2 files changed, 133 insertions, 0 deletions
diff --git a/media/base/byte_queue.cc b/media/base/byte_queue.cc
new file mode 100644
index 0000000..8f4fee8
--- /dev/null
+++ b/media/base/byte_queue.cc
@@ -0,0 +1,79 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/base/byte_queue.h"
+
+#include "base/logging.h"
+
+namespace media {
+
+// Default starting size for the queue.
+enum { kDefaultQueueSize = 1024 };
+
+ByteQueue::ByteQueue()
+    : buffer_(new uint8[kDefaultQueueSize]),
+      size_(kDefaultQueueSize),
+      offset_(0),
+      used_(0) {
+}
+
+ByteQueue::~ByteQueue() {}
+
+void ByteQueue::Push(const uint8* data, int size) {
+  DCHECK(data);
+  DCHECK_GT(size, 0);
+
+  size_t size_needed = used_ + size;
+
+  // Check to see if we need a bigger buffer.
+  if (size_needed > size_) {
+    size_t new_size = 2 * size_;
+    while (size_needed > new_size && new_size > size_)
+      new_size *= 2;
+
+    // Sanity check to make sure we didn't overflow.
+    CHECK_GT(new_size, size_);
+
+    scoped_array<uint8> new_buffer(new uint8[new_size]);
+
+    // Copy the data from the old buffer to the start of the new one.
+    if (used_ > 0)
+      memcpy(new_buffer.get(), front(), used_);
+
+    buffer_.reset(new_buffer.release());
+    size_ = new_size;
+    offset_ = 0;
+  } else if ((offset_ + used_ + size) > size_) {
+    // The buffer is big enough, but we need to move the data in the queue.
+    memmove(buffer_.get(), front(), used_);
+    offset_ = 0;
+  }
+
+  memcpy(front() + used_, data, size);
+  used_ += size;
+}
+
+void ByteQueue::Peek(const uint8** data, int* size) const {
+  DCHECK(data);
+  DCHECK(size);
+  *data = front();
+  *size = used_;
+}
+
+void ByteQueue::Pop(int count) {
+  DCHECK_LE(count, used_);
+
+  offset_ += count;
+  used_ -= count;
+
+  // Move the offset back to 0 if we have reached the end of the buffer.
+  if (offset_ == size_) {
+    DCHECK_EQ(used_, 0);
+    offset_ = 0;
+  }
+}
+
+uint8* ByteQueue::front() const { return buffer_.get() + offset_; }
+
+}  // namespace media
diff --git a/media/base/byte_queue.h b/media/base/byte_queue.h
new file mode 100644
index 0000000..69f2728
--- /dev/null
+++ b/media/base/byte_queue.h
@@ -0,0 +1,54 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_BASE_BYTE_QUEUE_H_
+#define MEDIA_BASE_BYTE_QUEUE_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace media {
+
+// Represents a queue of bytes.
+// Data is added to the end of the queue via an Push() call and removed via
+// Pop(). The contents of the queue can be observed via the Peek() method.
+// This class manages the underlying storage of the queue and tries to minimize
+// the number of buffer copies when data is appended and removed.
+class ByteQueue {
+ public:
+  ByteQueue();
+  ~ByteQueue();
+
+  // Appends new bytes onto the end of the queue.
+  void Push(const uint8* data, int size);
+
+  // Get a pointer to the front of the queue and the queue size.
+  // These values are only valid until the next Push() or
+  // Pop() call.
+  void Peek(const uint8** data, int* size) const;
+
+  // Remove |count| bytes from the front of the queue.
+  void Pop(int count);
+
+ private:
+  // Returns a pointer to the front of the queue.
+  uint8* front() const;
+
+  scoped_array<uint8> buffer_;
+
+  // Size of |buffer_|.
+  size_t size_;
+
+  // Offset from the start of |buffer_| that marks the front of the queue.
+  size_t offset_;
+
+  // Number of bytes stored in the queue.
+  int used_;
+
+  DISALLOW_COPY_AND_ASSIGN(ByteQueue);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_BYTE_QUEUE_H_