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A standalone packaging of AOSP's platform/dalvik dx library.
/*
* Copyright (C) 2011 The Android Open Source Project
*
* 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 com.android.dex;
import com.android.dex.util.ByteInput;
import com.android.dex.util.ByteOutput;
/**
* Read and write {@code encoded_value} primitives.
*/
public final class EncodedValueCodec {
private EncodedValueCodec() {
}
/**
* Writes a signed integral to {@code out}.
*/
public static void writeSignedIntegralValue(ByteOutput out, int type, long value) {
/*
* Figure out how many bits are needed to represent the value,
* including a sign bit: The bit count is subtracted from 65
* and not 64 to account for the sign bit. The xor operation
* has the effect of leaving non-negative values alone and
* unary complementing negative values (so that a leading zero
* count always returns a useful number for our present
* purpose).
*/
int requiredBits = 65 - Long.numberOfLeadingZeros(value ^ (value >> 63));
// Round up the requiredBits to a number of bytes.
int requiredBytes = (requiredBits + 0x07) >> 3;
/*
* Write the header byte, which includes the type and
* requiredBytes - 1.
*/
out.writeByte(type | ((requiredBytes - 1) << 5));
// Write the value, per se.
while (requiredBytes > 0) {
out.writeByte((byte) value);
value >>= 8;
requiredBytes--;
}
}
/**
* Writes an unsigned integral to {@code out}.
*/
public static void writeUnsignedIntegralValue(ByteOutput out, int type, long value) {
// Figure out how many bits are needed to represent the value.
int requiredBits = 64 - Long.numberOfLeadingZeros(value);
if (requiredBits == 0) {
requiredBits = 1;
}
// Round up the requiredBits to a number of bytes.
int requiredBytes = (requiredBits + 0x07) >> 3;
/*
* Write the header byte, which includes the type and
* requiredBytes - 1.
*/
out.writeByte(type | ((requiredBytes - 1) << 5));
// Write the value, per se.
while (requiredBytes > 0) {
out.writeByte((byte) value);
value >>= 8;
requiredBytes--;
}
}
/**
* Writes a right-zero-extended value to {@code out}.
*/
public static void writeRightZeroExtendedValue(ByteOutput out, int type, long value) {
// Figure out how many bits are needed to represent the value.
int requiredBits = 64 - Long.numberOfTrailingZeros(value);
if (requiredBits == 0) {
requiredBits = 1;
}
// Round up the requiredBits to a number of bytes.
int requiredBytes = (requiredBits + 0x07) >> 3;
// Scootch the first bits to be written down to the low-order bits.
value >>= 64 - (requiredBytes * 8);
/*
* Write the header byte, which includes the type and
* requiredBytes - 1.
*/
out.writeByte(type | ((requiredBytes - 1) << 5));
// Write the value, per se.
while (requiredBytes > 0) {
out.writeByte((byte) value);
value >>= 8;
requiredBytes--;
}
}
/**
* Read a signed integer.
*
* @param zwidth byte count minus one
*/
public static int readSignedInt(ByteInput in, int zwidth) {
int result = 0;
for (int i = zwidth; i >= 0; i--) {
result = (result >>> 8) | ((in.readByte() & 0xff) << 24);
}
result >>= (3 - zwidth) * 8;
return result;
}
/**
* Read an unsigned integer.
*
* @param zwidth byte count minus one
* @param fillOnRight true to zero fill on the right; false on the left
*/
public static int readUnsignedInt(ByteInput in, int zwidth, boolean fillOnRight) {
int result = 0;
if (!fillOnRight) {
for (int i = zwidth; i >= 0; i--) {
result = (result >>> 8) | ((in.readByte() & 0xff) << 24);
}
result >>>= (3 - zwidth) * 8;
} else {
for (int i = zwidth; i >= 0; i--) {
result = (result >>> 8) | ((in.readByte() & 0xff) << 24);
}
}
return result;
}
/**
* Read a signed long.
*
* @param zwidth byte count minus one
*/
public static long readSignedLong(ByteInput in, int zwidth) {
long result = 0;
for (int i = zwidth; i >= 0; i--) {
result = (result >>> 8) | ((in.readByte() & 0xffL) << 56);
}
result >>= (7 - zwidth) * 8;
return result;
}
/**
* Read an unsigned long.
*
* @param zwidth byte count minus one
* @param fillOnRight true to zero fill on the right; false on the left
*/
public static long readUnsignedLong(ByteInput in, int zwidth, boolean fillOnRight) {
long result = 0;
if (!fillOnRight) {
for (int i = zwidth; i >= 0; i--) {
result = (result >>> 8) | ((in.readByte() & 0xffL) << 56);
}
result >>>= (7 - zwidth) * 8;
} else {
for (int i = zwidth; i >= 0; i--) {
result = (result >>> 8) | ((in.readByte() & 0xffL) << 56);
}
}
return result;
}
}