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Snappy-Java Source Code
Snappy-Java is a Java port of the "snappy", a fast C++ compresser/decompresser developed by Google.
Snappy-Java Source Code files are provided in the source packge (snappy-java-1.1.8.4-sources.jar). You can download it at Snappy Maven Website.
You can also browse Snappy-Java Source Code below:
✍: FYIcenter.com
⏎ org/xerial/snappy/pure/SnappyRawDecompressor.java
/* * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.xerial.snappy.pure; import java.nio.ByteOrder; import org.xerial.snappy.SnappyError; import org.xerial.snappy.SnappyErrorCode; import static org.xerial.snappy.pure.SnappyConstants.LITERAL; import static org.xerial.snappy.pure.SnappyConstants.SIZE_OF_INT; import static org.xerial.snappy.pure.SnappyConstants.SIZE_OF_LONG; import static org.xerial.snappy.pure.UnsafeUtil.UNSAFE; import static java.lang.Integer.reverseBytes; public final class SnappyRawDecompressor { private static final int[] DEC_32_TABLE = {4, 1, 2, 1, 4, 4, 4, 4}; private static final int[] DEC_64_TABLE = {0, 0, 0, -1, 0, 1, 2, 3}; private SnappyRawDecompressor() {} private static final ByteOrder byteOrder = ByteOrder.nativeOrder(); private static int littleEndian(int i) { return (byteOrder == ByteOrder.LITTLE_ENDIAN) ? i : reverseBytes(i); } public static int getUncompressedLength(Object compressed, long compressedAddress, long compressedLimit) { return readUncompressedLength(compressed, compressedAddress, compressedLimit)[0]; } public static int decompress( final Object inputBase, final long inputAddress, final long inputLimit, final Object outputBase, final long outputAddress, final long outputLimit) { // Read the uncompressed length from the front of the input long input = inputAddress; int[] varInt = readUncompressedLength(inputBase, input, inputLimit); int expectedLength = varInt[0]; input += varInt[1]; if(!(expectedLength <= (outputLimit - outputAddress))) { throw new SnappyError(SnappyErrorCode.INVALID_CHUNK_SIZE, String.format("Uncompressed length %s must be less than %s", expectedLength, (outputLimit - outputAddress))); } // Process the entire input int uncompressedSize = uncompressAll( inputBase, input, inputLimit, outputBase, outputAddress, outputLimit); if (!(expectedLength == uncompressedSize)) { throw new SnappyError(SnappyErrorCode.INVALID_CHUNK_SIZE, String.format("Recorded length is %s bytes but actual length after decompression is %s bytes ", expectedLength, uncompressedSize)); } return expectedLength; } private static int uncompressAll( final Object inputBase, final long inputAddress, final long inputLimit, final Object outputBase, final long outputAddress, final long outputLimit) { final long fastOutputLimit = outputLimit - SIZE_OF_LONG; // maximum offset in output buffer to which it's safe to write long-at-a-time long output = outputAddress; long input = inputAddress; while (input < inputLimit) { int opCode = UNSAFE.getByte(inputBase, input++) & 0xFF; int entry = opLookupTable[opCode] & 0xFFFF; int trailerBytes = entry >>> 11; int trailer = 0; if (input + SIZE_OF_INT < inputLimit) { trailer = littleEndian(UNSAFE.getInt(inputBase, input)) & wordmask[trailerBytes]; } else { if (input + trailerBytes > inputLimit) { throw new SnappyError(SnappyErrorCode.PARSING_ERROR, String.format("position: %d", input - inputAddress)); } switch (trailerBytes) { case 4: trailer = (UNSAFE.getByte(inputBase, input + 3) & 0xff) << 24; case 3: trailer |= (UNSAFE.getByte(inputBase, input + 2) & 0xff) << 16; case 2: trailer |= (UNSAFE.getByte(inputBase, input + 1) & 0xff) << 8; case 1: trailer |= (UNSAFE.getByte(inputBase, input) & 0xff); } } if (trailer < 0) { throw new SnappyError(SnappyErrorCode.PARSING_ERROR, String.format("position: %d", input - inputAddress)); } input += trailerBytes; int length = entry & 0xff; if (length == 0) { continue; } if ((opCode & 0x3) == LITERAL) { int literalLength = length + trailer; // copy literal long literalOutputLimit = output + literalLength; if (literalOutputLimit > fastOutputLimit || input + literalLength > inputLimit - SIZE_OF_LONG) { if (literalOutputLimit > outputLimit) { throw new SnappyError(SnappyErrorCode.PARSING_ERROR, String.format("position: %d", input - inputAddress)); } // slow, precise copy UNSAFE.copyMemory(inputBase, input, outputBase, output, literalLength); input += literalLength; output += literalLength; } else { // fast copy. We may over-copy but there's enough room in input and output to not overrun them do { UNSAFE.putLong(outputBase, output, UNSAFE.getLong(inputBase, input)); input += SIZE_OF_LONG; output += SIZE_OF_LONG; } while (output < literalOutputLimit); input -= (output - literalOutputLimit); // adjust index if we over-copied output = literalOutputLimit; } } else { // matchOffset/256 is encoded in bits 8..10. By just fetching // those bits, we get matchOffset (since the bit-field starts at // bit 8). int matchOffset = entry & 0x700; matchOffset += trailer; long matchAddress = output - matchOffset; if (matchAddress < outputAddress || output + length > outputLimit) { throw new SnappyError(SnappyErrorCode.PARSING_ERROR, String.format("position: %d", input - inputAddress)); } long matchOutputLimit = output + length; if (output > fastOutputLimit) { // slow match copy while (output < matchOutputLimit) { UNSAFE.putByte(outputBase, output++, UNSAFE.getByte(outputBase, matchAddress++)); } } else { // copy repeated sequence if (matchOffset < SIZE_OF_LONG) { // 8 bytes apart so that we can copy long-at-a-time below int increment32 = DEC_32_TABLE[matchOffset]; int decrement64 = DEC_64_TABLE[matchOffset]; UNSAFE.putByte(outputBase, output, UNSAFE.getByte(outputBase, matchAddress)); UNSAFE.putByte(outputBase, output + 1, UNSAFE.getByte(outputBase, matchAddress + 1)); UNSAFE.putByte(outputBase, output + 2, UNSAFE.getByte(outputBase, matchAddress + 2)); UNSAFE.putByte(outputBase, output + 3, UNSAFE.getByte(outputBase, matchAddress + 3)); output += SIZE_OF_INT; matchAddress += increment32; UNSAFE.putInt(outputBase, output, UNSAFE.getInt(outputBase, matchAddress)); output += SIZE_OF_INT; matchAddress -= decrement64; } else { UNSAFE.putLong(outputBase, output, UNSAFE.getLong(outputBase, matchAddress)); matchAddress += SIZE_OF_LONG; output += SIZE_OF_LONG; } if (matchOutputLimit > fastOutputLimit) { if (matchOutputLimit > outputLimit) { throw new SnappyError(SnappyErrorCode.PARSING_ERROR, String.format("position: %d", input - inputAddress)); } while (output < fastOutputLimit) { UNSAFE.putLong(outputBase, output, UNSAFE.getLong(outputBase, matchAddress)); matchAddress += SIZE_OF_LONG; output += SIZE_OF_LONG; } while (output < matchOutputLimit) { UNSAFE.putByte(outputBase, output++, UNSAFE.getByte(outputBase, matchAddress++)); } } else { while (output < matchOutputLimit) { UNSAFE.putLong(outputBase, output, UNSAFE.getLong(outputBase, matchAddress)); matchAddress += SIZE_OF_LONG; output += SIZE_OF_LONG; } } } output = matchOutputLimit; // correction in case we over-copied } } return (int) (output - outputAddress); } // Mapping from i in range [0,4] to a mask to extract the bottom 8*i bits private static final int[] wordmask = new int[] { 0, 0xff, 0xffff, 0xffffff, 0xffffffff }; // Data stored per entry in lookup table: // Range Bits-used Description // ------------------------------------ // 1..64 0..7 Literal/copy length encoded in opcode byte // 0..7 8..10 Copy offset encoded in opcode byte / 256 // 0..4 11..13 Extra bytes after opcode // // We use eight bits for the length even though 7 would have sufficed // because of efficiency reasons: // (1) Extracting a byte is faster than a bit-field // (2) It properly aligns copy offset so we do not need a <<8 private static final short[] opLookupTable = new short[] { 0x0001, 0x0804, 0x1001, 0x2001, 0x0002, 0x0805, 0x1002, 0x2002, 0x0003, 0x0806, 0x1003, 0x2003, 0x0004, 0x0807, 0x1004, 0x2004, 0x0005, 0x0808, 0x1005, 0x2005, 0x0006, 0x0809, 0x1006, 0x2006, 0x0007, 0x080a, 0x1007, 0x2007, 0x0008, 0x080b, 0x1008, 0x2008, 0x0009, 0x0904, 0x1009, 0x2009, 0x000a, 0x0905, 0x100a, 0x200a, 0x000b, 0x0906, 0x100b, 0x200b, 0x000c, 0x0907, 0x100c, 0x200c, 0x000d, 0x0908, 0x100d, 0x200d, 0x000e, 0x0909, 0x100e, 0x200e, 0x000f, 0x090a, 0x100f, 0x200f, 0x0010, 0x090b, 0x1010, 0x2010, 0x0011, 0x0a04, 0x1011, 0x2011, 0x0012, 0x0a05, 0x1012, 0x2012, 0x0013, 0x0a06, 0x1013, 0x2013, 0x0014, 0x0a07, 0x1014, 0x2014, 0x0015, 0x0a08, 0x1015, 0x2015, 0x0016, 0x0a09, 0x1016, 0x2016, 0x0017, 0x0a0a, 0x1017, 0x2017, 0x0018, 0x0a0b, 0x1018, 0x2018, 0x0019, 0x0b04, 0x1019, 0x2019, 0x001a, 0x0b05, 0x101a, 0x201a, 0x001b, 0x0b06, 0x101b, 0x201b, 0x001c, 0x0b07, 0x101c, 0x201c, 0x001d, 0x0b08, 0x101d, 0x201d, 0x001e, 0x0b09, 0x101e, 0x201e, 0x001f, 0x0b0a, 0x101f, 0x201f, 0x0020, 0x0b0b, 0x1020, 0x2020, 0x0021, 0x0c04, 0x1021, 0x2021, 0x0022, 0x0c05, 0x1022, 0x2022, 0x0023, 0x0c06, 0x1023, 0x2023, 0x0024, 0x0c07, 0x1024, 0x2024, 0x0025, 0x0c08, 0x1025, 0x2025, 0x0026, 0x0c09, 0x1026, 0x2026, 0x0027, 0x0c0a, 0x1027, 0x2027, 0x0028, 0x0c0b, 0x1028, 0x2028, 0x0029, 0x0d04, 0x1029, 0x2029, 0x002a, 0x0d05, 0x102a, 0x202a, 0x002b, 0x0d06, 0x102b, 0x202b, 0x002c, 0x0d07, 0x102c, 0x202c, 0x002d, 0x0d08, 0x102d, 0x202d, 0x002e, 0x0d09, 0x102e, 0x202e, 0x002f, 0x0d0a, 0x102f, 0x202f, 0x0030, 0x0d0b, 0x1030, 0x2030, 0x0031, 0x0e04, 0x1031, 0x2031, 0x0032, 0x0e05, 0x1032, 0x2032, 0x0033, 0x0e06, 0x1033, 0x2033, 0x0034, 0x0e07, 0x1034, 0x2034, 0x0035, 0x0e08, 0x1035, 0x2035, 0x0036, 0x0e09, 0x1036, 0x2036, 0x0037, 0x0e0a, 0x1037, 0x2037, 0x0038, 0x0e0b, 0x1038, 0x2038, 0x0039, 0x0f04, 0x1039, 0x2039, 0x003a, 0x0f05, 0x103a, 0x203a, 0x003b, 0x0f06, 0x103b, 0x203b, 0x003c, 0x0f07, 0x103c, 0x203c, 0x0801, 0x0f08, 0x103d, 0x203d, 0x1001, 0x0f09, 0x103e, 0x203e, 0x1801, 0x0f0a, 0x103f, 0x203f, 0x2001, 0x0f0b, 0x1040, 0x2040 }; /** * Reads the variable length integer encoded a the specified offset, and * returns this length with the number of bytes read. */ static int[] readUncompressedLength(Object compressed, long compressedAddress, long compressedLimit) { int result; int bytesRead = 0; { int b = getUnsignedByteSafe(compressed, compressedAddress + bytesRead, compressedLimit); bytesRead++; result = b & 0x7f; if ((b & 0x80) != 0) { b = getUnsignedByteSafe(compressed, compressedAddress + bytesRead, compressedLimit); bytesRead++; result |= (b & 0x7f) << 7; if ((b & 0x80) != 0) { b = getUnsignedByteSafe(compressed, compressedAddress + bytesRead, compressedLimit); bytesRead++; result |= (b & 0x7f) << 14; if ((b & 0x80) != 0) { b = getUnsignedByteSafe(compressed, compressedAddress + bytesRead, compressedLimit); bytesRead++; result |= (b & 0x7f) << 21; if ((b & 0x80) != 0) { b = getUnsignedByteSafe(compressed, compressedAddress + bytesRead, compressedLimit); bytesRead++; result |= (b & 0x7f) << 28; if ((b & 0x80) != 0) { throw new SnappyError(SnappyErrorCode.PARSING_ERROR, String.format("position: %d, error: %s", compressedAddress + bytesRead, "last byte of compressed length int has high bit set")); } } } } } } return new int[] {result, bytesRead}; } private static int getUnsignedByteSafe(Object base, long address, long limit) { if (address >= limit) { throw new SnappyError(SnappyErrorCode.PARSING_ERROR, String.format("position: %d, error: %s", limit - address, "Input is truncated")); } return UNSAFE.getByte(base, address) & 0xFF; } }
⏎ org/xerial/snappy/pure/SnappyRawDecompressor.java
Or download all of them as a single archive file:
File name: snappy-java-1.1.8.4-sources.jar File size: 1962098 bytes Release date: 2021-01-25 Download
⇒ Download and Install Snappy-Java Binary Package
2021-07-13, 18944👍, 0💬
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