1 files changed, 81 insertions, 0 deletions
diff --git a/externals/oboe/src/flowgraph/RampLinear.cpp b/externals/oboe/src/flowgraph/RampLinear.cpp
new file mode 100644
index 0000000000..80ac72ad47
--- /dev/null
+++ b/externals/oboe/src/flowgraph/RampLinear.cpp
@@ -0,0 +1,81 @@
+/*
+ * 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 "FlowGraphNode.h"
+#include "RampLinear.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);
+    // If the ramp has not been used then start immediately at this level.
+    if (mLastCallCount == kInitialCallCount) {
+        forceCurrent(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;
+}