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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/util/zip/DeflaterEngine.java
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Diffstat (limited to 'libjava/classpath/java/util/zip/DeflaterEngine.java')
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diff --git a/libjava/classpath/java/util/zip/DeflaterEngine.java b/libjava/classpath/java/util/zip/DeflaterEngine.java
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+++ b/libjava/classpath/java/util/zip/DeflaterEngine.java
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+/* DeflaterEngine.java --
+ Copyright (C) 2001, 2004, 2005 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 java.util.zip;
+
+class DeflaterEngine implements DeflaterConstants
+{
+ private static final int TOO_FAR = 4096;
+
+ private int ins_h;
+
+ /**
+ * Hashtable, hashing three characters to an index for window, so
+ * that window[index]..window[index+2] have this hash code.
+ * Note that the array should really be unsigned short, so you need
+ * to and the values with 0xffff.
+ */
+ private short[] head;
+
+ /**
+ * prev[index & WMASK] points to the previous index that has the
+ * same hash code as the string starting at index. This way
+ * entries with the same hash code are in a linked list.
+ * Note that the array should really be unsigned short, so you need
+ * to and the values with 0xffff.
+ */
+ private short[] prev;
+
+ private int matchStart, matchLen;
+ private boolean prevAvailable;
+ private int blockStart;
+
+ /**
+ * strstart points to the current character in window.
+ */
+ private int strstart;
+
+ /**
+ * lookahead is the number of characters starting at strstart in
+ * window that are valid.
+ * So window[strstart] until window[strstart+lookahead-1] are valid
+ * characters.
+ */
+ private int lookahead;
+
+ /**
+ * This array contains the part of the uncompressed stream that
+ * is of relevance. The current character is indexed by strstart.
+ */
+ private byte[] window;
+
+ private int strategy, max_chain, max_lazy, niceLength, goodLength;
+
+ /** The current compression function. */
+ private int comprFunc;
+
+ /** The input data for compression. */
+ private byte[] inputBuf;
+
+ /** The total bytes of input read. */
+ private long totalIn;
+
+ /** The offset into inputBuf, where input data starts. */
+ private int inputOff;
+
+ /** The end offset of the input data. */
+ private int inputEnd;
+
+ private DeflaterPending pending;
+ private DeflaterHuffman huffman;
+
+ /** The adler checksum */
+ private Adler32 adler;
+
+ /* DEFLATE ALGORITHM:
+ *
+ * The uncompressed stream is inserted into the window array. When
+ * the window array is full the first half is thrown away and the
+ * second half is copied to the beginning.
+ *
+ * The head array is a hash table. Three characters build a hash value
+ * and they the value points to the corresponding index in window of
+ * the last string with this hash. The prev array implements a
+ * linked list of matches with the same hash: prev[index & WMASK] points
+ * to the previous index with the same hash.
+ *
+ *
+ */
+
+
+ DeflaterEngine(DeflaterPending pending) {
+ this.pending = pending;
+ huffman = new DeflaterHuffman(pending);
+ adler = new Adler32();
+
+ window = new byte[2*WSIZE];
+ head = new short[HASH_SIZE];
+ prev = new short[WSIZE];
+
+ /* We start at index 1, to avoid a implementation deficiency, that
+ * we cannot build a repeat pattern at index 0.
+ */
+ blockStart = strstart = 1;
+ }
+
+ public void reset()
+ {
+ huffman.reset();
+ adler.reset();
+ blockStart = strstart = 1;
+ lookahead = 0;
+ totalIn = 0;
+ prevAvailable = false;
+ matchLen = MIN_MATCH - 1;
+ for (int i = 0; i < HASH_SIZE; i++)
+ head[i] = 0;
+ for (int i = 0; i < WSIZE; i++)
+ prev[i] = 0;
+ }
+
+ public final void resetAdler()
+ {
+ adler.reset();
+ }
+
+ public final int getAdler()
+ {
+ int chksum = (int) adler.getValue();
+ return chksum;
+ }
+
+ public final long getTotalIn()
+ {
+ return totalIn;
+ }
+
+ public final void setStrategy(int strat)
+ {
+ strategy = strat;
+ }
+
+ public void setLevel(int lvl)
+ {
+ goodLength = DeflaterConstants.GOOD_LENGTH[lvl];
+ max_lazy = DeflaterConstants.MAX_LAZY[lvl];
+ niceLength = DeflaterConstants.NICE_LENGTH[lvl];
+ max_chain = DeflaterConstants.MAX_CHAIN[lvl];
+
+ if (DeflaterConstants.COMPR_FUNC[lvl] != comprFunc)
+ {
+ if (DeflaterConstants.DEBUGGING)
+ System.err.println("Change from "+comprFunc +" to "
+ + DeflaterConstants.COMPR_FUNC[lvl]);
+ switch (comprFunc)
+ {
+ case DEFLATE_STORED:
+ if (strstart > blockStart)
+ {
+ huffman.flushStoredBlock(window, blockStart,
+ strstart - blockStart, false);
+ blockStart = strstart;
+ }
+ updateHash();
+ break;
+ case DEFLATE_FAST:
+ if (strstart > blockStart)
+ {
+ huffman.flushBlock(window, blockStart, strstart - blockStart,
+ false);
+ blockStart = strstart;
+ }
+ break;
+ case DEFLATE_SLOW:
+ if (prevAvailable)
+ huffman.tallyLit(window[strstart-1] & 0xff);
+ if (strstart > blockStart)
+ {
+ huffman.flushBlock(window, blockStart, strstart - blockStart,
+ false);
+ blockStart = strstart;
+ }
+ prevAvailable = false;
+ matchLen = MIN_MATCH - 1;
+ break;
+ }
+ comprFunc = COMPR_FUNC[lvl];
+ }
+ }
+
+ private void updateHash() {
+ if (DEBUGGING)
+ System.err.println("updateHash: "+strstart);
+ ins_h = (window[strstart] << HASH_SHIFT) ^ window[strstart + 1];
+ }
+
+ /**
+ * Inserts the current string in the head hash and returns the previous
+ * value for this hash.
+ */
+ private int insertString() {
+ short match;
+ int hash = ((ins_h << HASH_SHIFT) ^ window[strstart + (MIN_MATCH -1)])
+ & HASH_MASK;
+
+ if (DEBUGGING)
+ {
+ if (hash != (((window[strstart] << (2*HASH_SHIFT))
+ ^ (window[strstart + 1] << HASH_SHIFT)
+ ^ (window[strstart + 2])) & HASH_MASK))
+ throw new InternalError("hash inconsistent: "+hash+"/"
+ +window[strstart]+","
+ +window[strstart+1]+","
+ +window[strstart+2]+","+HASH_SHIFT);
+ }
+
+ prev[strstart & WMASK] = match = head[hash];
+ head[hash] = (short) strstart;
+ ins_h = hash;
+ return match & 0xffff;
+ }
+
+ private void slideWindow()
+ {
+ System.arraycopy(window, WSIZE, window, 0, WSIZE);
+ matchStart -= WSIZE;
+ strstart -= WSIZE;
+ blockStart -= WSIZE;
+
+ /* Slide the hash table (could be avoided with 32 bit values
+ * at the expense of memory usage).
+ */
+ for (int i = 0; i < HASH_SIZE; i++)
+ {
+ int m = head[i] & 0xffff;
+ head[i] = m >= WSIZE ? (short) (m - WSIZE) : 0;
+ }
+
+ /* Slide the prev table.
+ */
+ for (int i = 0; i < WSIZE; i++)
+ {
+ int m = prev[i] & 0xffff;
+ prev[i] = m >= WSIZE ? (short) (m - WSIZE) : 0;
+ }
+ }
+
+ /**
+ * Fill the window when the lookahead becomes insufficient.
+ * Updates strstart and lookahead.
+ *
+ * OUT assertions: strstart + lookahead <= 2*WSIZE
+ * lookahead >= MIN_LOOKAHEAD or inputOff == inputEnd
+ */
+ private void fillWindow()
+ {
+ /* If the window is almost full and there is insufficient lookahead,
+ * move the upper half to the lower one to make room in the upper half.
+ */
+ if (strstart >= WSIZE + MAX_DIST)
+ slideWindow();
+
+ /* If there is not enough lookahead, but still some input left,
+ * read in the input
+ */
+ while (lookahead < DeflaterConstants.MIN_LOOKAHEAD && inputOff < inputEnd)
+ {
+ int more = 2*WSIZE - lookahead - strstart;
+
+ if (more > inputEnd - inputOff)
+ more = inputEnd - inputOff;
+
+ System.arraycopy(inputBuf, inputOff,
+ window, strstart + lookahead, more);
+ adler.update(inputBuf, inputOff, more);
+ inputOff += more;
+ totalIn += more;
+ lookahead += more;
+ }
+
+ if (lookahead >= MIN_MATCH)
+ updateHash();
+ }
+
+ /**
+ * Find the best (longest) string in the window matching the
+ * string starting at strstart.
+ *
+ * Preconditions:
+ * strstart + MAX_MATCH <= window.length.
+ *
+ *
+ * @param curMatch
+ */
+ private boolean findLongestMatch(int curMatch) {
+ int chainLength = this.max_chain;
+ int niceLength = this.niceLength;
+ short[] prev = this.prev;
+ int scan = this.strstart;
+ int match;
+ int best_end = this.strstart + matchLen;
+ int best_len = Math.max(matchLen, MIN_MATCH - 1);
+
+ int limit = Math.max(strstart - MAX_DIST, 0);
+
+ int strend = scan + MAX_MATCH - 1;
+ byte scan_end1 = window[best_end - 1];
+ byte scan_end = window[best_end];
+
+ /* Do not waste too much time if we already have a good match: */
+ if (best_len >= this.goodLength)
+ chainLength >>= 2;
+
+ /* Do not look for matches beyond the end of the input. This is necessary
+ * to make deflate deterministic.
+ */
+ if (niceLength > lookahead)
+ niceLength = lookahead;
+
+ if (DeflaterConstants.DEBUGGING
+ && strstart > 2*WSIZE - MIN_LOOKAHEAD)
+ throw new InternalError("need lookahead");
+
+ do {
+ if (DeflaterConstants.DEBUGGING && curMatch >= strstart)
+ throw new InternalError("future match");
+ if (window[curMatch + best_len] != scan_end
+ || window[curMatch + best_len - 1] != scan_end1
+ || window[curMatch] != window[scan]
+ || window[curMatch+1] != window[scan + 1])
+ continue;
+
+ match = curMatch + 2;
+ scan += 2;
+
+ /* We check for insufficient lookahead only every 8th comparison;
+ * the 256th check will be made at strstart+258.
+ */
+ while (window[++scan] == window[++match]
+ && window[++scan] == window[++match]
+ && window[++scan] == window[++match]
+ && window[++scan] == window[++match]
+ && window[++scan] == window[++match]
+ && window[++scan] == window[++match]
+ && window[++scan] == window[++match]
+ && window[++scan] == window[++match]
+ && scan < strend)
+ ;
+
+ if (scan > best_end) {
+// if (DeflaterConstants.DEBUGGING && ins_h == 0)
+// System.err.println("Found match: "+curMatch+"-"+(scan-strstart));
+ matchStart = curMatch;
+ best_end = scan;
+ best_len = scan - strstart;
+ if (best_len >= niceLength)
+ break;
+
+ scan_end1 = window[best_end-1];
+ scan_end = window[best_end];
+ }
+ scan = strstart;
+ } while ((curMatch = (prev[curMatch & WMASK] & 0xffff)) > limit
+ && --chainLength != 0);
+
+ matchLen = Math.min(best_len, lookahead);
+ return matchLen >= MIN_MATCH;
+ }
+
+ void setDictionary(byte[] buffer, int offset, int length) {
+ if (DeflaterConstants.DEBUGGING && strstart != 1)
+ throw new IllegalStateException("strstart not 1");
+ adler.update(buffer, offset, length);
+ if (length < MIN_MATCH)
+ return;
+ if (length > MAX_DIST) {
+ offset += length - MAX_DIST;
+ length = MAX_DIST;
+ }
+
+ System.arraycopy(buffer, offset, window, strstart, length);
+
+ updateHash();
+ length--;
+ while (--length > 0)
+ {
+ insertString();
+ strstart++;
+ }
+ strstart += 2;
+ blockStart = strstart;
+ }
+
+ private boolean deflateStored(boolean flush, boolean finish)
+ {
+ if (!flush && lookahead == 0)
+ return false;
+
+ strstart += lookahead;
+ lookahead = 0;
+
+ int storedLen = strstart - blockStart;
+
+ if ((storedLen >= DeflaterConstants.MAX_BLOCK_SIZE)
+ /* Block is full */
+ || (blockStart < WSIZE && storedLen >= MAX_DIST)
+ /* Block may move out of window */
+ || flush)
+ {
+ boolean lastBlock = finish;
+ if (storedLen > DeflaterConstants.MAX_BLOCK_SIZE)
+ {
+ storedLen = DeflaterConstants.MAX_BLOCK_SIZE;
+ lastBlock = false;
+ }
+
+ if (DeflaterConstants.DEBUGGING)
+ System.err.println("storedBlock["+storedLen+","+lastBlock+"]");
+
+ huffman.flushStoredBlock(window, blockStart, storedLen, lastBlock);
+ blockStart += storedLen;
+ return !lastBlock;
+ }
+ return true;
+ }
+
+ private boolean deflateFast(boolean flush, boolean finish)
+ {
+ if (lookahead < MIN_LOOKAHEAD && !flush)
+ return false;
+
+ while (lookahead >= MIN_LOOKAHEAD || flush)
+ {
+ if (lookahead == 0)
+ {
+ /* We are flushing everything */
+ huffman.flushBlock(window, blockStart, strstart - blockStart,
+ finish);
+ blockStart = strstart;
+ return false;
+ }
+
+ if (strstart > 2 * WSIZE - MIN_LOOKAHEAD)
+ {
+ /* slide window, as findLongestMatch need this.
+ * This should only happen when flushing and the window
+ * is almost full.
+ */
+ slideWindow();
+ }
+
+ int hashHead;
+ if (lookahead >= MIN_MATCH
+ && (hashHead = insertString()) != 0
+ && strategy != Deflater.HUFFMAN_ONLY
+ && strstart - hashHead <= MAX_DIST
+ && findLongestMatch(hashHead))
+ {
+ /* longestMatch sets matchStart and matchLen */
+ if (DeflaterConstants.DEBUGGING)
+ {
+ for (int i = 0 ; i < matchLen; i++)
+ {
+ if (window[strstart+i] != window[matchStart + i])
+ throw new InternalError();
+ }
+ }
+ boolean full = huffman.tallyDist(strstart - matchStart, matchLen);
+
+ lookahead -= matchLen;
+ if (matchLen <= max_lazy && lookahead >= MIN_MATCH)
+ {
+ while (--matchLen > 0)
+ {
+ strstart++;
+ insertString();
+ }
+ strstart++;
+ }
+ else
+ {
+ strstart += matchLen;
+ if (lookahead >= MIN_MATCH - 1)
+ updateHash();
+ }
+ matchLen = MIN_MATCH - 1;
+ if (!full)
+ continue;
+ }
+ else
+ {
+ /* No match found */
+ huffman.tallyLit(window[strstart] & 0xff);
+ strstart++;
+ lookahead--;
+ }
+
+ if (huffman.isFull())
+ {
+ boolean lastBlock = finish && lookahead == 0;
+ huffman.flushBlock(window, blockStart, strstart - blockStart,
+ lastBlock);
+ blockStart = strstart;
+ return !lastBlock;
+ }
+ }
+ return true;
+ }
+
+ private boolean deflateSlow(boolean flush, boolean finish)
+ {
+ if (lookahead < MIN_LOOKAHEAD && !flush)
+ return false;
+
+ while (lookahead >= MIN_LOOKAHEAD || flush)
+ {
+ if (lookahead == 0)
+ {
+ if (prevAvailable)
+ huffman.tallyLit(window[strstart-1] & 0xff);
+ prevAvailable = false;
+
+ /* We are flushing everything */
+ if (DeflaterConstants.DEBUGGING && !flush)
+ throw new InternalError("Not flushing, but no lookahead");
+ huffman.flushBlock(window, blockStart, strstart - blockStart,
+ finish);
+ blockStart = strstart;
+ return false;
+ }
+
+ if (strstart >= 2 * WSIZE - MIN_LOOKAHEAD)
+ {
+ /* slide window, as findLongestMatch need this.
+ * This should only happen when flushing and the window
+ * is almost full.
+ */
+ slideWindow();
+ }
+
+ int prevMatch = matchStart;
+ int prevLen = matchLen;
+ if (lookahead >= MIN_MATCH)
+ {
+ int hashHead = insertString();
+ if (strategy != Deflater.HUFFMAN_ONLY
+ && hashHead != 0 && strstart - hashHead <= MAX_DIST
+ && findLongestMatch(hashHead))
+ {
+ /* longestMatch sets matchStart and matchLen */
+
+ /* Discard match if too small and too far away */
+ if (matchLen <= 5
+ && (strategy == Deflater.FILTERED
+ || (matchLen == MIN_MATCH
+ && strstart - matchStart > TOO_FAR))) {
+ matchLen = MIN_MATCH - 1;
+ }
+ }
+ }
+
+ /* previous match was better */
+ if (prevLen >= MIN_MATCH && matchLen <= prevLen)
+ {
+ if (DeflaterConstants.DEBUGGING)
+ {
+ for (int i = 0 ; i < matchLen; i++)
+ {
+ if (window[strstart-1+i] != window[prevMatch + i])
+ throw new InternalError();
+ }
+ }
+ huffman.tallyDist(strstart - 1 - prevMatch, prevLen);
+ prevLen -= 2;
+ do
+ {
+ strstart++;
+ lookahead--;
+ if (lookahead >= MIN_MATCH)
+ insertString();
+ }
+ while (--prevLen > 0);
+ strstart ++;
+ lookahead--;
+ prevAvailable = false;
+ matchLen = MIN_MATCH - 1;
+ }
+ else
+ {
+ if (prevAvailable)
+ huffman.tallyLit(window[strstart-1] & 0xff);
+ prevAvailable = true;
+ strstart++;
+ lookahead--;
+ }
+
+ if (huffman.isFull())
+ {
+ int len = strstart - blockStart;
+ if (prevAvailable)
+ len--;
+ boolean lastBlock = (finish && lookahead == 0 && !prevAvailable);
+ huffman.flushBlock(window, blockStart, len, lastBlock);
+ blockStart += len;
+ return !lastBlock;
+ }
+ }
+ return true;
+ }
+
+ public boolean deflate(boolean flush, boolean finish)
+ {
+ boolean progress;
+ do
+ {
+ fillWindow();
+ boolean canFlush = flush && inputOff == inputEnd;
+ if (DeflaterConstants.DEBUGGING)
+ System.err.println("window: ["+blockStart+","+strstart+","
+ +lookahead+"], "+comprFunc+","+canFlush);
+ switch (comprFunc)
+ {
+ case DEFLATE_STORED:
+ progress = deflateStored(canFlush, finish);
+ break;
+ case DEFLATE_FAST:
+ progress = deflateFast(canFlush, finish);
+ break;
+ case DEFLATE_SLOW:
+ progress = deflateSlow(canFlush, finish);
+ break;
+ default:
+ throw new InternalError();
+ }
+ }
+ while (pending.isFlushed() /* repeat while we have no pending output */
+ && progress); /* and progress was made */
+
+ return progress;
+ }
+
+ public void setInput(byte[] buf, int off, int len)
+ {
+ if (inputOff < inputEnd)
+ throw new IllegalStateException
+ ("Old input was not completely processed");
+
+ int end = off + len;
+
+ /* We want to throw an ArrayIndexOutOfBoundsException early. The
+ * check is very tricky: it also handles integer wrap around.
+ */
+ if (0 > off || off > end || end > buf.length)
+ throw new ArrayIndexOutOfBoundsException();
+
+ inputBuf = buf;
+ inputOff = off;
+ inputEnd = end;
+ }
+
+ public final boolean needsInput()
+ {
+ return inputEnd == inputOff;
+ }
+}