File	Doc	Category	Size	Date	Package
LZW.java	API Doc	Apache Poi 3.0.1	9071	Mon Jun 18 19:04:08 BST 2007	org.apache.poi.hdgf.other_lzw

LZW

• java.lang.Object

Fields Summary
boolean	stopped
Dict	dict
int	numOfBits
final ByteArray	emptyBA
ByteArray	w

Constructors Summary
public LZW() // Constructor gets the number of bits to be written for each code numOfBits = 12 ; // Create a new Limited Dictionary // For maximum of 2^bits entries dict = new LimitedDict(1<<numOfBits) ; // Add all ascii characters to the dictionary for (int i=0;i<256;++i) dict.add(new ByteArray((byte)i)) ;

Methods Summary
org.apache.poi.hdgf.other_lzw.LZW$ByteArray	decodeOne(int code) // Either "ABA" or null, w="AB" ByteArray str = dict.strFromNum(code) ; if (str==null) { str = w.conc(w.getAt(0)) ; dict.add(str) ; } else if (! w.isEmpty()) dict.add(w.conc(str.getAt(0))) ; w = str ; return w ;
public void	decompress(java.io.InputStream is, java.io.OutputStream os) is = new BitInputStream(is) ; ByteArray str ; // Next entry int code ; // Next code to be read while ((code=readCode(is))>=0) { if (stopped) break ; str = decodeOne(code) ; os.write(str.getBytes()) ; }
int	encodeLast() ByteArray nw = w ; w = emptyBA ; return dict.numFromStr(nw) ;
int	encodeOneChar(int n) byte c = (byte) n ; ByteArray nw = w.conc(c) ; int code = dict.numFromStr(nw) ; // if it exists then we continue to search for a longer string if (code!=-1) { w = nw ; return -1 ; } else { dict.add(nw) ; nw = w ; w = new ByteArray(c) ; return dict.numFromStr(nw) ; }
int	readCode(java.io.InputStream is) int num = 0 ; for (int i=0;i<numOfBits;++i) { int next = is.read() ; if (next<0) return -1 ; num += next<<i ; } return num ;
public void	stop() stopped = true ;
void	writeCode(java.io.OutputStream os, int code) for (int i=0;i<numOfBits;++i) { os.write(code&1) ; code /= 2 ; }