01: /*
02: Copyright (c) 2006, Matthew Estes
03: All rights reserved.
04:
05: Redistribution and use in source and binary forms, with or without
06: modification, are permitted provided that the following conditions are met:
07:
08: * Redistributions of source code must retain the above copyright
09: notice, this list of conditions and the following disclaimer.
10: * Redistributions in binary form must reproduce the above copyright
11: notice, this list of conditions and the following disclaimer in the
12: documentation and/or other materials provided with the distribution.
13: * Neither the name of Metanotion Software nor the names of its
14: contributors may be used to endorse or promote products derived from this
15: software without specific prior written permission.
16:
17: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
18: IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
19: THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20: PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
21: CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
22: EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
23: PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
24: PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25: LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26: NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27: SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28: */
29: package net.metanotion.io.block;
30:
31: import java.io.IOException;
32:
33: import net.metanotion.io.RandomAccessInterface;
34:
35: public class FreeListBlock {
36: public int page;
37: public int nextPage;
38: public int len;
39: public int[] branches = null;
40: public RandomAccessInterface file;
41:
42: public FreeListBlock(RandomAccessInterface file, int startPage)
43: throws IOException {
44: this .file = file;
45: this .page = startPage;
46: BlockFile.pageSeek(file, startPage);
47: nextPage = file.readInt();
48: len = file.readInt();
49: if (len > 0) {
50: branches = new int[len];
51: for (int i = 0; i < len; i++) {
52: branches[i] = file.readInt();
53: }
54: }
55: }
56:
57: public void writeBlock() throws IOException {
58: BlockFile.pageSeek(file, page);
59: file.writeInt(nextPage);
60: if (len > 0) {
61: file.writeInt(len);
62: for (int i = 0; i < len; i++) {
63: file.writeInt(branches[i]);
64: }
65: } else {
66: file.writeInt(0);
67: }
68: }
69:
70: public boolean isFull() {
71: int cells = (int) ((BlockFile.PAGESIZE - 8) / 4);
72: if (cells - len > 0) {
73: return false;
74: }
75: return true;
76: }
77:
78: public void addPage(int page) {
79: int[] t = new int[len + 1];
80: if (len > 0) {
81: for (int i = 0; i < len; i++) {
82: t[i] = branches[i];
83: }
84: }
85: t[len] = page;
86: len++;
87: branches = t;
88: }
89:
90: public static void initPage(RandomAccessInterface file, int page)
91: throws IOException {
92: BlockFile.pageSeek(file, page);
93: file.writeInt(0);
94: file.writeInt(0);
95: }
96: }
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