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1 /*
2  * Copyright (C) 2010 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 //#define LOG_NDEBUG 0
18 #define LOG_TAG "AHierarchicalStateMachine"
19 #include <utils/Log.h>
20 
21 #include <media/stagefright/foundation/AHierarchicalStateMachine.h>
22 
23 #include <media/stagefright/foundation/ADebug.h>
24 #include <media/stagefright/foundation/AMessage.h>
25 #include <utils/Vector.h>
26 
27 namespace android {
28 
AState(const sp<AState> & parentState)29 AState::AState(const sp<AState> &parentState)
30     : mParentState(parentState) {
31 }
32 
~AState()33 AState::~AState() {
34 }
35 
parentState()36 sp<AState> AState::parentState() {
37     return mParentState;
38 }
39 
stateEntered()40 void AState::stateEntered() {
41 }
42 
stateExited()43 void AState::stateExited() {
44 }
45 
46 ////////////////////////////////////////////////////////////////////////////////
47 
AHierarchicalStateMachine()48 AHierarchicalStateMachine::AHierarchicalStateMachine() {
49 }
50 
~AHierarchicalStateMachine()51 AHierarchicalStateMachine::~AHierarchicalStateMachine() {
52 }
53 
handleMessage(const sp<AMessage> & msg)54 void AHierarchicalStateMachine::handleMessage(const sp<AMessage> &msg) {
55     sp<AState> save = mState;
56 
57     sp<AState> cur = mState;
58     while (cur != NULL && !cur->onMessageReceived(msg)) {
59         // If you claim not to have handled the message you shouldn't
60         // have called setState...
61         CHECK(save == mState);
62 
63         cur = cur->parentState();
64     }
65 
66     if (cur != NULL) {
67         return;
68     }
69 
70     ALOGW("Warning message %s unhandled in root state.",
71          msg->debugString().c_str());
72 }
73 
changeState(const sp<AState> & state)74 void AHierarchicalStateMachine::changeState(const sp<AState> &state) {
75     if (state == mState) {
76         // Quick exit for the easy case.
77         return;
78     }
79 
80     Vector<sp<AState> > A;
81     sp<AState> cur = mState;
82     for (;;) {
83         A.push(cur);
84         if (cur == NULL) {
85             break;
86         }
87         cur = cur->parentState();
88     }
89 
90     Vector<sp<AState> > B;
91     cur = state;
92     for (;;) {
93         B.push(cur);
94         if (cur == NULL) {
95             break;
96         }
97         cur = cur->parentState();
98     }
99 
100     // Remove the common tail.
101     while (A.size() > 0 && B.size() > 0 && A.top() == B.top()) {
102         A.pop();
103         B.pop();
104     }
105 
106     mState = state;
107 
108     for (size_t i = 0; i < A.size(); ++i) {
109         A.editItemAt(i)->stateExited();
110     }
111 
112     for (size_t i = B.size(); i > 0;) {
113         i--;
114         B.editItemAt(i)->stateEntered();
115     }
116 }
117 
118 }  // namespace android
119