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Java > Open Source Codes > smallsql > database > MemoryStream


1 /* =============================================================
2  * SmallSQL : a free Java DBMS library for the Java(tm) platform
3  * =============================================================
4  *
5  * (C) Copyright 2004-2006, by Volker Berlin.
6  *
7  * Project Info: http://www.smallsql.de/
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ---------------
28  * MemoryStream.java
29  * ---------------
30  * Author: Volker Berlin
31  *
32  */
33 package smallsql.database;
34
35 import java.io.*;
36
37 /**
38  * @author Volker Berlin
39  *
40  */
41 class MemoryStream {
42     private byte[] puffer;
43     private int offset;
44     
45     MemoryStream(){
46         puffer = new byte[256];
47     }
48     
49     void writeTo(RandomAccessFile file) throws IOException{
50         file.write(puffer, 0, offset);
51     }
52     
53     void writeByte(int value){
54         verifyFreePufferSize(1);
55         puffer[ offset++ ] = (byte)(value);
56     }
57     
58     void writeShort(int value){
59         verifyFreePufferSize(2);
60         puffer[ offset++ ] = (byte)(value >> 8);
61         puffer[ offset++ ] = (byte)(value);
62     }
63     
64     void writeInt(int value){
65         verifyFreePufferSize(4);
66         puffer[ offset++ ] = (byte)(value >> 24);
67         puffer[ offset++ ] = (byte)(value >> 16);
68         puffer[ offset++ ] = (byte)(value >> 8);
69         puffer[ offset++ ] = (byte)(value);
70     }
71     
72     void writeLong(long value){
73         verifyFreePufferSize(8);
74         puffer[ offset++ ] = (byte)(value >> 56);
75         puffer[ offset++ ] = (byte)(value >> 48);
76         puffer[ offset++ ] = (byte)(value >> 40);
77         puffer[ offset++ ] = (byte)(value >> 32);
78         puffer[ offset++ ] = (byte)(value >> 24);
79         puffer[ offset++ ] = (byte)(value >> 16);
80         puffer[ offset++ ] = (byte)(value >> 8);
81         puffer[ offset++ ] = (byte)(value);
82     }
83     
84     void writeChars(char[] value){
85         verifyFreePufferSize(2*value.length);
86         for(int i=0; i<value.length; i++){
87             char c = value[i];
88             puffer[ offset++ ] = (byte)(c >> 8);
89             puffer[ offset++ ] = (byte)(c);
90         }
91     }
92     
93     void writeBytes(byte[] value, int off, int length){
94         verifyFreePufferSize(length);
95         System.arraycopy(value, off, puffer, offset, length);
96         offset += length;
97     }
98     
99     private void verifyFreePufferSize(int freeSize){
100         int minSize = offset+freeSize;
101         if(minSize < puffer.length){
102             int newSize = puffer.length << 1;
103             if(newSize < minSize) newSize = minSize;
104             byte[] temp = new byte[newSize];
105             System.arraycopy(puffer, 0, temp, 0, offset);
106             puffer = temp;
107         }
108     }
109     
110     
111     void skip(int count){
112         offset += count;
113     }
114     
115     
116     int readByte(){
117         return puffer[ offset++ ];
118     }
119     
120
121     int readShort(){
122         return ((puffer[ offset++ ] & 0xFF) << 8) | (puffer[ offset++ ] & 0xFF);
123     }
124     
125
126     int readInt(){
127         return ((puffer[ offset++ ] & 0xFF) << 24)
128              | ((puffer[ offset++ ] & 0xFF) << 16)
129              | ((puffer[ offset++ ] & 0xFF) << 8)
130              | (puffer[ offset++ ] & 0xFF);
131     }
132     
133
134     long readLong(){
135         return (((long)(puffer[ offset++ ] & 0xFF)) << 56)
136              | (((long)(puffer[ offset++ ] & 0xFF)) << 48)
137              | (((long)(puffer[ offset++ ] & 0xFF)) << 40)
138              | (((long)(puffer[ offset++ ] & 0xFF)) << 32)
139              | ((puffer[ offset++ ] & 0xFF) << 24)
140              | ((puffer[ offset++ ] & 0xFF) << 16)
141              | ((puffer[ offset++ ] & 0xFF) << 8)
142              | (puffer[ offset++ ] & 0xFF);
143     }
144     
145
146     char[] readChars(int length){
147         char[] chars = new char[length];
148         for(int i=0; i<length; i++){
149             chars[i] = (char)readShort();
150         }
151         return chars;
152     }
153     
154     byte[] readBytes(int length){
155         byte[] bytes = new byte[length];
156         System.arraycopy(puffer, offset, bytes, 0, length);
157         offset += length;
158         return bytes;
159     }
160 }
161
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