AudioCore: Skeleton Implementation

This commit:
* Adds a new subproject, audio_core.
* Defines structures that exist in DSP shared memory.
* Hooks up various other parts of the emulator into audio core.

This sets the foundation for a later HLE DSP implementation.

src/audio_core/hle/pipe.h

@@ -0,0 +1,38 @@
+// Copyright 2016 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <vector>
+
+#include "common/common_types.h"
+
+namespace DSP {
+namespace HLE {
+
+/// Reset the pipes by setting pipe positions back to the beginning.
+void ResetPipes();
+
+/**
+ * Read a DSP pipe.
+ * Pipe IDs:
+ *   pipe_number = 0: Debug
+ *   pipe_number = 1: P-DMA
+ *   pipe_number = 2: Audio
+ *   pipe_number = 3: Binary
+ * @param pipe_number The Pipe ID
+ * @param length How much data to request.
+ * @return The data read from the pipe. The size of this vector can be less than the length requested.
+ */
+std::vector<u8> PipeRead(u32 pipe_number, u32 length);
+
+/**
+ * Write to a DSP pipe.
+ * @param pipe_number The Pipe ID
+ * @param buffer The data to write to the pipe.
+ */
+void PipeWrite(u32 pipe_number, const std::vector<u8>& buffer);
+
+} // namespace HLE
+} // namespace DSP