How To Run Custom Rule In Android.mk Before Compilation?

In Android NDK, I build JNI files generated automatically by SWIG. callmanager_wrap.cpp is part of a shared library: LOCAL_SRC_FILES += callmanager_wrap.cpp include $(BUILD_SHARED_

Solution 1:

I would suggest the following:

include$(CLEAR_VARS)

LOCAL_SRC_FILES += callmanager_wrap.cpp
MY_JNI_WRAP := $(LOCAL_PATH)/callmanager_wrap.cpp

$(MY_JNI_WRAP):
    echo "in myjni target"
    swig -c++ -java -package com.package.my -o $(MY_JNI_WRAP) callmanager.i
    cat jnistuff.txt >> $(MY_JNI_WRAP).PHONY: $(MY_JNI_WRAP)include$(BUILD_SHARED_LIBRARY)

That's it.

I probably owe you some explanations. So here we go:

1. $(LOCAL_SRC_FILES) is a list of file names relative to $(LOCAL_PATH), so to address a file from outside the standard NDK actions, you need the full path for your file, which is $(LOCAL_PATH)/callmanager_wrap.cpp.

2. We specify the file as .PHONY to guarantee that the custom action is executed every time you run ndk-build. But if you know which are actual dependencies of callmanager_wrap.cpp, you can specify them instead, like

   $(MY_JNI_WRAP): callmanager.i jnistuff.txt $(LOCAL_PATH)/../src/com/package/my/Something.java

   In this case, you will not need the .PHONY line.

3. If you want your source directory to remain clean, you can declare the wrapper file as .INTERMEDIATE like this:

   .INTERMEDIATE: $(MY_JNI_WRAP)

Now make will delete the wrapper file after build, if it did not exist before the build.

Solution 2:

I have done it this way: let's say I need to create .s file from .ll file

# custom build
source_ll_files := $(wildcard *.ll)%.s:
    llc -o $@$(patsubst %.s,%.ll,$@)

LOCAL_SRC_FILES += $(patsubst %.ll,%.s,$(source_ll_files))# end