 adb push use_hellolibrary-so /system/app 92 adb shell 93 # cd system/app 94 # ./use_hellolibrary-so 95 Library printing message: Hello from the NDK. 96 # exit 97 98 4) To make a static library: 99 100 make -f Makefile.lib clean 101 make -f Makefile.lib staticlib 102 make -f Makefile.uselib clean 103 make -f Makefile.uselib use_hellolibrary-a 104 105 5) Test the application use_hellolibrary-a by loading and running it on the ARM 106 device. 107 108 adb push use_hellolibrary-a system/app 109 adb shell 110 # cd system/app 111 # ./use_hellolibrary-a 112 Library printing message: Hello from the NDK. 113 # exit 114 115 116 SUMMARY: 117 --------- 118 119 To make everything execute the following: 120 121 make clean 122 make 123 make -f Makefile.lib clean 124 make -f Makefile.lib 125 make -f Makefile.uselib clean 126 make -f Makefile.uselib 127 make -f Makefile.hello_cpp clean 128 make -f Makefile.hello_cpp hello_cpp 129 130 131 You should have: 132 * The libraries libhello-static.a and libhello-shared.so built, the latter 133 ready for installation, 134 * The applications hello, use_hellolibrary-a, and use_hellolibrary-so 135 available for installation on the ARM device. 136
