/* Software Name : AsmDex
* Version : 1.0
*
* Copyright © 2012 France Télécom
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.ow2.asmdex.encodedValue;
import org.ow2.asmdex.Constants;
import org.ow2.asmdex.Opcodes;
/**
* Utility Class for the encoding of Encoded Value.
*
* @author Julien Névo
*/
public class EncodedValueUtil {
/**
* Encodes the Header of a Value (the first byte including the value_arg and value_type).
* @param size actual size of the encoded value (NOT decremented of 1).
* @param type type of the value.
* @return a byte representing the header.
*/
public static byte encodeHeader(int size, int type) {
if ((type == 0x00) || (type >= 0x1c)) {
return (byte)type;
}
return (byte)(type | ((size - 1) << 5));
}
/**
* Returns an unsigned encoded_value, including the header.
* @param val unsigned value to encode.
* @param type type of the value. This is only needed for the header.
* @return an array consisting of an encoded_value and its header.
*/
public static byte[] encodeUnsignedValue(int val, int type) {
byte[] result;
int nb1 = 0;
int nb2 = 0;
int nb3 = 0;
int nb4 = 0;
int size = 1;
if (val != 0) {
nb1 = val & 0xff;
val = val >>> 8;
if (val != 0) {
size++;
nb2 = val & 0xff;
val = val >>> 8;
if (val != 0) {
size++;
nb3 = val & 0xff;
val = val >>> 8;
if (val != 0) {
size++;
nb4 = val & 0xff;
}
}
}
}
result = new byte[size + 1]; // We keep the first entry to code the "header".
if (size > 3) { result[4] = (byte)nb4; }
if (size > 2) { result[3] = (byte)nb3; }
if (size > 1) { result[2] = (byte)nb2; }
result[1] = (byte)nb1;
result[0] = encodeHeader(size, type);
return result;
}
/**
* Returns an encoded_value, including the header.
* @param val value to encode.
* @param type type of the value. This is only needed for the header.
* @return an array consisting of an encoded_value and its header.
*/
public static byte[] encodeSignedValue(int val, int type) {
int nbBytes = getNbBytesInSignedValue(val);
byte[] bytes = new byte[nbBytes + 1]; // Leave one byte for the header.
for (int i = 1; i < (nbBytes + 1); i++) {
bytes[i] = (byte)val;
val = val >> 8;
}
bytes[0] = encodeHeader(nbBytes, type);
return bytes;
}
/**
* Returns an encoded_value (long), including the header.
* @param val value to encode.
* @param type type of the value. This is only needed for the header.
* @return an array consisting of an encoded_value and its header.
*/
public static byte[] encodeSignedValue(long val, int type) {
int nbBytes = getNbBytesInSignedValue(val);
byte[] bytes = new byte[nbBytes + 1]; // Leave one byte for the header.
for (int i = 1; i < (nbBytes + 1); i++) {
bytes[i] = (byte)val;
val = val >> 8;
}
bytes[0] = encodeHeader(nbBytes, type);
return bytes;
}
/**
* Returns an zero-extended-to-the-right encoded_value, including the header.
* @param val value to encode.
* @param type type of the value. This is only needed for the header.
* @return an array consisting of an encoded_value and its header.
*/
public static byte[] encodeZeroExtendedToRightValue(long val, int type) {
int nbBytes = getNbBytesForRightZeroExtendedValue(val);
val = val >> (64 - (nbBytes * 8));
byte[] bytes = new byte[nbBytes + 1]; // Leave one byte for the header.
for(int i = 1; i < (nbBytes + 1); i++) {
bytes[i] = (byte)val;
val = val >> 8;
}
bytes[0] = encodeHeader(nbBytes, type);
return bytes;
}
/**
* Returns the bytes count needed to encode the given signed value.
* @param value the signed value.
* @return the bytes count needed to encode the value.
*/
public static int getNbBytesInSignedValue(long value) {
int nbBits = 65 - Long.numberOfLeadingZeros(value ^ (value >> 63));
return (nbBits + 0x07) >> 3;
}
/**
* Returns the bytes count needed to encode the given signed value.
* @param value the signed value.
* @return the bytes count needed to encode the value.
*/
public static int getNbBytesInSignedValue(int value) {
int nbBits = 33 - Integer.numberOfLeadingZeros(value ^ (value >> 31));
return (nbBits + 0x07) >> 3;
}
/**
* Returns the bytes count needed to encoded the given value, zero-extended
* to the right.
* @param value the value.
* @return the bytes count needed to encode the value.
*/
public static int getNbBytesForRightZeroExtendedValue(long value) {
int requiredBits = 64 - Long.numberOfTrailingZeros(value);
if (requiredBits == 0) {
requiredBits = 1;
}
return (requiredBits + 0x07) >> 3;
}
/**
* Converts a Descriptor into a Value Type. Works only for primitives.
* @param desc descriptor. Should contain only one element, only the first is taken in account.
* @return the value type, see {@link Opcodes}.
*/
public static int getTypeFromDescriptor(String desc) {
int result = 0;
switch (desc.charAt(0)) {
case 'Z':
result = Opcodes.VALUE_BOOLEAN;
break;
case 'B':
result = Opcodes.VALUE_BYTE;
break;
case 'S':
result = Opcodes.VALUE_SHORT;
break;
case 'C':
result = Opcodes.VALUE_CHAR;
break;
case 'I':
result = Opcodes.VALUE_INT;
break;
case 'J':
result = Opcodes.VALUE_LONG;
break;
case 'F':
result = Opcodes.VALUE_FLOAT;
break;
case 'D':
result = Opcodes.VALUE_DOUBLE;
break;
default:
try { throw new Exception("Unknown descriptor to convert: " + desc); }
catch (Exception e) { e.printStackTrace(); }
}
return result;
}
/**
* Indicates whether the given descriptor is a reference or a primitive.
* @param desc descriptor. Should contain only one element, only the first is taken in account.
* @return true if the given descriptor is a reference.
*/
public static boolean isTypeAReference(String desc) {
boolean result = false;
switch (desc.charAt(0)) {
case 'L':
case '[':
result = true;
break;
}
return result;
}
/**
* Indicates whether the given descriptor is a String.
* @param desc descriptor. Should contain only one element.
* @return true if the given descriptor is a String.
*/
public static boolean isString(String desc) {
return desc.equals(Constants.STRING_TYPE);
}
}