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com.itextpdf.io.codec.brotli.dec.Decode Maven / Gradle / Ivy
/* Copyright 2015 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
package com.itextpdf.io.codec.brotli.dec;
/**
* API for Brotli decompression.
*/
final class Decode {
private static final int DEFAULT_CODE_LENGTH = 8;
private static final int CODE_LENGTH_REPEAT_CODE = 16;
private static final int NUM_LITERAL_CODES = 256;
private static final int NUM_INSERT_AND_COPY_CODES = 704;
private static final int NUM_BLOCK_LENGTH_CODES = 26;
private static final int LITERAL_CONTEXT_BITS = 6;
private static final int DISTANCE_CONTEXT_BITS = 2;
private static final int HUFFMAN_TABLE_BITS = 8;
private static final int HUFFMAN_TABLE_MASK = 0xFF;
private static final int CODE_LENGTH_CODES = 18;
private static final int[] CODE_LENGTH_CODE_ORDER = {
1, 2, 3, 4, 0, 5, 17, 6, 16, 7, 8, 9, 10, 11, 12, 13, 14, 15,
};
private static final int NUM_DISTANCE_SHORT_CODES = 16;
private static final int[] DISTANCE_SHORT_CODE_INDEX_OFFSET = {
3, 2, 1, 0, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2
};
private static final int[] DISTANCE_SHORT_CODE_VALUE_OFFSET = {
0, 0, 0, 0, -1, 1, -2, 2, -3, 3, -1, 1, -2, 2, -3, 3
};
/**
* Static Huffman code for the code length code lengths.
*/
private static final int[] FIXED_TABLE = {
0x020000, 0x020004, 0x020003, 0x030002, 0x020000, 0x020004, 0x020003, 0x040001,
0x020000, 0x020004, 0x020003, 0x030002, 0x020000, 0x020004, 0x020003, 0x040005
};
/**
* Decodes a number in the range [0..255], by reading 1 - 11 bits.
*/
private static int decodeVarLenUnsignedByte(BitReader br) {
if (BitReader.readBits(br, 1) != 0) {
int n = BitReader.readBits(br, 3);
if (n == 0) {
return 1;
} else {
return BitReader.readBits(br, n) + (1 << n);
}
}
return 0;
}
private static void decodeMetaBlockLength(BitReader br, State state) {
state.inputEnd = BitReader.readBits(br, 1) == 1;
state.metaBlockLength = 0;
state.isUncompressed = false;
state.isMetadata = false;
if (state.inputEnd && BitReader.readBits(br, 1) != 0) {
return;
}
int sizeNibbles = BitReader.readBits(br, 2) + 4;
if (sizeNibbles == 7) {
state.isMetadata = true;
if (BitReader.readBits(br, 1) != 0) {
throw new BrotliRuntimeException("Corrupted reserved bit");
}
int sizeBytes = BitReader.readBits(br, 2);
if (sizeBytes == 0) {
return;
}
for (int i = 0; i < sizeBytes; i++) {
int bits = BitReader.readBits(br, 8);
if (bits == 0 && i + 1 == sizeBytes && sizeBytes > 1) {
throw new BrotliRuntimeException("Exuberant nibble");
}
state.metaBlockLength |= bits << (i * 8);
}
} else {
for (int i = 0; i < sizeNibbles; i++) {
int bits = BitReader.readBits(br, 4);
if (bits == 0 && i + 1 == sizeNibbles && sizeNibbles > 4) {
throw new BrotliRuntimeException("Exuberant nibble");
}
state.metaBlockLength |= bits << (i * 4);
}
}
state.metaBlockLength++;
if (!state.inputEnd) {
state.isUncompressed = BitReader.readBits(br, 1) == 1;
}
}
/**
* Decodes the next Huffman code from bit-stream.
*/
private static int readSymbol(int[] table, int offset, BitReader br) {
int val = (int) (br.accumulator >>> br.bitOffset);
offset += val & HUFFMAN_TABLE_MASK;
int bits = table[offset] >> 16;
int sym = table[offset] & 0xFFFF;
if (bits <= HUFFMAN_TABLE_BITS) {
br.bitOffset += bits;
return sym;
}
offset += sym;
int mask = (1 << bits) - 1;
offset += (val & mask) >>> HUFFMAN_TABLE_BITS;
br.bitOffset += ((table[offset] >> 16) + HUFFMAN_TABLE_BITS);
return table[offset] & 0xFFFF;
}
private static int readBlockLength(int[] table, int offset, BitReader br) {
BitReader.fillBitWindow(br);
int code = readSymbol(table, offset, br);
int n = Prefix.BLOCK_LENGTH_N_BITS[code];
return Prefix.BLOCK_LENGTH_OFFSET[code] + BitReader.readBits(br, n);
}
private static int translateShortCodes(int code, int[] ringBuffer, int index) {
if (code < NUM_DISTANCE_SHORT_CODES) {
index += DISTANCE_SHORT_CODE_INDEX_OFFSET[code];
index &= 3;
return ringBuffer[index] + DISTANCE_SHORT_CODE_VALUE_OFFSET[code];
}
return code - NUM_DISTANCE_SHORT_CODES + 1;
}
private static void moveToFront(int[] v, int index) {
int value = v[index];
for (; index > 0; index--) {
v[index] = v[index - 1];
}
v[0] = value;
}
private static void inverseMoveToFrontTransform(byte[] v, int vLen) {
int[] mtf = new int[256];
for (int i = 0; i < 256; i++) {
mtf[i] = i;
}
for (int i = 0; i < vLen; i++) {
int index = v[i] & 0xFF;
v[i] = (byte) mtf[index];
if (index != 0) {
moveToFront(mtf, index);
}
}
}
private static void readHuffmanCodeLengths(
int[] codeLengthCodeLengths, int numSymbols, int[] codeLengths, BitReader br) {
int symbol = 0;
int prevCodeLen = DEFAULT_CODE_LENGTH;
int repeat = 0;
int repeatCodeLen = 0;
int space = 32768;
int[] table = new int[32];
Huffman.buildHuffmanTable(table, 0, 5, codeLengthCodeLengths, CODE_LENGTH_CODES);
while (symbol < numSymbols && space > 0) {
BitReader.readMoreInput(br);
BitReader.fillBitWindow(br);
int p = (int) ((br.accumulator >>> br.bitOffset)) & 31;
br.bitOffset += table[p] >> 16;
int codeLen = table[p] & 0xFFFF;
if (codeLen < CODE_LENGTH_REPEAT_CODE) {
repeat = 0;
codeLengths[symbol++] = codeLen;
if (codeLen != 0) {
prevCodeLen = codeLen;
space -= 32768 >> codeLen;
}
} else {
int extraBits = codeLen - 14;
int newLen = 0;
if (codeLen == CODE_LENGTH_REPEAT_CODE) {
newLen = prevCodeLen;
}
if (repeatCodeLen != newLen) {
repeat = 0;
repeatCodeLen = newLen;
}
int oldRepeat = repeat;
if (repeat > 0) {
repeat -= 2;
repeat <<= extraBits;
}
repeat += BitReader.readBits(br, extraBits) + 3;
int repeatDelta = repeat - oldRepeat;
if (symbol + repeatDelta > numSymbols) {
throw new BrotliRuntimeException("symbol + repeatDelta > numSymbols"); // COV_NF_LINE
}
for (int i = 0; i < repeatDelta; i++) {
codeLengths[symbol++] = repeatCodeLen;
}
if (repeatCodeLen != 0) {
space -= repeatDelta << (15 - repeatCodeLen);
}
}
}
if (space != 0) {
throw new BrotliRuntimeException("Unused space"); // COV_NF_LINE
}
// TODO: Pass max_symbol to Huffman table builder instead?
Utils.fillWithZeroes(codeLengths, symbol, numSymbols - symbol);
}
// TODO: Use specialized versions for smaller tables.
static void readHuffmanCode(int alphabetSize, int[] table, int offset, BitReader br) {
boolean ok = true;
int simpleCodeOrSkip;
BitReader.readMoreInput(br);
// TODO: Avoid allocation.
int[] codeLengths = new int[alphabetSize];
simpleCodeOrSkip = BitReader.readBits(br, 2);
if (simpleCodeOrSkip == 1) { // Read symbols, codes & code lengths directly.
int maxBitsCounter = alphabetSize - 1;
int maxBits = 0;
int[] symbols = new int[4];
int numSymbols = BitReader.readBits(br, 2) + 1;
while (maxBitsCounter != 0) {
maxBitsCounter >>= 1;
maxBits++;
}
// TODO: uncomment when codeLengths is reused.
// Utils.fillWithZeroes(codeLengths, 0, alphabetSize);
for (int i = 0; i < numSymbols; i++) {
symbols[i] = BitReader.readBits(br, maxBits) % alphabetSize;
codeLengths[symbols[i]] = 2;
}
codeLengths[symbols[0]] = 1;
switch (numSymbols) {
case 1:
break;
case 2:
ok = symbols[0] != symbols[1];
codeLengths[symbols[1]] = 1;
break;
case 3:
ok = symbols[0] != symbols[1] && symbols[0] != symbols[2] && symbols[1] != symbols[2];
break;
case 4:
default:
ok = symbols[0] != symbols[1] && symbols[0] != symbols[2] && symbols[0] != symbols[3]
&& symbols[1] != symbols[2] && symbols[1] != symbols[3] && symbols[2] != symbols[3];
if (BitReader.readBits(br, 1) == 1) {
codeLengths[symbols[2]] = 3;
codeLengths[symbols[3]] = 3;
} else {
codeLengths[symbols[0]] = 2;
}
break;
}
} else { // Decode Huffman-coded code lengths.
int[] codeLengthCodeLengths = new int[CODE_LENGTH_CODES];
int space = 32;
int numCodes = 0;
for (int i = simpleCodeOrSkip; i < CODE_LENGTH_CODES && space > 0; i++) {
int codeLenIdx = CODE_LENGTH_CODE_ORDER[i];
BitReader.fillBitWindow(br);
int p = (int) (br.accumulator >>> br.bitOffset) & 15;
// TODO: Demultiplex FIXED_TABLE.
br.bitOffset += FIXED_TABLE[p] >> 16;
int v = FIXED_TABLE[p] & 0xFFFF;
codeLengthCodeLengths[codeLenIdx] = v;
if (v != 0) {
space -= (32 >> v);
numCodes++;
}
}
ok = (numCodes == 1 || space == 0);
readHuffmanCodeLengths(codeLengthCodeLengths, alphabetSize, codeLengths, br);
}
if (!ok) {
throw new BrotliRuntimeException("Can't readHuffmanCode"); // COV_NF_LINE
}
Huffman.buildHuffmanTable(table, offset, HUFFMAN_TABLE_BITS, codeLengths, alphabetSize);
}
private static int decodeContextMap(int contextMapSize, byte[] contextMap, BitReader br) {
BitReader.readMoreInput(br);
int numTrees = decodeVarLenUnsignedByte(br) + 1;
if (numTrees == 1) {
Utils.fillWithZeroes(contextMap, 0, contextMapSize);
return numTrees;
}
boolean useRleForZeros = BitReader.readBits(br, 1) == 1;
int maxRunLengthPrefix = 0;
if (useRleForZeros) {
maxRunLengthPrefix = BitReader.readBits(br, 4) + 1;
}
int[] table = new int[Huffman.HUFFMAN_MAX_TABLE_SIZE];
readHuffmanCode(numTrees + maxRunLengthPrefix, table, 0, br);
for (int i = 0; i < contextMapSize; ) {
BitReader.readMoreInput(br);
BitReader.fillBitWindow(br);
int code = readSymbol(table, 0, br);
if (code == 0) {
contextMap[i] = 0;
i++;
} else if (code <= maxRunLengthPrefix) {
int reps = (1 << code) + BitReader.readBits(br, code);
while (reps != 0) {
if (i >= contextMapSize) {
throw new BrotliRuntimeException("Corrupted context map"); // COV_NF_LINE
}
contextMap[i] = 0;
i++;
reps--;
}
} else {
contextMap[i] = (byte) (code - maxRunLengthPrefix);
i++;
}
}
if (BitReader.readBits(br, 1) == 1) {
inverseMoveToFrontTransform(contextMap, contextMapSize);
}
return numTrees;
}
private static void decodeBlockTypeAndLength(State state, int treeType) {
final BitReader br = state.br;
final int[] ringBuffers = state.blockTypeRb;
final int offset = treeType * 2;
BitReader.fillBitWindow(br);
int blockType = readSymbol(
state.blockTypeTrees, treeType * Huffman.HUFFMAN_MAX_TABLE_SIZE, br);
state.blockLength[treeType] = readBlockLength(state.blockLenTrees,
treeType * Huffman.HUFFMAN_MAX_TABLE_SIZE, br);
if (blockType == 1) {
blockType = ringBuffers[offset + 1] + 1;
} else if (blockType == 0) {
blockType = ringBuffers[offset];
} else {
blockType -= 2;
}
if (blockType >= state.numBlockTypes[treeType]) {
blockType -= state.numBlockTypes[treeType];
}
ringBuffers[offset] = ringBuffers[offset + 1];
ringBuffers[offset + 1] = blockType;
}
private static void decodeLiteralBlockSwitch(State state) {
decodeBlockTypeAndLength(state, 0);
int literalBlockType = state.blockTypeRb[1];
state.contextMapSlice = literalBlockType << LITERAL_CONTEXT_BITS;
state.literalTreeIndex = state.contextMap[state.contextMapSlice] & 0xFF;
state.literalTree = state.hGroup0.trees[state.literalTreeIndex];
int contextMode = state.contextModes[literalBlockType];
state.contextLookupOffset1 = Context.LOOKUP_OFFSETS[contextMode];
state.contextLookupOffset2 = Context.LOOKUP_OFFSETS[contextMode + 1];
}
private static void decodeCommandBlockSwitch(State state) {
decodeBlockTypeAndLength(state, 1);
state.treeCommandOffset = state.hGroup1.trees[state.blockTypeRb[3]];
}
private static void decodeDistanceBlockSwitch(State state) {
decodeBlockTypeAndLength(state, 2);
state.distContextMapSlice = state.blockTypeRb[5] << DISTANCE_CONTEXT_BITS;
}
private static void maybeReallocateRingBuffer(State state) {
int newSize = state.maxRingBufferSize;
if ((long) newSize > state.expectedTotalSize) {
/* TODO: Handle 2GB+ cases more gracefully. */
int minimalNewSize = (int) state.expectedTotalSize + state.customDictionary.length;
while ((newSize >> 1) > minimalNewSize) {
newSize >>= 1;
}
if (!state.inputEnd && newSize < 16384 && state.maxRingBufferSize >= 16384) {
newSize = 16384;
}
}
if (newSize <= state.ringBufferSize) {
return;
}
int ringBufferSizeWithSlack = newSize + Dictionary.MAX_TRANSFORMED_WORD_LENGTH;
byte[] newBuffer = new byte[ringBufferSizeWithSlack];
if (state.ringBuffer != null) {
System.arraycopy(state.ringBuffer, 0, newBuffer, 0, state.ringBufferSize);
} else {
/* Prepend custom dictionary, if any. */
if (state.customDictionary.length != 0) {
int length = state.customDictionary.length;
int offset = 0;
if (length > state.maxBackwardDistance) {
offset = length - state.maxBackwardDistance;
length = state.maxBackwardDistance;
}
System.arraycopy(state.customDictionary, offset, newBuffer, 0, length);
state.pos = length;
state.bytesToIgnore = length;
}
}
state.ringBuffer = newBuffer;
state.ringBufferSize = newSize;
}
/**
* Reads next metablock header.
*
* @param state decoding state
*/
private static void readMetablockInfo(State state) {
final BitReader br = state.br;
if (state.inputEnd) {
state.nextRunningState = RunningState.FINISHED;
state.bytesToWrite = state.pos;
state.bytesWritten = 0;
state.runningState = RunningState.WRITE;
return;
}
// TODO: Reset? Do we need this?
state.hGroup0.codes = null;
state.hGroup0.trees = null;
state.hGroup1.codes = null;
state.hGroup1.trees = null;
state.hGroup2.codes = null;
state.hGroup2.trees = null;
BitReader.readMoreInput(br);
decodeMetaBlockLength(br, state);
if (state.metaBlockLength == 0 && !state.isMetadata) {
return;
}
if (state.isUncompressed || state.isMetadata) {
BitReader.jumpToByteBoundary(br);
state.runningState = state.isMetadata ? RunningState.READ_METADATA : RunningState.COPY_UNCOMPRESSED;
} else {
state.runningState = RunningState.COMPRESSED_BLOCK_START;
}
if (state.isMetadata) {
return;
}
state.expectedTotalSize += state.metaBlockLength;
if (state.ringBufferSize < state.maxRingBufferSize) {
maybeReallocateRingBuffer(state);
}
}
private static void readMetablockHuffmanCodesAndContextMaps(State state) {
final BitReader br = state.br;
for (int i = 0; i < 3; i++) {
state.numBlockTypes[i] = decodeVarLenUnsignedByte(br) + 1;
state.blockLength[i] = 1 << 28;
if (state.numBlockTypes[i] > 1) {
readHuffmanCode(state.numBlockTypes[i] + 2, state.blockTypeTrees,
i * Huffman.HUFFMAN_MAX_TABLE_SIZE, br);
readHuffmanCode(NUM_BLOCK_LENGTH_CODES, state.blockLenTrees,
i * Huffman.HUFFMAN_MAX_TABLE_SIZE, br);
state.blockLength[i] = readBlockLength(state.blockLenTrees,
i * Huffman.HUFFMAN_MAX_TABLE_SIZE, br);
}
}
BitReader.readMoreInput(br);
state.distancePostfixBits = BitReader.readBits(br, 2);
state.numDirectDistanceCodes =
NUM_DISTANCE_SHORT_CODES + (BitReader.readBits(br, 4) << state.distancePostfixBits);
state.distancePostfixMask = (1 << state.distancePostfixBits) - 1;
int numDistanceCodes = state.numDirectDistanceCodes + (48 << state.distancePostfixBits);
// TODO: Reuse?
state.contextModes = new byte[state.numBlockTypes[0]];
for (int i = 0; i < state.numBlockTypes[0];) {
/* Ensure that less than 256 bits read between readMoreInput. */
int limit = Math.min(i + 96, state.numBlockTypes[0]);
for (; i < limit; ++i) {
state.contextModes[i] = (byte) (BitReader.readBits(br, 2) << 1);
}
BitReader.readMoreInput(br);
}
// TODO: Reuse?
state.contextMap = new byte[state.numBlockTypes[0] << LITERAL_CONTEXT_BITS];
int numLiteralTrees = decodeContextMap(state.numBlockTypes[0] << LITERAL_CONTEXT_BITS,
state.contextMap, br);
state.trivialLiteralContext = true;
for (int j = 0; j < state.numBlockTypes[0] << LITERAL_CONTEXT_BITS; j++) {
if (state.contextMap[j] != j >> LITERAL_CONTEXT_BITS) {
state.trivialLiteralContext = false;
break;
}
}
// TODO: Reuse?
state.distContextMap = new byte[state.numBlockTypes[2] << DISTANCE_CONTEXT_BITS];
int numDistTrees = decodeContextMap(state.numBlockTypes[2] << DISTANCE_CONTEXT_BITS,
state.distContextMap, br);
HuffmanTreeGroup.init(state.hGroup0, NUM_LITERAL_CODES, numLiteralTrees);
HuffmanTreeGroup.init(state.hGroup1, NUM_INSERT_AND_COPY_CODES, state.numBlockTypes[1]);
HuffmanTreeGroup.init(state.hGroup2, numDistanceCodes, numDistTrees);
HuffmanTreeGroup.decode(state.hGroup0, br);
HuffmanTreeGroup.decode(state.hGroup1, br);
HuffmanTreeGroup.decode(state.hGroup2, br);
state.contextMapSlice = 0;
state.distContextMapSlice = 0;
state.contextLookupOffset1 = Context.LOOKUP_OFFSETS[state.contextModes[0]];
state.contextLookupOffset2 = Context.LOOKUP_OFFSETS[state.contextModes[0] + 1];
state.literalTreeIndex = 0;
state.literalTree = state.hGroup0.trees[0];
state.treeCommandOffset = state.hGroup1.trees[0]; // TODO: == 0?
state.blockTypeRb[0] = state.blockTypeRb[2] = state.blockTypeRb[4] = 1;
state.blockTypeRb[1] = state.blockTypeRb[3] = state.blockTypeRb[5] = 0;
}
private static void copyUncompressedData(State state) {
final BitReader br = state.br;
final byte[] ringBuffer = state.ringBuffer;
// Could happen if block ends at ring buffer end.
if (state.metaBlockLength <= 0) {
BitReader.reload(br);
state.runningState = RunningState.BLOCK_START;
return;
}
int chunkLength = Math.min(state.ringBufferSize - state.pos, state.metaBlockLength);
BitReader.copyBytes(br, ringBuffer, state.pos, chunkLength);
state.metaBlockLength -= chunkLength;
state.pos += chunkLength;
if (state.pos == state.ringBufferSize) {
state.nextRunningState = RunningState.COPY_UNCOMPRESSED;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.WRITE;
return;
}
BitReader.reload(br);
state.runningState = RunningState.BLOCK_START;
}
private static boolean writeRingBuffer(State state) {
/* Ignore custom dictionary bytes. */
if (state.bytesToIgnore != 0) {
state.bytesWritten += state.bytesToIgnore;
state.bytesToIgnore = 0;
}
int toWrite = Math.min(state.outputLength - state.outputUsed,
state.bytesToWrite - state.bytesWritten);
if (toWrite != 0) {
System.arraycopy(state.ringBuffer, state.bytesWritten, state.output,
state.outputOffset + state.outputUsed, toWrite);
state.outputUsed += toWrite;
state.bytesWritten += toWrite;
}
return state.outputUsed < state.outputLength;
}
static void setCustomDictionary(State state, byte[] data) {
state.customDictionary = (data == null) ? new byte[0] : data;
}
/**
* Actual decompress implementation.
*/
static void decompress(State state) {
if (state.runningState == RunningState.UNINITIALIZED) {
throw new IllegalStateException("Can't decompress until initialized");
}
if (state.runningState == RunningState.CLOSED) {
throw new IllegalStateException("Can't decompress after close");
}
final BitReader br = state.br;
int ringBufferMask = state.ringBufferSize - 1;
byte[] ringBuffer = state.ringBuffer;
while (state.runningState != RunningState.FINISHED) {
// TODO: extract cases to methods for the better readability.
switch (state.runningState) {
case RunningState.BLOCK_START:
if (state.metaBlockLength < 0) {
throw new BrotliRuntimeException("Invalid metablock length");
}
readMetablockInfo(state);
/* Ring-buffer would be reallocated here. */
ringBufferMask = state.ringBufferSize - 1;
ringBuffer = state.ringBuffer;
continue;
case RunningState.COMPRESSED_BLOCK_START:
readMetablockHuffmanCodesAndContextMaps(state);
state.runningState = RunningState.MAIN_LOOP;
// Fall through
case RunningState.MAIN_LOOP:
if (state.metaBlockLength <= 0) {
state.runningState = RunningState.BLOCK_START;
continue;
}
BitReader.readMoreInput(br);
if (state.blockLength[1] == 0) {
decodeCommandBlockSwitch(state);
}
state.blockLength[1]--;
BitReader.fillBitWindow(br);
int cmdCode = readSymbol(state.hGroup1.codes, state.treeCommandOffset, br);
int rangeIdx = cmdCode >>> 6;
state.distanceCode = 0;
if (rangeIdx >= 2) {
rangeIdx -= 2;
state.distanceCode = -1;
}
int insertCode = Prefix.INSERT_RANGE_LUT[rangeIdx] + ((cmdCode >>> 3) & 7);
int copyCode = Prefix.COPY_RANGE_LUT[rangeIdx] + (cmdCode & 7);
state.insertLength = Prefix.INSERT_LENGTH_OFFSET[insertCode] + BitReader
.readBits(br, Prefix.INSERT_LENGTH_N_BITS[insertCode]);
state.copyLength = Prefix.COPY_LENGTH_OFFSET[copyCode] + BitReader
.readBits(br, Prefix.COPY_LENGTH_N_BITS[copyCode]);
state.j = 0;
state.runningState = RunningState.INSERT_LOOP;
// Fall through
case RunningState.INSERT_LOOP:
if (state.trivialLiteralContext) {
while (state.j < state.insertLength) {
BitReader.readMoreInput(br);
if (state.blockLength[0] == 0) {
decodeLiteralBlockSwitch(state);
}
state.blockLength[0]--;
BitReader.fillBitWindow(br);
ringBuffer[state.pos] =
(byte) readSymbol(state.hGroup0.codes, state.literalTree, br);
state.j++;
if (state.pos++ == ringBufferMask) {
state.nextRunningState = RunningState.INSERT_LOOP;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.WRITE;
break;
}
}
} else {
int prevByte1 = ringBuffer[(state.pos - 1) & ringBufferMask] & 0xFF;
int prevByte2 = ringBuffer[(state.pos - 2) & ringBufferMask] & 0xFF;
while (state.j < state.insertLength) {
BitReader.readMoreInput(br);
if (state.blockLength[0] == 0) {
decodeLiteralBlockSwitch(state);
}
int literalTreeIndex = state.contextMap[state.contextMapSlice
+ (Context.LOOKUP[state.contextLookupOffset1 + prevByte1]
| Context.LOOKUP[state.contextLookupOffset2 + prevByte2])] & 0xFF;
state.blockLength[0]--;
prevByte2 = prevByte1;
BitReader.fillBitWindow(br);
prevByte1 = readSymbol(
state.hGroup0.codes, state.hGroup0.trees[literalTreeIndex], br);
ringBuffer[state.pos] = (byte) prevByte1;
state.j++;
if (state.pos++ == ringBufferMask) {
state.nextRunningState = RunningState.INSERT_LOOP;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.WRITE;
break;
}
}
}
if (state.runningState != RunningState.INSERT_LOOP) {
continue;
}
state.metaBlockLength -= state.insertLength;
if (state.metaBlockLength <= 0) {
state.runningState = RunningState.MAIN_LOOP;
continue;
}
if (state.distanceCode < 0) {
BitReader.readMoreInput(br);
if (state.blockLength[2] == 0) {
decodeDistanceBlockSwitch(state);
}
state.blockLength[2]--;
BitReader.fillBitWindow(br);
state.distanceCode = readSymbol(state.hGroup2.codes, state.hGroup2.trees[
state.distContextMap[state.distContextMapSlice
+ (state.copyLength > 4 ? 3 : state.copyLength - 2)] & 0xFF], br);
if (state.distanceCode >= state.numDirectDistanceCodes) {
state.distanceCode -= state.numDirectDistanceCodes;
int postfix = state.distanceCode & state.distancePostfixMask;
state.distanceCode >>>= state.distancePostfixBits;
int n = (state.distanceCode >>> 1) + 1;
int offset = ((2 + (state.distanceCode & 1)) << n) - 4;
state.distanceCode = state.numDirectDistanceCodes + postfix
+ ((offset + BitReader.readBits(br, n)) << state.distancePostfixBits);
}
}
// Convert the distance code to the actual distance by possibly looking up past distances
// from the ringBuffer.
state.distance = translateShortCodes(state.distanceCode, state.distRb, state.distRbIdx);
if (state.distance < 0) {
throw new BrotliRuntimeException("Negative distance"); // COV_NF_LINE
}
if (state.maxDistance != state.maxBackwardDistance
&& state.pos < state.maxBackwardDistance) {
state.maxDistance = state.pos;
} else {
state.maxDistance = state.maxBackwardDistance;
}
state.copyDst = state.pos;
if (state.distance > state.maxDistance) {
state.runningState = RunningState.TRANSFORM;
continue;
}
if (state.distanceCode > 0) {
state.distRb[state.distRbIdx & 3] = state.distance;
state.distRbIdx++;
}
if (state.copyLength > state.metaBlockLength) {
throw new BrotliRuntimeException("Invalid backward reference"); // COV_NF_LINE
}
state.j = 0;
state.runningState = RunningState.COPY_LOOP;
// fall through
case RunningState.COPY_LOOP:
int src = (state.pos - state.distance) & ringBufferMask;
int dst = state.pos;
int copyLength = state.copyLength - state.j;
if ((src + copyLength < ringBufferMask) && (dst + copyLength < ringBufferMask)) {
for (int k = 0; k < copyLength; ++k) {
ringBuffer[dst++] = ringBuffer[src++];
}
state.j += copyLength;
state.metaBlockLength -= copyLength;
state.pos += copyLength;
} else {
for (; state.j < state.copyLength;) {
ringBuffer[state.pos] =
ringBuffer[(state.pos - state.distance) & ringBufferMask];
state.metaBlockLength--;
state.j++;
if (state.pos++ == ringBufferMask) {
state.nextRunningState = RunningState.COPY_LOOP;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.WRITE;
break;
}
}
}
if (state.runningState == RunningState.COPY_LOOP) {
state.runningState = RunningState.MAIN_LOOP;
}
continue;
case RunningState.TRANSFORM:
if (state.copyLength >= Dictionary.MIN_WORD_LENGTH
&& state.copyLength <= Dictionary.MAX_WORD_LENGTH) {
int offset = Dictionary.OFFSETS_BY_LENGTH[state.copyLength];
int wordId = state.distance - state.maxDistance - 1;
int shift = Dictionary.SIZE_BITS_BY_LENGTH[state.copyLength];
int mask = (1 << shift) - 1;
int wordIdx = wordId & mask;
int transformIdx = wordId >>> shift;
offset += wordIdx * state.copyLength;
if (transformIdx < Transform.TRANSFORMS.length) {
int len = Transform.transformDictionaryWord(ringBuffer, state.copyDst,
Dictionary.getData(), offset, state.copyLength,
Transform.TRANSFORMS[transformIdx]);
state.copyDst += len;
state.pos += len;
state.metaBlockLength -= len;
if (state.copyDst >= state.ringBufferSize) {
state.nextRunningState = RunningState.COPY_WRAP_BUFFER;
state.bytesToWrite = state.ringBufferSize;
state.bytesWritten = 0;
state.runningState = RunningState.WRITE;
continue;
}
} else {
throw new BrotliRuntimeException("Invalid backward reference"); // COV_NF_LINE
}
} else {
throw new BrotliRuntimeException("Invalid backward reference"); // COV_NF_LINE
}
state.runningState = RunningState.MAIN_LOOP;
continue;
case RunningState.COPY_WRAP_BUFFER:
System.arraycopy(ringBuffer, state.ringBufferSize, ringBuffer, 0,
state.copyDst - state.ringBufferSize);
state.runningState = RunningState.MAIN_LOOP;
continue;
case RunningState.READ_METADATA:
while (state.metaBlockLength > 0) {
BitReader.readMoreInput(br);
// Optimize
BitReader.readBits(br, 8);
state.metaBlockLength--;
}
state.runningState = RunningState.BLOCK_START;
continue;
case RunningState.COPY_UNCOMPRESSED:
copyUncompressedData(state);
continue;
case RunningState.WRITE:
if (!writeRingBuffer(state)) {
// Output buffer is full.
return;
}
if (state.pos >= state.maxBackwardDistance) {
state.maxDistance = state.maxBackwardDistance;
}
state.pos &= ringBufferMask;
state.runningState = state.nextRunningState;
continue;
default:
throw new BrotliRuntimeException("Unexpected state " + state.runningState);
}
}
if (state.runningState == RunningState.FINISHED) {
if (state.metaBlockLength < 0) {
throw new BrotliRuntimeException("Invalid metablock length");
}
BitReader.jumpToByteBoundary(br);
BitReader.checkHealth(state.br, true);
}
}
}
