1 files changed, 35 insertions, 0 deletions
diff --git a/third_party/webrtc/src/webrtc/common_audio/signal_processing/sqrt_of_one_minus_x_squared.c b/third_party/webrtc/src/webrtc/common_audio/signal_processing/sqrt_of_one_minus_x_squared.c
new file mode 100644
index 00000000..ff78b522
--- /dev/null
+++ b/third_party/webrtc/src/webrtc/common_audio/signal_processing/sqrt_of_one_minus_x_squared.c
@@ -0,0 +1,35 @@
+/*
+ *  Copyright (c) 2011 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.
+ */
+
+
+/*
+ * This file contains the function WebRtcSpl_SqrtOfOneMinusXSquared().
+ * The description header can be found in signal_processing_library.h
+ *
+ */
+
+#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
+
+void WebRtcSpl_SqrtOfOneMinusXSquared(int16_t *xQ15, size_t vector_length,
+                                      int16_t *yQ15)
+{
+    int32_t sq;
+    size_t m;
+    int16_t tmp;
+
+    for (m = 0; m < vector_length; m++)
+    {
+        tmp = xQ15[m];
+        sq = tmp * tmp;  // x^2 in Q30
+        sq = 1073741823 - sq; // 1-x^2, where 1 ~= 0.99999999906 is 1073741823 in Q30
+        sq = WebRtcSpl_Sqrt(sq); // sqrt(1-x^2) in Q15
+        yQ15[m] = (int16_t)sq;
+    }
+}