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diff --git a/include/gui/BufferSlot.h b/include/gui/BufferSlot.h
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--- /dev/null
+++ b/include/gui/BufferSlot.h
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+/*
+ * Copyright 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_GUI_BUFFERSLOT_H
+#define ANDROID_GUI_BUFFERSLOT_H
+
+#include <ui/Fence.h>
+#include <ui/GraphicBuffer.h>
+
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+
+#include <utils/StrongPointer.h>
+
+namespace android {
+
+class Fence;
+
+struct BufferSlot {
+
+    BufferSlot()
+    : mEglDisplay(EGL_NO_DISPLAY),
+      mBufferState(BufferSlot::FREE),
+      mRequestBufferCalled(false),
+      mFrameNumber(0),
+      mEglFence(EGL_NO_SYNC_KHR),
+      mAcquireCalled(false),
+      mNeedsCleanupOnRelease(false) {
+    }
+
+    // mGraphicBuffer points to the buffer allocated for this slot or is NULL
+    // if no buffer has been allocated.
+    sp<GraphicBuffer> mGraphicBuffer;
+
+    // mEglDisplay is the EGLDisplay used to create EGLSyncKHR objects.
+    EGLDisplay mEglDisplay;
+
+    // BufferState represents the different states in which a buffer slot
+    // can be.  All slots are initially FREE.
+    enum BufferState {
+        // FREE indicates that the buffer is available to be dequeued
+        // by the producer.  The buffer may be in use by the consumer for
+        // a finite time, so the buffer must not be modified until the
+        // associated fence is signaled.
+        //
+        // The slot is "owned" by BufferQueue.  It transitions to DEQUEUED
+        // when dequeueBuffer is called.
+        FREE = 0,
+
+        // DEQUEUED indicates that the buffer has been dequeued by the
+        // producer, but has not yet been queued or canceled.  The
+        // producer may modify the buffer's contents as soon as the
+        // associated ready fence is signaled.
+        //
+        // The slot is "owned" by the producer.  It can transition to
+        // QUEUED (via queueBuffer) or back to FREE (via cancelBuffer).
+        DEQUEUED = 1,
+
+        // QUEUED indicates that the buffer has been filled by the
+        // producer and queued for use by the consumer.  The buffer
+        // contents may continue to be modified for a finite time, so
+        // the contents must not be accessed until the associated fence
+        // is signaled.
+        //
+        // The slot is "owned" by BufferQueue.  It can transition to
+        // ACQUIRED (via acquireBuffer) or to FREE (if another buffer is
+        // queued in asynchronous mode).
+        QUEUED = 2,
+
+        // ACQUIRED indicates that the buffer has been acquired by the
+        // consumer.  As with QUEUED, the contents must not be accessed
+        // by the consumer until the fence is signaled.
+        //
+        // The slot is "owned" by the consumer.  It transitions to FREE
+        // when releaseBuffer is called.
+        ACQUIRED = 3
+    };
+
+    static const char* bufferStateName(BufferState state);
+
+    // mBufferState is the current state of this buffer slot.
+    BufferState mBufferState;
+
+    // mRequestBufferCalled is used for validating that the producer did
+    // call requestBuffer() when told to do so. Technically this is not
+    // needed but useful for debugging and catching producer bugs.
+    bool mRequestBufferCalled;
+
+    // mFrameNumber is the number of the queued frame for this slot.  This
+    // is used to dequeue buffers in LRU order (useful because buffers
+    // may be released before their release fence is signaled).
+    uint64_t mFrameNumber;
+
+    // mEglFence is the EGL sync object that must signal before the buffer
+    // associated with this buffer slot may be dequeued. It is initialized
+    // to EGL_NO_SYNC_KHR when the buffer is created and may be set to a
+    // new sync object in releaseBuffer.  (This is deprecated in favor of
+    // mFence, below.)
+    EGLSyncKHR mEglFence;
+
+    // mFence is a fence which will signal when work initiated by the
+    // previous owner of the buffer is finished. When the buffer is FREE,
+    // the fence indicates when the consumer has finished reading
+    // from the buffer, or when the producer has finished writing if it
+    // called cancelBuffer after queueing some writes. When the buffer is
+    // QUEUED, it indicates when the producer has finished filling the
+    // buffer. When the buffer is DEQUEUED or ACQUIRED, the fence has been
+    // passed to the consumer or producer along with ownership of the
+    // buffer, and mFence is set to NO_FENCE.
+    sp<Fence> mFence;
+
+    // Indicates whether this buffer has been seen by a consumer yet
+    bool mAcquireCalled;
+
+    // Indicates whether this buffer needs to be cleaned up by the
+    // consumer.  This is set when a buffer in ACQUIRED state is freed.
+    // It causes releaseBuffer to return STALE_BUFFER_SLOT.
+    bool mNeedsCleanupOnRelease;
+};
+
+} // namespace android
+
+#endif