Playing with buffers.

src/xenia/gpu/gl4/circular_buffer.h

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+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2014 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_GPU_GL4_CIRCULAR_BUFFER_H_
+#define XENIA_GPU_GL4_CIRCULAR_BUFFER_H_
+
+#include <xenia/gpu/gl4/gl_context.h>
+
+namespace xe {
+namespace gpu {
+namespace gl4 {
+
+// TODO(benvanik): uh, make this circular.
+// TODO(benvanik): fences to prevent this from ever flushing.
+class CircularBuffer {
+ public:
+  CircularBuffer(size_t capacity);
+  ~CircularBuffer();
+
+  struct Allocation {
+    void* host_ptr;
+    GLuint64 gpu_ptr;
+    size_t length;
+  };
+
+  bool Initialize();
+
+  Allocation Acquire(size_t length);
+  void Commit(Allocation allocation);
+
+  void WaitUntilClean();
+
+ private:
+  size_t capacity_;
+  uintptr_t write_head_;
+  GLuint buffer_;
+  GLuint64 gpu_base_;
+  uint8_t* host_base_;
+};
+
+}  // namespace gl4
+}  // namespace gpu
+}  // namespace xe
+
+#endif  // XENIA_GPU_GL4_CIRCULAR_BUFFER_H_