ebiten/audio/internal/oboe/oboe_flowgraph_RampLinear_android.cpp

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/*
* Copyright 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.
*/
#include <algorithm>
#include <unistd.h>
#include "oboe_flowgraph_FlowGraphNode_android.h"
#include "oboe_flowgraph_RampLinear_android.h"
using namespace FLOWGRAPH_OUTER_NAMESPACE::flowgraph;
RampLinear::RampLinear(int32_t channelCount)
: FlowGraphFilter(channelCount) {
mTarget.store(1.0f);
}
void RampLinear::setLengthInFrames(int32_t frames) {
mLengthInFrames = frames;
}
void RampLinear::setTarget(float target) {
mTarget.store(target);
}
float RampLinear::interpolateCurrent() {
return mLevelTo - (mRemaining * mScaler);
}
int32_t RampLinear::onProcess(int32_t numFrames) {
const float *inputBuffer = input.getBuffer();
float *outputBuffer = output.getBuffer();
int32_t channelCount = output.getSamplesPerFrame();
float target = getTarget();
if (target != mLevelTo) {
// Start new ramp. Continue from previous level.
mLevelFrom = interpolateCurrent();
mLevelTo = target;
mRemaining = mLengthInFrames;
mScaler = (mLevelTo - mLevelFrom) / mLengthInFrames; // for interpolation
}
int32_t framesLeft = numFrames;
if (mRemaining > 0) { // Ramping? This doesn't happen very often.
int32_t framesToRamp = std::min(framesLeft, mRemaining);
framesLeft -= framesToRamp;
while (framesToRamp > 0) {
float currentLevel = interpolateCurrent();
for (int ch = 0; ch < channelCount; ch++) {
*outputBuffer++ = *inputBuffer++ * currentLevel;
}
mRemaining--;
framesToRamp--;
}
}
// Process any frames after the ramp.
int32_t samplesLeft = framesLeft * channelCount;
for (int i = 0; i < samplesLeft; i++) {
*outputBuffer++ = *inputBuffer++ * mLevelTo;
}
return numFrames;
}