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Use the Project Explorer (left pane in Eclipse) to open the different files and familiarize yourself with each component.

Building the project

Building the project actually consists of first building your Native C code as a library using ndk-build , and then building the Java code, which is responsible for loading the C library and executing your functions.

For this lab project, the build process in Eclipse has already been configured to build everything automatically, and so building your project is as simple as clicking Project>Build Project .

You may want to uncheck Build Automatically , and then build by first Clean ing the project and checking the "Immediately start build" option.

C syntax support

Open .\jni\process.c in the Eclipse editor. This file contains the processing function, which is where you will implement your signal processing. If you see notifications for syntax errors, then in the Project Explorer , right-click on the project name and go to Project Properties>C/C++ General>Paths and Symbols and add the following three files into the Include directories for GNU C : C:\NvPack\android-ndk-r8\platforms\android-9\arch-arm\usr\include C:\NvPack\android-ndk-r8\sources\cxx-stl\gnu-libstdc++\includeC:\NvPack\android-ndk-r8\sources\cxx-stl\gnu-libstdc++\libs\armeabi-v7a\include

Part 2: a development environment for signal-processing applications

Function declarations in java and c

In the Lab4Activity Java class, the following function declaration is made:

public static native void process(ShortBuffer inbuf, DoubleBuffer outbuf, int N);

Where is the Lab4Activity class defined?

According to the "Understanding the Android Project Structure" section in Part 1, you can find it in Lab4Activity.java in a sub-directory of .\src\

Here, the native keyword states that process() is a Native C function. The first argument points to the Java-equivalent of a short[N] array, which holds a block of the 16-bit audio data. The second argument points to the Java-equivalent of a double[N] array, which you have to fill with data to visualize on-screen.

In process.c , the C-equivalent function declaration for process() , along with pointers to the input and output buffers have already been written for you. Appropriate header files have also been included, including the FFTW library, a popular C library for implementing the FFT.

Debugging in java

To introduce the Java debugging environment, you will verify that the mechanism for using test vectors is working correctly. First, in the Lab4Activity class definition, set the variable FILE_INPUT to true . Set a breakpoint on the line where process() is called.

Click Run>Debug , and debug as an Android Application . The project will automatically rebuild if out-of-date, and should switch to the Debug Perspective . The application will automatically run and be halted at the set breakpoint.

Click Window>Show View>Expressions and add the following expression: sb.get(0) , which returns the first value in the buffer. Verify that the value is correct by comparing to the values in the lookup table defined in LOOKUP.java . Repeat this for other values in the table to convince yourself that the test vector values were copied correctly.

The Android Reference guide contains detailed information about the classes you will encounter in Java (e.g., the ShortBuffer class).

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Ece 420 fall 2013. OpenStax CNX. Sep 26, 2013 Download for free at http://cnx.org/content/col11560/1.3
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