/******************************************************************************* * SDR Trunk * Copyright (C) 2014 Dennis Sheirer * * This program 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. * * This program 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 this program. If not, see <http://www.gnu.org/licenses/> ******************************************************************************/ package bits; import org.apache.commons.lang3.Validate; import java.util.ArrayList; import java.util.List; /** * Multi-Sync pattern matcher. Accepts multiple sync detector objects for * comparision against the incoming bit stream. * * Note: works for sync patterns up to 63 bits (integer size - 1 ) long. * If a 64 bit or larger sync pattern is applied, then the wrapping feature * of the Long.rotate methods will wrap the MSB around to the LSB and * corrupt the matching value. * */ public class MultiSyncPatternMatcher { private List<ISyncProcessor> mSyncProcessors = new ArrayList<ISyncProcessor>(); private long mBits = 0; private long mMask = 0; public MultiSyncPatternMatcher( int syncSize ) { Validate.isTrue(syncSize < 64); //Setup a bit mask of all ones the length of the sync pattern mMask = (long)( ( Math.pow( 2, syncSize ) ) - 1 ); } public void dispose() { mSyncProcessors.clear(); } /** * Processes two bits before checking sync processors for a match. */ public void receive( boolean bit1, boolean bit2 ) { mBits = Long.rotateLeft( mBits, 1 ); mBits &= mMask; if( bit1 ) { mBits += 1; } mBits = Long.rotateLeft( mBits, 1 ); mBits &= mMask; if( bit2 ) { mBits += 1; } for( ISyncProcessor processor: mSyncProcessors ) { processor.checkSync( mBits ); } } /** * Processes one bit before checking sync processors for a match. */ public void receive( boolean bit ) { mBits = Long.rotateLeft( mBits, 1 ); mBits &= mMask; if( bit ) { mBits += 1; } for( ISyncProcessor processor: mSyncProcessors ) { processor.checkSync( mBits ); } } /** * Adds a sync processor to receive the bit stream. */ public void add( ISyncProcessor processor ) { mSyncProcessors.add( processor ); } }