philippe lhardy
36e58808d5
use directly sharedrawweb java code here Signed-off-by: philippe lhardy <philippe.lhardy@astrolabe.coop>
147 lines
3.9 KiB
Java
147 lines
3.9 KiB
Java
/*
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This file is part of ShareDrawWeb.
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ShareDrawWeb is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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ShareDrawWeb is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with ShareDrawWeb; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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package org.artisanlogiciel.compression.graphics;
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/*
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simple class to read bitfields
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@see BitFieldWriter
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@author Philippe Lhardy
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*/
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import java.io.*;
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class BitFieldReader {
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// size of nextWord
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final int dataSize = 32;
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/* offset of next bit to be read in current word
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should ensure bitOffset < dataSize
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*/
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private int bitOffset = 0;
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/* word used waiting to be fully read
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dataSize is bit size of currentWord
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currentWord is part of word read that begins at bitOffset.
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*/
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private int currentWord = 0;
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private DataInputStream inputStream;
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/* value returned is an int between 0 and 2^bits-1 */
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public int read( int bits) throws java.io.IOException {
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int field = 0;
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int head = 0;
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// a new word is needed
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if ( bitOffset == 0 ) {
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nextWord();
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}
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// if more bits needed that word currently used.
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if ( bits + bitOffset > dataSize) {
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// warning recursive call ( not terminal )
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int bitsize = dataSize - bitOffset;
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head = read( dataSize - bitOffset);
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// current word had entirely been read, need a new one
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// don't do that... nextWord() will be done by next read...
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field = read( bits - bitsize);
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// reconstruct all
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// more significant bits in first word, least in last
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field = field | ( head << (bits - bitsize));
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}
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else {
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// terminal part do the job
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if ( bits == dataSize) {
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// special case to keep sign
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field = currentWord;
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currentWord = 0;
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bitOffset = 0;
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}
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else {
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field = ( currentWord >> ( dataSize - bits) )
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& ( 0x7fffffff >> ( dataSize - 1 - bits) );
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// bits are read then remove them from currentWord
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currentWord <<= bits;
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bitOffset = ( bitOffset + bits ) % dataSize;
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/*
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System.out.println( "size " + Integer.toString(bits)
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+ " value " + Integer.toString(field)
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+ " offset " + Integer.toString(bitOffset)
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+ " currentWord " + Integer.toString( currentWord)
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);
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*/
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}
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}
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return field;
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}
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private int getInt( byte[] pBytes)
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{
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long field = 0;
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field = pBytes[0]<<24 | pBytes[1]<<16 | pBytes[2]<<8 | pBytes[3];
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return (int) field;
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}
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/**
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* doesn't work correctly as readInt
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*/
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private int readInt()
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throws IOException
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{
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byte bytes[]=new byte[4];
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int nr=0;
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int index = 0;
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/* read at least 4 bytes */
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while ( ( nr != -1) && ( index < 4 ) )
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{
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nr = inputStream.read( bytes, index, 4 - index);
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index +=nr;
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}
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return getInt( bytes);
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}
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private void nextWord() throws java.io.IOException {
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// read next word
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// currentWord = readInt();
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currentWord= inputStream.readInt();
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bitOffset = 0;
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}
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/*
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go to next entire word.
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*/
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public void padToWord() throws java.io.IOException {
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if ( bitOffset != 0) {
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nextWord();
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}
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}
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/* set InputStream */
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public void setInputStream( InputStream input) {
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inputStream = new DataInputStream(input);
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}
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}
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