Form22t.java revision 72e93344b4d1ffc71e9c832ec23de0657e5b04a5 
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
25/**
26 * Instruction format {@code 22t}. See the instruction format spec
27 * for details.
28 */
29public final class Form22t extends InsnFormat {
30    /** {@code non-null;} unique instance of this class */
31    public static final InsnFormat THE_ONE = new Form22t();
32
33    /**
34     * Constructs an instance. This class is not publicly
35     * instantiable. Use {@link #THE_ONE}.
36     */
37    private Form22t() {
38        // This space intentionally left blank.
39    }
40
41    /** {@inheritDoc} */
42    @Override
43    public String insnArgString(DalvInsn insn) {
44        RegisterSpecList regs = insn.getRegisters();
45        return regs.get(0).regString() + ", " + regs.get(1).regString() +
46            ", " + branchString(insn);
47    }
48
49    /** {@inheritDoc} */
50    @Override
51    public String insnCommentString(DalvInsn insn, boolean noteIndices) {
52        return branchComment(insn);
53    }
54
55    /** {@inheritDoc} */
56    @Override
57    public int codeSize() {
58        return 2;
59    }
60
61    /** {@inheritDoc} */
62    @Override
63    public boolean isCompatible(DalvInsn insn) {
64        RegisterSpecList regs = insn.getRegisters();
65
66        if (!((insn instanceof TargetInsn) &&
67              (regs.size() == 2) &&
68              unsignedFitsInNibble(regs.get(0).getReg()) &&
69              unsignedFitsInNibble(regs.get(1).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 boolean branchFits(TargetInsn insn) {
80        int offset = insn.getTargetOffset();
81
82        // Note: A zero offset would fit, but it is prohibited by the spec.
83        return (offset != 0) && signedFitsInShort(offset);
84    }
85
86    /** {@inheritDoc} */
87    @Override
88    public InsnFormat nextUp() {
89        return null;
90    }
91
92    /** {@inheritDoc} */
93    @Override
94    public void writeTo(AnnotatedOutput out, DalvInsn insn) {
95        RegisterSpecList regs = insn.getRegisters();
96        int offset = ((TargetInsn) insn).getTargetOffset();
97
98        write(out,
99              opcodeUnit(insn,
100                         makeByte(regs.get(0).getReg(), regs.get(1).getReg())),
101              (short) offset);
102    }
103}
104