Form21t.java revision 579d7739c53a2707ad711a2d2cae46d7d782f061 
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
17package com.android.dx.dex.code.form;
18
19import com.android.dx.dex.code.DalvInsn;
20import com.android.dx.dex.code.InsnFormat;
21import com.android.dx.dex.code.TargetInsn;
22import com.android.dx.rop.code.RegisterSpecList;
23import com.android.dx.util.AnnotatedOutput;
24
25import java.util.BitSet;
26
27/**
28 * Instruction format {@code 21t}. See the instruction format spec
29 * for details.
30 */
31public final class Form21t extends InsnFormat {
32    /** {@code non-null;} unique instance of this class */
33    public static final InsnFormat THE_ONE = new Form21t();
34
35    /**
36     * Constructs an instance. This class is not publicly
37     * instantiable. Use {@link #THE_ONE}.
38     */
39    private Form21t() {
40        // This space intentionally left blank.
41    }
42
43    /** {@inheritDoc} */
44    @Override
45    public String insnArgString(DalvInsn insn) {
46        RegisterSpecList regs = insn.getRegisters();
47        return regs.get(0).regString() + ", " + branchString(insn);
48    }
49
50    /** {@inheritDoc} */
51    @Override
52    public String insnCommentString(DalvInsn insn, boolean noteIndices) {
53        return branchComment(insn);
54    }
55
56    /** {@inheritDoc} */
57    @Override
58    public int codeSize() {
59        return 2;
60    }
61
62    /** {@inheritDoc} */
63    @Override
64    public boolean isCompatible(DalvInsn insn) {
65        RegisterSpecList regs = insn.getRegisters();
66
67        if (!((insn instanceof TargetInsn) &&
68              (regs.size() == 1) &&
69              unsignedFitsInByte(regs.get(0).getReg()))) {
70            return false;
71        }
72
73        TargetInsn ti = (TargetInsn) insn;
74        return ti.hasTargetOffset() ? branchFits(ti) : true;
75    }
76
77    /** {@inheritDoc} */
78    @Override
79    public BitSet compatibleRegs(DalvInsn insn) {
80        RegisterSpecList regs = insn.getRegisters();
81        BitSet bits = new BitSet(1);
82
83        bits.set(0, unsignedFitsInByte(regs.get(0).getReg()));
84        return bits;
85    }
86
87    /** {@inheritDoc} */
88    @Override
89    public boolean branchFits(TargetInsn insn) {
90        int offset = insn.getTargetOffset();
91
92        // Note: A zero offset would fit, but it is prohibited by the spec.
93        return (offset != 0) && signedFitsInShort(offset);
94    }
95
96    /** {@inheritDoc} */
97    @Override
98    public void writeTo(AnnotatedOutput out, DalvInsn insn) {
99        RegisterSpecList regs = insn.getRegisters();
100        int offset = ((TargetInsn) insn).getTargetOffset();
101
102        write(out,
103              opcodeUnit(insn, regs.get(0).getReg()),
104              (short) offset);
105    }
106}
107