package net.sf.jack4j.util;
   
   /*
   Copyright (C) 2008 Ondrej Par
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
  
  You should have received a copy of the GNU Lesser General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  
  */
  
  import java.nio.ByteBuffer;
  
  /**
   * Converts samples stored in WAVE file to <code>float</code> and vice-versa.
   * 
   * @author repa
   * 
   */
  public abstract class IntSampleConverter {
  
  	private static final IntSampleConverter[] converters = { new IntSampleConverter8BitUnsigned(),
  	        new IntSampleConverter16BitSignedLittleEndian(), new IntSampleConverter24BitSignedLittleEndian(),
  	        new IntSampleConverter32BitSignedLittleEndian() };
  
  	private final static class IntSampleConverter8BitUnsigned extends IntSampleConverter {
  
  		@Override
  		public int bytesPerSample() {
  			return 1;
  		}
  
  		@Override
  		public void floatToIntSample(float sample, ByteBuffer byteBuffer) {
  			int value = (int) (sample * 127 + 128);
  
  			byteBuffer.put((byte) value);
  		}
  
  		@Override
  		public float intSampleToFloat(ByteBuffer byteBuffer) {
  			return (byteBuffer.get() - 128) / 128.0f;
  		}
  
  		@Override
  		public boolean isBigEndian() {
  			// doesn't really matter for 8 bits
  			return false;
  		}
  
  		@Override
  		public boolean isSigned() {
  			return false;
  		}
  
  	}
  
  	private final static class IntSampleConverter16BitSignedLittleEndian extends IntSampleConverter {
  
  		@Override
  		public int bytesPerSample() {
  			return 2;
  		}
  
  		@Override
  		public void floatToIntSample(float sample, ByteBuffer byteBuffer) {
  			int value = (int) (sample * 0x8000);
  			byteBuffer.put((byte) (value & 0xff));
  			byteBuffer.put((byte) ((value >> 8) & 0xff));
  		}
  
  		@Override
  		public float intSampleToFloat(ByteBuffer byteBuffer) {
  			int intValue = ((byteBuffer.get() & 0xff) | (byteBuffer.get() << 8));
  			return ((float) intValue) / 0x8000;
  		}
  
  		@Override
  		public boolean isBigEndian() {
  			return false;
  		}
  
  		@Override
  		public boolean isSigned() {
  			return true;
  		}
  
  	}
  
 	private final static class IntSampleConverter24BitSignedLittleEndian extends IntSampleConverter {
 
 		@Override
 		public int bytesPerSample() {
 			return 3;
 		}
 
 		@Override
 		public void floatToIntSample(float sample, ByteBuffer byteBuffer) {
 			int value = (int) (sample * 0x800000);
 			byteBuffer.put((byte) (value & 0xff));
 			byteBuffer.put((byte) ((value >> 8) & 0xff));
 			byteBuffer.put((byte) ((value >> 16) & 0xff));
 		}
 
 		@Override
 		public float intSampleToFloat(ByteBuffer byteBuffer) {
 			int intValue = ((byteBuffer.get() & 0xff) | (byteBuffer.get() << 8) | (byteBuffer.get() << 16));
 			return ((float) intValue) / 0x800000;
 		}
 
 		@Override
 		public boolean isBigEndian() {
 			return false;
 		}
 
 		@Override
 		public boolean isSigned() {
 			return true;
 		}
 
 	}
 
 	private final static class IntSampleConverter32BitSignedLittleEndian extends IntSampleConverter {
 
 		@Override
 		public int bytesPerSample() {
 			return 4;
 		}
 
 		@Override
 		public void floatToIntSample(float sample, ByteBuffer byteBuffer) {
 			int value = (int) (sample * 0x80000000);
 			byteBuffer.put((byte) (value & 0xff));
 			byteBuffer.put((byte) ((value >> 8) & 0xff));
 			byteBuffer.put((byte) ((value >> 16) & 0xff));
 			byteBuffer.put((byte) ((value >> 24) & 0xff));
 		}
 
 		@Override
 		public float intSampleToFloat(ByteBuffer byteBuffer) {
 			int intValue = ((byteBuffer.get() & 0xff) | (byteBuffer.get() << 8) | (byteBuffer.get() << 16) | (byteBuffer
 			        .get() << 24));
 			return ((float) intValue) / 0x80000000;
 		}
 
 		@Override
 		public boolean isBigEndian() {
 			return false;
 		}
 
 		@Override
 		public boolean isSigned() {
 			return true;
 		}
 
 	}
 
 	public static IntSampleConverter createIntSampleConverter(int bitsPerSample, boolean signed, boolean bigEndian) {
 		if ((bitsPerSample <= 0) || (bitsPerSample > 32)) {
 			throw new IllegalArgumentException();
 		}
 
 		int bytesPerSample = (bitsPerSample / 8) + (((bitsPerSample % 8) == 0) ? 0 : 1);
 
 		for (IntSampleConverter converter : converters) {
 			if ((bytesPerSample == converter.bytesPerSample()) && (signed == converter.isSigned())
 			        && ((bytesPerSample == 1) || (bigEndian == converter.isBigEndian()))) {
 				return converter;
 			}
 		}
 
 		throw new IllegalArgumentException();
 	}
 
 	public abstract int bytesPerSample();
 
 	public abstract boolean isSigned();
 
 	public abstract boolean isBigEndian();
 
 	public abstract void floatToIntSample(float sample, ByteBuffer byteBuffer);
 
 	public abstract float intSampleToFloat(ByteBuffer byteBuffer);
 }