/*
* Copyright (c) 2008-2010, Matthias Mann
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Matthias Mann nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package de.matthiasmann.jpegdecoder;
import java.io.IOException;
import java.util.Arrays;
/**
*
* @author Matthias Mann
*/
class Huffman {
static final int FAST_BITS = 9;
static final int FAST_MASK = (1 << FAST_BITS) - 1;
final byte[] fast;
final byte[] values;
final byte[] size;
final int[] maxCode;
final int[] delta;
public Huffman(int[] count) throws IOException {
int numSymbols = 0;
for(int i=0 ; i<16 ; i++) {
numSymbols += count[i];
}
fast = new byte[1 << FAST_BITS];
values = new byte[numSymbols];
size = new byte[numSymbols];
maxCode = new int[18];
delta = new int[17];
for(int i=0,k=0 ; i<16 ; i++) {
for(int j=0 ; j<count[i] ; j++) {
size[k++] = (byte)(i+1);
}
}
final int[] code = new int[256];
int i = 1;
int k = 0;
for(int c=0 ; i<=16 ; i++) {
delta[i] = k - c;
if(k < numSymbols && size[k] == i) {
do {
code[k++] = c++;
}while(k < numSymbols && size[k] == i);
if(c-1 >= (1<<i)) {
throw new IOException("Bad code length");
}
}
maxCode[i] = c << (16 - i);
c <<= 1;
}
maxCode[i] = Integer.MAX_VALUE;
Arrays.fill(fast, (byte)-1);
for(i=0 ; i<k ; i++) {
int s = size[i];
if(s <= FAST_BITS) {
int c = code[i] << (FAST_BITS - s);
int m = 1 << (FAST_BITS - s);
for(int j=0 ; j<m ; j++) {
fast[c+j] = (byte)i;
}
}
}
}
public int getNumSymbols() {
return values.length;
}
}