Avoid overflow in WebRtcSpl_DotProductWithScale

webrtc/common_audio/signal_processing/dot_product_with_scale.h

Index: webrtc/common_audio/signal_processing/dot_product_with_scale.h
diff --git a/webrtc/common_audio/signal_processing/dot_product_with_scale.h b/webrtc/common_audio/signal_processing/dot_product_with_scale.h
new file mode 100644
index 0000000000000000000000000000000000000000..288fe5e73822dba299ebe19286b0556bf99fcce0
--- /dev/null
+++ b/webrtc/common_audio/signal_processing/dot_product_with_scale.h
@@ -0,0 +1,41 @@
+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#ifndef WEBRTC_COMMON_AUDIO_SIGNAL_PROCESSING_DOT_PRODUCT_WITH_SCALE_H_
+#define WEBRTC_COMMON_AUDIO_SIGNAL_PROCESSING_DOT_PRODUCT_WITH_SCALE_H_
+
+#include <string.h>
+
+#include "webrtc/typedefs.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Calculates the dot product between two (int16_t) vectors.
+//
+// Input:
+//      - vector1       : Vector 1
+//      - vector2       : Vector 2
+//      - vector_length : Number of samples used in the dot product
+//      - scaling       : The number of right bit shifts to apply on each term
+//                        during calculation to avoid overflow, i.e., the
+//                        output will be in Q(-|scaling|)
+//
+// Return value         : The dot product in Q(-scaling)
+int32_t WebRtcSpl_DotProductWithScale(const int16_t* vector1,
+                                      const int16_t* vector2,
+                                      size_t length,
+                                      int scaling);
+
+#ifdef __cplusplus
+}
+#endif  // __cplusplus
+#endif  // WEBRTC_COMMON_AUDIO_SIGNAL_PROCESSING_DOT_PRODUCT_WITH_SCALE_H_