Source Code Cross Referenced for GZIPInputStream.java in  » 6.0-JDK-Modules » j2me » com » sun » pisces » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » 6.0 JDK Modules » j2me » com.sun.pisces 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * 
003:         * Copyright  1990-2007 Sun Microsystems, Inc. All Rights Reserved. 
004:         * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER 
005:         *  
006:         * This program is free software; you can redistribute it and/or 
007:         * modify it under the terms of the GNU General Public License version 
008:         * 2 only, as published by the Free Software Foundation. 
009:         *  
010:         * This program is distributed in the hope that it will be useful, but 
011:         * WITHOUT ANY WARRANTY; without even the implied warranty of 
012:         * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 
013:         * General Public License version 2 for more details (a copy is 
014:         * included at /legal/license.txt). 
015:         *  
016:         * You should have received a copy of the GNU General Public License 
017:         * version 2 along with this work; if not, write to the Free Software 
018:         * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 
019:         * 02110-1301 USA 
020:         *  
021:         * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa 
022:         * Clara, CA 95054 or visit www.sun.com if you need additional 
023:         * information or have any questions.
024:         */
025:
026:        package com.sun.pisces;
027:
028:        import java.io.InputStream;
029:        import java.io.IOException;
030:        import java.util.Hashtable;
031:
032:        class HuffmanTable {
033:
034:            GZIPInputStream in;
035:            Hashtable codeTable;
036:            int minLen;
037:
038:            public HuffmanTable(GZIPInputStream in, int[] lengths) {
039:                this .in = in;
040:                this .codeTable = buildHuffman(lengths);
041:                this .minLen = Integer.MAX_VALUE;
042:                for (int i = 0; i < lengths.length; i++) {
043:                    if (lengths[i] < minLen) {
044:                        minLen = lengths[i];
045:                    }
046:                }
047:            }
048:
049:            private static Integer getKey(int code, int len) {
050:                return new Integer((code << 8) | len);
051:            }
052:
053:            private static Hashtable buildHuffman(int[] tlen) {
054:                int len = tlen.length;
055:
056:                int[] bl_count = new int[33];
057:                int[] next_code = new int[33];
058:
059:                int maxlen = -1;
060:                for (int i = 0; i < len; i++) {
061:                    if (tlen[i] > maxlen) {
062:                        maxlen = tlen[i];
063:                    }
064:                    ++bl_count[tlen[i]];
065:                }
066:
067:                int code = 0;
068:                bl_count[0] = 0;
069:                for (int bits = 1; bits <= maxlen; bits++) {
070:                    code = (code + bl_count[bits - 1]) << 1;
071:                    next_code[bits] = code;
072:                }
073:
074:                Hashtable codeTable = new Hashtable(len);
075:                for (int n = 0; n < len; n++) {
076:                    int l = tlen[n];
077:                    if (l != 0) {
078:                        codeTable.put(getKey(next_code[l], l), new Integer(n));
079:                        ++next_code[l];
080:                    }
081:                }
082:
083:                return codeTable;
084:            }
085:
086:            private int getVal(int code, int len) {
087:                Object o = codeTable.get(getKey(code, len));
088:                if (o != null) {
089:                    return ((Integer) o).intValue();
090:                }
091:                return -1;
092:            }
093:
094:            public int readSymbol() throws IOException {
095:                int code = in.readHuffmanBits(minLen);
096:                int len = minLen;
097:
098:                while (true) {
099:                    int val = getVal(code, len);
100:                    if (val != -1) {
101:                        return val;
102:                    }
103:                    code = (code << 1) | in.readBit();
104:                    ++len;
105:                }
106:            }
107:        }
108:
109:        /**
110:         * A simple implementation of the gzip/deflate compression scheme.
111:         * The entire source stream is read and decoded at once; although this
112:         * requires allocating storage for the entire output, it avoids the
113:         * need for a pair of 32K buffers that would normally be used for
114:         * decompression purposes.  For the common use case of loading font
115:         * files, which will be decompressed and parsed into a
116:         * <code>PiscesFont</code> object immediately, there is no real
117:         * drawback to this eager approach.
118:         *
119:         * <p> For simplicitly, <code>mark</code> and <code>reset</code> are
120:         * not supported.
121:         *
122:         */
123:        class GZIPInputStream extends InputStream {
124:
125:            private static final int[] perm = { 16, 17, 18, 0, 8, 7, 9, 6, 10,
126:                    5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
127:
128:            private static final int[] lengthsTable;
129:            /* {
130:                 3, 4, 5, 6, 7, 8, 9, 10,
131:                 11, 13, 15, 17,
132:                 19, 23, 27, 31,
133:                 35, 43, 51, 59,
134:                 67, 83, 99, 115,
135:                 131, 163, 195, 227,
136:                 258
137:              } */
138:
139:            private static final int[] lengthExtraBitsTable;
140:            /* {
141:                 0, 0, 0, 0, 0, 0, 0, 0,
142:                 1, 1, 1, 1,
143:                 2, 2, 2, 2,
144:                 3, 3, 3, 3,
145:                 4, 4, 4, 4, 
146:                 5, 5, 5, 5,
147:                 0
148:               } */
149:
150:            private static final int[] distancesTable;
151:            /* {
152:                 1, 2, 3, 4,
153:                 5, 7,
154:                 9, 13,
155:                 17, 25,
156:                 33, 49,
157:                 65, 97,
158:                 129, 193,
159:                 257, 385,
160:                 513, 769,
161:                 1025, 1537,
162:                 2049, 3073,
163:                 4097, 6145,
164:                 8193, 12289,
165:                 16385, 24577,
166:               } */
167:
168:            private static final int[] distanceExtraBitsTable;
169:            /* {
170:                 0, 0, 0, 0,
171:                 1, 1,
172:                 2, 2, 
173:                 3, 3,
174:                 4, 4,
175:                 5, 5,
176:                 6, 6,
177:                 7, 7,
178:                 8, 8,
179:                 9, 9,
180:                 10, 10,
181:                 11, 11,
182:                 12, 12,
183:                 13, 13
184:               } */
185:
186:            InputStream in;
187:
188:            byte[] data = new byte[100];
189:            int count = 0;
190:            int idx = 0;
191:
192:            int curByte;
193:            int curPos = 8;
194:
195:            // It takes less space to initialize the literal/length and 
196:            // distance tables programatically than using explicit initialzers
197:            // due to the verbose way initializers are translated into bytecode.
198:            static {
199:                lengthExtraBitsTable = new int[29];
200:                lengthsTable = new int[29];
201:                distanceExtraBitsTable = new int[30];
202:                distancesTable = new int[30];
203:
204:                int idx = 0;
205:                for (int i = 4; i < 29; i++) {
206:                    lengthExtraBitsTable[i] = idx;
207:                    if ((i % 4) == 3) {
208:                        ++idx;
209:                    }
210:                }
211:
212:                int len = 3;
213:                for (int i = 0; i < lengthExtraBitsTable.length; i++) {
214:                    lengthsTable[i] = len;
215:                    len += 1 << lengthExtraBitsTable[i];
216:                }
217:                lengthsTable[28] = 258; // that's what the spec says...
218:
219:                idx = 0;
220:                for (int i = 2; i < 30; i++) {
221:                    distanceExtraBitsTable[i] = idx;
222:                    if ((i % 2) == 1) {
223:                        ++idx;
224:                    }
225:                }
226:
227:                int code = 1;
228:                for (int i = 0; i < distancesTable.length; i++) {
229:                    distancesTable[i] = code;
230:                    code += 1 << distanceExtraBitsTable[i];
231:                }
232:            }
233:
234:            public GZIPInputStream(InputStream in) throws IOException {
235:                this .in = in;
236:
237:                // Read GZIP header
238:                readGZIPHeader();
239:
240:                // Read blocks until final block is reached
241:                while (!readBlock()) {
242:                }
243:            }
244:
245:            private void readGZIPHeader() throws IOException {
246:                int id1 = in.read(); // 31
247:                int id2 = in.read(); // 139
248:                int cm = in.read();
249:
250:                int flg = in.read();
251:                int ftext = flg & 0x1;
252:                int fhcrc = (flg >> 1) & 0x1;
253:                int fextra = (flg >> 2) & 0x1;
254:                int fname = (flg >> 3) & 0x1;
255:                int fcomment = (flg >> 4) & 0x1;
256:
257:                int mtime0 = in.read();
258:                int mtime1 = in.read();
259:                int mtime2 = in.read();
260:                int mtime3 = in.read();
261:                long mtime = ((long) mtime3 << 24) | ((long) mtime2 << 16)
262:                        | ((long) mtime1 << 8) | ((long) mtime0);
263:
264:                int xfl = in.read();
265:                int os = in.read();
266:
267:                // Skip optional header fields
268:                if (fextra == 0x1) {
269:                    int xlen = (in.read() << 8) | in.read();
270:                    for (int i = 0; i < xlen; i++) {
271:                        in.read();
272:                    }
273:                }
274:
275:                if (fname == 0x1) {
276:                    while (in.read() != 0) {
277:                    }
278:                }
279:                if (fcomment == 0x1) {
280:                    while (in.read() != 0) {
281:                    }
282:                }
283:                if (fhcrc == 0x1) {
284:                    int crc = (in.read() << 8) | in.read();
285:                }
286:            }
287:
288:            int readBit() throws IOException {
289:                if (curPos == 8) {
290:                    curByte = in.read();
291:                    curPos = 0;
292:                }
293:
294:                int bit = (curByte >> curPos++) & 0x1;
295:                return bit;
296:            }
297:
298:            int readBits(int numBits) throws IOException {
299:                int val = 0;
300:                for (int i = 0; i < numBits; i++) {
301:                    val |= readBit() << i;
302:                }
303:                return val;
304:            }
305:
306:            int readHuffmanBits(int numBits) throws IOException {
307:                int val = 0;
308:                for (int i = 0; i < numBits; i++) {
309:                    val <<= 1;
310:                    val |= readBit();
311:                }
312:                return val;
313:            }
314:
315:            private void emit(int b) {
316:                if (count >= data.length) {
317:                    byte[] tmp = new byte[data.length + 512];
318:                    System.arraycopy(data, 0, tmp, 0, data.length);
319:                    data = tmp;
320:                }
321:                data[count++] = (byte) b;
322:            }
323:
324:            private boolean readBlock() throws IOException {
325:                int bfinal = readBits(1);
326:                int btype = readBits(2);
327:
328:                if (btype == 0) {
329:                    // Uncompressed data
330:                    readBits(5); // skip extra bits
331:                    int len = (in.read() << 8) | in.read();
332:                    in.read();
333:                    in.read();
334:                    for (int i = 0; i < len; i++) {
335:                        emit(in.read());
336:                    }
337:                } else if (btype == 1 || btype == 2) {
338:                    HuffmanTable lltable = null;
339:                    HuffmanTable dtable = null;
340:
341:                    if (btype == 2) {
342:                        // Dynamic Huffman codes
343:
344:                        int hlit = readBits(5) + 257;
345:                        int hdist = readBits(5) + 1;
346:                        int hclen = readBits(4) + 4;
347:
348:                        int[] hlengths = new int[19];
349:                        for (int i = 0; i < hclen; i++) {
350:                            int len = readBits(3);
351:                            hlengths[perm[i]] = len;
352:                        }
353:                        HuffmanTable htable = new HuffmanTable(this , hlengths);
354:
355:                        int[] lengths = new int[hlit + hdist];
356:                        int idx = 0;
357:
358:                        do {
359:                            int sym = htable.readSymbol();
360:                            if (sym <= 15) {
361:                                lengths[idx++] = sym;
362:                            } else if (sym == 16) {
363:                                int repeat = readBits(2) + 3;
364:                                int prev = lengths[idx - 1];
365:                                for (int i = 0; i < repeat; i++) {
366:                                    lengths[idx++] = prev;
367:                                }
368:                            } else {
369:                                int bits = (sym == 17) ? 3 : 7;
370:                                int repeat = readBits(bits);
371:                                repeat += (sym == 17) ? 3 : 11;
372:                                for (int i = 0; i < repeat; i++) {
373:                                    lengths[idx++] = 0;
374:                                }
375:                            }
376:                        } while (idx < hlit + hdist);
377:
378:                        int[] hlitlengths = new int[hlit];
379:                        System.arraycopy(lengths, 0, hlitlengths, 0, hlit);
380:                        lltable = new HuffmanTable(this , hlitlengths);
381:
382:                        int[] hdistlengths = new int[hdist];
383:                        System.arraycopy(lengths, hlit, hdistlengths, 0, hdist);
384:                        dtable = new HuffmanTable(this , hdistlengths);
385:                    }
386:
387:                    // Decompress actual data
388:                    while (true) {
389:                        int llcode = -1;
390:                        if (btype == 1) {
391:                            int code = readHuffmanBits(7);
392:
393:                            if (code <= 23) {
394:                                llcode = 256 + code;
395:                            } else {
396:                                // 8 bit codes
397:                                code <<= 1;
398:                                code |= readBit();
399:
400:                                if (code < 192) {
401:                                    llcode = code - 48;
402:                                } else if (code < 200) {
403:                                    llcode = 280 + code - 192;
404:                                } else {
405:                                    // 9 bit codes
406:                                    code <<= 1;
407:                                    code |= readBit();
408:                                    llcode = 144 + code - 400;
409:                                }
410:                            }
411:                        } else if (btype == 2) {
412:                            llcode = lltable.readSymbol();
413:                        }
414:
415:                        if (llcode < 256) {
416:                            emit(llcode);
417:                        } else if (llcode == 256) {
418:                            break;
419:                        } else if (llcode <= 285) {
420:                            int length = lengthsTable[llcode - 257];
421:                            int extraLengthBits = lengthExtraBitsTable[llcode - 257];
422:                            if (extraLengthBits > 0) {
423:                                int extra = readBits(extraLengthBits);
424:                                length += extra;
425:                            }
426:
427:                            int distanceCode = -1;
428:                            if (btype == 1) {
429:                                distanceCode = readHuffmanBits(5);
430:                            } else if (btype == 2) {
431:                                distanceCode = dtable.readSymbol();
432:                            }
433:
434:                            int distance = distancesTable[distanceCode];
435:                            int extraDistBits = distanceExtraBitsTable[distanceCode];
436:                            if (extraDistBits > 0) {
437:                                int extra = readBits(extraDistBits);
438:                                distance += extra;
439:                            }
440:
441:                            for (int i = 0; i < length; i++) {
442:                                emit(data[count - distance]);
443:                            }
444:                        } else {
445:                            // error
446:                        }
447:                    }
448:                } else {
449:                    // error
450:                }
451:
452:                return (bfinal == 0x1);
453:            }
454:
455:            public int available() throws IOException {
456:                return count - idx;
457:            }
458:
459:            public int read() throws IOException {
460:                if (idx == count) {
461:                    return -1;
462:                } else {
463:                    return data[idx++] & 0xff;
464:                }
465:            }
466:
467:            public int read(byte[] buf, int off, int len) throws IOException {
468:                for (int i = off; i < off + len; i++) {
469:                    if (idx == count) {
470:                        return i - off;
471:                    }
472:                    buf[i] = data[idx++];
473:                }
474:                return len;
475:            }
476:
477:            public long skip(long n) throws IOException {
478:                int saveIdx = idx;
479:                idx = Math.min((int) (idx + n), count);
480:                return idx - saveIdx;
481:            }
482:
483:            public void close() throws IOException {
484:                // do nothing
485:            }
486:
487:            public boolean markSupported() {
488:                return false;
489:            }
490:
491:            public synchronized void mark(int readlimit) {
492:                // do nothing
493:            }
494:
495:            public synchronized void reset() throws IOException {
496:                throw new IOException("mark/reset not supported");
497:            }
498:        }
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