/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.compress;
import java.io.IOException;
import java.io.OutputStream;
import org.h2.engine.Constants;
/**
* An output stream to write an LZF stream.
* The data is automatically compressed.
*/
public class LZFOutputStream extends OutputStream {
/**
* The file header of a LZF file.
*/
static final int MAGIC = ('H' << 24) | ('2' << 16) | ('I' << 8) | 'S';
private final OutputStream out;
private final CompressLZF compress = new CompressLZF();
private final byte[] buffer;
private int pos;
private byte[] outBuffer;
public LZFOutputStream(OutputStream out) throws IOException {
this.out = out;
int len = Constants.IO_BUFFER_SIZE_COMPRESS;
buffer = new byte[len];
ensureOutput(len);
writeInt(MAGIC);
}
private void ensureOutput(int len) {
// TODO calculate the maximum overhead (worst case) for the output
// buffer
int outputLen = (len < 100 ? len + 100 : len) * 2;
if (outBuffer == null || outBuffer.length < outputLen) {
outBuffer = new byte[outputLen];
}
}
@Override
public void write(int b) throws IOException {
if (pos >= buffer.length) {
flush();
}
buffer[pos++] = (byte) b;
}
private void compressAndWrite(byte[] buff, int len) throws IOException {
if (len > 0) {
ensureOutput(len);
int compressed = compress.compress(buff, 0, len, outBuffer, 0);
if (compressed > len) {
writeInt(-len);
out.write(buff, 0, len);
} else {
writeInt(compressed);
writeInt(len);
out.write(outBuffer, 0, compressed);
}
}
}
private void writeInt(int x) throws IOException {
out.write((byte) (x >> 24));
out.write((byte) (x >> 16));
out.write((byte) (x >> 8));
out.write((byte) x);
}
@Override
public void write(byte[] buff, int off, int len) throws IOException {
while (len > 0) {
int copy = Math.min(buffer.length - pos, len);
System.arraycopy(buff, off, buffer, pos, copy);
pos += copy;
if (pos >= buffer.length) {
flush();
}
off += copy;
len -= copy;
}
}
@Override
public void flush() throws IOException {
compressAndWrite(buffer, pos);
pos = 0;
}
@Override
public void close() throws IOException {
flush();
out.close();
}
}