org.glassfish.grizzly.compression.lzma.impl.rangecoder.RangeDecoder Maven / Gradle / Ivy
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package org.glassfish.grizzly.compression.lzma.impl.rangecoder;
import org.glassfish.grizzly.Buffer;
import java.io.IOException;
import org.glassfish.grizzly.compression.lzma.LZMADecoder;
/**
* RangeDecoder
*
* @author Igor Pavlov
*/
public class RangeDecoder {
static final int kTopMask = ~((1 << 24) - 1);
static final int kNumBitModelTotalBits = 11;
static final int kBitModelTotal = (1 << kNumBitModelTotalBits);
static final int kNumMoveBits = 5;
int Range;
int Code;
Buffer inputBuffer;
int newBound;
int decodeBitState;
int decodeDirectBitsState;
int decodeDirectBitsResult;
int decodeDirectBitsI;
public final void initFromState(final LZMADecoder.LZMAInputState decoderState) {
this.inputBuffer = decoderState.getSrc();
}
public final void releaseBuffer() {
inputBuffer = null;
}
public final void init() throws IOException {
Code = 0;
Range = -1;
decodeBitState = 0;
decodeDirectBitsState = 0;
for (int i = 0; i < 5; i++) {
Code = (Code << 8) | (inputBuffer.get() & 0xFF);
}
}
public final boolean decodeDirectBits(LZMADecoder.LZMAInputState decodeState,
int numTotalBits) throws IOException {
do {
switch (decodeDirectBitsState) {
case 0:
{
decodeDirectBitsResult = 0;
decodeDirectBitsI = numTotalBits;
decodeDirectBitsState = 1;
}
case 1:
{
if (decodeDirectBitsI == 0) {
decodeDirectBitsState = 4;
continue;
}
Range >>>= 1;
final int t = ((Code - Range) >>> 31);
Code -= Range & (t - 1);
decodeDirectBitsResult = (decodeDirectBitsResult << 1) | (1 - t);
final boolean condition = (Range & kTopMask) == 0;
decodeDirectBitsState = condition ? 2 : 3;
continue;
}
case 2: {
if (!inputBuffer.hasRemaining()) {
return false;
}
Code = (Code << 8) | (inputBuffer.get() & 0xFF);
Range <<= 8;
}
case 3: {
decodeDirectBitsI--;
decodeDirectBitsState = 1;
continue;
}
case 4: {
decodeState.lastMethodResult = decodeDirectBitsResult;
decodeDirectBitsState = 0;
return true;
}
}
} while (true);
}
public boolean decodeBit(LZMADecoder.LZMAInputState decodeState, short[] probs, int index)
throws IOException {
do {
switch (decodeBitState) {
case 0: {
int prob = probs[index];
newBound = (Range >>> kNumBitModelTotalBits) * prob;
final boolean condition = (Code ^ 0x80000000) < (newBound ^ 0x80000000);
decodeBitState = condition ? 1 : 4;
continue;
}
case 1: {
int prob = probs[index];
Range = newBound;
probs[index] = (short) (prob + ((kBitModelTotal - prob) >>> kNumMoveBits));
final boolean condition = (Range & kTopMask) == 0;
decodeBitState = condition ? 2 : 3;
continue;
}
case 2: {
if (!inputBuffer.hasRemaining()) {
return false;
}
Code = (Code << 8) | (inputBuffer.get() & 0xFF);
Range <<= 8;
}
case 3: {
decodeState.lastMethodResult = 0;
decodeBitState = 0;
return true;
}
case 4: {
int prob = probs[index];
Range -= newBound;
Code -= newBound;
probs[index] = (short) (prob - ((prob) >>> kNumMoveBits));
final boolean condition = (Range & kTopMask) == 0;
decodeBitState = condition ? 5 : 6;
continue;
}
case 5: {
if (!inputBuffer.hasRemaining()) {
return false;
}
Code = (Code << 8) | (inputBuffer.get() & 0xFF);
Range <<= 8;
}
case 6: {
decodeState.lastMethodResult = 1;
decodeBitState = 0;
return true;
}
}
} while (true);
}
public static void initBitModels(short[] probs) {
for (int i = 0; i < probs.length; i++) {
probs[i] = (kBitModelTotal >>> 1);
}
}
}
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