org.gjt.convert.binhex
Class RLE_CRCInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--java.io.FilterInputStream
              |
              +--org.gjt.convert.binhex.RLE_CRCInputStream

public class RLE_CRCInputStream

extends java.io.FilterInputStream

Decodes Run-length encoding LE from a 8-bit BinHex stream and calculates CRCs (Cyclic Redundancy Check) from the decoded bytes as it passes them to the caller.

Author:

Erwin Bolwidt

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

RLE_CRCInputStream(java.io.InputStream source)
Constructs a RLE_CRCInputStream from a stream that is a source of 7-bit Hqx7 encoded data.

RLE_CRCInputStream(java.io.InputStream source, boolean eightBit)
Constructs a RLE_CRCInputStream from a stream that is either a source of 7-bit Hqx7 encoded data or of pure 8-bit data in Hqx8 format.

Method Summary

int	getCRC() Returns the CRC calculated over the data that was read since the beginning of the stream or since the last call to resetCRC.
static void	main(java.lang.String[] args)
int	read()
int	read(byte[] b)
int	read(byte[] b, int off, int len)
void	resetCRC() Resets the calculated CRC to zero.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, reset, skip

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RLE_CRCInputStream

public RLE_CRCInputStream(java.io.InputStream source)

Constructs a RLE_CRCInputStream from a stream that is a source of 7-bit Hqx7 encoded data. This is the typical use for files fetched from the Internet or through e-mail. Internally, a Hqx7_to_Hqx8InputStream is created to translate from 7-bit to 8-bit format before passing the data through this stream.

RLE_CRCInputStream

public RLE_CRCInputStream(java.io.InputStream source,
                          boolean eightBit)

Constructs a RLE_CRCInputStream from a stream that is either a source of 7-bit Hqx7 encoded data or of pure 8-bit data in Hqx8 format. The flag eightBit tells this class what to expect.

Parameters:

source - the data source

eightBit - if true, the data source must supply 8-bit data in Hqx8 format. If false, the data source must supply 7-bit data in Hqx7 format.

Method Detail

resetCRC

public void resetCRC()

Resets the calculated CRC to zero. If your file contains multiple sections, as the BinHex4 format does, you must reset it before switching to a new section if you want to calculate CRCs for that section.

getCRC

public int getCRC()

Returns the CRC calculated over the data that was read since the beginning of the stream or since the last call to resetCRC. Must only be called after all the data was read in a section, because the CRC is updated as if two extra 0 bytes were read. This is dictated by the BinHex4 protocol.

read

public int read()
         throws java.io.IOException

Overrides:

read in class java.io.FilterInputStream

read

public int read(byte[] b)
         throws java.io.IOException

Overrides:

read in class java.io.FilterInputStream

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Overrides:

read in class java.io.FilterInputStream

main

public static void main(java.lang.String[] args)