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/*
* Copyright (C) 2010, 2011 Herbert von Broeuschmeul
* Copyright (C) 2010, 2011 BluetoothGPS4Droid Project
*
* This file is part of BluetoothGPS4Droid.
*
* BluetoothGPS4Droid is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* BluetoothGPS4Droid is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with BluetoothGPS4Droid. If not, see <http://www.gnu.org/licenses/>.
*/
package org.broeuschmeul.android.gps.sirf.util;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.Formatter;
import java.util.Locale;
/**
* Utilities for generation of SIRF III binary command.
*
* It can be used to generate a array of byte corresponding
* to a SIRF III binary command expressed in an hexadecimal string.
*
* The input can be a complete SIRF III command or just the payload.
* In this last case the utility will add the start and end parts of the command
* (including the size and the checksum).
*
* @author Herbert von Broeuschmeul
*
*/
public class SirfUtils {
private static final String start ="A0A2";
private static final String end ="B0B3";
public static byte[] genSirfCommand(String commandHexa){
int length = commandHexa.length()/2;
ByteBuffer command = ByteBuffer.allocate(length);
command.put(new BigInteger(commandHexa,16).toByteArray(), 1,length);
return command.array();
}
public static byte[] genSirfCommandFromPayload(String payload){
String commandHexa = createSirfCommandFromPayload(payload);
return genSirfCommand(commandHexa);
}
public static String createSirfCommandFromPayload(String payload){
int length = payload.length()/2;
String res;
byte[] command = new BigInteger(payload,16).toByteArray();
int checkSum = 0;
for (byte b : command){
checkSum += (b & 0xff);
}
checkSum &= 0x7FFF;
res = String.format((Locale)null, "%s%04X%s%04X%s", start, length, payload, checkSum, end);
return res;
}
public static String showSirfCommandFromPayload(String payload){
byte[] command = genSirfCommandFromPayload(payload);
StringBuilder out = new StringBuilder(payload.length()+16);
Formatter fmt = new Formatter(out, null);
for (byte b : command){
fmt.format("%02X", b);
}
return out.toString();
}
}
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