Add a ASCII85 encoding to the stream
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id: ASCII85OutputStream.java 426584 2006-07-28 16:01:47Z jeremias $ */
import java.io.OutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
/**
* This class applies a ASCII85 encoding to the stream.
*
* @version $Id: ASCII85OutputStream.java 426584 2006-07-28 16:01:47Z jeremias $
*/
public class ASCII85OutputStream extends FilterOutputStream
implements ASCII85Constants {
private static final boolean DEBUG = false;
private int pos = 0;
private long buffer = 0;
private int posinline = 0;
private int bw = 0;
/** @see java.io.FilterOutputStream **/
public ASCII85OutputStream(OutputStream out) {
super(out);
}
/** @see java.io.FilterOutputStream **/
public void write(int b) throws IOException {
if (pos == 0) {
buffer += (b << 24) & 0xff000000L;
} else if (pos == 1) {
buffer += (b << 16) & 0xff0000L;
} else if (pos == 2) {
buffer += (b << 8) & 0xff00L;
} else {
buffer += b & 0xffL;
}
pos++;
if (pos > 3) {
checkedWrite(convertWord(buffer));
buffer = 0;
pos = 0;
}
}
/* UNUSED ATM
private void checkedWrite(int b) throws IOException {
if (posinline == 80) {
out.write(EOL); bw++;
posinline = 0;
}
checkedWrite(b);
posinline++;
bw++;
}*/
private void checkedWrite(byte[] buf) throws IOException {
checkedWrite(buf, buf.length, false);
}
private void checkedWrite(byte[] buf, boolean nosplit) throws IOException {
checkedWrite(buf, buf.length, nosplit);
}
private void checkedWrite(byte[] buf , int len) throws IOException {
checkedWrite(buf, len, false);
}
private void checkedWrite(byte[] buf , int len, boolean nosplit) throws IOException {
if (posinline + len > 80) {
int firstpart = (nosplit ? 0 : len - (posinline + len - 80));
if (firstpart > 0) {
out.write(buf, 0, firstpart);
}
out.write(EOL); bw++;
int rest = len - firstpart;
if (rest > 0) {
out.write(buf, firstpart, rest);
}
posinline = rest;
} else {
out.write(buf, 0, len);
posinline += len;
}
bw += len;
}
/**
* This converts a 32 bit value (4 bytes) into 5 bytes using base 85.
* each byte in the result starts with zero at the '!' character so
* the resulting base85 number fits into printable ascii chars
*
* @param word the 32 bit unsigned (hence the long datatype) word
* @return 5 bytes (or a single byte of the 'z' character for word
* values of 0)
*/
private byte[] convertWord(long word) {
word = word & 0xffffffff;
if (word == 0) {
return ZERO_ARRAY;
} else {
if (word < 0) {
word = -word;
}
byte c1 =
(byte)((word
/ POW85[0]) & 0xFF);
byte c2 =
(byte)(((word - (c1 * POW85[0]))
/ POW85[1]) & 0xFF);
byte c3 =
(byte)(((word - (c1 * POW85[0])
- (c2 * POW85[1]))
/ POW85[2]) & 0xFF);
byte c4 =
(byte)(((word - (c1 * POW85[0])
- (c2 * POW85[1])
- (c3 * POW85[2]))
/ POW85[3]) & 0xFF);
byte c5 =
(byte)(((word - (c1 * POW85[0])
- (c2 * POW85[1])
- (c3 * POW85[2])
- (c4 * POW85[3])))
& 0xFF);
byte[] ret = {
(byte)(c1 + START), (byte)(c2 + START),
(byte)(c3 + START), (byte)(c4 + START),
(byte)(c5 + START)
};
if (DEBUG) {
for (int i = 0; i < ret.length; i++) {
if (ret[i] < 33 || ret[i] > 117) {
System.out.println("Illegal char value "
+ new Integer(ret[i]));
}
}
}
return ret;
}
}
/** @see Finalizable **/
public void finalizeStream() throws IOException {
// now take care of the trailing few bytes.
// with n leftover bytes, we append 0 bytes to make a full group of 4
// then convert like normal (except not applying the special zero rule)
// and write out the first n+1 bytes from the result
if (pos > 0) {
int rest = pos;
/*
byte[] lastdata = new byte[4];
int i = 0;
for (int j = 0; j < 4; j++) {
if (j < rest) {
lastdata[j] = data[i++];
} else {
lastdata[j] = 0;
}
}
long val = ((lastdata[0] << 24) & 0xff000000L)
+ ((lastdata[1] << 16) & 0xff0000L)
+ ((lastdata[2] << 8) & 0xff00L)
+ (lastdata[3] & 0xffL);
*/
byte[] conv;
// special rule for handling zeros at the end
if (buffer != 0) {
conv = convertWord(buffer);
} else {
conv = new byte[5];
for (int j = 0; j < 5; j++) {
conv[j] = (byte)'!';
}
}
// assert rest+1 <= 5
checkedWrite(conv, rest + 1);
}
// finally write the two character end of data marker
checkedWrite(EOD, true);
flush();
}
/** @see java.io.FilterOutputStream **/
public void close() throws IOException {
finalizeStream();
super.close();
}
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id: ASCII85Constants.java 426584 2006-07-28 16:01:47Z jeremias $ */
/**
* This interface defines constants used by the ASCII85 filters.
*
* @version $Id: ASCII85Constants.java 426584 2006-07-28 16:01:47Z jeremias $
*/
interface ASCII85Constants {
/** Special character "z" stands for four NULL bytes (short-cut for !!!!!) */
public static final int ZERO = 0x7A; //"z"
/** ZERO as a byte array */
public static final byte[] ZERO_ARRAY = {(byte)ZERO};
/** The start index for ASCII85 characters (!) */
public static final int START = 0x21; //"!"
/** The end index for ASCII85 characters (u) */
public static final int END = 0x75; //"u"
/** The EOL indicator (LF) */
public static final int EOL = 0x0A; //"\n"
/** The EOD (end of data) indicator */
public static final byte[] EOD = {0x7E, 0x3E}; //"~>"
/** Array of powers of 85 (4, 3, 2, 1, 0) */
public static final long POW85[] = new long[] {85 * 85 * 85 * 85,
85 * 85 * 85,
85 * 85,
85,
1};
/*
public static final long BASE85_4 = 85;
public static final long BASE85_3 = BASE85_4 * BASE85_4;
public static final long BASE85_2 = BASE85_3 * BASE85_4;
public static final long BASE85_1 = BASE85_2 * BASE85_4;
*/
}
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