1 files changed, 146 insertions, 0 deletions
diff --git a/include/utils/SharedBuffer.h b/include/utils/SharedBuffer.h
new file mode 100644
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+++ b/include/utils/SharedBuffer.h
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+/*
+ * Copyright (C) 2005 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_SHARED_BUFFER_H
+#define ANDROID_SHARED_BUFFER_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+// ---------------------------------------------------------------------------
+
+namespace android {
+
+class SharedBuffer
+{
+public:
+
+    /* flags to use with release() */
+    enum {
+        eKeepStorage = 0x00000001
+    };
+
+    /*! allocate a buffer of size 'size' and acquire() it.
+     *  call release() to free it.
+     */
+    static          SharedBuffer*           alloc(size_t size);
+    
+    /*! free the memory associated with the SharedBuffer.
+     * Fails if there are any users associated with this SharedBuffer.
+     * In other words, the buffer must have been release by all its
+     * users.
+     */
+    static          ssize_t                 dealloc(const SharedBuffer* released);
+    
+    //! get the SharedBuffer from the data pointer
+    static  inline  const SharedBuffer*     sharedBuffer(const void* data);
+
+    //! access the data for read
+    inline          const void*             data() const;
+    
+    //! access the data for read/write
+    inline          void*                   data();
+
+    //! get size of the buffer
+    inline          size_t                  size() const;
+ 
+    //! get back a SharedBuffer object from its data
+    static  inline  SharedBuffer*           bufferFromData(void* data);
+    
+    //! get back a SharedBuffer object from its data
+    static  inline  const SharedBuffer*     bufferFromData(const void* data);
+
+    //! get the size of a SharedBuffer object from its data
+    static  inline  size_t                  sizeFromData(const void* data);
+    
+    //! edit the buffer (get a writtable, or non-const, version of it)
+                    SharedBuffer*           edit() const;
+
+    //! edit the buffer, resizing if needed
+                    SharedBuffer*           editResize(size_t size) const;
+
+    //! like edit() but fails if a copy is required
+                    SharedBuffer*           attemptEdit() const;
+    
+    //! resize and edit the buffer, loose it's content.
+                    SharedBuffer*           reset(size_t size) const;
+
+    //! acquire/release a reference on this buffer
+                    void                    acquire() const;
+                    
+    /*! release a reference on this buffer, with the option of not
+     * freeing the memory associated with it if it was the last reference
+     * returns the previous reference count
+     */     
+                    int32_t                 release(uint32_t flags = 0) const;
+    
+    //! returns wether or not we're the only owner
+    inline          bool                    onlyOwner() const;
+    
+
+private:
+        inline SharedBuffer() { }
+        inline ~SharedBuffer() { }
+        inline SharedBuffer(const SharedBuffer&);
+ 
+        // 16 bytes. must be sized to preserve correct alingment.
+        mutable int32_t        mRefs;
+                size_t         mSize;
+                uint32_t       mReserved[2];
+};
+
+// ---------------------------------------------------------------------------
+
+const SharedBuffer* SharedBuffer::sharedBuffer(const void* data) {
+    return data ? reinterpret_cast<const SharedBuffer *>(data)-1 : 0;
+}
+
+const void* SharedBuffer::data() const {
+    return this + 1;
+}
+
+void* SharedBuffer::data() {
+    return this + 1;
+}
+
+size_t SharedBuffer::size() const {
+    return mSize;
+}
+
+SharedBuffer* SharedBuffer::bufferFromData(void* data)
+{
+    return ((SharedBuffer*)data)-1;
+}
+    
+const SharedBuffer* SharedBuffer::bufferFromData(const void* data)
+{
+    return ((const SharedBuffer*)data)-1;
+}
+
+size_t SharedBuffer::sizeFromData(const void* data)
+{
+    return (((const SharedBuffer*)data)-1)->mSize;
+}
+
+bool SharedBuffer::onlyOwner() const {
+    return (mRefs == 1);
+}
+
+}; // namespace android
+
+// ---------------------------------------------------------------------------
+
+#endif // ANDROID_VECTOR_H