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1
5 package org.h2.compress;
6
7 import java.io.IOException  ;
8 import java.io.OutputStream ;
9
10 import org.h2.engine.Constants;
11
12 public class LZFOutputStream extends OutputStream {
13
14 static final int MAGIC = ('H' << 24) | ('2' << 16) | ('I' << 8) | 'S';
15 private OutputStream out;
16 private byte[] buffer;
17 private int pos;
18 private byte[] outBuffer;
19 private CompressLZF compress = new CompressLZF();
20
21 public LZFOutputStream(OutputStream out) throws IOException {
22 this.out = out;
23 int len = Constants.IO_BUFFER_SIZE_COMPRESS;
24 buffer = new byte[len];
25 ensureOutput(len);
26 writeInt(MAGIC);
27 }
28
29 private void ensureOutput(int len) {
30 int outputLen = (len < 100 ? len + 100 : len) * 2;
32 if(outBuffer == null || outBuffer.length < outputLen) {
33 outBuffer = new byte[outputLen];
34 }
35 }
36
37 public void write(int b) throws IOException {
38 if(pos >= buffer.length) {
39 flush();
40 }
41 buffer[pos++] = (byte)b;
42 }
43
44 private void compressAndWrite(byte[] buff, int len) throws IOException {
45 if(len > 0) {
46 ensureOutput(len);
47 int compressed = compress.compress(buff, len, outBuffer, 0);
48 if(compressed > len) {
49 writeInt(-len);
50 out.write(buff, 0, len);
51 } else {
52 writeInt(compressed);
53 writeInt(len);
54 out.write(outBuffer, 0, compressed);
55 }
56 }
57 }
58
59 private void writeInt(int x) throws IOException {
60 out.write((byte) (x >> 24));
61 out.write((byte) (x >> 16));
62 out.write((byte) (x >> 8));
63 out.write((byte) x);
64 }
65
66 public void write(byte[] buff, int off, int len) throws IOException {
67 while(len > 0) {
68 int copy = Math.min(buffer.length - pos, len);
69 System.arraycopy(buff, off, buffer, pos, copy);
70 pos += copy;
71 if(pos >= buffer.length) {
72 flush();
73 }
74 off += copy;
75 len -= copy;
76 }
77 }
78
79 public void flush() throws IOException {
80 compressAndWrite(buffer, pos);
81 pos = 0;
82 }
83
84 public void close() throws IOException {
85 flush();
86 out.close();
87 }
88
89 }
90 |
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