[Opus] Update to v1.2.1

third_party/opus/src/silk/fixed/k2a_Q16_FIX.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_FIX.h"
 
 /* Step up function, converts reflection coefficients to prediction coefficients */
 void silk_k2a_Q16(
     opus_int32                  *A_Q24,             /* O    Prediction coefficients [order] Q24                         */
     const opus_int32            *rc_Q16,            /* I    Reflection coefficients [order] Q16                         */
     const opus_int32            order               /* I    Prediction order                                            */
 )
 {
     opus_int   k, n;
-    opus_int32 Atmp[ SILK_MAX_ORDER_LPC ];
+    opus_int32 rc, tmp1, tmp2;
 
     for( k = 0; k < order; k++ ) {
-        for( n = 0; n < k; n++ ) {
-            Atmp[ n ] = A_Q24[ n ];
+        rc = rc_Q16[ k ];
+        for( n = 0; n < (k + 1) >> 1; n++ ) {
+            tmp1 = A_Q24[ n ];
+            tmp2 = A_Q24[ k - n - 1 ];
+            A_Q24[ n ]         = silk_SMLAWW( tmp1, tmp2, rc );
+            A_Q24[ k - n - 1 ] = silk_SMLAWW( tmp2, tmp1, rc );
         }
-        for( n = 0; n < k; n++ ) {
-            A_Q24[ n ] = silk_SMLAWW( A_Q24[ n ], Atmp[ k - n - 1 ], rc_Q16[ k ] );
-        }
-        A_Q24[ k ] = -silk_LSHIFT( rc_Q16[ k ], 8 );
+        A_Q24[ k ] = -silk_LSHIFT( rc, 8 );
     }
 }