1 files changed, 103 insertions, 0 deletions
diff --git a/src/common_audio/signal_processing/auto_corr_to_refl_coef.c b/src/common_audio/signal_processing/auto_corr_to_refl_coef.c
new file mode 100644
index 0000000000..b7e885898a
--- /dev/null
+++ b/src/common_audio/signal_processing/auto_corr_to_refl_coef.c
@@ -0,0 +1,103 @@
+/*
+ *  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_AutoCorrToReflCoef().
+ * The description header can be found in signal_processing_library.h
+ *
+ */
+
+#include "signal_processing_library.h"
+
+void WebRtcSpl_AutoCorrToReflCoef(G_CONST WebRtc_Word32 *R, int use_order, WebRtc_Word16 *K)
+{
+    int i, n;
+    WebRtc_Word16 tmp;
+    G_CONST WebRtc_Word32 *rptr;
+    WebRtc_Word32 L_num, L_den;
+    WebRtc_Word16 *acfptr, *pptr, *wptr, *p1ptr, *w1ptr, ACF[WEBRTC_SPL_MAX_LPC_ORDER],
+            P[WEBRTC_SPL_MAX_LPC_ORDER], W[WEBRTC_SPL_MAX_LPC_ORDER];
+
+    // Initialize loop and pointers.
+    acfptr = ACF;
+    rptr = R;
+    pptr = P;
+    p1ptr = &P[1];
+    w1ptr = &W[1];
+    wptr = w1ptr;
+
+    // First loop; n=0. Determine shifting.
+    tmp = WebRtcSpl_NormW32(*R);
+    *acfptr = (WebRtc_Word16)((*rptr++ << tmp) >> 16);
+    *pptr++ = *acfptr++;
+
+    // Initialize ACF, P and W.
+    for (i = 1; i <= use_order; i++)
+    {
+        *acfptr = (WebRtc_Word16)((*rptr++ << tmp) >> 16);
+        *wptr++ = *acfptr;
+        *pptr++ = *acfptr++;
+    }
+
+    // Compute reflection coefficients.
+    for (n = 1; n <= use_order; n++, K++)
+    {
+        tmp = WEBRTC_SPL_ABS_W16(*p1ptr);
+        if (*P < tmp)
+        {
+            for (i = n; i <= use_order; i++)
+                *K++ = 0;
+
+            return;
+        }
+
+        // Division: WebRtcSpl_div(tmp, *P)
+        *K = 0;
+        if (tmp != 0)
+        {
+            L_num = tmp;
+            L_den = *P;
+            i = 15;
+            while (i--)
+            {
+                (*K) <<= 1;
+                L_num <<= 1;
+                if (L_num >= L_den)
+                {
+                    L_num -= L_den;
+                    (*K)++;
+                }
+            }
+            if (*p1ptr > 0)
+                *K = -*K;
+        }
+
+        // Last iteration; don't do Schur recursion.
+        if (n == use_order)
+            return;
+
+        // Schur recursion.
+        pptr = P;
+        wptr = w1ptr;
+        tmp = (WebRtc_Word16)(((WebRtc_Word32)*p1ptr * (WebRtc_Word32)*K + 16384) >> 15);
+        *pptr = WEBRTC_SPL_ADD_SAT_W16( *pptr, tmp );
+        pptr++;
+        for (i = 1; i <= use_order - n; i++)
+        {
+            tmp = (WebRtc_Word16)(((WebRtc_Word32)*wptr * (WebRtc_Word32)*K + 16384) >> 15);
+            *pptr = WEBRTC_SPL_ADD_SAT_W16( *(pptr+1), tmp );
+            pptr++;
+            tmp = (WebRtc_Word16)(((WebRtc_Word32)*pptr * (WebRtc_Word32)*K + 16384) >> 15);
+            *wptr = WEBRTC_SPL_ADD_SAT_W16( *wptr, tmp );
+            wptr++;
+        }
+    }
+}