media/libaudioclient/include/media/AudioBufferProvider.h

/*
 * Copyright (C) 2007 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_BUFFER_PROVIDER_H
#define ANDROID_AUDIO_BUFFER_PROVIDER_H

#include <utils/Errors.h>

namespace android {
// ----------------------------------------------------------------------------

class AudioBufferProvider
{
public:

    // FIXME merge with AudioTrackShared::Buffer, AudioTrack::Buffer, and AudioRecord::Buffer
    //       and rename getNextBuffer() to obtainBuffer()
    struct Buffer {
        Buffer() : raw(NULL), frameCount(0) { }
        union {
            void*       raw;
            short*      i16;
            int8_t*     i8;
        };
        size_t frameCount;
    };

    virtual ~AudioBufferProvider() {}

    // On entry:
    //  buffer              != NULL
    //  buffer->raw         unused
    //  buffer->frameCount  maximum number of desired frames
    // On successful return:
    //  status              NO_ERROR
    //  buffer->raw         non-NULL pointer to buffer->frameCount contiguous available frames
    //  buffer->frameCount  number of contiguous available frames at buffer->raw,
    //                      0 < buffer->frameCount <= entry value
    // On error return:
    //  status              != NO_ERROR
    //  buffer->raw         NULL
    //  buffer->frameCount  0
    virtual status_t getNextBuffer(Buffer* buffer) = 0;

    // Release (a portion of) the buffer previously obtained by getNextBuffer().
    // It is permissible to call releaseBuffer() multiple times per getNextBuffer().
    // On entry:
    //  buffer->frameCount  number of frames to release, must be <= number of frames
    //                      obtained but not yet released
    //  buffer->raw         unused
    // On return:
    //  buffer->frameCount  0; implementation MUST set to zero
    //  buffer->raw         undefined; implementation is PERMITTED to set to any value,
    //                      so if caller needs to continue using this buffer it must
    //                      keep track of the pointer itself
    virtual void releaseBuffer(Buffer* buffer) = 0;
};

// ----------------------------------------------------------------------------
}; // namespace android

#endif // ANDROID_AUDIO_BUFFER_PROVIDER_H