Revert of Moved ring-buffer related files from common_audio to audio_processing

webrtc/common_audio/ring_buffer.h

+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+// A ring buffer to hold arbitrary data. Provides no thread safety. Unless
+// otherwise specified, functions return 0 on success and -1 on error.
+
+#ifndef WEBRTC_COMMON_AUDIO_RING_BUFFER_H_
+#define WEBRTC_COMMON_AUDIO_RING_BUFFER_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stddef.h>  // size_t
+
+typedef struct RingBuffer RingBuffer;
+
+// Creates and initializes the buffer. Returns NULL on failure.
+RingBuffer* WebRtc_CreateBuffer(size_t element_count, size_t element_size);
+void WebRtc_InitBuffer(RingBuffer* handle);
+void WebRtc_FreeBuffer(void* handle);
+
+// Reads data from the buffer. The |data_ptr| will point to the address where
+// it is located. If all |element_count| data are feasible to read without
+// buffer wrap around |data_ptr| will point to the location in the buffer.
+// Otherwise, the data will be copied to |data| (memory allocation done by the
+// user) and |data_ptr| points to the address of |data|. |data_ptr| is only
+// guaranteed to be valid until the next call to WebRtc_WriteBuffer().
+//
+// To force a copying to |data|, pass a NULL |data_ptr|.
+//
+// Returns number of elements read.
+size_t WebRtc_ReadBuffer(RingBuffer* handle,
+                         void** data_ptr,
+                         void* data,
+                         size_t element_count);
+
+// Writes |data| to buffer and returns the number of elements written.
+size_t WebRtc_WriteBuffer(RingBuffer* handle, const void* data,
+                          size_t element_count);
+
+// Moves the buffer read position and returns the number of elements moved.
+// Positive |element_count| moves the read position towards the write position,
+// that is, flushing the buffer. Negative |element_count| moves the read
+// position away from the the write position, that is, stuffing the buffer.
+// Returns number of elements moved.
+int WebRtc_MoveReadPtr(RingBuffer* handle, int element_count);
+
+// Returns number of available elements to read.
+size_t WebRtc_available_read(const RingBuffer* handle);
+
+// Returns number of available elements for write.
+size_t WebRtc_available_write(const RingBuffer* handle);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // WEBRTC_COMMON_AUDIO_RING_BUFFER_H_