diff -r 8e1ed2a15845 -r 4690a2871b44 src/java.net.http/share/classes/jdk/internal/net/http/hpack/QuickHuffman.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/java.net.http/share/classes/jdk/internal/net/http/hpack/QuickHuffman.java Wed May 02 02:36:17 2018 -0700 @@ -0,0 +1,826 @@ +/* + * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code 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 + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +package jdk.internal.net.http.hpack; + +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.List; +import java.util.Objects; + +public final class QuickHuffman { + + /* + * Huffman codes for encoding. + * + * EOS will never be matched, since there is no symbol for it, thus no need + * to store it in the array. Thus, the length of the array is 256, not 257. + * Code information for each character is encoded as follows: + * + * MSB LSB + * +----------------+----------------+ + * |~code | length~| + * +----------------+----------------+ + * |<----- 32 ----->|<----- 32 ----->| + * |<------------- 64 -------------->| + * + * The leftmost 32 bits hold the code value. This value is aligned left + * (or MSB). The rightmost 32 bits hold the length of the code value. + * This length is aligned right (or LSB). + */ + private static final long[] codes = new long[256]; + + private static long codeValueOf(char c) { + return codes[c] & 0xffffffff00000000L; + } + + private static long codeLengthOf(char c) { + return codes[c] & 0x00000000ffffffffL; + } + + private static final int EOS_LENGTH = 30; + private static final int EOS_LSB = 0x3fffffff; + private static final long EOS_MSB = EOS_LSB << (64 - EOS_LENGTH); + + /* + * Huffman codes for decoding. + * + * Root node contains 257 descendant nodes, including EOS. + */ + private static final Node root; + + static { + TemporaryNode tmpRoot = new TemporaryNode(); + addChar(tmpRoot, 0, 0x1ff8, 13); + addChar(tmpRoot, 1, 0x7fffd8, 23); + addChar(tmpRoot, 2, 0xfffffe2, 28); + addChar(tmpRoot, 3, 0xfffffe3, 28); + addChar(tmpRoot, 4, 0xfffffe4, 28); + addChar(tmpRoot, 5, 0xfffffe5, 28); + addChar(tmpRoot, 6, 0xfffffe6, 28); + addChar(tmpRoot, 7, 0xfffffe7, 28); + addChar(tmpRoot, 8, 0xfffffe8, 28); + addChar(tmpRoot, 9, 0xffffea, 24); + addChar(tmpRoot, 10, 0x3ffffffc, 30); + addChar(tmpRoot, 11, 0xfffffe9, 28); + addChar(tmpRoot, 12, 0xfffffea, 28); + addChar(tmpRoot, 13, 0x3ffffffd, 30); + addChar(tmpRoot, 14, 0xfffffeb, 28); + addChar(tmpRoot, 15, 0xfffffec, 28); + addChar(tmpRoot, 16, 0xfffffed, 28); + addChar(tmpRoot, 17, 0xfffffee, 28); + addChar(tmpRoot, 18, 0xfffffef, 28); + addChar(tmpRoot, 19, 0xffffff0, 28); + addChar(tmpRoot, 20, 0xffffff1, 28); + addChar(tmpRoot, 21, 0xffffff2, 28); + addChar(tmpRoot, 22, 0x3ffffffe, 30); + addChar(tmpRoot, 23, 0xffffff3, 28); + addChar(tmpRoot, 24, 0xffffff4, 28); + addChar(tmpRoot, 25, 0xffffff5, 28); + addChar(tmpRoot, 26, 0xffffff6, 28); + addChar(tmpRoot, 27, 0xffffff7, 28); + addChar(tmpRoot, 28, 0xffffff8, 28); + addChar(tmpRoot, 29, 0xffffff9, 28); + addChar(tmpRoot, 30, 0xffffffa, 28); + addChar(tmpRoot, 31, 0xffffffb, 28); + addChar(tmpRoot, 32, 0x14, 6); + addChar(tmpRoot, 33, 0x3f8, 10); + addChar(tmpRoot, 34, 0x3f9, 10); + addChar(tmpRoot, 35, 0xffa, 12); + addChar(tmpRoot, 36, 0x1ff9, 13); + addChar(tmpRoot, 37, 0x15, 6); + addChar(tmpRoot, 38, 0xf8, 8); + addChar(tmpRoot, 39, 0x7fa, 11); + addChar(tmpRoot, 40, 0x3fa, 10); + addChar(tmpRoot, 41, 0x3fb, 10); + addChar(tmpRoot, 42, 0xf9, 8); + addChar(tmpRoot, 43, 0x7fb, 11); + addChar(tmpRoot, 44, 0xfa, 8); + addChar(tmpRoot, 45, 0x16, 6); + addChar(tmpRoot, 46, 0x17, 6); + addChar(tmpRoot, 47, 0x18, 6); + addChar(tmpRoot, 48, 0x0, 5); + addChar(tmpRoot, 49, 0x1, 5); + addChar(tmpRoot, 50, 0x2, 5); + addChar(tmpRoot, 51, 0x19, 6); + addChar(tmpRoot, 52, 0x1a, 6); + addChar(tmpRoot, 53, 0x1b, 6); + addChar(tmpRoot, 54, 0x1c, 6); + addChar(tmpRoot, 55, 0x1d, 6); + addChar(tmpRoot, 56, 0x1e, 6); + addChar(tmpRoot, 57, 0x1f, 6); + addChar(tmpRoot, 58, 0x5c, 7); + addChar(tmpRoot, 59, 0xfb, 8); + addChar(tmpRoot, 60, 0x7ffc, 15); + addChar(tmpRoot, 61, 0x20, 6); + addChar(tmpRoot, 62, 0xffb, 12); + addChar(tmpRoot, 63, 0x3fc, 10); + addChar(tmpRoot, 64, 0x1ffa, 13); + addChar(tmpRoot, 65, 0x21, 6); + addChar(tmpRoot, 66, 0x5d, 7); + addChar(tmpRoot, 67, 0x5e, 7); + addChar(tmpRoot, 68, 0x5f, 7); + addChar(tmpRoot, 69, 0x60, 7); + addChar(tmpRoot, 70, 0x61, 7); + addChar(tmpRoot, 71, 0x62, 7); + addChar(tmpRoot, 72, 0x63, 7); + addChar(tmpRoot, 73, 0x64, 7); + addChar(tmpRoot, 74, 0x65, 7); + addChar(tmpRoot, 75, 0x66, 7); + addChar(tmpRoot, 76, 0x67, 7); + addChar(tmpRoot, 77, 0x68, 7); + addChar(tmpRoot, 78, 0x69, 7); + addChar(tmpRoot, 79, 0x6a, 7); + addChar(tmpRoot, 80, 0x6b, 7); + addChar(tmpRoot, 81, 0x6c, 7); + addChar(tmpRoot, 82, 0x6d, 7); + addChar(tmpRoot, 83, 0x6e, 7); + addChar(tmpRoot, 84, 0x6f, 7); + addChar(tmpRoot, 85, 0x70, 7); + addChar(tmpRoot, 86, 0x71, 7); + addChar(tmpRoot, 87, 0x72, 7); + addChar(tmpRoot, 88, 0xfc, 8); + addChar(tmpRoot, 89, 0x73, 7); + addChar(tmpRoot, 90, 0xfd, 8); + addChar(tmpRoot, 91, 0x1ffb, 13); + addChar(tmpRoot, 92, 0x7fff0, 19); + addChar(tmpRoot, 93, 0x1ffc, 13); + addChar(tmpRoot, 94, 0x3ffc, 14); + addChar(tmpRoot, 95, 0x22, 6); + addChar(tmpRoot, 96, 0x7ffd, 15); + addChar(tmpRoot, 97, 0x3, 5); + addChar(tmpRoot, 98, 0x23, 6); + addChar(tmpRoot, 99, 0x4, 5); + addChar(tmpRoot, 100, 0x24, 6); + addChar(tmpRoot, 101, 0x5, 5); + addChar(tmpRoot, 102, 0x25, 6); + addChar(tmpRoot, 103, 0x26, 6); + addChar(tmpRoot, 104, 0x27, 6); + addChar(tmpRoot, 105, 0x6, 5); + addChar(tmpRoot, 106, 0x74, 7); + addChar(tmpRoot, 107, 0x75, 7); + addChar(tmpRoot, 108, 0x28, 6); + addChar(tmpRoot, 109, 0x29, 6); + addChar(tmpRoot, 110, 0x2a, 6); + addChar(tmpRoot, 111, 0x7, 5); + addChar(tmpRoot, 112, 0x2b, 6); + addChar(tmpRoot, 113, 0x76, 7); + addChar(tmpRoot, 114, 0x2c, 6); + addChar(tmpRoot, 115, 0x8, 5); + addChar(tmpRoot, 116, 0x9, 5); + addChar(tmpRoot, 117, 0x2d, 6); + addChar(tmpRoot, 118, 0x77, 7); + addChar(tmpRoot, 119, 0x78, 7); + addChar(tmpRoot, 120, 0x79, 7); + addChar(tmpRoot, 121, 0x7a, 7); + addChar(tmpRoot, 122, 0x7b, 7); + addChar(tmpRoot, 123, 0x7ffe, 15); + addChar(tmpRoot, 124, 0x7fc, 11); + addChar(tmpRoot, 125, 0x3ffd, 14); + addChar(tmpRoot, 126, 0x1ffd, 13); + addChar(tmpRoot, 127, 0xffffffc, 28); + addChar(tmpRoot, 128, 0xfffe6, 20); + addChar(tmpRoot, 129, 0x3fffd2, 22); + addChar(tmpRoot, 130, 0xfffe7, 20); + addChar(tmpRoot, 131, 0xfffe8, 20); + addChar(tmpRoot, 132, 0x3fffd3, 22); + addChar(tmpRoot, 133, 0x3fffd4, 22); + addChar(tmpRoot, 134, 0x3fffd5, 22); + addChar(tmpRoot, 135, 0x7fffd9, 23); + addChar(tmpRoot, 136, 0x3fffd6, 22); + addChar(tmpRoot, 137, 0x7fffda, 23); + addChar(tmpRoot, 138, 0x7fffdb, 23); + addChar(tmpRoot, 139, 0x7fffdc, 23); + addChar(tmpRoot, 140, 0x7fffdd, 23); + addChar(tmpRoot, 141, 0x7fffde, 23); + addChar(tmpRoot, 142, 0xffffeb, 24); + addChar(tmpRoot, 143, 0x7fffdf, 23); + addChar(tmpRoot, 144, 0xffffec, 24); + addChar(tmpRoot, 145, 0xffffed, 24); + addChar(tmpRoot, 146, 0x3fffd7, 22); + addChar(tmpRoot, 147, 0x7fffe0, 23); + addChar(tmpRoot, 148, 0xffffee, 24); + addChar(tmpRoot, 149, 0x7fffe1, 23); + addChar(tmpRoot, 150, 0x7fffe2, 23); + addChar(tmpRoot, 151, 0x7fffe3, 23); + addChar(tmpRoot, 152, 0x7fffe4, 23); + addChar(tmpRoot, 153, 0x1fffdc, 21); + addChar(tmpRoot, 154, 0x3fffd8, 22); + addChar(tmpRoot, 155, 0x7fffe5, 23); + addChar(tmpRoot, 156, 0x3fffd9, 22); + addChar(tmpRoot, 157, 0x7fffe6, 23); + addChar(tmpRoot, 158, 0x7fffe7, 23); + addChar(tmpRoot, 159, 0xffffef, 24); + addChar(tmpRoot, 160, 0x3fffda, 22); + addChar(tmpRoot, 161, 0x1fffdd, 21); + addChar(tmpRoot, 162, 0xfffe9, 20); + addChar(tmpRoot, 163, 0x3fffdb, 22); + addChar(tmpRoot, 164, 0x3fffdc, 22); + addChar(tmpRoot, 165, 0x7fffe8, 23); + addChar(tmpRoot, 166, 0x7fffe9, 23); + addChar(tmpRoot, 167, 0x1fffde, 21); + addChar(tmpRoot, 168, 0x7fffea, 23); + addChar(tmpRoot, 169, 0x3fffdd, 22); + addChar(tmpRoot, 170, 0x3fffde, 22); + addChar(tmpRoot, 171, 0xfffff0, 24); + addChar(tmpRoot, 172, 0x1fffdf, 21); + addChar(tmpRoot, 173, 0x3fffdf, 22); + addChar(tmpRoot, 174, 0x7fffeb, 23); + addChar(tmpRoot, 175, 0x7fffec, 23); + addChar(tmpRoot, 176, 0x1fffe0, 21); + addChar(tmpRoot, 177, 0x1fffe1, 21); + addChar(tmpRoot, 178, 0x3fffe0, 22); + addChar(tmpRoot, 179, 0x1fffe2, 21); + addChar(tmpRoot, 180, 0x7fffed, 23); + addChar(tmpRoot, 181, 0x3fffe1, 22); + addChar(tmpRoot, 182, 0x7fffee, 23); + addChar(tmpRoot, 183, 0x7fffef, 23); + addChar(tmpRoot, 184, 0xfffea, 20); + addChar(tmpRoot, 185, 0x3fffe2, 22); + addChar(tmpRoot, 186, 0x3fffe3, 22); + addChar(tmpRoot, 187, 0x3fffe4, 22); + addChar(tmpRoot, 188, 0x7ffff0, 23); + addChar(tmpRoot, 189, 0x3fffe5, 22); + addChar(tmpRoot, 190, 0x3fffe6, 22); + addChar(tmpRoot, 191, 0x7ffff1, 23); + addChar(tmpRoot, 192, 0x3ffffe0, 26); + addChar(tmpRoot, 193, 0x3ffffe1, 26); + addChar(tmpRoot, 194, 0xfffeb, 20); + addChar(tmpRoot, 195, 0x7fff1, 19); + addChar(tmpRoot, 196, 0x3fffe7, 22); + addChar(tmpRoot, 197, 0x7ffff2, 23); + addChar(tmpRoot, 198, 0x3fffe8, 22); + addChar(tmpRoot, 199, 0x1ffffec, 25); + addChar(tmpRoot, 200, 0x3ffffe2, 26); + addChar(tmpRoot, 201, 0x3ffffe3, 26); + addChar(tmpRoot, 202, 0x3ffffe4, 26); + addChar(tmpRoot, 203, 0x7ffffde, 27); + addChar(tmpRoot, 204, 0x7ffffdf, 27); + addChar(tmpRoot, 205, 0x3ffffe5, 26); + addChar(tmpRoot, 206, 0xfffff1, 24); + addChar(tmpRoot, 207, 0x1ffffed, 25); + addChar(tmpRoot, 208, 0x7fff2, 19); + addChar(tmpRoot, 209, 0x1fffe3, 21); + addChar(tmpRoot, 210, 0x3ffffe6, 26); + addChar(tmpRoot, 211, 0x7ffffe0, 27); + addChar(tmpRoot, 212, 0x7ffffe1, 27); + addChar(tmpRoot, 213, 0x3ffffe7, 26); + addChar(tmpRoot, 214, 0x7ffffe2, 27); + addChar(tmpRoot, 215, 0xfffff2, 24); + addChar(tmpRoot, 216, 0x1fffe4, 21); + addChar(tmpRoot, 217, 0x1fffe5, 21); + addChar(tmpRoot, 218, 0x3ffffe8, 26); + addChar(tmpRoot, 219, 0x3ffffe9, 26); + addChar(tmpRoot, 220, 0xffffffd, 28); + addChar(tmpRoot, 221, 0x7ffffe3, 27); + addChar(tmpRoot, 222, 0x7ffffe4, 27); + addChar(tmpRoot, 223, 0x7ffffe5, 27); + addChar(tmpRoot, 224, 0xfffec, 20); + addChar(tmpRoot, 225, 0xfffff3, 24); + addChar(tmpRoot, 226, 0xfffed, 20); + addChar(tmpRoot, 227, 0x1fffe6, 21); + addChar(tmpRoot, 228, 0x3fffe9, 22); + addChar(tmpRoot, 229, 0x1fffe7, 21); + addChar(tmpRoot, 230, 0x1fffe8, 21); + addChar(tmpRoot, 231, 0x7ffff3, 23); + addChar(tmpRoot, 232, 0x3fffea, 22); + addChar(tmpRoot, 233, 0x3fffeb, 22); + addChar(tmpRoot, 234, 0x1ffffee, 25); + addChar(tmpRoot, 235, 0x1ffffef, 25); + addChar(tmpRoot, 236, 0xfffff4, 24); + addChar(tmpRoot, 237, 0xfffff5, 24); + addChar(tmpRoot, 238, 0x3ffffea, 26); + addChar(tmpRoot, 239, 0x7ffff4, 23); + addChar(tmpRoot, 240, 0x3ffffeb, 26); + addChar(tmpRoot, 241, 0x7ffffe6, 27); + addChar(tmpRoot, 242, 0x3ffffec, 26); + addChar(tmpRoot, 243, 0x3ffffed, 26); + addChar(tmpRoot, 244, 0x7ffffe7, 27); + addChar(tmpRoot, 245, 0x7ffffe8, 27); + addChar(tmpRoot, 246, 0x7ffffe9, 27); + addChar(tmpRoot, 247, 0x7ffffea, 27); + addChar(tmpRoot, 248, 0x7ffffeb, 27); + addChar(tmpRoot, 249, 0xffffffe, 28); + addChar(tmpRoot, 250, 0x7ffffec, 27); + addChar(tmpRoot, 251, 0x7ffffed, 27); + addChar(tmpRoot, 252, 0x7ffffee, 27); + addChar(tmpRoot, 253, 0x7ffffef, 27); + addChar(tmpRoot, 254, 0x7fffff0, 27); + addChar(tmpRoot, 255, 0x3ffffee, 26); + addEOS (tmpRoot, 256, EOS_LSB, EOS_LENGTH); + + // The difference in performance can always be checked by not using + // the immutable trie: + // root = tmpRoot; + root = ImmutableNode.copyOf(tmpRoot); + } + + private QuickHuffman() { } + + private static void addChar(Node root, int symbol, int code, int bitLength) + { + addLeaf(root, (char) symbol, code, bitLength, false); + long value = ((long) code) << (64 - bitLength); // re-align MSB <- LSB + codes[symbol] = value | bitLength; + } + + private static void addEOS(Node root, int symbol, int code, int bitLength) + { + addLeaf(root, (char) symbol, code, bitLength, true); + } + + private static void addLeaf(Node root, + char symbol, + int code, + int bitLength, + boolean isEOS) + { + assert 0 < bitLength && bitLength <= 32 : bitLength; + Node curr = root; + int nBytes = bytesForBits(bitLength); + // The number of bits the code needs to be shifted to the left in order + // to align with the byte #nBytes boundary: + int align = (nBytes << 3) - bitLength; + code <<= align; + // descend the trie until the last element + int l = 0; + for (int i = 0, probe = 0xff << ((nBytes - 1) << 3); + i < nBytes - 1; + i++, probe >>>= 8) + { + curr.setEOSPath(curr.isEOSPath() | isEOS); + int idx = (code & probe) >>> ((nBytes - 1 - i) << 3); + curr = curr.getOrCreateChild(idx); + curr.setLength(8); + l += 8; + } + // Assign the same char to all byte variants. For example, if the code + // and its length are 00011b and 5 respectively (letter 'a') then, in + // order to be able to match any byte starting with 00011b prefix, + // the following nodes need to be created: + // + // 00011000b, 00011001b, 00011010b, 00011011b, 00011100b, 00011101b, + // 00011110b and 00011111b + int idx = code & 0xff; + curr.setEOSPath(curr.isEOSPath() | isEOS); + for (int i = 0; i < (1 << align); i++) { + Node child = curr.getOrCreateChild(idx | i); + child.setSymbol(symbol); + child.setEOSPath(child.isEOSPath() | isEOS); + child.setLength(bitLength - l); + } + } + + /* + * A node in the Huffman trie. + */ + interface Node { + + boolean isEOSPath(); + + void setEOSPath(boolean value); + + boolean isLeaf(); + + Node getChild(int index); + + Node getOrCreateChild(int index); + + Node[] getChildren(); + + char getSymbol(); + + void setSymbol(char symbol); + + int getLength(); + + void setLength(int value); + } + + /* + * Mutable nodes used for initial construction of the Huffman trie. + * (These nodes are perfectly ok to be used after that.) + */ + static final class TemporaryNode implements Node { + + private char symbol; + private boolean eosPath; + private TemporaryNode[] children; + private int length; + + @Override + public TemporaryNode getOrCreateChild(int index) { + ensureChildrenExist(); + if (children[index] == null) { + children[index] = new TemporaryNode(); + } + return children[index]; + } + + private void ensureChildrenExist() { + if (children == null) { + children = new TemporaryNode[256]; + } + } + + @Override + public boolean isLeaf() { + return children == null; + } + + @Override + public boolean isEOSPath() { + return eosPath; + } + + @Override + public void setEOSPath(boolean value) { + eosPath = value; + } + + @Override + public TemporaryNode getChild(int index) { + ensureChildrenExist(); + return children[index]; + } + + @Override + public Node[] getChildren() { + if (children == null) { + return new Node[0]; + } + return children; + } + + @Override + public char getSymbol() { + return symbol; + } + + @Override + public int getLength() { + return length; + } + + @Override + public void setSymbol(char value) { + this.symbol = value; + } + + @Override + public void setLength(int value) { + this.length = value; + } + } + + /* + * Immutable node used to construct traversal-only Huffman trie. + * + * Once the trie has been built, the support of modifications is no longer + * required. An immutable trie should be used. Not only it will help to + * catch possible bugs, but hopefully speedup the traversal operations. + */ + static final class ImmutableNode implements Node { + + private final char symbol; + private final boolean eosPath; + private final int length; + private final List children; + + public static ImmutableNode copyOf(Node node) { + if (node.isLeaf()) { + return new ImmutableNode(node.getSymbol(), node.isEOSPath(), + node.getLength()); + } + Node[] children = node.getChildren(); + ImmutableNode[] immutableChildren = new ImmutableNode[children.length]; + for (int i = 0; i < children.length; i++) { + immutableChildren[i] = copyOf(children[i]); + } + return new ImmutableNode(node.isEOSPath(), node.getLength(), + immutableChildren); + } + + /* Creates a leaf node */ + private ImmutableNode(char symbol, + boolean eosPath, + int length) { + this.symbol = symbol; + this.eosPath = eosPath; + this.length = length; + this.children = List.of(); + } + + /* Creates a node with children */ + private ImmutableNode(boolean eosPath, + int length, + ImmutableNode[] children) + { + this.symbol = 0; + this.eosPath = eosPath; + this.length = length; + if (children.length == 0) { + throw new IllegalArgumentException(); + } + // A list produced by List.of should not be slower than array for + // accessing elements by index, and hopefully use additional + // optimizations (e.g. jdk.internal.vm.annotation.Stable) + this.children = List.of(children); + } + + @Override + public boolean isLeaf() { + return children.isEmpty(); + } + + @Override + public boolean isEOSPath() { + return eosPath; + } + + @Override + public void setEOSPath(boolean value) { + throw new UnsupportedOperationException(); + } + + @Override + public ImmutableNode getChild(int index) { + return children.get(index); + } + + @Override + public ImmutableNode getOrCreateChild(int index) { + throw new UnsupportedOperationException(); + } + + @Override + public ImmutableNode[] getChildren() { + // This method is not expected to be called on an immutable node. + // If it is called, it requires some investigation. + throw new UnsupportedOperationException(); + } + + @Override + public char getSymbol() { + return symbol; + } + + @Override + public void setSymbol(char symbol) { + throw new UnsupportedOperationException(); + } + + @Override + public int getLength() { + return length; + } + + @Override + public void setLength(int value) { + throw new UnsupportedOperationException(); + } + } + + static final class Reader implements Huffman.Reader { + + private Node curr = root; // current position in the trie + private long buffer; // bits left from the previous match (aligned to the left, or MSB) + private int bufferLen; // number of bits in the buffer + private int len; // length (in bits) of path to curr + private boolean done; + + @Override + public void read(ByteBuffer source, + Appendable destination, + boolean isLast) throws IOException + { + read(source, destination, true, isLast); + } + + @Override + public void reset() { + curr = root; + len = 0; + buffer = 0; + bufferLen = 0; + done = false; + } + + @SuppressWarnings("fallthrough") + void read(ByteBuffer source, + Appendable destination, + boolean reportEOS, /* reportEOS is exposed for tests */ + boolean isLast) throws IOException + { + while (!done) { + // read as much as possible (up to 8 bytes) + int remaining = source.remaining(); + int nBytes = Math.min((64 - bufferLen) >> 3, remaining); + switch (nBytes) { + case 0: + break; + case 3: + readByte(source); + case 2: + readByte(source); + case 1: + readByte(source); + break; + case 7: + readByte(source); + case 6: + readByte(source); + case 5: + readByte(source); + case 4: + readInt(source); + break; + case 8: + readLong(source); + break; + default: + throw new InternalError(String.valueOf(nBytes)); + } + // write as much as possible + while (true) { + if (bufferLen < 8) { + if (nBytes < remaining) { // read again + break; + } else if (!isLast) { // exit the method to accept more input + return; + } else if (bufferLen > 0) { // no more data is expected, pad + // (this padding may be done more than once) + buffer |= ((0xff00000000000000L >>> bufferLen) + & 0xff00000000000000L); + // do not update bufferLen, since all those ones are + // synthetic and are appended merely for the sake of + // lookup + } else { + done = true; + break; + } + } + int idx = (int) (buffer >>> 56); + Node node = curr.getChild(idx); + if (node == null) { // TODO: TEST + throw new IOException("Unexpected byte"); + } + if (node.isLeaf()) { + if (node.getLength() > bufferLen) { // matched more than we actually could (because of padding) + throw new IOException( + "Not a EOS prefix padding or unexpected end of data"); + } + if (reportEOS && node.isEOSPath()) { + throw new IOException("Encountered EOS"); + } + destination.append(node.getSymbol()); + curr = root; + len = 0; + } else { + curr = node; + // because of the padding, we can't match more bits than + // there are currently in the buffer + len += Math.min(bufferLen, node.getLength()); + } + buffer <<= node.getLength(); + bufferLen -= node.getLength(); + } + if (done && (curr.isEOSPath() && len > 7)) { + throw new IOException( + "Padding is too long (len=" + len + ") " + + "or unexpected end of data"); + } + } + } + + private void readLong(ByteBuffer source) { + buffer = source.getLong(); + bufferLen = 64; + } + + private void readInt(ByteBuffer source) { + long b; + b = source.getInt() & 0x00000000ffffffffL; + buffer |= (b << (32 - bufferLen)); + bufferLen += 32; + } + + private void readByte(ByteBuffer source) { + long b = source.get() & 0x00000000000000ffL; + buffer |= (b << (56 - bufferLen)); + bufferLen += 8; + } + } + + static final class Writer implements Huffman.Writer { + + private CharSequence source; + private boolean padded; + private int pos; + private int end; + private long buffer; + private int bufferLen; + + @Override + public QuickHuffman.Writer from(CharSequence input, int start, int end) { + Objects.checkFromToIndex(start, end, input.length()); + this.pos = start; + this.end = end; + this.source = input; + return this; + } + + @SuppressWarnings("fallthrough") + @Override + public boolean write(ByteBuffer destination) { + while (true) { + while (bufferLen < 32 && pos < end) { + char c = source.charAt(pos++); + buffer |= (codeValueOf(c) >>> bufferLen); // append + bufferLen += codeLengthOf(c); + } + if (bufferLen == 0) { + return true; + } + if (pos >= end && !padded) { // no more chars, pad + padded = true; + buffer |= (EOS_MSB >>> bufferLen); + bufferLen = bytesForBits(bufferLen) << 3; + } + // The number of bytes that can be written at once + // (calculating in bytes, not bits, since + // destination.remaining() * 8 might overflow) + + int nBytes = Math.min(bytesForBits(bufferLen), destination.remaining()); // ceil? + switch (nBytes) { + case 0: + return false; + case 1: + case 2: + case 3: + destination.put((byte) (buffer >>> 56)); + buffer <<= 8; + bufferLen -= 8; + break; + default: + destination.putInt((int) (buffer >>> 32)); + buffer <<= 32; + bufferLen -= 32; + break; + } + } + } + + @Override + public QuickHuffman.Writer reset() { + source = null; + buffer = 0; + bufferLen = 0; + end = 0; + pos = 0; + padded = false; + return this; + } + + @Override + public int lengthOf(CharSequence value, int start, int end) { + int len = 0; + for (int i = start; i < end; i++) { + char c = value.charAt(i); + len += codeLengthOf(c); + } + return bytesForBits(len); + } + } + + /* + * Returns the number of bytes the given number of bits constitute. + */ + private static int bytesForBits(int n) { + assert (n / 8 + (n % 8 != 0 ? 1 : 0)) == (n + 7) / 8 + && (n + 7) / 8 == ((n + 7) >> 3) : n; + return (n + 7) >> 3; + } +}