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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

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
I'm not good at math so would you help me
what is the problem that i will help you to self with?
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris 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?
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
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele 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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