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      1 /*
      2  * Copyright (C) 2007 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_BUFFER_PROVIDER_H
     18 #define ANDROID_AUDIO_BUFFER_PROVIDER_H
     19 
     20 #include <utils/Errors.h>
     21 
     22 namespace android {
     23 // ----------------------------------------------------------------------------
     24 
     25 class AudioBufferProvider
     26 {
     27 public:
     28 
     29     // FIXME merge with AudioTrackShared::Buffer, AudioTrack::Buffer, and AudioRecord::Buffer
     30     //       and rename getNextBuffer() to obtainBuffer()
     31     struct Buffer {
     32         Buffer() : raw(NULL), frameCount(0) { }
     33         union {
     34             void*       raw;
     35             short*      i16;
     36             int8_t*     i8;
     37         };
     38         size_t frameCount;
     39     };
     40 
     41     virtual ~AudioBufferProvider() {}
     42 
     43     // On entry:
     44     //  buffer              != NULL
     45     //  buffer->raw         unused
     46     //  buffer->frameCount  maximum number of desired frames
     47     // On successful return:
     48     //  status              NO_ERROR
     49     //  buffer->raw         non-NULL pointer to buffer->frameCount contiguous available frames
     50     //  buffer->frameCount  number of contiguous available frames at buffer->raw,
     51     //                      0 < buffer->frameCount <= entry value
     52     // On error return:
     53     //  status              != NO_ERROR
     54     //  buffer->raw         NULL
     55     //  buffer->frameCount  0
     56     virtual status_t getNextBuffer(Buffer* buffer) = 0;
     57 
     58     // Release (a portion of) the buffer previously obtained by getNextBuffer().
     59     // It is permissible to call releaseBuffer() multiple times per getNextBuffer().
     60     // On entry:
     61     //  buffer->frameCount  number of frames to release, must be <= number of frames
     62     //                      obtained but not yet released
     63     //  buffer->raw         unused
     64     // On return:
     65     //  buffer->frameCount  0; implementation MUST set to zero
     66     //  buffer->raw         undefined; implementation is PERMITTED to set to any value,
     67     //                      so if caller needs to continue using this buffer it must
     68     //                      keep track of the pointer itself
     69     virtual void releaseBuffer(Buffer* buffer) = 0;
     70 };
     71 
     72 // ----------------------------------------------------------------------------
     73 }; // namespace android
     74 
     75 #endif // ANDROID_AUDIO_BUFFER_PROVIDER_H
     76