[Opus] Update to v1.2.1

third_party/opus/src/silk/float/k2a_FLP.c

 /***********************************************************************
 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 - Redistributions of source code must retain the above copyright notice,
 this list of conditions and the following disclaimer.
 - Redistributions in binary form must reproduce the above copyright
 notice, this list of conditions and the following disclaimer in the
 documentation and/or other materials provided with the distribution.
@@ skipping 21 matching lines @@
 #include "SigProc_FLP.h"
 
 /* step up function, converts reflection coefficients to prediction coefficients */
 void silk_k2a_FLP(
     silk_float          *A,                 /* O     prediction coefficients [order]                            */
     const silk_float    *rc,                /* I     reflection coefficients [order]                            */
     opus_int32          order               /* I     prediction order                                           */
 )
 {
     opus_int   k, n;
-    silk_float Atmp[ SILK_MAX_ORDER_LPC ];
+    silk_float rck, tmp1, tmp2;
 
     for( k = 0; k < order; k++ ) {
-        for( n = 0; n < k; n++ ) {
-            Atmp[ n ] = A[ n ];
+        rck = rc[ k ];
+        for( n = 0; n < (k + 1) >> 1; n++ ) {
+            tmp1 = A[ n ];
+            tmp2 = A[ k - n - 1 ];
+            A[ n ]         = tmp1 + tmp2 * rck;
+            A[ k - n - 1 ] = tmp2 + tmp1 * rck;
         }
-        for( n = 0; n < k; n++ ) {
-            A[ n ] += Atmp[ k - n - 1 ] * rc[ k ];
-        }
-        A[ k ] = -rc[ k ];
+        A[ k ] = -rck;
     }
 }