Home | History | Annotate | Download | only in cst 
      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.dexgen.rop.cst;
     18 
     19 /**
     20  * Constants which are literal bitwise values of some sort.
     21  */
     22 public abstract class CstLiteralBits
     23         extends TypedConstant {
     24     /**
     25      * Returns whether or not this instance's value may be accurately
     26      * represented as an {@code int}. The rule is that if there
     27      * is an {@code int} which may be sign-extended to yield this
     28      * instance's value, then this method returns {@code true}.
     29      * Otherwise, it returns {@code false}.
     30      *
     31      * @return {@code true} iff this instance fits in an {@code int}
     32      */
     33     public abstract boolean fitsInInt();
     34 
     35     /**
     36      * Gets the value as {@code int} bits. If this instance contains
     37      * more bits than fit in an {@code int}, then this returns only
     38      * the low-order bits.
     39      *
     40      * @return the bits
     41      */
     42     public abstract int getIntBits();
     43 
     44     /**
     45      * Gets the value as {@code long} bits. If this instance contains
     46      * fewer bits than fit in a {@code long}, then the result of this
     47      * method is the sign extension of the value.
     48      *
     49      * @return the bits
     50      */
     51     public abstract long getLongBits();
     52 
     53     /**
     54      * Returns true if this value can fit in 16 bits with sign-extension.
     55      *
     56      * @return true if the sign-extended lower 16 bits are the same as
     57      * the value.
     58      */
     59     public boolean fitsIn16Bits() {
     60         if (! fitsInInt()) {
     61             return false;
     62         }
     63 
     64         int bits = getIntBits();
     65         return (short) bits == bits;
     66     }
     67 
     68     /**
     69      * Returns true if this value can fit in 8 bits with sign-extension.
     70      *
     71      * @return true if the sign-extended lower 8 bits are the same as
     72      * the value.
     73      */
     74     public boolean fitsIn8Bits() {
     75         if (! fitsInInt()) {
     76             return false;
     77         }
     78 
     79         int bits = getIntBits();
     80         return (byte) bits == bits;
     81     }
     82 }
     83