jpexs-decompiler/libsrc/ffdec_lib/src/com/jpexs/helpers/MemoryInputStream.java

/*
 *  Copyright (C) 2010-2021 JPEXS, All rights reserved.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3.0 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.
 */
package com.jpexs.helpers;

import com.jpexs.helpers.streams.SeekableInputStream;
import java.io.IOException;

/**
 *
 * @author JPEXS
 */
public class MemoryInputStream extends SeekableInputStream {

    private final byte[] buffer;

    private long pos;

    private int startPos;

    private int maxLength;

    public MemoryInputStream(byte[] buffer) throws IOException {
        this(buffer, 0, buffer.length);
    }

    public MemoryInputStream(byte[] buffer, int startPos) throws IOException {
        this(buffer, startPos, buffer.length - startPos);
    }

    public MemoryInputStream(byte[] buffer, int startPos, int maxLength) throws IOException {
        this.buffer = buffer;
        this.startPos = startPos;
        if (startPos > buffer.length) {
            throw new IOException("Invalid startPos");
        }
        this.maxLength = maxLength;
        if (startPos + maxLength >= buffer.length) {
            this.maxLength = buffer.length - startPos;
        }
    }

    public byte[] getAllRead() {
        return buffer;
    }

    public long getPos() {
        return pos;
    }

    @Override
    public void seek(long pos) throws IOException {
        if (pos < 0) {
            throw new IOException("Seek to negative position");
        }
        this.pos = pos;
    }

    @Override
    public synchronized void reset() throws IOException {
        seek(0);
    }

    @Override
    public int read() throws IOException {
        if (pos < maxLength) {
            int ret = buffer[(int) pos + startPos] & 0xff;
            pos++;
            return ret;
        }

        return -1;
    }

    @Override
    public int read(byte[] bytes) throws IOException {
        if (pos < maxLength) {
            int toRead = Math.min(available(), bytes.length);
            System.arraycopy(buffer, (int) pos + startPos, bytes, 0, toRead);
            pos += toRead;
            return toRead;
        }

        return -1;
    }

    @Override
    public int available() throws IOException {
        return maxLength - (int) pos;
    }
}