/*
* #%L
* BSD implementations of Bio-Formats readers and writers
* %%
* Copyright (C) 2005 - 2015 Open Microscopy Environment:
* - Board of Regents of the University of Wisconsin-Madison
* - Glencoe Software, Inc.
* - University of Dundee
* %%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. 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.
*
* 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 HOLDERS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* 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
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* #L%
*/
package loci.formats.codec;
import java.io.IOException;
import loci.common.RandomAccessInputStream;
import loci.formats.FormatException;
/**
* Implements encoding (compress) and decoding (decompress) methods
* for Base64. This code was adapted from the Jakarta Commons Codec source,
* http://jakarta.apache.org/commons
*
* @author Melissa Linkert melissa at glencoesoftware.com
*/
public class Base64Codec extends BaseCodec {
// Base64 alphabet and codes
private static final byte PAD = (byte) '=';
private static byte[] base64Alphabet = new byte[255];
private static byte[] lookupBase64Alphabet = new byte[255];
static {
for (int i=0; i<255; i++) {
base64Alphabet[i] = (byte) -1;
}
for (int i = 'Z'; i >= 'A'; i--) {
base64Alphabet[i] = (byte) (i - 'A');
lookupBase64Alphabet[i - 'A'] = (byte) i;
}
for (int i = 'z'; i >= 'a'; i--) {
base64Alphabet[i] = (byte) (i - 'a' + 26);
lookupBase64Alphabet[i - 'a' + 26] = (byte) i;
}
for (int i = '9'; i >= '0'; i--) {
base64Alphabet[i] = (byte) (i - '0' + 52);
lookupBase64Alphabet[i - '0' + 52] = (byte) i;
}
base64Alphabet['+'] = 62;
base64Alphabet['/'] = 63;
lookupBase64Alphabet[62] = (byte) '+';
lookupBase64Alphabet[63] = (byte) '/';
}
/* @see Codec#compress(byte[], CodecOptions) */
@Override
public byte[] compress(byte[] input, CodecOptions options)
throws FormatException
{
if (input == null || input.length == 0) return null;
int dataBits = input.length * 8;
int fewerThan24 = dataBits % 24;
int numTriples = dataBits / 24;
ByteVector encoded = new ByteVector();
byte k, l, b1, b2, b3;
int dataIndex = 0;
for (int i=0; i<numTriples; i++) {
dataIndex = i * 3;
b1 = input[dataIndex];
b2 = input[dataIndex + 1];
b3 = input[dataIndex + 2];
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);
byte v1 = ((b1 & -128) == 0) ? (byte) (b1 >> 2) :
(byte) ((b1) >> 2 ^ 0xc0);
byte v2 = ((b2 & -128) == 0) ? (byte) (b2 >> 4) :
(byte) ((b2) >> 4 ^ 0xf0);
byte v3 = ((b3 & -128) == 0) ? (byte) (b3 >> 6) :
(byte) ((b3) >> 6 ^ 0xfc);
encoded.add(lookupBase64Alphabet[v1]);
encoded.add(lookupBase64Alphabet[v2 | (k << 4)]);
encoded.add(lookupBase64Alphabet[(l << 2) | v3]);
encoded.add(lookupBase64Alphabet[b3 & 0x3f]);
}
dataIndex = numTriples * 3;
if (fewerThan24 == 8) {
b1 = input[dataIndex];
k = (byte) (b1 & 0x03);
byte v = ((b1 & -128) == 0) ? (byte) (b1 >> 2) :
(byte) ((b1) >> 2 ^ 0xc0);
encoded.add(lookupBase64Alphabet[v]);
encoded.add(lookupBase64Alphabet[k << 4]);
encoded.add(PAD);
encoded.add(PAD);
}
else if (fewerThan24 == 16) {
b1 = input[dataIndex];
b2 = input[dataIndex + 1];
l = (byte) (b2 & 0x0f);
k = (byte) (b1 & 0x03);
byte v1 = ((b1 & -128) == 0) ? (byte) (b1 >> 2) :
(byte) ((b1) >> 2 ^ 0xc0);
byte v2 = ((b2 & -128) == 0) ? (byte) (b2 >> 4) :
(byte) ((b2) >> 4 ^ 0xf0);
encoded.add(lookupBase64Alphabet[v1]);
encoded.add(lookupBase64Alphabet[v2 | (k << 4)]);
encoded.add(lookupBase64Alphabet[l << 2]);
encoded.add(PAD);
}
return encoded.toByteArray();
}
/* @see Codec#decompress(RandomAccessInputStream, CodecOptions) */
@Override
public byte[] decompress(RandomAccessInputStream in, CodecOptions options)
throws FormatException, IOException
{
if (in == null)
throw new IllegalArgumentException("No data to decompress.");
if (in.length() == 0) return new byte[0];
byte b3 = 0, b4 = 0, marker0 = 0, marker1 = 0;
ByteVector decodedData = new ByteVector();
byte[] block = new byte[8192];
int nRead = in.read(block);
int p = 0;
byte b1 = base64Alphabet[block[p++]];
byte b2 = base64Alphabet[block[p++]];
while (b1 != -1 && b2 != -1 &&
(in.getFilePointer() - nRead + p < in.length()))
{
marker0 = block[p++];
marker1 = block[p++];
if (p == block.length) {
nRead = in.read(block);
p = 0;
}
decodedData.add((byte) (b1 << 2 | b2 >> 4));
if (p >= nRead && in.getFilePointer() >= in.length()) break;
if (marker0 != PAD && marker1 != PAD) {
b3 = base64Alphabet[marker0];
b4 = base64Alphabet[marker1];
decodedData.add((byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf)));
decodedData.add((byte) (b3 << 6 | b4));
}
else if (marker0 == PAD) {
decodedData.add((byte) 0);
decodedData.add((byte) 0);
}
else if (marker1 == PAD) {
b3 = base64Alphabet[marker0];
decodedData.add((byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf)));
decodedData.add((byte) 0);
}
b1 = base64Alphabet[block[p++]];
b2 = base64Alphabet[block[p++]];
}
return decodedData.toByteArray();
}
}