1 files changed, 94 insertions, 0 deletions
diff --git a/src/3rdparty/resonance-audio/resonance_audio/dsp/gain_processor.cc b/src/3rdparty/resonance-audio/resonance_audio/dsp/gain_processor.cc
new file mode 100644
index 000000000..f5eaea22d
--- /dev/null
+++ b/src/3rdparty/resonance-audio/resonance_audio/dsp/gain_processor.cc
@@ -0,0 +1,94 @@
+/*
+Copyright 2018 Google Inc. All Rights Reserved.
+
+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 "dsp/gain_processor.h"
+
+#include <algorithm>
+#include <cmath>
+
+#include "base/constants_and_types.h"
+
+#include "dsp/gain.h"
+
+namespace vraudio {
+
+// Delegate default constructor.
+GainProcessor::GainProcessor() : current_gain_(0.0f), is_initialized_(false) {}
+
+GainProcessor::GainProcessor(float initial_gain)
+    : current_gain_(initial_gain), is_initialized_(true) {}
+
+void GainProcessor::ApplyGain(float target_gain,
+                              const AudioBuffer::Channel& input,
+                              AudioBuffer::Channel* output,
+                              bool accumulate_output) {
+
+  DCHECK(output);
+
+  if (!is_initialized_) {
+    Reset(target_gain);
+  }
+
+  // Check buffer length.
+  const size_t input_length = input.size();
+  DCHECK_GT(input_length, 0U);
+  DCHECK_EQ(input_length, output->size());
+
+  // Index for where to stop interpolating.
+  size_t ramp_length =
+      static_cast<size_t>(std::abs(target_gain - current_gain_) *
+                          static_cast<float>(kUnitRampLength));
+
+  // Check if there is a new gain value.
+  if (ramp_length > 0) {
+    // Apply gain ramp to buffer.
+    current_gain_ = LinearGainRamp(ramp_length, current_gain_, target_gain,
+                                   input, output, accumulate_output);
+  } else {
+    // No ramping needed.
+    current_gain_ = target_gain;
+  }
+
+  // Apply constant gain to the rest of the buffer.
+  if (ramp_length < input_length) {
+    if (IsGainNearZero(current_gain_)) {
+      // Skip processing if the gain is zero.
+      if (!accumulate_output) {
+        // Directly fill the remaining output with zeros.
+        std::fill(output->begin() + ramp_length, output->end(), 0.0f);
+      }
+      return;
+    } else if (IsGainNearUnity(current_gain_) && !accumulate_output) {
+      // Skip processing if the gain is unity.
+      if (&input != output) {
+        // Directly copy the remaining input samples into output.
+        std::copy(input.begin() + ramp_length, input.end(),
+                  output->begin() + ramp_length);
+      }
+      return;
+    }
+    ConstantGain(ramp_length, current_gain_, input, output, accumulate_output);
+  }
+}
+
+float GainProcessor::GetGain() const { return current_gain_; }
+
+void GainProcessor::Reset(float gain) {
+  current_gain_ = gain;
+  is_initialized_ = true;
+}
+
+}  // namespace vraudio