1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_AUDIO_FIFO_H
18#define ANDROID_AUDIO_FIFO_H
19
20#include <stdlib.h>
21
22// FIXME use atomic_int_least32_t and new atomic operations instead of legacy Android ones
23// #include <stdatomic.h>
24
25#ifdef __cplusplus
26extern "C" {
27#endif
28
29// Single writer, single reader non-blocking FIFO.
30// Writer and reader must be in same process.
31
32// No user-serviceable parts within.
33struct audio_utils_fifo {
34    // These fields are const after initialization
35    size_t     mFrameCount;   // max number of significant frames to be stored in the FIFO > 0
36    size_t     mFrameCountP2; // roundup(mFrameCount)
37    size_t     mFudgeFactor;  // mFrameCountP2 - mFrameCount, the number of "wasted" frames after
38                              // the end of mBuffer.  Only the indices are wasted, not any memory.
39    size_t     mFrameSize;    // size of each frame in bytes
40    void      *mBuffer;       // pointer to caller-allocated buffer of size mFrameCount frames
41
42    volatile int32_t mFront; // frame index of first frame slot available to read, or read index
43    volatile int32_t mRear;  // frame index of next frame slot available to write, or write index
44};
45
46// Initialize a FIFO object.
47// Input parameters:
48//  fifo        Pointer to the FIFO object.
49//  frameCount  Max number of significant frames to be stored in the FIFO > 0.
50//              If writes and reads always use the same count, and that count is a divisor of
51//              frameCount, then the writes and reads will never do a partial transfer.
52//  frameSize   Size of each frame in bytes.
53//  buffer      Pointer to a caller-allocated buffer of frameCount frames.
54void audio_utils_fifo_init(struct audio_utils_fifo *fifo, size_t frameCount, size_t frameSize,
55        void *buffer);
56
57// De-initialize a FIFO object.
58// Input parameters:
59//  fifo        Pointer to the FIFO object.
60void audio_utils_fifo_deinit(struct audio_utils_fifo *fifo);
61
62// Write to FIFO.
63// Input parameters:
64//  fifo        Pointer to the FIFO object.
65//  buffer      Pointer to source buffer containing 'count' frames of data.
66// Returns actual number of frames written <= count.
67// The actual transfer count may be zero if the FIFO is full,
68// or partial if the FIFO was almost full.
69// A negative return value indicates an error.  Currently there are no errors defined.
70ssize_t audio_utils_fifo_write(struct audio_utils_fifo *fifo, const void *buffer, size_t count);
71
72// Read from FIFO.
73// Input parameters:
74//  fifo        Pointer to the FIFO object.
75//  buffer      Pointer to destination buffer to be filled with up to 'count' frames of data.
76// Returns actual number of frames read <= count.
77// The actual transfer count may be zero if the FIFO is empty,
78// or partial if the FIFO was almost empty.
79// A negative return value indicates an error.  Currently there are no errors defined.
80ssize_t audio_utils_fifo_read(struct audio_utils_fifo *fifo, void *buffer, size_t count);
81
82size_t audio_utils_fifo_availToRead(struct audio_utils_fifo *fifo);
83
84#ifdef __cplusplus
85}
86#endif
87
88#endif  // !ANDROID_AUDIO_FIFO_H
89