dx/src/com/android/dx/rop/cst/CstLiteralBits.java

/*
 * Copyright (C) 2007 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.dx.rop.cst;

/**
 * Constants which are literal bitwise values of some sort.
 */
public abstract class CstLiteralBits
        extends TypedConstant {
    /**
     * Returns whether or not this instance's value may be accurately
     * represented as an <code>int</code>. The rule is that if there
     * is an <code>int</code> which may be sign-extended to yield this
     * instance's value, then this method returns <code>true</code>.
     * Otherwise, it returns <code>false</code>.
     *
     * @return <code>true</code> iff this instance fits in an <code>int</code>
     */
    public abstract boolean fitsInInt();

    /**
     * Gets the value as <code>int</code> bits. If this instance contains
     * more bits than fit in an <code>int</code>, then this returns only
     * the low-order bits.
     *
     * @return the bits
     */
    public abstract int getIntBits();

    /**
     * Gets the value as <code>long</code> bits. If this instance contains
     * fewer bits than fit in a <code>long</code>, then the result of this
     * method is the sign extension of the value.
     * 
     * @return the bits
     */
    public abstract long getLongBits();

    /**
     * Returns true if this value can fit in 16 bits with sign-extension.
     *
     * @return true if the sign-extended lower 16 bits are the same as
     * the value.
     */
    public boolean fitsIn16Bits() {
        if (! fitsInInt()) {
            return false;
        }
        
        int bits = getIntBits();
        return (short) bits == bits;
    }

    /**
     * Returns true if this value can fit in 8 bits with sign-extension.
     *
     * @return true if the sign-extended lower 8 bits are the same as
     * the value.
     */
    public boolean fitsIn8Bits() {
        if (! fitsInInt()) {
            return false;
        }

        int bits = getIntBits();
        return (byte) bits == bits;
    }
}