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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/gnu/javax/imageio/jpeg/HuffmanTable.java')
| -rw-r--r-- | gcc-4.4.3/libjava/classpath/gnu/javax/imageio/jpeg/HuffmanTable.java | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/gnu/javax/imageio/jpeg/HuffmanTable.java b/gcc-4.4.3/libjava/classpath/gnu/javax/imageio/jpeg/HuffmanTable.java new file mode 100644 index 000000000..78f3c1c4f --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/gnu/javax/imageio/jpeg/HuffmanTable.java @@ -0,0 +1,207 @@ +/* HuffmanTable.java -- + Copyright (C) 2006 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath 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 +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package gnu.javax.imageio.jpeg; + +import java.io.IOException; + +import javax.imageio.plugins.jpeg.JPEGHuffmanTable; + + +/** + * This Object construct a JPEGHuffmanTable which can be used to encode/decode + * a scan from a JPEG codec stream. The table must be initalized with either a + * BITS byte amount and a Huffman Table Value for decoding or a Huffman Size + * and Huffman Code table for encoding. + */ +public class HuffmanTable +{ + public final static int HUFFMAN_MAX_TABLES = 4; + + private short[] huffcode = new short[256]; + private short[] huffsize = new short[256]; + private short[] EHUFCO; + private short[] EHUFSI; + private short[] valptr = new short[16]; + private short[] mincode = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1,-1,-1}; + private short[] maxcode = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1}; + private short[] huffval; + private short[] bits; + + static byte JPEG_DC_TABLE = 0; + static byte JPEG_AC_TABLE = 1; + + private short lastk = 0; + + public HuffmanTable(JPEGHuffmanTable table) + { + huffcode = table.getValues(); + bits = table.getLengths(); + } + + /** + * Generated from FIGURE C.1 - Generation of table of Huffman code sizes on + * ISO DIS 10918-1. Requirements and Guidelines + */ + private void generateSizeTable() + { + short index=0; + for(short i=0; i < bits.length ; i++) + { + for(short j=0; j < bits[i] ; j++) + { + huffsize[index] = (short) (i+1); + index++; + } + } + lastk = index; + } + + /** + * Generated from FIGURE C.2 - Generation of table of Huffman codes on + * ISO DIS 10918-1. Requirements and Guidelines + */ + private void generateCodeTable() + { + short k=0; + short si = huffsize[0]; + short code = 0; + for(short i=0; i < huffsize.length ; i++) + { + while(huffsize[k]==si) + { + huffcode[k] = code; + code++; + k++; + } + code <<= 1; + si++; + } + } + + /** + * Generated from FIGURE F.15 - Generation of decode table generation on + * ISO DIS 10918-1. Requirements and Guidelines + */ + private void generateDecoderTables() + { + short bitcount = 0; + for(int i=0; i < 16 ; i++) + { + if(bits[i]!=0) + valptr[i] = bitcount; + for(int j=0 ; j < bits[i] ; j++) + { + if(huffcode[j+bitcount] < mincode[i] || mincode[i] == -1) + mincode[i] = huffcode[j+bitcount]; + + if(huffcode[j+bitcount] > maxcode[i]) + maxcode[i] = huffcode[j+bitcount]; + } + if(mincode[i]!=-1) + valptr[i] = (short) (valptr[i] - mincode[i]); + bitcount += bits[i]; + } + } + + /** + * Generated from FIGURE C.3 - Generation of Order Codes and tables EHUFCO + * and EHUFSI from the ISO DIS 10918-1. Requirements and Guidelines + */ + public void orderCodes(boolean isDC) + { + EHUFCO = new short[isDC ? 15 : 255]; + EHUFSI = new short[isDC ? 15 : 255]; + + for (int p=0; p < lastk ; p++) + { + int i = huffval[p]; + if(i < 0 || i > EHUFCO.length || EHUFSI[i]!=0) + System.err.println("Error, bad huffman table."); + EHUFCO[i] = huffcode[p]; + EHUFSI[i] = huffsize[p]; + } + } + + /** + * Generated from FIGURE F.12 - Extending the sign bit of a decoded value in on + * ISO DIS 10918-1. Requirements and Guidelines<p> + * + * @param diff TODO + * @param t TODO + * @return TODO + */ + public static int extend(int diff, int t) + { + int Vt = (int)Math.pow(2,(t-1)); + if(diff<Vt) + { + Vt=(-1 << t)+1; + diff=diff+Vt; + } + return diff; + } + + /** + * Generated from FIGURE F.16 - Procedure for DECODE on + * ISO DIS 10918-1. Requirements and Guidelines<p> + * + * This function takes in a dynamic amount of bits and using the Huffman + * table returns information on how many bits must be read in to a byte in + * order to reconstruct said byte. + * + * @param JPEGStream the bits of the data stream. + */ + public int decode(JPEGImageInputStream JPEGStream) + throws IOException, JPEGException + { + int i=0; + short code = (short) JPEGStream.readBits(1); + while(code > maxcode[i]) + { + i++; + code <<= 1; + code |= JPEGStream.readBits(1); + } + int val = huffval[code+(valptr[i])]; + if(val < 0) + val = 256 + val; + return val; + } +} |