tikhomirov@51: /*
tikhomirov@157:  * Copyright (c) 2011 TMate Software Ltd
tikhomirov@157:  *  
tikhomirov@157:  * This program is free software; you can redistribute it and/or modify
tikhomirov@157:  * it under the terms of the GNU General Public License as published by
tikhomirov@157:  * the Free Software Foundation; version 2 of the License.
tikhomirov@157:  *
tikhomirov@157:  * This program is distributed in the hope that it will be useful,
tikhomirov@157:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
tikhomirov@157:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
tikhomirov@157:  * GNU General Public License for more details.
tikhomirov@157:  *
tikhomirov@157:  * For information on how to redistribute this software under
tikhomirov@157:  * the terms of a license other than GNU General Public License
tikhomirov@157:  * contact TMate Software at support@hg4j.com
tikhomirov@51:  */
tikhomirov@157: package org.tmatesoft.hg.internal;
tikhomirov@51: 
tikhomirov@51: import java.io.IOException;
tikhomirov@51: 
tikhomirov@157: 
tikhomirov@51: /**
tikhomirov@157:  *   
tikhomirov@157:  * @author Artem Tikhomirov
tikhomirov@157:  * @author TMate Software Ltd.
tikhomirov@51:  */
tikhomirov@51: public class ByteArrayDataAccess extends DataAccess {
tikhomirov@51: 
tikhomirov@51: 	private final byte[] data;
tikhomirov@51: 	private final int offset;
tikhomirov@51: 	private final int length;
tikhomirov@51: 	private int pos;
tikhomirov@51: 
tikhomirov@51: 	public ByteArrayDataAccess(byte[] data) {
tikhomirov@51: 		this(data, 0, data.length);
tikhomirov@51: 	}
tikhomirov@51: 
tikhomirov@51: 	public ByteArrayDataAccess(byte[] data, int offset, int length) {
tikhomirov@51: 		this.data = data;
tikhomirov@51: 		this.offset = offset;
tikhomirov@51: 		this.length = length;
tikhomirov@51: 		pos = 0;
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	@Override
tikhomirov@51: 	public byte readByte() throws IOException {
tikhomirov@51: 		if (pos >= length) {
tikhomirov@51: 			throw new IOException();
tikhomirov@51: 		}
tikhomirov@51: 		return data[offset + pos++];
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public void readBytes(byte[] buf, int off, int len) throws IOException {
tikhomirov@51: 		if (len > (this.length - pos)) {
tikhomirov@663: 			throw new IOException(String.format("Requested %d bytes at position %d of %d total", len, pos, length));
tikhomirov@51: 		}
tikhomirov@599: 		System.arraycopy(data, offset+pos, buf, off, len);
tikhomirov@51: 		pos += len;
tikhomirov@51: 	}
tikhomirov@599: 	@Override
tikhomirov@599: 	public int readInt() throws IOException {
tikhomirov@599: 		// overridden not to create an intermediate array
tikhomirov@599: 		if (length - pos < 4) {
tikhomirov@599: 			throw new IOException();
tikhomirov@599: 		}
tikhomirov@599: 		int x = offset + pos;
tikhomirov@599: 		int rv = data[x++] << 24 | (data[x++] & 0xFF) << 16 | (data[x++] & 0xFF) << 8 | (data[x] & 0xFF);
tikhomirov@599: 		pos += 4;
tikhomirov@599: 		return rv;
tikhomirov@599: 	}
tikhomirov@599: 	@Override
tikhomirov@599: 	public long readLong() throws IOException {
tikhomirov@599: 		// overridden not to create an intermediate array
tikhomirov@599: 		if (length - pos < 8) {
tikhomirov@599: 			throw new IOException();
tikhomirov@599: 		}
tikhomirov@599: 		int x = offset + pos;
tikhomirov@599: 		int i1 = data[x++] << 24 | (data[x++] & 0xFF) << 16 | (data[x++] & 0xFF) << 8 | (data[x++] & 0xFF);
tikhomirov@599: 		int i2 = data[x++] << 24 | (data[x++] & 0xFF) << 16 | (data[x++] & 0xFF) << 8 | (data[x] & 0xFF);
tikhomirov@599: 		pos += 8;
tikhomirov@599: 		return ((long) i1) << 32 | ((long) i2 & 0x0FFFFFFFFl);
tikhomirov@599: 	}
tikhomirov@51: 
tikhomirov@51: 	@Override
tikhomirov@157: 	public ByteArrayDataAccess reset() {
tikhomirov@51: 		pos = 0;
tikhomirov@157: 		return this;
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@158: 	public int length() {
tikhomirov@51: 		return length;
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@158: 	public void seek(int offset) {
tikhomirov@420: 		pos = offset;
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public void skip(int bytes) throws IOException {
tikhomirov@51: 		seek(pos + bytes);
tikhomirov@51: 	}
tikhomirov@51: 	@Override
tikhomirov@51: 	public boolean isEmpty() {
tikhomirov@51: 		return pos >= length;
tikhomirov@51: 	}
tikhomirov@51: 	
tikhomirov@51: 	//
tikhomirov@51: 	
tikhomirov@51: 	// when byte[] needed from DA, we may save few cycles and some memory giving this (otherwise unsafe) access to underlying data
tikhomirov@51: 	@Override
tikhomirov@51: 	public byte[] byteArray() {
tikhomirov@51: 		return data;
tikhomirov@51: 	}
tikhomirov@51: }