1 files changed, 89 insertions, 0 deletions
diff --git a/third_party/webrtc/src/webrtc/common_audio/signal_processing/filter_ar.c b/third_party/webrtc/src/webrtc/common_audio/signal_processing/filter_ar.c
new file mode 100644
index 00000000..dfbc4c2f
--- /dev/null
+++ b/third_party/webrtc/src/webrtc/common_audio/signal_processing/filter_ar.c
@@ -0,0 +1,89 @@
+/*
+ *  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_FilterAR().
+ * The description header can be found in signal_processing_library.h
+ *
+ */
+
+#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
+
+size_t WebRtcSpl_FilterAR(const int16_t* a,
+                          size_t a_length,
+                          const int16_t* x,
+                          size_t x_length,
+                          int16_t* state,
+                          size_t state_length,
+                          int16_t* state_low,
+                          size_t state_low_length,
+                          int16_t* filtered,
+                          int16_t* filtered_low,
+                          size_t filtered_low_length)
+{
+    int32_t o;
+    int32_t oLOW;
+    size_t i, j, stop;
+    const int16_t* x_ptr = &x[0];
+    int16_t* filteredFINAL_ptr = filtered;
+    int16_t* filteredFINAL_LOW_ptr = filtered_low;
+
+    for (i = 0; i < x_length; i++)
+    {
+        // Calculate filtered[i] and filtered_low[i]
+        const int16_t* a_ptr = &a[1];
+        int16_t* filtered_ptr = &filtered[i - 1];
+        int16_t* filtered_low_ptr = &filtered_low[i - 1];
+        int16_t* state_ptr = &state[state_length - 1];
+        int16_t* state_low_ptr = &state_low[state_length - 1];
+
+        o = (int32_t)(*x_ptr++) << 12;
+        oLOW = (int32_t)0;
+
+        stop = (i < a_length) ? i + 1 : a_length;
+        for (j = 1; j < stop; j++)
+        {
+          o -= *a_ptr * *filtered_ptr--;
+          oLOW -= *a_ptr++ * *filtered_low_ptr--;
+        }
+        for (j = i + 1; j < a_length; j++)
+        {
+          o -= *a_ptr * *state_ptr--;
+          oLOW -= *a_ptr++ * *state_low_ptr--;
+        }
+
+        o += (oLOW >> 12);
+        *filteredFINAL_ptr = (int16_t)((o + (int32_t)2048) >> 12);
+        *filteredFINAL_LOW_ptr++ = (int16_t)(o - ((int32_t)(*filteredFINAL_ptr++)
+                << 12));
+    }
+
+    // Save the filter state
+    if (x_length >= state_length)
+    {
+        WebRtcSpl_CopyFromEndW16(filtered, x_length, a_length - 1, state);
+        WebRtcSpl_CopyFromEndW16(filtered_low, x_length, a_length - 1, state_low);
+    } else
+    {
+        for (i = 0; i < state_length - x_length; i++)
+        {
+            state[i] = state[i + x_length];
+            state_low[i] = state_low[i + x_length];
+        }
+        for (i = 0; i < x_length; i++)
+        {
+            state[state_length - x_length + i] = filtered[i];
+            state[state_length - x_length + i] = filtered_low[i];
+        }
+    }
+
+    return x_length;
+}