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CompressionInputStream.javaAPI DocExample4935Wed Apr 19 11:20:14 BST 2000examples.rmisocfac

CompressionInputStream

public class CompressionInputStream extends FilterInputStream implements CompressionConstants

Fields Summary
int[]
buf
int
bufPos
Constructors Summary
public CompressionInputStream(InputStream in)

        super(in);
Methods Summary
public intread()

 
    /*
     * Reads in format code and decompresses character accordingly.
     */

         
        try {
            int code;

            // Read in and ignore empty bytes (NOP's) as long as they
            // arrive. 
            do {
	      code = readCode();
	    } while (code == NOP);      
 
            if (code >= BASE) {
                // Retrieve index of character in codeTable if the
                // code is in the correct range.
                return codeTable.charAt(code - BASE);
            } else if (code == RAW) {
                // read in the lower 4 bits and the higher 4 bits,
                // and return the reconstructed character
                int high = readCode();
                int low = readCode();
                return (high << 4) | low;
            } else 
                throw new IOException("unknown compression code: " + code);
        } catch (EOFException e) {
            // Return the end of file code
            return -1;
        }
public intread(byte[] b, int off, int len)


	if (len <= 0) {
	    return 0;
	}

	int c = read();
	if (c == -1) {
	    return -1;
	}
	b[off] = (byte)c;

	int i = 1;
        // Try to read up to len bytes or until no
        // more bytes can be read without blocking.
       	try {
		for (; (i < len) && (in.available() > 0); i++) {
		c = read();
		if (c == -1) {
		    break;
		}
		if (b != null) {
		    b[off + i] = (byte)c;
		}
	    }
	} catch (IOException ee) {
	}
	return i;
private intreadCode()

        // As soon as all the data in buf has been read
        // (when bufPos == 5) read in another four bytes.
        if (bufPos == 5) {
            int b1 = in.read();
            int b2 = in.read();
            int b3 = in.read();
            int b4 = in.read();

            // make sure none of the bytes signify the
            // end of the data in the stream
            if ((b1 | b2 | b3 | b4) < 0) {
                throw new EOFException();
            }
            // Assign each group of 6 bits to an element of
            // buf
            int pack = (b1 << 24) | (b2 << 16) | (b3 << 8) | b4;
            buf[0] = (pack >>> 24) & 0x3F;
            buf[1] = (pack >>> 18) & 0x3F;
            buf[2] = (pack >>> 12) & 0x3F;
            buf[3] = (pack >>>  6) & 0x3F;
            buf[4] = (pack >>>  0) & 0x3F;
            bufPos = 0;
        }
        return buf[bufPos++];