NetEq: Allow negative shift in BackgroundNoise::SaveParameters

webrtc/modules/audio_coding/neteq/background_noise.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 228 matching lines @@
   // Never get under 1.0 in average sample energy.
   parameters.energy = std::max(sample_energy, 1);
   parameters.energy_update_threshold = parameters.energy;
   parameters.low_energy_update_threshold = 0;
 
   // Normalize residual_energy to 29 or 30 bits before sqrt.
   int16_t norm_shift = WebRtcSpl_NormW32(residual_energy) - 1;
   if (norm_shift & 0x1) {
     norm_shift -= 1;  // Even number of shifts required.
   }
-  assert(norm_shift >= 0);  // Should always be positive.
-  residual_energy = residual_energy << norm_shift;
+  residual_energy = WEBRTC_SPL_SHIFT_W32(residual_energy, norm_shift);
 
   // Calculate scale and shift factor.
   parameters.scale = static_cast<int16_t>(WebRtcSpl_SqrtFloor(residual_energy));
   // Add 13 to the |scale_shift_|, since the random numbers table is in
   // Q13.
   // TODO(hlundin): Move the "13" to where the |scale_shift_| is used?
   parameters.scale_shift =
       static_cast<int16_t>(13 + ((kLogResidualLength + norm_shift) / 2));
 
   initialized_ = true;
 }
 
 }  // namespace webrtc