dexlib/src/main/java/org/jf/dexlib/Code/Format/Instruction20bc.java

/*
 * [The "BSD licence"]
 * Copyright (c) 2011 Ben Gruver
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.jf.dexlib.Code.Format;

import org.jf.dexlib.*;
import org.jf.dexlib.Code.*;
import org.jf.dexlib.Util.AnnotatedOutput;
import org.jf.dexlib.Util.NumberUtils;

public class Instruction20bc extends InstructionWithReference {
    public static final Instruction.InstructionFactory Factory = new Factory();

    private VerificationErrorType validationErrorType;

    public Instruction20bc(Opcode opcode, VerificationErrorType validationErrorType, Item referencedItem) {
        super(opcode, referencedItem, getReferenceType(referencedItem));

        this.validationErrorType = validationErrorType;
    }

    private static ReferenceType getReferenceType(Item item) {
        if (item instanceof TypeIdItem) {
            return ReferenceType.type;
        }
        if (item instanceof FieldIdItem) {
            return ReferenceType.field;
        }
        if (item instanceof MethodIdItem) {
            return ReferenceType.method;
        }
        return null;
    }

    private Instruction20bc(DexFile dexFile, Opcode opcode, byte[] buffer, int bufferIndex) {
        super(dexFile, opcode, buffer, bufferIndex);

        short val = NumberUtils.decodeUnsignedByte(buffer[bufferIndex+1]);
        validationErrorType = VerificationErrorType.getValidationErrorType(val & 0x3f);
    }

    protected ReferenceType readReferenceType(Opcode opcode, byte[] buffer, int bufferIndex) {
        short val = NumberUtils.decodeUnsignedByte(buffer[bufferIndex+1]);
        short referenceType = (short)(val >> 6);
        return ReferenceType.fromValidationErrorReferenceType(referenceType);
    }

    @Override
    public Format getFormat() {
        return Format.Format20bc;
    }

    @Override
    protected void writeInstruction(AnnotatedOutput out, int currentCodeAddress) {
        if(opcode == Opcode.CONST_STRING && getReferencedItem().getIndex() > 0xFFFF) {
            throw new RuntimeException("String offset is too large for const-string. Use string-const/jumbo instead.");
        }

        out.writeByte(opcode.value);
        out.writeByte((this.getReferenceType().getValidationErrorReferenceType() << 6) &
                validationErrorType.getValue());

        out.writeShort(getReferencedItem().getIndex());
    }

    public VerificationErrorType getValidationErrorType() {
        return validationErrorType;
    }

    private static class Factory implements Instruction.InstructionFactory {
        public Instruction makeInstruction(DexFile dexFile, Opcode opcode, byte[] buffer, int bufferIndex) {
            return new Instruction20bc(dexFile, opcode, buffer, bufferIndex);
        }
    }
}