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-rw-r--r--media/libstagefright/foundation/AHierarchicalStateMachine.cpp97
1 files changed, 97 insertions, 0 deletions
diff --git a/media/libstagefright/foundation/AHierarchicalStateMachine.cpp b/media/libstagefright/foundation/AHierarchicalStateMachine.cpp
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+++ b/media/libstagefright/foundation/AHierarchicalStateMachine.cpp
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+#include <media/stagefright/foundation/AHierarchicalStateMachine.h>
+
+#include <media/stagefright/foundation/ADebug.h>
+#include <media/stagefright/foundation/AMessage.h>
+#include <utils/Vector.h>
+
+namespace android {
+
+AState::AState(const sp<AState> &parentState)
+ : mParentState(parentState) {
+}
+
+AState::~AState() {
+}
+
+sp<AState> AState::parentState() {
+ return mParentState;
+}
+
+void AState::stateEntered() {
+}
+
+void AState::stateExited() {
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+AHierarchicalStateMachine::AHierarchicalStateMachine() {
+}
+
+AHierarchicalStateMachine::~AHierarchicalStateMachine() {
+}
+
+void AHierarchicalStateMachine::onMessageReceived(const sp<AMessage> &msg) {
+ sp<AState> save = mState;
+
+ sp<AState> cur = mState;
+ while (cur != NULL && !cur->onMessageReceived(msg)) {
+ // If you claim not to have handled the message you shouldn't
+ // have called setState...
+ CHECK(save == mState);
+
+ cur = cur->parentState();
+ }
+
+ if (cur != NULL) {
+ return;
+ }
+
+ LOGW("Warning message %s unhandled in root state.",
+ msg->debugString().c_str());
+}
+
+void AHierarchicalStateMachine::changeState(const sp<AState> &state) {
+ if (state == mState) {
+ // Quick exit for the easy case.
+ return;
+ }
+
+ Vector<sp<AState> > A;
+ sp<AState> cur = mState;
+ for (;;) {
+ A.push(cur);
+ if (cur == NULL) {
+ break;
+ }
+ cur = cur->parentState();
+ }
+
+ Vector<sp<AState> > B;
+ cur = state;
+ for (;;) {
+ B.push(cur);
+ if (cur == NULL) {
+ break;
+ }
+ cur = cur->parentState();
+ }
+
+ // Remove the common tail.
+ while (A.size() > 0 && B.size() > 0 && A.top() == B.top()) {
+ A.pop();
+ B.pop();
+ }
+
+ mState = state;
+
+ for (size_t i = 0; i < A.size(); ++i) {
+ A.editItemAt(i)->stateExited();
+ }
+
+ for (size_t i = B.size(); i-- > 0;) {
+ B.editItemAt(i)->stateEntered();
+ }
+}
+
+} // namespace android