io.airlift.compress.lzo.LzoRawDecompressor Maven / Gradle / Ivy
/*
* 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 io.airlift.compress.lzo;
import io.airlift.compress.MalformedInputException;
import static io.airlift.compress.lzo.LzoConstants.SIZE_OF_INT;
import static io.airlift.compress.lzo.LzoConstants.SIZE_OF_LONG;
import static io.airlift.compress.lzo.LzoConstants.SIZE_OF_SHORT;
import static io.airlift.compress.lzo.UnsafeUtil.UNSAFE;
import static java.lang.Integer.toBinaryString;
public final class LzoRawDecompressor
{
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 LzoRawDecompressor() {}
public static int decompress(
final Object inputBase,
final long inputAddress,
final long inputLimit,
final Object outputBase,
final long outputAddress,
final long outputLimit)
throws MalformedInputException
{
// nothing compresses to nothing
if (inputAddress == inputLimit) {
return 0;
}
// maximum offset in buffers to which it's safe to write long-at-a-time
final long fastOutputLimit = outputLimit - SIZE_OF_LONG;
// LZO can concat two blocks together so, decode until the input data is consumed
long input = inputAddress;
long output = outputAddress;
while (input < inputLimit) {
//
// Note: For safety some of the code below may stop decoding early or skip decoding,
// because input is not available. This makes the code safe, and since LZO requires
// an explicit "stop" command, the decoder will still throw a exception.
//
boolean firstCommand = true;
int lastLiteralLength = 0;
while (true) {
if (input >= inputLimit) {
throw new MalformedInputException(input - inputAddress);
}
int command = UNSAFE.getByte(inputBase, input++) & 0xFF;
if (command == 0b0001_0001) {
break;
}
// Commands are described using a bit pattern notation:
// 0: bit is not set
// 1: bit is set
// L: part of literal length
// P: part of match offset position
// M: part of match length
// ?: see documentation in command decoder
int matchLength;
int matchOffset;
int literalLength;
if ((command & 0b1111_0000) == 0b0000_0000) {
if (lastLiteralLength == 0) {
// 0b0000_LLLL (0bLLLL_LLLL)*
// copy length :: fixed
// 0
matchOffset = 0;
// copy offset :: fixed
// 0
matchLength = 0;
// literal length - 3 :: variable bits :: valid range [4..]
// 3 + variableLength(command bits [0..3], 4)
literalLength = command & 0b1111;
if (literalLength == 0) {
literalLength = 0b1111;
int nextByte = 0;
while (input < inputLimit && (nextByte = UNSAFE.getByte(inputBase, input++) & 0xFF) == 0) {
literalLength += 0b1111_1111;
}
literalLength += nextByte;
}
literalLength += 3;
}
else if (lastLiteralLength <= 3) {
// 0b0000_PPLL 0bPPPP_PPPP
// copy length: fixed
// 3
matchLength = 3;
// copy offset :: 12 bits :: valid range [2048..3071]
// [0..1] from command [2..3]
// [2..9] from trailer [0..7]
// [10] unset
// [11] set
if (input >= inputLimit) {
throw new MalformedInputException(input - inputAddress);
}
matchOffset = (command & 0b1100) >>> 2;
matchOffset |= (UNSAFE.getByte(inputBase, input++) & 0xFF) << 2;
matchOffset |= 0b1000_0000_0000;
// literal length :: 2 bits :: valid range [0..3]
// [0..1] from command [0..1]
literalLength = (command & 0b0000_0011);
}
else {
// 0b0000_PPLL 0bPPPP_PPPP
// copy length :: fixed
// 2
matchLength = 2;
// copy offset :: 10 bits :: valid range [0..1023]
// [0..1] from command [2..3]
// [2..9] from trailer [0..7]
if (input >= inputLimit) {
throw new MalformedInputException(input - inputAddress);
}
matchOffset = (command & 0b1100) >>> 2;
matchOffset |= (UNSAFE.getByte(inputBase, input++) & 0xFF) << 2;
// literal length :: 2 bits :: valid range [0..3]
// [0..1] from command [0..1]
literalLength = (command & 0b0000_0011);
}
}
else if (firstCommand) {
// first command has special handling when high nibble is set
matchLength = 0;
matchOffset = 0;
literalLength = command - 17;
}
else if ((command & 0b1111_0000) == 0b0001_0000) {
// 0b0001_?MMM (0bMMMM_MMMM)* 0bPPPP_PPPP_PPPP_PPLL
// copy length - 2 :: variable bits :: valid range [3..]
// 2 + variableLength(command bits [0..2], 3)
matchLength = command & 0b111;
if (matchLength == 0) {
matchLength = 0b111;
int nextByte = 0;
while (input < inputLimit && (nextByte = UNSAFE.getByte(inputBase, input++) & 0xFF) == 0) {
matchLength += 0b1111_1111;
}
matchLength += nextByte;
}
matchLength += 2;
// read trailer
if (input + SIZE_OF_SHORT > inputLimit) {
throw new MalformedInputException(input - inputAddress);
}
int trailer = UNSAFE.getShort(inputBase, input) & 0xFFFF;
input += SIZE_OF_SHORT;
// copy offset :: 16 bits :: valid range [32767..49151]
// [0..13] from trailer [2..15]
// [14] if command bit [3] unset
// [15] if command bit [3] set
matchOffset = trailer >> 2;
if ((command & 0b1000) == 0) {
matchOffset |= 0b0100_0000_0000_0000;
}
else {
matchOffset |= 0b1000_0000_0000_0000;
}
matchOffset--;
// literal length :: 2 bits :: valid range [0..3]
// [0..1] from trailer [0..1]
literalLength = trailer & 0b11;
}
else if ((command & 0b1110_0000) == 0b0010_0000) {
// 0b001M_MMMM (0bMMMM_MMMM)* 0bPPPP_PPPP_PPPP_PPLL
// copy length - 2 :: variable bits :: valid range [3..]
// 2 + variableLength(command bits [0..4], 5)
matchLength = command & 0b1_1111;
if (matchLength == 0) {
matchLength = 0b1_1111;
int nextByte = 0;
while (input < inputLimit && (nextByte = UNSAFE.getByte(inputBase, input++) & 0xFF) == 0) {
matchLength += 0b1111_1111;
}
matchLength += nextByte;
}
matchLength += 2;
// read trailer
if (input + SIZE_OF_SHORT > inputLimit) {
throw new MalformedInputException(input - inputAddress);
}
int trailer = UNSAFE.getShort(inputBase, input) & 0xFFFF;
input += SIZE_OF_SHORT;
// copy offset :: 14 bits :: valid range [0..16383]
// [0..13] from trailer [2..15]
matchOffset = trailer >>> 2;
// literal length :: 2 bits :: valid range [0..3]
// [0..1] from trailer [0..1]
literalLength = trailer & 0b11;
}
else if ((command & 0b1100_0000) != 0) {
// 0bMMMP_PPLL 0bPPPP_PPPP
// copy length - 1 :: 3 bits :: valid range [1..8]
// [0..2] from command [5..7]
// add 1
matchLength = (command & 0b1110_0000) >>> 5;
matchLength += 1;
// copy offset :: 11 bits :: valid range [0..4095]
// [0..2] from command [2..4]
// [3..10] from trailer [0..7]
if (input >= inputLimit) {
throw new MalformedInputException(input - inputAddress);
}
matchOffset = (command & 0b0001_1100) >>> 2;
matchOffset |= (UNSAFE.getByte(inputBase, input++) & 0xFF) << 3;
// literal length :: 2 bits :: valid range [0..3]
// [0..1] from command [0..1]
literalLength = (command & 0b0000_0011);
}
else {
String binary = toBinary(command);
throw new MalformedInputException(input - 1, "Invalid LZO command " + binary);
}
firstCommand = false;
// copy match
if (matchLength != 0) {
// lzo encodes match offset minus one
matchOffset++;
long matchAddress = output - matchOffset;
if (matchAddress < outputAddress || output + matchLength > outputLimit) {
throw new MalformedInputException(input - inputAddress);
}
long matchOutputLimit = output + matchLength;
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 MalformedInputException(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
}
// copy literal
long literalOutputLimit = output + literalLength;
if (literalOutputLimit > fastOutputLimit || input + literalLength > inputLimit - SIZE_OF_LONG) {
if (literalOutputLimit > outputLimit) {
throw new MalformedInputException(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;
}
lastLiteralLength = literalLength;
}
if (input + SIZE_OF_SHORT > inputLimit && UNSAFE.getShort(inputBase, input) != 0) {
throw new MalformedInputException(input - inputAddress);
}
input += SIZE_OF_SHORT;
}
return (int) (output - outputAddress);
}
private static String toBinary(int command)
{
String binaryString = String.format("%8s", toBinaryString(command)).replace(' ', '0');
return "0b" + binaryString.substring(0, 4) + "_" + binaryString.substring(4);
}
}
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