jgit/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/DeltaIndex.java

/*
 * Copyright (C) 2010, Google Inc. and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.internal.storage.pack;

import java.io.IOException;
import java.io.OutputStream;

/**
 * Index of blocks in a source file.
 * <p>
 * The index can be passed a result buffer, and output an instruction sequence
 * that transforms the source buffer used by the index into the result buffer.
 * The instruction sequence can be executed by
 * {@link org.eclipse.jgit.internal.storage.pack.BinaryDelta} to recreate the
 * result buffer.
 * <p>
 * An index stores the entire contents of the source buffer, but also a table of
 * block identities mapped to locations where the block appears in the source
 * buffer. The mapping table uses 12 bytes for every 16 bytes of source buffer,
 * and is therefore ~75% of the source buffer size. The overall index is ~1.75x
 * the size of the source buffer. This relationship holds for any JVM, as only a
 * constant number of objects are allocated per index. Callers can use the
 * method {@link #getIndexSize()} to obtain a reasonably accurate estimate of
 * the complete heap space used by this index.
 * <p>
 * A {@code DeltaIndex} is thread-safe. Concurrent threads can use the same
 * index to encode delta instructions for different result buffers.
 */
public class DeltaIndex {
	/** Number of bytes in a block. */
	static final int BLKSZ = 16; // must be 16, see unrolled loop in hashBlock

	/**
	 * Estimate the size of an index for a given source.
	 * <p>
	 * This is roughly a worst-case estimate. The actual index may be smaller.
	 *
	 * @param sourceLength
	 *            length of the source, in bytes.
	 * @return estimated size. Approximately {@code 1.75 * sourceLength}.
	 */
	public static long estimateIndexSize(int sourceLength) {
		return sourceLength + (sourceLength * 3 / 4);
	}

	/**
	 * Maximum number of positions to consider for a given content hash.
	 * <p>
	 * All positions with the same content hash are stored into a single chain.
	 * The chain size is capped to ensure delta encoding stays linear time at
	 * O(len_src + len_dst) rather than quadratic at O(len_src * len_dst).
	 */
	private static final int MAX_CHAIN_LENGTH = 64;

	/** Original source file that we indexed. */
	private final byte[] src;

	/**
	 * Pointers into the {@link #entries} table, indexed by block hash.
	 * <p>
	 * A block hash is masked with {@link #tableMask} to become the array index
	 * of this table. The value stored here is the first index within
	 * {@link #entries} that starts the consecutive list of blocks with that
	 * same masked hash. If there are no matching blocks, 0 is stored instead.
	 * <p>
	 * Note that this table is always a power of 2 in size, to support fast
	 * normalization of a block hash into an array index.
	 */
	private final int[] table;

	/**
	 * Pairs of block hash value and {@link #src} offsets.
	 * <p>
	 * The very first entry in this table at index 0 is always empty, this is to
	 * allow fast evaluation when {@link #table} has no values under any given
	 * slot. Remaining entries are pairs of integers, with the upper 32 bits
	 * holding the block hash and the lower 32 bits holding the source offset.
	 */
	private final long[] entries;

	/** Mask to make block hashes into an array index for {@link #table}. */
	private final int tableMask;

	/**
	 * Construct an index from the source file.
	 *
	 * @param sourceBuffer
	 *            the source file's raw contents. The buffer will be held by the
	 *            index instance to facilitate matching, and therefore must not
	 *            be modified by the caller.
	 */
	public DeltaIndex(byte[] sourceBuffer) {
		src = sourceBuffer;

		DeltaIndexScanner scan = new DeltaIndexScanner(src, src.length);

		// Reuse the same table the scanner made. We will replace the
		// values at each position, but we want the same-length array.
		//
		table = scan.table;
		tableMask = scan.tableMask;

		// Because entry index 0 means there are no entries for the
		// slot in the table, we have to allocate one extra position.
		//
		entries = new long[1 + countEntries(scan)];
		copyEntries(scan);
	}

	private int countEntries(DeltaIndexScanner scan) {
		// Figure out exactly how many entries we need. As we do the
		// enumeration truncate any delta chains longer than what we
		// are willing to scan during encode. This keeps the encode
		// logic linear in the size of the input rather than quadratic.
		//
		int cnt = 0;
		for (int element : table) {
			int h = element;
			if (h == 0)
				continue;

			int len = 0;
			do {
				if (++len == MAX_CHAIN_LENGTH) {
					scan.next[h] = 0;
					break;
				}
				h = scan.next[h];
			} while (h != 0);
			cnt += len;
		}
		return cnt;
	}

	private void copyEntries(DeltaIndexScanner scan) {
		// Rebuild the entries list from the scanner, positioning all
		// blocks in the same hash chain next to each other. We can
		// then later discard the next list, along with the scanner.
		//
		int next = 1;
		for (int i = 0; i < table.length; i++) {
			int h = table[i];
			if (h == 0)
				continue;

			table[i] = next;
			do {
				entries[next++] = scan.entries[h];
				h = scan.next[h];
			} while (h != 0);
		}
	}

	/**
	 * Get size of the source buffer this index has scanned.
	 *
	 * @return size of the source buffer this index has scanned.
	 */
	public long getSourceSize() {
		return src.length;
	}

	/**
	 * Get an estimate of the memory required by this index.
	 *
	 * @return an approximation of the number of bytes used by this index in
	 *         memory. The size includes the cached source buffer size from
	 *         {@link #getSourceSize()}, as well as a rough approximation of JVM
	 *         object overheads.
	 */
	public long getIndexSize() {
		long sz = 8 /* object header */;
		sz += 4 /* fields */* 4 /* guessed size per field */;
		sz += sizeOf(src);
		sz += sizeOf(table);
		sz += sizeOf(entries);
		return sz;
	}

	private static long sizeOf(byte[] b) {
		return sizeOfArray(1, b.length);
	}

	private static long sizeOf(int[] b) {
		return sizeOfArray(4, b.length);
	}

	private static long sizeOf(long[] b) {
		return sizeOfArray(8, b.length);
	}

	private static int sizeOfArray(int entSize, int len) {
		return 12 /* estimated array header size */+ (len * entSize);
	}

	/**
	 * Generate a delta sequence to recreate the result buffer.
	 * <p>
	 * There is no limit on the size of the delta sequence created. This is the
	 * same as {@code encode(out, res, 0)}.
	 *
	 * @param out
	 *            stream to receive the delta instructions that can transform
	 *            this index's source buffer into {@code res}. This stream
	 *            should be buffered, as instructions are written directly to it
	 *            in small bursts.
	 * @param res
	 *            the desired result buffer. The generated instructions will
	 *            recreate this buffer when applied to the source buffer stored
	 *            within this index.
	 * @throws java.io.IOException
	 *             the output stream refused to write the instructions.
	 */
	public void encode(OutputStream out, byte[] res) throws IOException {
		encode(out, res, 0 /* no limit */);
	}

	/**
	 * Generate a delta sequence to recreate the result buffer.
	 *
	 * @param out
	 *            stream to receive the delta instructions that can transform
	 *            this index's source buffer into {@code res}. This stream
	 *            should be buffered, as instructions are written directly to it
	 *            in small bursts. If the caller might need to discard the
	 *            instructions (such as when deltaSizeLimit would be exceeded)
	 *            the caller is responsible for discarding or rewinding the
	 *            stream when this method returns false.
	 * @param res
	 *            the desired result buffer. The generated instructions will
	 *            recreate this buffer when applied to the source buffer stored
	 *            within this index.
	 * @param deltaSizeLimit
	 *            maximum number of bytes that the delta instructions can
	 *            occupy. If the generated instructions would be longer than
	 *            this amount, this method returns false. If 0, there is no
	 *            limit on the length of delta created.
	 * @return true if the delta is smaller than deltaSizeLimit; false if the
	 *         encoder aborted because the encoded delta instructions would be
	 *         longer than deltaSizeLimit bytes.
	 * @throws java.io.IOException
	 *             the output stream refused to write the instructions.
	 */
	public boolean encode(OutputStream out, byte[] res, int deltaSizeLimit)
			throws IOException {
		final int end = res.length;
		final DeltaEncoder enc = newEncoder(out, end, deltaSizeLimit);

		// If either input is smaller than one full block, we simply punt
		// and construct a delta as a literal. This implies that any file
		// smaller than our block size is never delta encoded as the delta
		// will always be larger than the file itself would be.
		//
		if (end < BLKSZ || table.length == 0)
			return enc.insert(res);

		// Bootstrap the scan by constructing a hash for the first block
		// in the input.
		//
		int blkPtr = 0;
		int blkEnd = BLKSZ;
		int hash = hashBlock(res, 0);

		int resPtr = 0;
		while (blkEnd < end) {
			final int tableIdx = hash & tableMask;
			int entryIdx = table[tableIdx];
			if (entryIdx == 0) {
				// No matching blocks, slide forward one byte.
				//
				hash = step(hash, res[blkPtr++], res[blkEnd++]);
				continue;
			}

			// For every possible location of the current block, try to
			// extend the match out to the longest common substring.
			//
			int bestLen = -1;
			int bestPtr = -1;
			int bestNeg = 0;
			do {
				long ent = entries[entryIdx++];
				if (keyOf(ent) == hash) {
					int neg = 0;
					if (resPtr < blkPtr) {
						// If we need to do an insertion, check to see if
						// moving the starting point of the copy backwards
						// will allow us to shorten the insert. Our hash
						// may not have allowed us to identify this area.
						// Since it is quite fast to perform a negative
						// scan, try to stretch backwards too.
						//
						neg = blkPtr - resPtr;
						neg = negmatch(res, blkPtr, src, valOf(ent), neg);
					}

					int len = neg + fwdmatch(res, blkPtr, src, valOf(ent));
					if (bestLen < len) {
						bestLen = len;
						bestPtr = valOf(ent);
						bestNeg = neg;
					}
				} else if ((keyOf(ent) & tableMask) != tableIdx)
					break;
			} while (bestLen < 4096 && entryIdx < entries.length);

			if (bestLen < BLKSZ) {
				// All of the locations were false positives, or the copy
				// is shorter than a block. In the latter case this won't
				// give us a very great copy instruction, so delay and try
				// at the next byte.
				//
				hash = step(hash, res[blkPtr++], res[blkEnd++]);
				continue;
			}

			blkPtr -= bestNeg;

			if (resPtr < blkPtr) {
				// There are bytes between the last instruction we made
				// and the current block pointer. None of these matched
				// during the earlier iteration so insert them directly
				// into the instruction stream.
				//
				int cnt = blkPtr - resPtr;
				if (!enc.insert(res, resPtr, cnt))
					return false;
			}

			if (!enc.copy(bestPtr - bestNeg, bestLen))
				return false;

			blkPtr += bestLen;
			resPtr = blkPtr;
			blkEnd = blkPtr + BLKSZ;

			// If we don't have a full block available to us, abort now.
			//
			if (end <= blkEnd)
				break;

			// Start a new hash of the block after the copy region.
			//
			hash = hashBlock(res, blkPtr);
		}

		if (resPtr < end) {
			// There were bytes at the end which didn't match, or maybe
			// didn't make a full block. Insert whatever is left over.
			//
			int cnt = end - resPtr;
			return enc.insert(res, resPtr, cnt);
		}
		return true;
	}

	private DeltaEncoder newEncoder(OutputStream out, long resSize, int limit)
			throws IOException {
		return new DeltaEncoder(out, getSourceSize(), resSize, limit);
	}

	private static int fwdmatch(byte[] res, int resPtr, byte[] src, int srcPtr) {
		int start = resPtr;
		for (; resPtr < res.length && srcPtr < src.length; resPtr++, srcPtr++) {
			if (res[resPtr] != src[srcPtr])
				break;
		}
		return resPtr - start;
	}

	private static int negmatch(byte[] res, int resPtr, byte[] src, int srcPtr,
			int limit) {
		if (srcPtr == 0)
			return 0;

		resPtr--;
		srcPtr--;
		int start = resPtr;
		do {
			if (res[resPtr] != src[srcPtr])
				break;
			resPtr--;
			srcPtr--;
		} while (0 <= srcPtr && 0 < --limit);
		return start - resPtr;
	}

	/** {@inheritDoc} */
	@Override
	@SuppressWarnings("nls")
	public String toString() {
		String[] units = { "bytes", "KiB", "MiB", "GiB" };
		long sz = getIndexSize();
		int u = 0;
		while (1024 <= sz && u < units.length - 1) {
			int rem = (int) (sz % 1024);
			sz /= 1024;
			if (rem != 0)
				sz++;
			u++;
		}
		return "DeltaIndex[" + sz + " " + units[u] + "]";
	}

	static int hashBlock(byte[] raw, int ptr) {
		int hash;

		// The first 4 steps collapse out into a 4 byte big-endian decode,
		// with a larger right shift as we combined shift lefts together.
		//
		hash = ((raw[ptr] & 0xff) << 24) //
				| ((raw[ptr + 1] & 0xff) << 16) //
				| ((raw[ptr + 2] & 0xff) << 8) //
				| (raw[ptr + 3] & 0xff);
		hash ^= T[hash >>> 31];

		hash = ((hash << 8) | (raw[ptr + 4] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 5] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 6] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 7] & 0xff)) ^ T[hash >>> 23];

		hash = ((hash << 8) | (raw[ptr + 8] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 9] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 10] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 11] & 0xff)) ^ T[hash >>> 23];

		hash = ((hash << 8) | (raw[ptr + 12] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 13] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 14] & 0xff)) ^ T[hash >>> 23];
		hash = ((hash << 8) | (raw[ptr + 15] & 0xff)) ^ T[hash >>> 23];

		return hash;
	}

	private static int step(int hash, byte toRemove, byte toAdd) {
		hash ^= U[toRemove & 0xff];
		return ((hash << 8) | (toAdd & 0xff)) ^ T[hash >>> 23];
	}

	private static int keyOf(long ent) {
		return (int) (ent >>> 32);
	}

	private static int valOf(long ent) {
		return (int) ent;
	}

	private static final int[] T = { 0x00000000, 0xd4c6b32d, 0x7d4bd577,
			0xa98d665a, 0x2e5119c3, 0xfa97aaee, 0x531accb4, 0x87dc7f99,
			0x5ca23386, 0x886480ab, 0x21e9e6f1, 0xf52f55dc, 0x72f32a45,
			0xa6359968, 0x0fb8ff32, 0xdb7e4c1f, 0x6d82d421, 0xb944670c,
			0x10c90156, 0xc40fb27b, 0x43d3cde2, 0x97157ecf, 0x3e981895,
			0xea5eabb8, 0x3120e7a7, 0xe5e6548a, 0x4c6b32d0, 0x98ad81fd,
			0x1f71fe64, 0xcbb74d49, 0x623a2b13, 0xb6fc983e, 0x0fc31b6f,
			0xdb05a842, 0x7288ce18, 0xa64e7d35, 0x219202ac, 0xf554b181,
			0x5cd9d7db, 0x881f64f6, 0x536128e9, 0x87a79bc4, 0x2e2afd9e,
			0xfaec4eb3, 0x7d30312a, 0xa9f68207, 0x007be45d, 0xd4bd5770,
			0x6241cf4e, 0xb6877c63, 0x1f0a1a39, 0xcbcca914, 0x4c10d68d,
			0x98d665a0, 0x315b03fa, 0xe59db0d7, 0x3ee3fcc8, 0xea254fe5,
			0x43a829bf, 0x976e9a92, 0x10b2e50b, 0xc4745626, 0x6df9307c,
			0xb93f8351, 0x1f8636de, 0xcb4085f3, 0x62cde3a9, 0xb60b5084,
			0x31d72f1d, 0xe5119c30, 0x4c9cfa6a, 0x985a4947, 0x43240558,
			0x97e2b675, 0x3e6fd02f, 0xeaa96302, 0x6d751c9b, 0xb9b3afb6,
			0x103ec9ec, 0xc4f87ac1, 0x7204e2ff, 0xa6c251d2, 0x0f4f3788,
			0xdb8984a5, 0x5c55fb3c, 0x88934811, 0x211e2e4b, 0xf5d89d66,
			0x2ea6d179, 0xfa606254, 0x53ed040e, 0x872bb723, 0x00f7c8ba,
			0xd4317b97, 0x7dbc1dcd, 0xa97aaee0, 0x10452db1, 0xc4839e9c,
			0x6d0ef8c6, 0xb9c84beb, 0x3e143472, 0xead2875f, 0x435fe105,
			0x97995228, 0x4ce71e37, 0x9821ad1a, 0x31accb40, 0xe56a786d,
			0x62b607f4, 0xb670b4d9, 0x1ffdd283, 0xcb3b61ae, 0x7dc7f990,
			0xa9014abd, 0x008c2ce7, 0xd44a9fca, 0x5396e053, 0x8750537e,
			0x2edd3524, 0xfa1b8609, 0x2165ca16, 0xf5a3793b, 0x5c2e1f61,
			0x88e8ac4c, 0x0f34d3d5, 0xdbf260f8, 0x727f06a2, 0xa6b9b58f,
			0x3f0c6dbc, 0xebcade91, 0x4247b8cb, 0x96810be6, 0x115d747f,
			0xc59bc752, 0x6c16a108, 0xb8d01225, 0x63ae5e3a, 0xb768ed17,
			0x1ee58b4d, 0xca233860, 0x4dff47f9, 0x9939f4d4, 0x30b4928e,
			0xe47221a3, 0x528eb99d, 0x86480ab0, 0x2fc56cea, 0xfb03dfc7,
			0x7cdfa05e, 0xa8191373, 0x01947529, 0xd552c604, 0x0e2c8a1b,
			0xdaea3936, 0x73675f6c, 0xa7a1ec41, 0x207d93d8, 0xf4bb20f5,
			0x5d3646af, 0x89f0f582, 0x30cf76d3, 0xe409c5fe, 0x4d84a3a4,
			0x99421089, 0x1e9e6f10, 0xca58dc3d, 0x63d5ba67, 0xb713094a,
			0x6c6d4555, 0xb8abf678, 0x11269022, 0xc5e0230f, 0x423c5c96,
			0x96faefbb, 0x3f7789e1, 0xebb13acc, 0x5d4da2f2, 0x898b11df,
			0x20067785, 0xf4c0c4a8, 0x731cbb31, 0xa7da081c, 0x0e576e46,
			0xda91dd6b, 0x01ef9174, 0xd5292259, 0x7ca44403, 0xa862f72e,
			0x2fbe88b7, 0xfb783b9a, 0x52f55dc0, 0x8633eeed, 0x208a5b62,
			0xf44ce84f, 0x5dc18e15, 0x89073d38, 0x0edb42a1, 0xda1df18c,
			0x739097d6, 0xa75624fb, 0x7c2868e4, 0xa8eedbc9, 0x0163bd93,
			0xd5a50ebe, 0x52797127, 0x86bfc20a, 0x2f32a450, 0xfbf4177d,
			0x4d088f43, 0x99ce3c6e, 0x30435a34, 0xe485e919, 0x63599680,
			0xb79f25ad, 0x1e1243f7, 0xcad4f0da, 0x11aabcc5, 0xc56c0fe8,
			0x6ce169b2, 0xb827da9f, 0x3ffba506, 0xeb3d162b, 0x42b07071,
			0x9676c35c, 0x2f49400d, 0xfb8ff320, 0x5202957a, 0x86c42657,
			0x011859ce, 0xd5deeae3, 0x7c538cb9, 0xa8953f94, 0x73eb738b,
			0xa72dc0a6, 0x0ea0a6fc, 0xda6615d1, 0x5dba6a48, 0x897cd965,
			0x20f1bf3f, 0xf4370c12, 0x42cb942c, 0x960d2701, 0x3f80415b,
			0xeb46f276, 0x6c9a8def, 0xb85c3ec2, 0x11d15898, 0xc517ebb5,
			0x1e69a7aa, 0xcaaf1487, 0x632272dd, 0xb7e4c1f0, 0x3038be69,
			0xe4fe0d44, 0x4d736b1e, 0x99b5d833 };

	private static final int[] U = { 0x00000000, 0x12c6e90f, 0x258dd21e,
			0x374b3b11, 0x4b1ba43c, 0x59dd4d33, 0x6e967622, 0x7c509f2d,
			0x42f1fb55, 0x5037125a, 0x677c294b, 0x75bac044, 0x09ea5f69,
			0x1b2cb666, 0x2c678d77, 0x3ea16478, 0x51254587, 0x43e3ac88,
			0x74a89799, 0x666e7e96, 0x1a3ee1bb, 0x08f808b4, 0x3fb333a5,
			0x2d75daaa, 0x13d4bed2, 0x011257dd, 0x36596ccc, 0x249f85c3,
			0x58cf1aee, 0x4a09f3e1, 0x7d42c8f0, 0x6f8421ff, 0x768c3823,
			0x644ad12c, 0x5301ea3d, 0x41c70332, 0x3d979c1f, 0x2f517510,
			0x181a4e01, 0x0adca70e, 0x347dc376, 0x26bb2a79, 0x11f01168,
			0x0336f867, 0x7f66674a, 0x6da08e45, 0x5aebb554, 0x482d5c5b,
			0x27a97da4, 0x356f94ab, 0x0224afba, 0x10e246b5, 0x6cb2d998,
			0x7e743097, 0x493f0b86, 0x5bf9e289, 0x655886f1, 0x779e6ffe,
			0x40d554ef, 0x5213bde0, 0x2e4322cd, 0x3c85cbc2, 0x0bcef0d3,
			0x190819dc, 0x39dec36b, 0x2b182a64, 0x1c531175, 0x0e95f87a,
			0x72c56757, 0x60038e58, 0x5748b549, 0x458e5c46, 0x7b2f383e,
			0x69e9d131, 0x5ea2ea20, 0x4c64032f, 0x30349c02, 0x22f2750d,
			0x15b94e1c, 0x077fa713, 0x68fb86ec, 0x7a3d6fe3, 0x4d7654f2,
			0x5fb0bdfd, 0x23e022d0, 0x3126cbdf, 0x066df0ce, 0x14ab19c1,
			0x2a0a7db9, 0x38cc94b6, 0x0f87afa7, 0x1d4146a8, 0x6111d985,
			0x73d7308a, 0x449c0b9b, 0x565ae294, 0x4f52fb48, 0x5d941247,
			0x6adf2956, 0x7819c059, 0x04495f74, 0x168fb67b, 0x21c48d6a,
			0x33026465, 0x0da3001d, 0x1f65e912, 0x282ed203, 0x3ae83b0c,
			0x46b8a421, 0x547e4d2e, 0x6335763f, 0x71f39f30, 0x1e77becf,
			0x0cb157c0, 0x3bfa6cd1, 0x293c85de, 0x556c1af3, 0x47aaf3fc,
			0x70e1c8ed, 0x622721e2, 0x5c86459a, 0x4e40ac95, 0x790b9784,
			0x6bcd7e8b, 0x179de1a6, 0x055b08a9, 0x321033b8, 0x20d6dab7,
			0x73bd86d6, 0x617b6fd9, 0x563054c8, 0x44f6bdc7, 0x38a622ea,
			0x2a60cbe5, 0x1d2bf0f4, 0x0fed19fb, 0x314c7d83, 0x238a948c,
			0x14c1af9d, 0x06074692, 0x7a57d9bf, 0x689130b0, 0x5fda0ba1,
			0x4d1ce2ae, 0x2298c351, 0x305e2a5e, 0x0715114f, 0x15d3f840,
			0x6983676d, 0x7b458e62, 0x4c0eb573, 0x5ec85c7c, 0x60693804,
			0x72afd10b, 0x45e4ea1a, 0x57220315, 0x2b729c38, 0x39b47537,
			0x0eff4e26, 0x1c39a729, 0x0531bef5, 0x17f757fa, 0x20bc6ceb,
			0x327a85e4, 0x4e2a1ac9, 0x5cecf3c6, 0x6ba7c8d7, 0x796121d8,
			0x47c045a0, 0x5506acaf, 0x624d97be, 0x708b7eb1, 0x0cdbe19c,
			0x1e1d0893, 0x29563382, 0x3b90da8d, 0x5414fb72, 0x46d2127d,
			0x7199296c, 0x635fc063, 0x1f0f5f4e, 0x0dc9b641, 0x3a828d50,
			0x2844645f, 0x16e50027, 0x0423e928, 0x3368d239, 0x21ae3b36,
			0x5dfea41b, 0x4f384d14, 0x78737605, 0x6ab59f0a, 0x4a6345bd,
			0x58a5acb2, 0x6fee97a3, 0x7d287eac, 0x0178e181, 0x13be088e,
			0x24f5339f, 0x3633da90, 0x0892bee8, 0x1a5457e7, 0x2d1f6cf6,
			0x3fd985f9, 0x43891ad4, 0x514ff3db, 0x6604c8ca, 0x74c221c5,
			0x1b46003a, 0x0980e935, 0x3ecbd224, 0x2c0d3b2b, 0x505da406,
			0x429b4d09, 0x75d07618, 0x67169f17, 0x59b7fb6f, 0x4b711260,
			0x7c3a2971, 0x6efcc07e, 0x12ac5f53, 0x006ab65c, 0x37218d4d,
			0x25e76442, 0x3cef7d9e, 0x2e299491, 0x1962af80, 0x0ba4468f,
			0x77f4d9a2, 0x653230ad, 0x52790bbc, 0x40bfe2b3, 0x7e1e86cb,
			0x6cd86fc4, 0x5b9354d5, 0x4955bdda, 0x350522f7, 0x27c3cbf8,
			0x1088f0e9, 0x024e19e6, 0x6dca3819, 0x7f0cd116, 0x4847ea07,
			0x5a810308, 0x26d19c25, 0x3417752a, 0x035c4e3b, 0x119aa734,
			0x2f3bc34c, 0x3dfd2a43, 0x0ab61152, 0x1870f85d, 0x64206770,
			0x76e68e7f, 0x41adb56e, 0x536b5c61 };
}