| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef ANDROID_AUDIO_FIFO_H |
| #define ANDROID_AUDIO_FIFO_H |
| |
| #include <stdlib.h> |
| |
| // FIXME use atomic_int_least32_t and new atomic operations instead of legacy Android ones |
| // #include <stdatomic.h> |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| // Single writer, single reader non-blocking FIFO. |
| // Writer and reader must be in same process. |
| |
| // No user-serviceable parts within. |
| struct audio_utils_fifo { |
| // These fields are const after initialization |
| size_t mFrameCount; // max number of significant frames to be stored in the FIFO > 0 |
| size_t mFrameCountP2; // roundup(mFrameCount) |
| size_t mFudgeFactor; // mFrameCountP2 - mFrameCount, the number of "wasted" frames after |
| // the end of mBuffer. Only the indices are wasted, not any memory. |
| size_t mFrameSize; // size of each frame in bytes |
| void *mBuffer; // pointer to caller-allocated buffer of size mFrameCount frames |
| |
| volatile int32_t mFront; // frame index of first frame slot available to read, or read index |
| volatile int32_t mRear; // frame index of next frame slot available to write, or write index |
| }; |
| |
| // Initialize a FIFO object. |
| // Input parameters: |
| // fifo Pointer to the FIFO object. |
| // frameCount Max number of significant frames to be stored in the FIFO > 0. |
| // If writes and reads always use the same count, and that count is a divisor of |
| // frameCount, then the writes and reads will never do a partial transfer. |
| // frameSize Size of each frame in bytes. |
| // buffer Pointer to a caller-allocated buffer of frameCount frames. |
| void audio_utils_fifo_init(struct audio_utils_fifo *fifo, size_t frameCount, size_t frameSize, |
| void *buffer); |
| |
| // De-initialize a FIFO object. |
| // Input parameters: |
| // fifo Pointer to the FIFO object. |
| void audio_utils_fifo_deinit(struct audio_utils_fifo *fifo); |
| |
| // Write to FIFO. |
| // Input parameters: |
| // fifo Pointer to the FIFO object. |
| // buffer Pointer to source buffer containing 'count' frames of data. |
| // Returns actual number of frames written <= count. |
| // The actual transfer count may be zero if the FIFO is full, |
| // or partial if the FIFO was almost full. |
| // A negative return value indicates an error. Currently there are no errors defined. |
| ssize_t audio_utils_fifo_write(struct audio_utils_fifo *fifo, const void *buffer, size_t count); |
| |
| // Read from FIFO. |
| // Input parameters: |
| // fifo Pointer to the FIFO object. |
| // buffer Pointer to destination buffer to be filled with up to 'count' frames of data. |
| // Returns actual number of frames read <= count. |
| // The actual transfer count may be zero if the FIFO is empty, |
| // or partial if the FIFO was almost empty. |
| // A negative return value indicates an error. Currently there are no errors defined. |
| ssize_t audio_utils_fifo_read(struct audio_utils_fifo *fifo, void *buffer, size_t count); |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif // !ANDROID_AUDIO_FIFO_H |