1 files changed, 70 insertions, 0 deletions
diff --git a/src/common_audio/vad/main/source/vad_gmm.c b/src/common_audio/vad/main/source/vad_gmm.c
new file mode 100644
index 0000000000..23d12fb335
--- /dev/null
+++ b/src/common_audio/vad/main/source/vad_gmm.c
@@ -0,0 +1,70 @@
+/*
+ *  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 includes the implementation of the internal VAD call
+ * WebRtcVad_GaussianProbability. For function description, see vad_gmm.h.
+ */
+
+#include "vad_gmm.h"
+#include "signal_processing_library.h"
+#include "vad_const.h"
+
+WebRtc_Word32 WebRtcVad_GaussianProbability(WebRtc_Word16 in_sample,
+                                            WebRtc_Word16 mean,
+                                            WebRtc_Word16 std,
+                                            WebRtc_Word16 *delta)
+{
+    WebRtc_Word16 tmp16, tmpDiv, tmpDiv2, expVal, tmp16_1, tmp16_2;
+    WebRtc_Word32 tmp32, y32;
+
+    // Calculate tmpDiv=1/std, in Q10
+    tmp32 = (WebRtc_Word32)WEBRTC_SPL_RSHIFT_W16(std,1) + (WebRtc_Word32)131072; // 1 in Q17
+    tmpDiv = (WebRtc_Word16)WebRtcSpl_DivW32W16(tmp32, std); // Q17/Q7 = Q10
+
+    // Calculate tmpDiv2=1/std^2, in Q14
+    tmp16 = WEBRTC_SPL_RSHIFT_W16(tmpDiv, 2); // From Q10 to Q8
+    tmpDiv2 = (WebRtc_Word16)WEBRTC_SPL_MUL_16_16_RSFT(tmp16, tmp16, 2); // (Q8 * Q8)>>2 = Q14
+
+    tmp16 = WEBRTC_SPL_LSHIFT_W16(in_sample, 3); // Q7
+    tmp16 = tmp16 - mean; // Q7 - Q7 = Q7
+
+    // To be used later, when updating noise/speech model
+    // delta = (x-m)/std^2, in Q11
+    *delta = (WebRtc_Word16)WEBRTC_SPL_MUL_16_16_RSFT(tmpDiv2, tmp16, 10); //(Q14*Q7)>>10 = Q11
+
+    // Calculate tmp32=(x-m)^2/(2*std^2), in Q10
+    tmp32 = (WebRtc_Word32)WEBRTC_SPL_MUL_16_16_RSFT(*delta, tmp16, 9); // One shift for /2
+
+    // Calculate expVal ~= exp(-(x-m)^2/(2*std^2)) ~= exp2(-log2(exp(1))*tmp32)
+    if (tmp32 < kCompVar)
+    {
+        // Calculate tmp16 = log2(exp(1))*tmp32 , in Q10
+        tmp16 = (WebRtc_Word16)WEBRTC_SPL_MUL_16_16_RSFT((WebRtc_Word16)tmp32,
+                                                         kLog10Const, 12);
+        tmp16 = -tmp16;
+        tmp16_2 = (WebRtc_Word16)(0x0400 | (tmp16 & 0x03FF));
+        tmp16_1 = (WebRtc_Word16)(tmp16 ^ 0xFFFF);
+        tmp16 = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W16(tmp16_1, 10);
+        tmp16 += 1;
+        // Calculate expVal=log2(-tmp32), in Q10
+        expVal = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32((WebRtc_Word32)tmp16_2, tmp16);
+
+    } else
+    {
+        expVal = 0;
+    }
+
+    // Calculate y32=(1/std)*exp(-(x-m)^2/(2*std^2)), in Q20
+    y32 = WEBRTC_SPL_MUL_16_16(tmpDiv, expVal); // Q10 * Q10 = Q20
+
+    return y32; // Q20
+}