| /* |
| * Copyright (C) 2017 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_WRITER32_H |
| #define ANDROID_AUDIO_FIFO_WRITER32_H |
| |
| #include <audio_utils/fifo.h> |
| |
| /** |
| * Optimized FIFO writer for 32-bit words. |
| * |
| * Has these restrictions compared to the ordinary FIFO writer: |
| * - buffer must be aligned on a 32-bit boundary |
| * - frame size must be sizeof(int32_t) |
| * - capacity must be power-of-2 |
| * - effective size must be equal to capacity |
| * - no support for throttling of writer by one reader, and thus no blocking writes |
| * - does not implement the provider interface |
| * - does not implement the ordinary writer interface |
| * - does not unblock a reader |
| * - return value from write methods is void |
| * - no implied store-release; must be done explicitly |
| * - may not be combined with ordinary writer |
| * |
| * Usage: |
| * - construct an ordinary FIFO that follows the restrictions above |
| * - construct an ordinary reader based on that FIFO |
| * - construct a writer32 using the FIFO |
| * - use a sequence of write and write1, followed by storeRelease to commit |
| */ |
| class audio_utils_fifo_writer32 /* : public audio_utils_fifo_provider */ { |
| |
| public: |
| /** |
| * Construct a writer32 from a FIFO. |
| */ |
| explicit audio_utils_fifo_writer32(audio_utils_fifo& fifo); |
| /*virtual*/ ~audio_utils_fifo_writer32(); |
| |
| /** |
| * Write an array of int32_t to FIFO. |
| * If count is larger than capacity, then only the initial 'capacity' frames will be written. |
| * TODO Instead of a silent truncation, consider adding a size_t or ssize_t return value |
| * to indicate the actual transfer count. |
| */ |
| void write(const int32_t *buffer, uint32_t count /* FIXME size_t in writer */); |
| |
| /** |
| * Write one int32_t value to FIFO. |
| */ |
| void write1(const int32_t value) |
| __attribute__((no_sanitize("integer"))) // mLocalRear ++ can wrap |
| { |
| mBuffer[mLocalRear++ & (mFrameCountP2 - 1)] = value; |
| } |
| |
| /** |
| * Commit all previous write and write1 so that they are observable by reader(s). |
| */ |
| void storeRelease() { |
| mWriterRear.storeRelease(mLocalRear); |
| } |
| |
| private: |
| // Accessed by writer only using ordinary operations |
| uint32_t mLocalRear; // frame index of next frame slot available to write, or write index |
| |
| // These fields are copied from fifo for better performance (avoids an extra de-reference) |
| const uint32_t mFrameCountP2; |
| int32_t * const mBuffer; |
| audio_utils_fifo_index& mWriterRear; |
| }; |
| |
| #endif // ANDROID_AUDIO_FIFO_WRITER32_H |