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1 /*
2  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 // A ring buffer to hold arbitrary data. Provides no thread safety. Unless
12 // otherwise specified, functions return 0 on success and -1 on error.
13 
14 #ifndef COMMON_AUDIO_RING_BUFFER_H_
15 #define COMMON_AUDIO_RING_BUFFER_H_
16 
17 // TODO(alessiob): Used by AEC, AECm and AudioRingBuffer. Remove when possible.
18 
19 #ifdef __cplusplus
20 extern "C" {
21 #endif
22 
23 #include <stddef.h>  // size_t
24 
25 enum Wrap { SAME_WRAP, DIFF_WRAP };
26 
27 typedef struct RingBuffer {
28   size_t read_pos;
29   size_t write_pos;
30   size_t element_count;
31   size_t element_size;
32   enum Wrap rw_wrap;
33   char* data;
34 } RingBuffer;
35 
36 // Creates and initializes the buffer. Returns null on failure.
37 RingBuffer* WebRtc_CreateBuffer(size_t element_count, size_t element_size);
38 void WebRtc_InitBuffer(RingBuffer* handle);
39 void WebRtc_FreeBuffer(void* handle);
40 
41 // Reads data from the buffer. Returns the number of elements that were read.
42 // The |data_ptr| will point to the address where the read data is located.
43 // If no data can be read, |data_ptr| is set to |NULL|. If all data can be read
44 // without buffer wrap around then |data_ptr| will point to the location in the
45 // buffer. Otherwise, the data will be copied to |data| (memory allocation done
46 // by the user) and |data_ptr| points to the address of |data|. |data_ptr| is
47 // only guaranteed to be valid until the next call to WebRtc_WriteBuffer().
48 //
49 // To force a copying to |data|, pass a null |data_ptr|.
50 //
51 // Returns number of elements read.
52 size_t WebRtc_ReadBuffer(RingBuffer* handle,
53                          void** data_ptr,
54                          void* data,
55                          size_t element_count);
56 
57 // Writes |data| to buffer and returns the number of elements written.
58 size_t WebRtc_WriteBuffer(RingBuffer* handle,
59                           const void* data,
60                           size_t element_count);
61 
62 // Moves the buffer read position and returns the number of elements moved.
63 // Positive |element_count| moves the read position towards the write position,
64 // that is, flushing the buffer. Negative |element_count| moves the read
65 // position away from the the write position, that is, stuffing the buffer.
66 // Returns number of elements moved.
67 int WebRtc_MoveReadPtr(RingBuffer* handle, int element_count);
68 
69 // Returns number of available elements to read.
70 size_t WebRtc_available_read(const RingBuffer* handle);
71 
72 // Returns number of available elements for write.
73 size_t WebRtc_available_write(const RingBuffer* handle);
74 
75 #ifdef __cplusplus
76 }
77 #endif
78 
79 #endif  // COMMON_AUDIO_RING_BUFFER_H_
80