HdmiCecMessage.java revision 8e93c84739902f5adaa499b474f39e3c4807bc1c 
1/*
2 * Copyright (C) 2014 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.server.hdmi;
18
19import libcore.util.EmptyArray;
20
21import java.util.Arrays;
22
23/**
24 * A class to encapsulate HDMI-CEC message used for the devices connected via
25 * HDMI cable to communicate with one another. A message is defined by its
26 * source and destination address, command (or opcode), and optional parameters.
27 */
28public final class HdmiCecMessage {
29    public static final byte[] EMPTY_PARAM = EmptyArray.BYTE;
30
31    private static final int MAX_MESSAGE_PARAM_LENGTH = 14;
32
33    private final int mSource;
34    private final int mDestination;
35
36    private final int mOpcode;
37    private final byte[] mParams;
38
39    /**
40     * Constructor.
41     */
42    public HdmiCecMessage(int source, int destination, int opcode, byte[] params) {
43        mSource = source;
44        mDestination = destination;
45        mOpcode = opcode & 0xFF;
46
47        if (params.length > MAX_MESSAGE_PARAM_LENGTH) {
48            throw new IllegalArgumentException(
49                    "Param length should be at most 13 but current param length is "
50                    + params.length);
51        }
52        mParams = Arrays.copyOf(params, params.length);
53    }
54
55    /**
56     * Return the source address field of the message. It is the logical address
57     * of the device which generated the message.
58     *
59     * @return source address
60     */
61    public int getSource() {
62        return mSource;
63    }
64
65    /**
66     * Return the destination address field of the message. It is the logical address
67     * of the device to which the message is sent.
68     *
69     * @return destination address
70     */
71    public int getDestination() {
72        return mDestination;
73    }
74
75    /**
76     * Return the opcode field of the message. It is the type of the message that
77     * tells the destination device what to do.
78     *
79     * @return opcode
80     */
81    public int getOpcode() {
82        return mOpcode;
83    }
84
85    /**
86     * Return the parameter field of the message. The contents of parameter varies
87     * from opcode to opcode, and is used together with opcode to describe
88     * the action for the destination device to take.
89     *
90     * @return parameter
91     */
92    public byte[] getParams() {
93        return mParams;
94    }
95
96    @Override
97    public String toString() {
98        StringBuffer s = new StringBuffer();
99        s.append(String.format("<%s> src: %d, dst: %d",
100                opcodeToString(mOpcode), mSource, mDestination));
101        if (mParams.length > 0) {
102            s.append(", params:");
103            for (byte data : mParams) {
104                s.append(String.format(" %02X", data));
105            }
106        }
107        return s.toString();
108    }
109
110    private static String opcodeToString(int opcode) {
111        switch (opcode) {
112            case Constants.MESSAGE_FEATURE_ABORT:
113                return "Feature Abort";
114            case Constants.MESSAGE_CEC_VERSION:
115                return "CEC Version";
116            case Constants.MESSAGE_REQUEST_ARC_INITIATION:
117                return "Request ARC Initiation";
118            case Constants.MESSAGE_REQUEST_ARC_TERMINATION:
119                return "Request ARC Termination";
120            case Constants.MESSAGE_REPORT_ARC_INITIATED:
121                return "Report ARC Initiated";
122            case Constants.MESSAGE_REPORT_ARC_TERMINATED:
123                return "Report ARC Terminated";
124            case Constants.MESSAGE_TEXT_VIEW_ON:
125                return "Text View On";
126            case Constants.MESSAGE_ACTIVE_SOURCE:
127                return "Active Source";
128            case Constants.MESSAGE_GIVE_DEVICE_POWER_STATUS:
129                return "Give Device Power Status";
130            case Constants.MESSAGE_VENDOR_COMMAND:
131                return "Vendor Command";
132            case Constants.MESSAGE_VENDOR_COMMAND_WITH_ID:
133                return "Vendor Command With ID";
134            default:
135                return String.format("Opcode: %02X", opcode);
136        }
137    }
138}
139
140