MotionAccelerometerSampleStream.java

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package com.buglabs.bug.module.motion;

import java.io.IOException;
import java.io.InputStream;

import com.buglabs.bug.accelerometer.pub.AccelerometerConfiguration;
import com.buglabs.bug.accelerometer.pub.AccelerometerSample;
import com.buglabs.bug.accelerometer.pub.AccelerometerSampleStream;
import com.buglabs.bug.accelerometer.pub.IAccelerometerConfigurationListener;

public class MotionAccelerometerSampleStream extends AccelerometerSampleStream implements IAccelerometerConfigurationListener {

	private AccelerometerConfiguration config;
	private AccelerometerControl accControl;

	public MotionAccelerometerSampleStream(InputStream is, AccelerometerControl accControl) {
		super(is);
		this.accControl = accControl;
		this.config = accControl.getConfiguration();
		accControl.registerListener(this);
	}

	public void close() throws IOException {
		super.close();
		accControl.unregisterListener(this);
	}

	public AccelerometerSample readSample() throws IOException {
		byte[] data = new byte[6];
		short[] sample = null;

		int result = read(data);
		if (result == data.length) {
			sample = new short[3];

			for (int i = 0; i < sample.length; ++i) {
				short byte0 = (short) (0x00FF & (short) data[i * 2 + 1]);
				short byte1 = (short) (0x00FF & (short) data[i * 2]);

				sample[i] = (short) (byte1 >> 6);
				sample[i] += (byte0 << 2);
			}
		} else {
			throw new IOException("Unable to read sample from accelerometer\n Read length = " + result);
		}

		return new AccelerometerSample(convertToGs(sample[2]), convertToGs(sample[1]), convertToGs(sample[0]));
	}

	private float convertToGs(short s) {
		float mVperBit = 2900.0f / 1024.0f;
		short scale_factors[] = { 421, 316, 158, 105 };
		float result = 0;
		synchronized (config) {
			result = (((float) (s * mVperBit) - 1450)) / scale_factors[config.getSensitivity()];
		}

		return result;
	}

	public void configurationChanged(AccelerometerConfiguration c) {
		synchronized (config) {
			config = c;
		}
	}
}