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      1 /*
      2  * Copyright 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 FLOWGRAPH_RAMP_LINEAR_H
     18 #define FLOWGRAPH_RAMP_LINEAR_H
     19 
     20 #include <atomic>
     21 #include <unistd.h>
     22 #include <sys/types.h>
     23 
     24 #include "AudioProcessorBase.h"
     25 
     26 namespace flowgraph {
     27 
     28 class RampLinear : public AudioProcessorBase {
     29 public:
     30     explicit RampLinear(int32_t channelCount);
     31 
     32     virtual ~RampLinear() = default;
     33 
     34     int32_t onProcess(int64_t framePosition, int32_t numFrames) override;
     35 
     36     /**
     37      * This is used for the next ramp.
     38      * Calling this does not affect a ramp that is in progress.
     39      */
     40     void setLengthInFrames(int32_t frames);
     41 
     42     int32_t getLengthInFrames() const {
     43         return mLengthInFrames;
     44     }
     45 
     46     /**
     47      * This may be safely called by another thread.
     48      * @param target
     49      */
     50     void setTarget(float target);
     51 
     52     float getTarget() const {
     53         return mTarget.load();
     54     }
     55 
     56     /**
     57      * Force the nextSegment to start from this level.
     58      *
     59      * WARNING: this can cause a discontinuity if called while the ramp is being used.
     60      * Only call this when setting the initial ramp.
     61      *
     62      * @param level
     63      */
     64     void forceCurrent(float level) {
     65         mLevelFrom = level;
     66         mLevelTo = level;
     67     }
     68 
     69     AudioFloatInputPort input;
     70     AudioFloatOutputPort output;
     71 
     72 private:
     73 
     74     float interpolateCurrent();
     75 
     76     std::atomic<float>  mTarget;
     77 
     78     int32_t             mLengthInFrames  = 48000.0f / 100.0f ; // 10 msec at 48000 Hz;
     79     int32_t             mRemaining       = 0;
     80     float               mScaler          = 0.0f;
     81     float               mLevelFrom       = 0.0f;
     82     float               mLevelTo         = 0.0f;
     83 };
     84 
     85 } /* namespace flowgraph */
     86 
     87 #endif //FLOWGRAPH_RAMP_LINEAR_H
     88