Decode.java
/* 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 org.brotli.dec;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* API for Brotli decompression.
*/
final class Decode {
static final int MIN_LARGE_WINDOW_BITS = 10;
/* Maximum was chosen to be 30 to allow efficient decoder implementation.
* Format allows bigger window, but Java does not support 2G+ arrays. */
static final int MAX_LARGE_WINDOW_BITS = 30;
//----------------------------------------------------------------------------
// RunningState
//----------------------------------------------------------------------------
private static final int UNINITIALIZED = 0;
private static final int INITIALIZED = 1;
private static final int BLOCK_START = 2;
private static final int COMPRESSED_BLOCK_START = 3;
private static final int MAIN_LOOP = 4;
private static final int READ_METADATA = 5;
private static final int COPY_UNCOMPRESSED = 6;
private static final int INSERT_LOOP = 7;
private static final int COPY_LOOP = 8;
private static final int USE_DICTIONARY = 9;
private static final int FINISHED = 10;
private static final int CLOSED = 11;
private static final int INIT_WRITE = 12;
private static final int WRITE = 13;
private static final int COPY_FROM_COMPOUND_DICTIONARY = 14;
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_COMMAND_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 CD_BLOCK_MAP_BITS = 8;
private static final int HUFFMAN_TABLE_BITS = 8;
private static final int HUFFMAN_TABLE_MASK = 0xFF;
/**
* Maximum possible Huffman table size for an alphabet size of (index * 32),
* max code length 15 and root table bits 8.
* The biggest alphabet is "command" - 704 symbols. Though "distance" alphabet could theoretically
* outreach that limit (for 62 extra bit distances), practically it is limited by
* MAX_ALLOWED_DISTANCE and never gets bigger than 544 symbols.
*/
static final int[] MAX_HUFFMAN_TABLE_SIZE = {
256, 402, 436, 468, 500, 534, 566, 598, 630, 662, 694, 726, 758, 790, 822,
854, 886, 920, 952, 984, 1016, 1048, 1080
};
private static final int HUFFMAN_TABLE_SIZE_26 = 396;
private static final int HUFFMAN_TABLE_SIZE_258 = 632;
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 = {
0, 3, 2, 1, 0, 0, 0, 0, 0, 0, 3, 3, 3, 3, 3, 3
};
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
};
// TODO(eustas): generalize.
static final int MAX_TRANSFORMED_WORD_LENGTH = 5 + 24 + 8;
private static final int MAX_DISTANCE_BITS = 24;
private static final int MAX_LARGE_WINDOW_DISTANCE_BITS = 62;
/**
* Safe distance limit.
*
* Limit ((1 << 31) - 4) allows safe distance calculation without overflows,
* given the distance alphabet size is limited to corresponding size.
*/
private static final int MAX_ALLOWED_DISTANCE = 0x7FFFFFFC;
//----------------------------------------------------------------------------
// Prefix code LUT.
//----------------------------------------------------------------------------
static final int[] BLOCK_LENGTH_OFFSET = {
1, 5, 9, 13, 17, 25, 33, 41, 49, 65, 81, 97, 113, 145, 177, 209, 241, 305, 369, 497,
753, 1265, 2289, 4337, 8433, 16625
};
static final int[] BLOCK_LENGTH_N_BITS = {
2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8, 9, 10, 11, 12, 13, 24
};
static final short[] INSERT_LENGTH_N_BITS = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x02, 0x02, 0x03, 0x03,
0x04, 0x04, 0x05, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0C, 0x0E, 0x18
};
static final short[] COPY_LENGTH_N_BITS = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x02, 0x02,
0x03, 0x03, 0x04, 0x04, 0x05, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x18
};
// Each command is represented with 4x16-bit values:
// * [insertLenExtraBits, copyLenExtraBits]
// * insertLenOffset
// * copyLenOffset
// * distanceContext
static final short[] CMD_LOOKUP = new short[NUM_COMMAND_CODES * 4];
static {
unpackCommandLookupTable(CMD_LOOKUP);
}
private static int log2floor(int i) {
int result = -1;
int step = 16;
while (step > 0) {
if ((i >>> step) != 0) {
result += step;
i = i >>> step;
}
step = step >> 1;
}
return result + i;
}
private static int calculateDistanceAlphabetSize(int npostfix, int ndirect, int maxndistbits) {
return NUM_DISTANCE_SHORT_CODES + ndirect + 2 * (maxndistbits << npostfix);
}
// TODO(eustas): add a correctness test for this function when
// large-window and dictionary are implemented.
private static int calculateDistanceAlphabetLimit(int maxDistance, int npostfix, int ndirect) {
if (maxDistance < ndirect + (2 << npostfix)) {
throw new IllegalArgumentException("maxDistance is too small");
}
final int offset = ((maxDistance - ndirect) >> npostfix) + 4;
final int ndistbits = log2floor(offset) - 1;
final int group = ((ndistbits - 1) << 1) | ((offset >> ndistbits) & 1);
return ((group - 1) << npostfix) + (1 << npostfix) + ndirect + NUM_DISTANCE_SHORT_CODES;
}
private static void unpackCommandLookupTable(short[] cmdLookup) {
final short[] insertLengthOffsets = new short[24];
final short[] copyLengthOffsets = new short[24];
copyLengthOffsets[0] = 2;
for (int i = 0; i < 23; ++i) {
insertLengthOffsets[i + 1] =
(short) (insertLengthOffsets[i] + (1 << INSERT_LENGTH_N_BITS[i]));
copyLengthOffsets[i + 1] =
(short) (copyLengthOffsets[i] + (1 << COPY_LENGTH_N_BITS[i]));
}
for (int cmdCode = 0; cmdCode < NUM_COMMAND_CODES; ++cmdCode) {
int rangeIdx = cmdCode >>> 6;
/* -4 turns any regular distance code to negative. */
int distanceContextOffset = -4;
if (rangeIdx >= 2) {
rangeIdx -= 2;
distanceContextOffset = 0;
}
final int insertCode = (((0x29850 >>> (rangeIdx * 2)) & 0x3) << 3) | ((cmdCode >>> 3) & 7);
final int copyCode = (((0x26244 >>> (rangeIdx * 2)) & 0x3) << 3) | (cmdCode & 7);
final short copyLengthOffset = copyLengthOffsets[copyCode];
final int distanceContext =
distanceContextOffset + (copyLengthOffset > 4 ? 3 : copyLengthOffset - 2);
final int index = cmdCode * 4;
cmdLookup[index + 0] =
(short) (INSERT_LENGTH_N_BITS[insertCode] | (COPY_LENGTH_N_BITS[copyCode] << 8));
cmdLookup[index + 1] = insertLengthOffsets[insertCode];
cmdLookup[index + 2] = copyLengthOffsets[copyCode];
cmdLookup[index + 3] = (short) distanceContext;
}
}
/**
* Reads brotli stream header and parses "window bits".
*
* @param s initialized state, before any read is performed.
* @return -1 if header is invalid
*/
private static int decodeWindowBits(State s) {
/* Change the meaning of flag. Before that step it means "decoder must be capable of reading
* "large-window" brotli stream. After this step it means that "large-window" feature
* is actually detected. Despite the window size could be same as before (lgwin = 10..24),
* encoded distances are allowed to be much greater, thus bigger dictinary could be used. */
final int largeWindowEnabled = s.isLargeWindow;
s.isLargeWindow = 0;
BitReader.fillBitWindow(s);
if (BitReader.readFewBits(s, 1) == 0) {
return 16;
}
int n = BitReader.readFewBits(s, 3);
if (n != 0) {
return 17 + n;
}
n = BitReader.readFewBits(s, 3);
if (n != 0) {
if (n == 1) {
if (largeWindowEnabled == 0) {
/* Reserved value in regular brotli stream. */
return -1;
}
s.isLargeWindow = 1;
/* Check "reserved" bit for future (post-large-window) extensions. */
if (BitReader.readFewBits(s, 1) == 1) {
return -1;
}
n = BitReader.readFewBits(s, 6);
if (n < MIN_LARGE_WINDOW_BITS || n > MAX_LARGE_WINDOW_BITS) {
/* Encoded window bits value is too small or too big. */
return -1;
}
return n;
} else {
return 8 + n;
}
}
return 17;
}
/**
* Switch decoder to "eager" mode.
*
* In "eager" mode decoder returns as soon as there is enough data to fill output buffer.
*
* @param s initialized state, before any read is performed.
*/
static void enableEagerOutput(State s) {
if (s.runningState != INITIALIZED) {
throw new IllegalStateException("State MUST be freshly initialized");
}
s.isEager = 1;
}
static void enableLargeWindow(State s) {
if (s.runningState != INITIALIZED) {
throw new IllegalStateException("State MUST be freshly initialized");
}
s.isLargeWindow = 1;
}
// TODO(eustas): do we need byte views?
static void attachDictionaryChunk(State s, byte[] data) {
if (s.runningState != INITIALIZED) {
throw new IllegalStateException("State MUST be freshly initialized");
}
if (s.cdNumChunks == 0) {
s.cdChunks = new byte[16][];
s.cdChunkOffsets = new int[16];
s.cdBlockBits = -1;
}
if (s.cdNumChunks == 15) {
throw new IllegalStateException("Too many dictionary chunks");
}
s.cdChunks[s.cdNumChunks] = data;
s.cdNumChunks++;
s.cdTotalSize += data.length;
s.cdChunkOffsets[s.cdNumChunks] = s.cdTotalSize;
}
/**
* Associate input with decoder state.
*
* @param s uninitialized state without associated input
* @param input compressed data source
*/
static void initState(State s) {
if (s.runningState != UNINITIALIZED) {
throw new IllegalStateException("State MUST be uninitialized");
}
/* 6 trees + 1 extra "offset" slot to simplify table decoding logic. */
s.blockTrees = new int[7 + 3 * (HUFFMAN_TABLE_SIZE_258 + HUFFMAN_TABLE_SIZE_26)];
s.blockTrees[0] = 7;
s.distRbIdx = 3;
final int maxDistanceAlphabetLimit =
calculateDistanceAlphabetLimit(MAX_ALLOWED_DISTANCE, 3, 15 << 3);
s.distExtraBits = new byte[maxDistanceAlphabetLimit];
s.distOffset = new int[maxDistanceAlphabetLimit];
BitReader.initBitReader(s);
s.runningState = INITIALIZED;
}
static void close(State s) throws IOException {
if (s.runningState == UNINITIALIZED) {
throw new IllegalStateException("State MUST be initialized");
}
if (s.runningState == CLOSED) {
return;
}
s.runningState = CLOSED;
Utils.closeInput(s);
}
/**
* Decodes a number in the range [0..255], by reading 1 - 11 bits.
*/
private static int decodeVarLenUnsignedByte(State s) {
BitReader.fillBitWindow(s);
if (BitReader.readFewBits(s, 1) != 0) {
final int n = BitReader.readFewBits(s, 3);
if (n == 0) {
return 1;
} else {
return BitReader.readFewBits(s, n) + (1 << n);
}
}
return 0;
}
private static void decodeMetaBlockLength(State s) {
BitReader.fillBitWindow(s);
s.inputEnd = BitReader.readFewBits(s, 1);
s.metaBlockLength = 0;
s.isUncompressed = 0;
s.isMetadata = 0;
if ((s.inputEnd != 0) && BitReader.readFewBits(s, 1) != 0) {
return;
}
final int sizeNibbles = BitReader.readFewBits(s, 2) + 4;
if (sizeNibbles == 7) {
s.isMetadata = 1;
if (BitReader.readFewBits(s, 1) != 0) {
throw new BrotliRuntimeException("Corrupted reserved bit");
}
final int sizeBytes = BitReader.readFewBits(s, 2);
if (sizeBytes == 0) {
return;
}
for (int i = 0; i < sizeBytes; i++) {
BitReader.fillBitWindow(s);
final int bits = BitReader.readFewBits(s, 8);
if (bits == 0 && i + 1 == sizeBytes && sizeBytes > 1) {
throw new BrotliRuntimeException("Exuberant nibble");
}
s.metaBlockLength |= bits << (i * 8);
}
} else {
for (int i = 0; i < sizeNibbles; i++) {
BitReader.fillBitWindow(s);
final int bits = BitReader.readFewBits(s, 4);
if (bits == 0 && i + 1 == sizeNibbles && sizeNibbles > 4) {
throw new BrotliRuntimeException("Exuberant nibble");
}
s.metaBlockLength |= bits << (i * 4);
}
}
s.metaBlockLength++;
if (s.inputEnd == 0) {
s.isUncompressed = BitReader.readFewBits(s, 1);
}
}
/**
* Decodes the next Huffman code from bit-stream.
*/
private static int readSymbol(int[] tableGroup, int tableIdx, State s) {
int offset = tableGroup[tableIdx];
final int val = BitReader.peekBits(s);
offset += val & HUFFMAN_TABLE_MASK;
final int bits = tableGroup[offset] >> 16;
final int sym = tableGroup[offset] & 0xFFFF;
if (bits <= HUFFMAN_TABLE_BITS) {
s.bitOffset += bits;
return sym;
}
offset += sym;
final int mask = (1 << bits) - 1;
offset += (val & mask) >>> HUFFMAN_TABLE_BITS;
s.bitOffset += ((tableGroup[offset] >> 16) + HUFFMAN_TABLE_BITS);
return tableGroup[offset] & 0xFFFF;
}
private static int readBlockLength(int[] tableGroup, int tableIdx, State s) {
BitReader.fillBitWindow(s);
final int code = readSymbol(tableGroup, tableIdx, s);
final int n = BLOCK_LENGTH_N_BITS[code];
BitReader.fillBitWindow(s);
return BLOCK_LENGTH_OFFSET[code] + BitReader.readBits(s, n);
}
private static void moveToFront(int[] v, int index) {
final int value = v[index];
for (; index > 0; index--) {
v[index] = v[index - 1];
}
v[0] = value;
}
private static void inverseMoveToFrontTransform(byte[] v, int vLen) {
final int[] mtf = new int[256];
for (int i = 0; i < 256; i++) {
mtf[i] = i;
}
for (int i = 0; i < vLen; i++) {
final 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, State s) {
int symbol = 0;
int prevCodeLen = DEFAULT_CODE_LENGTH;
int repeat = 0;
int repeatCodeLen = 0;
int space = 32768;
final int[] table = new int[32 + 1]; /* Speculative single entry table group. */
final int tableIdx = table.length - 1;
Huffman.buildHuffmanTable(table, tableIdx, 5, codeLengthCodeLengths, CODE_LENGTH_CODES);
while (symbol < numSymbols && space > 0) {
BitReader.readMoreInput(s);
BitReader.fillBitWindow(s);
final int p = BitReader.peekBits(s) & 31;
s.bitOffset += table[p] >> 16;
final 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 {
final int extraBits = codeLen - 14;
int newLen = 0;
if (codeLen == CODE_LENGTH_REPEAT_CODE) {
newLen = prevCodeLen;
}
if (repeatCodeLen != newLen) {
repeat = 0;
repeatCodeLen = newLen;
}
final int oldRepeat = repeat;
if (repeat > 0) {
repeat -= 2;
repeat <<= extraBits;
}
BitReader.fillBitWindow(s);
repeat += BitReader.readFewBits(s, extraBits) + 3;
final 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(eustas): Pass max_symbol to Huffman table builder instead?
Utils.fillIntsWithZeroes(codeLengths, symbol, numSymbols);
}
private static void checkDupes(int[] symbols, int length) {
for (int i = 0; i < length - 1; ++i) {
for (int j = i + 1; j < length; ++j) {
if (symbols[i] == symbols[j]) {
throw new BrotliRuntimeException("Duplicate simple Huffman code symbol"); // COV_NF_LINE
}
}
}
}
/**
* Reads up to 4 symbols directly and applies predefined histograms.
*/
private static int readSimpleHuffmanCode(int alphabetSizeMax, int alphabetSizeLimit,
int[] tableGroup, int tableIdx, State s) {
// TODO(eustas): Avoid allocation?
final int[] codeLengths = new int[alphabetSizeLimit];
final int[] symbols = new int[4];
final int maxBits = 1 + log2floor(alphabetSizeMax - 1);
final int numSymbols = BitReader.readFewBits(s, 2) + 1;
for (int i = 0; i < numSymbols; i++) {
BitReader.fillBitWindow(s);
final int symbol = BitReader.readFewBits(s, maxBits);
if (symbol >= alphabetSizeLimit) {
throw new BrotliRuntimeException("Can't readHuffmanCode"); // COV_NF_LINE
}
symbols[i] = symbol;
}
checkDupes(symbols, numSymbols);
int histogramId = numSymbols;
if (numSymbols == 4) {
histogramId += BitReader.readFewBits(s, 1);
}
switch (histogramId) {
case 1:
codeLengths[symbols[0]] = 1;
break;
case 2:
codeLengths[symbols[0]] = 1;
codeLengths[symbols[1]] = 1;
break;
case 3:
codeLengths[symbols[0]] = 1;
codeLengths[symbols[1]] = 2;
codeLengths[symbols[2]] = 2;
break;
case 4: // uniform 4-symbol histogram
codeLengths[symbols[0]] = 2;
codeLengths[symbols[1]] = 2;
codeLengths[symbols[2]] = 2;
codeLengths[symbols[3]] = 2;
break;
case 5: // prioritized 4-symbol histogram
codeLengths[symbols[0]] = 1;
codeLengths[symbols[1]] = 2;
codeLengths[symbols[2]] = 3;
codeLengths[symbols[3]] = 3;
break;
default:
break;
}
// TODO(eustas): Use specialized version?
return Huffman.buildHuffmanTable(
tableGroup, tableIdx, HUFFMAN_TABLE_BITS, codeLengths, alphabetSizeLimit);
}
// Decode Huffman-coded code lengths.
private static int readComplexHuffmanCode(int alphabetSizeLimit, int skip,
int[] tableGroup, int tableIdx, State s) {
// TODO(eustas): Avoid allocation?
final int[] codeLengths = new int[alphabetSizeLimit];
final int[] codeLengthCodeLengths = new int[CODE_LENGTH_CODES];
int space = 32;
int numCodes = 0;
for (int i = skip; i < CODE_LENGTH_CODES && space > 0; i++) {
final int codeLenIdx = CODE_LENGTH_CODE_ORDER[i];
BitReader.fillBitWindow(s);
final int p = BitReader.peekBits(s) & 15;
// TODO(eustas): Demultiplex FIXED_TABLE.
s.bitOffset += FIXED_TABLE[p] >> 16;
final int v = FIXED_TABLE[p] & 0xFFFF;
codeLengthCodeLengths[codeLenIdx] = v;
if (v != 0) {
space -= (32 >> v);
numCodes++;
}
}
if (space != 0 && numCodes != 1) {
throw new BrotliRuntimeException("Corrupted Huffman code histogram"); // COV_NF_LINE
}
readHuffmanCodeLengths(codeLengthCodeLengths, alphabetSizeLimit, codeLengths, s);
return Huffman.buildHuffmanTable(
tableGroup, tableIdx, HUFFMAN_TABLE_BITS, codeLengths, alphabetSizeLimit);
}
/**
* Decodes Huffman table from bit-stream.
*
* @return number of slots used by resulting Huffman table
*/
private static int readHuffmanCode(int alphabetSizeMax, int alphabetSizeLimit,
int[] tableGroup, int tableIdx, State s) {
BitReader.readMoreInput(s);
BitReader.fillBitWindow(s);
final int simpleCodeOrSkip = BitReader.readFewBits(s, 2);
if (simpleCodeOrSkip == 1) {
return readSimpleHuffmanCode(alphabetSizeMax, alphabetSizeLimit, tableGroup, tableIdx, s);
} else {
return readComplexHuffmanCode(alphabetSizeLimit, simpleCodeOrSkip, tableGroup, tableIdx, s);
}
}
private static int decodeContextMap(int contextMapSize, byte[] contextMap, State s) {
BitReader.readMoreInput(s);
final int numTrees = decodeVarLenUnsignedByte(s) + 1;
if (numTrees == 1) {
Utils.fillBytesWithZeroes(contextMap, 0, contextMapSize);
return numTrees;
}
BitReader.fillBitWindow(s);
final int useRleForZeros = BitReader.readFewBits(s, 1);
int maxRunLengthPrefix = 0;
if (useRleForZeros != 0) {
maxRunLengthPrefix = BitReader.readFewBits(s, 4) + 1;
}
final int alphabetSize = numTrees + maxRunLengthPrefix;
final int tableSize = MAX_HUFFMAN_TABLE_SIZE[(alphabetSize + 31) >> 5];
/* Speculative single entry table group. */
final int[] table = new int[tableSize + 1];
final int tableIdx = table.length - 1;
readHuffmanCode(alphabetSize, alphabetSize, table, tableIdx, s);
for (int i = 0; i < contextMapSize; ) {
BitReader.readMoreInput(s);
BitReader.fillBitWindow(s);
final int code = readSymbol(table, tableIdx, s);
if (code == 0) {
contextMap[i] = 0;
i++;
} else if (code <= maxRunLengthPrefix) {
BitReader.fillBitWindow(s);
int reps = (1 << code) + BitReader.readFewBits(s, 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++;
}
}
BitReader.fillBitWindow(s);
if (BitReader.readFewBits(s, 1) == 1) {
inverseMoveToFrontTransform(contextMap, contextMapSize);
}
return numTrees;
}
private static int decodeBlockTypeAndLength(State s, int treeType, int numBlockTypes) {
final int[] ringBuffers = s.rings;
final int offset = 4 + treeType * 2;
BitReader.fillBitWindow(s);
int blockType = readSymbol(s.blockTrees, 2 * treeType, s);
final int result = readBlockLength(s.blockTrees, 2 * treeType + 1, s);
if (blockType == 1) {
blockType = ringBuffers[offset + 1] + 1;
} else if (blockType == 0) {
blockType = ringBuffers[offset];
} else {
blockType -= 2;
}
if (blockType >= numBlockTypes) {
blockType -= numBlockTypes;
}
ringBuffers[offset] = ringBuffers[offset + 1];
ringBuffers[offset + 1] = blockType;
return result;
}
private static void decodeLiteralBlockSwitch(State s) {
s.literalBlockLength = decodeBlockTypeAndLength(s, 0, s.numLiteralBlockTypes);
final int literalBlockType = s.rings[5];
s.contextMapSlice = literalBlockType << LITERAL_CONTEXT_BITS;
s.literalTreeIdx = s.contextMap[s.contextMapSlice] & 0xFF;
final int contextMode = s.contextModes[literalBlockType];
s.contextLookupOffset1 = contextMode << 9;
s.contextLookupOffset2 = s.contextLookupOffset1 + 256;
}
private static void decodeCommandBlockSwitch(State s) {
s.commandBlockLength = decodeBlockTypeAndLength(s, 1, s.numCommandBlockTypes);
s.commandTreeIdx = s.rings[7];
}
private static void decodeDistanceBlockSwitch(State s) {
s.distanceBlockLength = decodeBlockTypeAndLength(s, 2, s.numDistanceBlockTypes);
s.distContextMapSlice = s.rings[9] << DISTANCE_CONTEXT_BITS;
}
private static void maybeReallocateRingBuffer(State s) {
int newSize = s.maxRingBufferSize;
if (newSize > s.expectedTotalSize) {
/* TODO(eustas): Handle 2GB+ cases more gracefully. */
final int minimalNewSize = s.expectedTotalSize;
while ((newSize >> 1) > minimalNewSize) {
newSize >>= 1;
}
if ((s.inputEnd == 0) && newSize < 16384 && s.maxRingBufferSize >= 16384) {
newSize = 16384;
}
}
if (newSize <= s.ringBufferSize) {
return;
}
final int ringBufferSizeWithSlack = newSize + MAX_TRANSFORMED_WORD_LENGTH;
final byte[] newBuffer = new byte[ringBufferSizeWithSlack];
if (s.ringBuffer.length != 0) {
System.arraycopy(s.ringBuffer, 0, newBuffer, 0, s.ringBufferSize);
}
s.ringBuffer = newBuffer;
s.ringBufferSize = newSize;
}
private static void readNextMetablockHeader(State s) {
if (s.inputEnd != 0) {
s.nextRunningState = FINISHED;
s.runningState = INIT_WRITE;
return;
}
// TODO(eustas): Reset? Do we need this?
s.literalTreeGroup = new int[0];
s.commandTreeGroup = new int[0];
s.distanceTreeGroup = new int[0];
BitReader.readMoreInput(s);
decodeMetaBlockLength(s);
if ((s.metaBlockLength == 0) && (s.isMetadata == 0)) {
return;
}
if ((s.isUncompressed != 0) || (s.isMetadata != 0)) {
BitReader.jumpToByteBoundary(s);
s.runningState = (s.isMetadata != 0) ? READ_METADATA : COPY_UNCOMPRESSED;
} else {
s.runningState = COMPRESSED_BLOCK_START;
}
if (s.isMetadata != 0) {
return;
}
s.expectedTotalSize += s.metaBlockLength;
if (s.expectedTotalSize > 1 << 30) {
s.expectedTotalSize = 1 << 30;
}
if (s.ringBufferSize < s.maxRingBufferSize) {
maybeReallocateRingBuffer(s);
}
}
private static int readMetablockPartition(State s, int treeType, int numBlockTypes) {
int offset = s.blockTrees[2 * treeType];
if (numBlockTypes <= 1) {
s.blockTrees[2 * treeType + 1] = offset;
s.blockTrees[2 * treeType + 2] = offset;
return 1 << 28;
}
final int blockTypeAlphabetSize = numBlockTypes + 2;
offset += readHuffmanCode(
blockTypeAlphabetSize, blockTypeAlphabetSize, s.blockTrees, 2 * treeType, s);
s.blockTrees[2 * treeType + 1] = offset;
final int blockLengthAlphabetSize = NUM_BLOCK_LENGTH_CODES;
offset += readHuffmanCode(
blockLengthAlphabetSize, blockLengthAlphabetSize, s.blockTrees, 2 * treeType + 1, s);
s.blockTrees[2 * treeType + 2] = offset;
return readBlockLength(s.blockTrees, 2 * treeType + 1, s);
}
private static void calculateDistanceLut(State s, int alphabetSizeLimit) {
final byte[] distExtraBits = s.distExtraBits;
final int[] distOffset = s.distOffset;
final int npostfix = s.distancePostfixBits;
final int ndirect = s.numDirectDistanceCodes;
final int postfix = 1 << npostfix;
int bits = 1;
int half = 0;
/* Skip short codes. */
int i = NUM_DISTANCE_SHORT_CODES;
/* Fill direct codes. */
for (int j = 0; j < ndirect; ++j) {
distExtraBits[i] = 0;
distOffset[i] = j + 1;
++i;
}
/* Fill regular distance codes. */
while (i < alphabetSizeLimit) {
final int base = ndirect + ((((2 + half) << bits) - 4) << npostfix) + 1;
/* Always fill the complete group. */
for (int j = 0; j < postfix; ++j) {
distExtraBits[i] = (byte) bits;
distOffset[i] = base + j;
++i;
}
bits = bits + half;
half = half ^ 1;
}
}
private static void readMetablockHuffmanCodesAndContextMaps(State s) {
s.numLiteralBlockTypes = decodeVarLenUnsignedByte(s) + 1;
s.literalBlockLength = readMetablockPartition(s, 0, s.numLiteralBlockTypes);
s.numCommandBlockTypes = decodeVarLenUnsignedByte(s) + 1;
s.commandBlockLength = readMetablockPartition(s, 1, s.numCommandBlockTypes);
s.numDistanceBlockTypes = decodeVarLenUnsignedByte(s) + 1;
s.distanceBlockLength = readMetablockPartition(s, 2, s.numDistanceBlockTypes);
BitReader.readMoreInput(s);
BitReader.fillBitWindow(s);
s.distancePostfixBits = BitReader.readFewBits(s, 2);
s.numDirectDistanceCodes = BitReader.readFewBits(s, 4) << s.distancePostfixBits;
// TODO(eustas): Reuse?
s.contextModes = new byte[s.numLiteralBlockTypes];
for (int i = 0; i < s.numLiteralBlockTypes;) {
/* Ensure that less than 256 bits read between readMoreInput. */
final int limit = Math.min(i + 96, s.numLiteralBlockTypes);
for (; i < limit; ++i) {
BitReader.fillBitWindow(s);
s.contextModes[i] = (byte) BitReader.readFewBits(s, 2);
}
BitReader.readMoreInput(s);
}
// TODO(eustas): Reuse?
s.contextMap = new byte[s.numLiteralBlockTypes << LITERAL_CONTEXT_BITS];
final int numLiteralTrees = decodeContextMap(s.numLiteralBlockTypes << LITERAL_CONTEXT_BITS,
s.contextMap, s);
s.trivialLiteralContext = 1;
for (int j = 0; j < s.numLiteralBlockTypes << LITERAL_CONTEXT_BITS; j++) {
if (s.contextMap[j] != j >> LITERAL_CONTEXT_BITS) {
s.trivialLiteralContext = 0;
break;
}
}
// TODO(eustas): Reuse?
s.distContextMap = new byte[s.numDistanceBlockTypes << DISTANCE_CONTEXT_BITS];
final int numDistTrees = decodeContextMap(s.numDistanceBlockTypes << DISTANCE_CONTEXT_BITS,
s.distContextMap, s);
s.literalTreeGroup = decodeHuffmanTreeGroup(NUM_LITERAL_CODES, NUM_LITERAL_CODES,
numLiteralTrees, s);
s.commandTreeGroup = decodeHuffmanTreeGroup(NUM_COMMAND_CODES, NUM_COMMAND_CODES,
s.numCommandBlockTypes, s);
int distanceAlphabetSizeMax = calculateDistanceAlphabetSize(
s.distancePostfixBits, s.numDirectDistanceCodes, MAX_DISTANCE_BITS);
int distanceAlphabetSizeLimit = distanceAlphabetSizeMax;
if (s.isLargeWindow == 1) {
distanceAlphabetSizeMax = calculateDistanceAlphabetSize(
s.distancePostfixBits, s.numDirectDistanceCodes, MAX_LARGE_WINDOW_DISTANCE_BITS);
distanceAlphabetSizeLimit = calculateDistanceAlphabetLimit(
MAX_ALLOWED_DISTANCE, s.distancePostfixBits, s.numDirectDistanceCodes);
}
s.distanceTreeGroup = decodeHuffmanTreeGroup(distanceAlphabetSizeMax, distanceAlphabetSizeLimit,
numDistTrees, s);
calculateDistanceLut(s, distanceAlphabetSizeLimit);
s.contextMapSlice = 0;
s.distContextMapSlice = 0;
s.contextLookupOffset1 = s.contextModes[0] * 512;
s.contextLookupOffset2 = s.contextLookupOffset1 + 256;
s.literalTreeIdx = 0;
s.commandTreeIdx = 0;
s.rings[4] = 1;
s.rings[5] = 0;
s.rings[6] = 1;
s.rings[7] = 0;
s.rings[8] = 1;
s.rings[9] = 0;
}
private static void copyUncompressedData(State s) {
final byte[] ringBuffer = s.ringBuffer;
// Could happen if block ends at ring buffer end.
if (s.metaBlockLength <= 0) {
BitReader.reload(s);
s.runningState = BLOCK_START;
return;
}
final int chunkLength = Math.min(s.ringBufferSize - s.pos, s.metaBlockLength);
BitReader.copyRawBytes(s, ringBuffer, s.pos, chunkLength);
s.metaBlockLength -= chunkLength;
s.pos += chunkLength;
if (s.pos == s.ringBufferSize) {
s.nextRunningState = COPY_UNCOMPRESSED;
s.runningState = INIT_WRITE;
return;
}
BitReader.reload(s);
s.runningState = BLOCK_START;
}
private static int writeRingBuffer(State s) {
final int toWrite = Math.min(s.outputLength - s.outputUsed,
s.ringBufferBytesReady - s.ringBufferBytesWritten);
// TODO(eustas): DCHECK(toWrite >= 0)
if (toWrite != 0) {
System.arraycopy(s.ringBuffer, s.ringBufferBytesWritten, s.output,
s.outputOffset + s.outputUsed, toWrite);
s.outputUsed += toWrite;
s.ringBufferBytesWritten += toWrite;
}
if (s.outputUsed < s.outputLength) {
return 1;
} else {
return 0;
}
}
private static int[] decodeHuffmanTreeGroup(int alphabetSizeMax, int alphabetSizeLimit,
int n, State s) {
final int maxTableSize = MAX_HUFFMAN_TABLE_SIZE[(alphabetSizeLimit + 31) >> 5];
final int[] group = new int[n + n * maxTableSize];
int next = n;
for (int i = 0; i < n; ++i) {
group[i] = next;
next += readHuffmanCode(alphabetSizeMax, alphabetSizeLimit, group, i, s);
}
return group;
}
// Returns offset in ringBuffer that should trigger WRITE when filled.
private static int calculateFence(State s) {
int result = s.ringBufferSize;
if (s.isEager != 0) {
result = Math.min(result, s.ringBufferBytesWritten + s.outputLength - s.outputUsed);
}
return result;
}
private static void doUseDictionary(State s, int fence) {
if (s.distance > MAX_ALLOWED_DISTANCE) {
throw new BrotliRuntimeException("Invalid backward reference");
}
final int address = s.distance - s.maxDistance - 1 - s.cdTotalSize;
if (address < 0) {
initializeCompoundDictionaryCopy(s, -address - 1, s.copyLength);
s.runningState = COPY_FROM_COMPOUND_DICTIONARY;
} else {
// Force lazy dictionary initialization.
final ByteBuffer dictionaryData = Dictionary.getData();
final int wordLength = s.copyLength;
if (wordLength > Dictionary.MAX_DICTIONARY_WORD_LENGTH) {
throw new BrotliRuntimeException("Invalid backward reference"); // COV_NF_LINE
}
final int shift = Dictionary.sizeBits[wordLength];
if (shift == 0) {
throw new BrotliRuntimeException("Invalid backward reference"); // COV_NF_LINE
}
int offset = Dictionary.offsets[wordLength];
final int mask = (1 << shift) - 1;
final int wordIdx = address & mask;
final int transformIdx = address >>> shift;
offset += wordIdx * wordLength;
final Transform.Transforms transforms = Transform.RFC_TRANSFORMS;
if (transformIdx >= transforms.numTransforms) {
throw new BrotliRuntimeException("Invalid backward reference"); // COV_NF_LINE
}
final int len = Transform.transformDictionaryWord(s.ringBuffer, s.pos, dictionaryData,
offset, wordLength, transforms, transformIdx);
s.pos += len;
s.metaBlockLength -= len;
if (s.pos >= fence) {
s.nextRunningState = MAIN_LOOP;
s.runningState = INIT_WRITE;
return;
}
s.runningState = MAIN_LOOP;
}
}
private static void initializeCompoundDictionary(State s) {
s.cdBlockMap = new byte[1 << CD_BLOCK_MAP_BITS];
int blockBits = CD_BLOCK_MAP_BITS;
// If this function is executed, then s.cdTotalSize > 0.
while (((s.cdTotalSize - 1) >>> blockBits) != 0) {
blockBits++;
}
blockBits -= CD_BLOCK_MAP_BITS;
s.cdBlockBits = blockBits;
int cursor = 0;
int index = 0;
while (cursor < s.cdTotalSize) {
while (s.cdChunkOffsets[index + 1] < cursor) {
index++;
}
s.cdBlockMap[cursor >>> blockBits] = (byte) index;
cursor += 1 << blockBits;
}
}
private static void initializeCompoundDictionaryCopy(State s, int address, int length) {
if (s.cdBlockBits == -1) {
initializeCompoundDictionary(s);
}
int index = s.cdBlockMap[address >>> s.cdBlockBits];
while (address >= s.cdChunkOffsets[index + 1]) {
index++;
}
if (s.cdTotalSize > address + length) {
throw new BrotliRuntimeException("Invalid backward reference");
}
/* Update the recent distances cache */
s.distRbIdx = (s.distRbIdx + 1) & 0x3;
s.rings[s.distRbIdx] = s.distance;
s.metaBlockLength -= length;
s.cdBrIndex = index;
s.cdBrOffset = address - s.cdChunkOffsets[index];
s.cdBrLength = length;
s.cdBrCopied = 0;
}
private static int copyFromCompoundDictionary(State s, int fence) {
int pos = s.pos;
final int origPos = pos;
while (s.cdBrLength != s.cdBrCopied) {
final int space = fence - pos;
final int chunkLength = s.cdChunkOffsets[s.cdBrIndex + 1] - s.cdChunkOffsets[s.cdBrIndex];
final int remChunkLength = chunkLength - s.cdBrOffset;
int length = s.cdBrLength - s.cdBrCopied;
if (length > remChunkLength) {
length = remChunkLength;
}
if (length > space) {
length = space;
}
Utils.copyBytes(
s.ringBuffer, pos, s.cdChunks[s.cdBrIndex], s.cdBrOffset, s.cdBrOffset + length);
pos += length;
s.cdBrOffset += length;
s.cdBrCopied += length;
if (length == remChunkLength) {
s.cdBrIndex++;
s.cdBrOffset = 0;
}
if (pos >= fence) {
break;
}
}
return pos - origPos;
}
/**
* Actual decompress implementation.
*/
static void decompress(State s) {
if (s.runningState == UNINITIALIZED) {
throw new IllegalStateException("Can't decompress until initialized");
}
if (s.runningState == CLOSED) {
throw new IllegalStateException("Can't decompress after close");
}
if (s.runningState == INITIALIZED) {
final int windowBits = decodeWindowBits(s);
if (windowBits == -1) { /* Reserved case for future expansion. */
throw new BrotliRuntimeException("Invalid 'windowBits' code");
}
s.maxRingBufferSize = 1 << windowBits;
s.maxBackwardDistance = s.maxRingBufferSize - 16;
s.runningState = BLOCK_START;
}
int fence = calculateFence(s);
int ringBufferMask = s.ringBufferSize - 1;
byte[] ringBuffer = s.ringBuffer;
while (s.runningState != FINISHED) {
// TODO(eustas): extract cases to methods for the better readability.
switch (s.runningState) {
case BLOCK_START:
if (s.metaBlockLength < 0) {
throw new BrotliRuntimeException("Invalid metablock length");
}
readNextMetablockHeader(s);
/* Ring-buffer would be reallocated here. */
fence = calculateFence(s);
ringBufferMask = s.ringBufferSize - 1;
ringBuffer = s.ringBuffer;
continue;
case COMPRESSED_BLOCK_START:
readMetablockHuffmanCodesAndContextMaps(s);
s.runningState = MAIN_LOOP;
// fall through
case MAIN_LOOP:
if (s.metaBlockLength <= 0) {
s.runningState = BLOCK_START;
continue;
}
BitReader.readMoreInput(s);
if (s.commandBlockLength == 0) {
decodeCommandBlockSwitch(s);
}
s.commandBlockLength--;
BitReader.fillBitWindow(s);
final int cmdCode = readSymbol(s.commandTreeGroup, s.commandTreeIdx, s) << 2;
final short insertAndCopyExtraBits = CMD_LOOKUP[cmdCode];
final int insertLengthOffset = CMD_LOOKUP[cmdCode + 1];
final int copyLengthOffset = CMD_LOOKUP[cmdCode + 2];
s.distanceCode = CMD_LOOKUP[cmdCode + 3];
BitReader.fillBitWindow(s);
{
final int insertLengthExtraBits = insertAndCopyExtraBits & 0xFF;
s.insertLength = insertLengthOffset + BitReader.readBits(s, insertLengthExtraBits);
}
BitReader.fillBitWindow(s);
{
final int copyLengthExtraBits = insertAndCopyExtraBits >> 8;
s.copyLength = copyLengthOffset + BitReader.readBits(s, copyLengthExtraBits);
}
s.j = 0;
s.runningState = INSERT_LOOP;
// fall through
case INSERT_LOOP:
if (s.trivialLiteralContext != 0) {
while (s.j < s.insertLength) {
BitReader.readMoreInput(s);
if (s.literalBlockLength == 0) {
decodeLiteralBlockSwitch(s);
}
s.literalBlockLength--;
BitReader.fillBitWindow(s);
ringBuffer[s.pos] = (byte) readSymbol(s.literalTreeGroup, s.literalTreeIdx, s);
s.pos++;
s.j++;
if (s.pos >= fence) {
s.nextRunningState = INSERT_LOOP;
s.runningState = INIT_WRITE;
break;
}
}
} else {
int prevByte1 = ringBuffer[(s.pos - 1) & ringBufferMask] & 0xFF;
int prevByte2 = ringBuffer[(s.pos - 2) & ringBufferMask] & 0xFF;
while (s.j < s.insertLength) {
BitReader.readMoreInput(s);
if (s.literalBlockLength == 0) {
decodeLiteralBlockSwitch(s);
}
final int literalContext = Context.LOOKUP[s.contextLookupOffset1 + prevByte1]
| Context.LOOKUP[s.contextLookupOffset2 + prevByte2];
final int literalTreeIdx = s.contextMap[s.contextMapSlice + literalContext] & 0xFF;
s.literalBlockLength--;
prevByte2 = prevByte1;
BitReader.fillBitWindow(s);
prevByte1 = readSymbol(s.literalTreeGroup, literalTreeIdx, s);
ringBuffer[s.pos] = (byte) prevByte1;
s.pos++;
s.j++;
if (s.pos >= fence) {
s.nextRunningState = INSERT_LOOP;
s.runningState = INIT_WRITE;
break;
}
}
}
if (s.runningState != INSERT_LOOP) {
continue;
}
s.metaBlockLength -= s.insertLength;
if (s.metaBlockLength <= 0) {
s.runningState = MAIN_LOOP;
continue;
}
int distanceCode = s.distanceCode;
if (distanceCode < 0) {
// distanceCode in untouched; assigning it 0 won't affect distance ring buffer rolling.
s.distance = s.rings[s.distRbIdx];
} else {
BitReader.readMoreInput(s);
if (s.distanceBlockLength == 0) {
decodeDistanceBlockSwitch(s);
}
s.distanceBlockLength--;
BitReader.fillBitWindow(s);
final int distTreeIdx = s.distContextMap[s.distContextMapSlice + distanceCode] & 0xFF;
distanceCode = readSymbol(s.distanceTreeGroup, distTreeIdx, s);
if (distanceCode < NUM_DISTANCE_SHORT_CODES) {
final int index =
(s.distRbIdx + DISTANCE_SHORT_CODE_INDEX_OFFSET[distanceCode]) & 0x3;
s.distance = s.rings[index] + DISTANCE_SHORT_CODE_VALUE_OFFSET[distanceCode];
if (s.distance < 0) {
throw new BrotliRuntimeException("Negative distance"); // COV_NF_LINE
}
} else {
final int extraBits = s.distExtraBits[distanceCode];
int bits;
if (s.bitOffset + extraBits <= BitReader.BITNESS) {
bits = BitReader.readFewBits(s, extraBits);
} else {
BitReader.fillBitWindow(s);
bits = BitReader.readBits(s, extraBits);
}
s.distance = s.distOffset[distanceCode] + (bits << s.distancePostfixBits);
}
}
if (s.maxDistance != s.maxBackwardDistance
&& s.pos < s.maxBackwardDistance) {
s.maxDistance = s.pos;
} else {
s.maxDistance = s.maxBackwardDistance;
}
if (s.distance > s.maxDistance) {
s.runningState = USE_DICTIONARY;
continue;
}
if (distanceCode > 0) {
s.distRbIdx = (s.distRbIdx + 1) & 0x3;
s.rings[s.distRbIdx] = s.distance;
}
if (s.copyLength > s.metaBlockLength) {
throw new BrotliRuntimeException("Invalid backward reference"); // COV_NF_LINE
}
s.j = 0;
s.runningState = COPY_LOOP;
// fall through
case COPY_LOOP:
int src = (s.pos - s.distance) & ringBufferMask;
int dst = s.pos;
final int copyLength = s.copyLength - s.j;
final int srcEnd = src + copyLength;
final int dstEnd = dst + copyLength;
if ((srcEnd < ringBufferMask) && (dstEnd < ringBufferMask)) {
if (copyLength < 12 || (srcEnd > dst && dstEnd > src)) {
for (int k = 0; k < copyLength; k += 4) {
ringBuffer[dst++] = ringBuffer[src++];
ringBuffer[dst++] = ringBuffer[src++];
ringBuffer[dst++] = ringBuffer[src++];
ringBuffer[dst++] = ringBuffer[src++];
}
} else {
Utils.copyBytesWithin(ringBuffer, dst, src, srcEnd);
}
s.j += copyLength;
s.metaBlockLength -= copyLength;
s.pos += copyLength;
} else {
for (; s.j < s.copyLength;) {
ringBuffer[s.pos] =
ringBuffer[(s.pos - s.distance) & ringBufferMask];
s.metaBlockLength--;
s.pos++;
s.j++;
if (s.pos >= fence) {
s.nextRunningState = COPY_LOOP;
s.runningState = INIT_WRITE;
break;
}
}
}
if (s.runningState == COPY_LOOP) {
s.runningState = MAIN_LOOP;
}
continue;
case USE_DICTIONARY:
doUseDictionary(s, fence);
continue;
case COPY_FROM_COMPOUND_DICTIONARY:
s.pos += copyFromCompoundDictionary(s, fence);
if (s.pos >= fence) {
s.nextRunningState = COPY_FROM_COMPOUND_DICTIONARY;
s.runningState = INIT_WRITE;
return;
}
s.runningState = MAIN_LOOP;
continue;
case READ_METADATA:
while (s.metaBlockLength > 0) {
BitReader.readMoreInput(s);
// Optimize
BitReader.fillBitWindow(s);
BitReader.readFewBits(s, 8);
s.metaBlockLength--;
}
s.runningState = BLOCK_START;
continue;
case COPY_UNCOMPRESSED:
copyUncompressedData(s);
continue;
case INIT_WRITE:
s.ringBufferBytesReady = Math.min(s.pos, s.ringBufferSize);
s.runningState = WRITE;
// fall through
case WRITE:
if (writeRingBuffer(s) == 0) {
// Output buffer is full.
return;
}
if (s.pos >= s.maxBackwardDistance) {
s.maxDistance = s.maxBackwardDistance;
}
// Wrap the ringBuffer.
if (s.pos >= s.ringBufferSize) {
if (s.pos > s.ringBufferSize) {
Utils.copyBytesWithin(ringBuffer, 0, s.ringBufferSize, s.pos);
}
s.pos &= ringBufferMask;
s.ringBufferBytesWritten = 0;
}
s.runningState = s.nextRunningState;
continue;
default:
throw new BrotliRuntimeException("Unexpected state " + String.valueOf(s.runningState));
}
}
if (s.runningState == FINISHED) {
if (s.metaBlockLength < 0) {
throw new BrotliRuntimeException("Invalid metablock length");
}
BitReader.jumpToByteBoundary(s);
BitReader.checkHealth(s, 1);
}
}
}