Initial commit

src/main/java/org/rebotted/cache/FileArchive.java

@@ -0,0 +1,101 @@
+package org.rebotted.cache;
+
+import org.rebotted.cache.bzip.BZip2Decompressor;
+import org.rebotted.io.Buffer;
+
+public final class FileArchive {
+	
+	/**
+	 * The buffer containing the decompressed data in this Archive.
+	 */
+	private final byte[] buffer;
+	
+	/**
+	 * The amount of entries in this Archive.
+	 */
+	private final int entries;
+	
+	/**
+	 * The identifiers (i.e. hashed names) of each of the entries in this Archive.
+	 */
+	private final int[] identifiers;
+	
+	/**
+	 * The raw (i.e. decompressed) sizes of each of the entries in this Archive.
+	 */
+	private final int[] extractedSizes;
+	
+	/**
+	 * The compressed sizes of each of the entries in this Archive.
+	 */
+	private final int[] sizes;
+	private final int[] indices;
+	
+	/**
+	 * Whether or not this Archive was compressed as a whole: if false, decompression will be performed on each of the
+	 * individual entries.
+	 */
+	private final boolean extracted;
+
+	public FileArchive(byte data[]) {
+		Buffer buffer = new Buffer(data);
+		
+		int decompressedLength = buffer.readTriByte();		
+		int compressedLength = buffer.readTriByte();		
+		
+		if (compressedLength != decompressedLength) {
+			
+			byte output[] = new byte[decompressedLength];
+			
+			BZip2Decompressor.decompress(output, decompressedLength, data, compressedLength, 6);
+			
+			this.buffer = output;
+			
+			buffer = new Buffer(this.buffer);
+			extracted = true;
+		} else {
+			this.buffer = data;
+			extracted = false;
+		}
+		entries = buffer.readUShort();
+		identifiers = new int[entries];
+		extractedSizes = new int[entries];
+		sizes = new int[entries];
+		indices = new int[entries];
+		int offset = buffer.currentPosition + entries * 10;
+		for (int file = 0; file < entries; file++) {
+			identifiers[file] = buffer.readInt();
+			extractedSizes[file] = buffer.readTriByte();
+			sizes[file] = buffer.readTriByte();
+			indices[file] = offset;
+			offset += sizes[file];
+		}
+	}
+
+	public byte[] readFile(String name) {		
+		byte output[] = null;
+		int hash = 0;
+		name = name.toUpperCase();
+		for (int index = 0; index < name.length(); index++) {
+			hash = (hash * 61 + name.charAt(index)) - 32;
+		}
+
+		for (int file = 0; file < entries; file++) {
+			if (identifiers[file] == hash) {
+				if (output == null) {
+					output = new byte[extractedSizes[file]];
+				}
+				if (!extracted) {
+					BZip2Decompressor.decompress(output, extractedSizes[file], this.buffer,
+							sizes[file], indices[file]);
+				} else {
+					System.arraycopy(this.buffer, indices[file], output,
+							0, extractedSizes[file]);
+				}
+				return output;
+			}
+		}
+		return null;
+	}
+
+}