[Opus] Update to v1.2.1

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

Index: third_party/opus/src/silk/float/LPC_inv_pred_gain_FLP.c
diff --git a/third_party/opus/src/silk/float/LPC_inv_pred_gain_FLP.c b/third_party/opus/src/silk/float/LPC_inv_pred_gain_FLP.c
index 25178bacdde4610be09a31b59fff79b35f71e033..2be2122d61408afffb1dbfd8cd06723fb28229b9 100644
--- a/third_party/opus/src/silk/float/LPC_inv_pred_gain_FLP.c
+++ b/third_party/opus/src/silk/float/LPC_inv_pred_gain_FLP.c
@@ -31,8 +31,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include "SigProc_FIX.h"
 #include "SigProc_FLP.h"
-
-#define RC_THRESHOLD        0.9999f
+#include "define.h"
 
 /* compute inverse of LPC prediction gain, and                          */
 /* test if LPC coefficients are stable (all poles within unit circle)   */
@@ -43,34 +42,32 @@ silk_float silk_LPC_inverse_pred_gain_FLP(  /* O    return inverse prediction ga
 )
 {
     opus_int   k, n;
-    double     invGain, rc, rc_mult1, rc_mult2;
-    silk_float Atmp[ 2 ][ SILK_MAX_ORDER_LPC ];
-    silk_float *Aold, *Anew;
+    double     invGain, rc, rc_mult1, rc_mult2, tmp1, tmp2;
+    silk_float Atmp[ SILK_MAX_ORDER_LPC ];
 
-    Anew = Atmp[ order & 1 ];
-    silk_memcpy( Anew, A, order * sizeof(silk_float) );
+    silk_memcpy( Atmp, A, order * sizeof(silk_float) );
 
     invGain = 1.0;
     for( k = order - 1; k > 0; k-- ) {
-        rc = -Anew[ k ];
-        if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) {
+        rc = -Atmp[ k ];
+        rc_mult1 = 1.0f - rc * rc;
+        invGain *= rc_mult1;
+        if( invGain * MAX_PREDICTION_POWER_GAIN < 1.0f ) {
             return 0.0f;
         }
-        rc_mult1 = 1.0f - rc * rc;
         rc_mult2 = 1.0f / rc_mult1;
-        invGain *= rc_mult1;
-        /* swap pointers */
-        Aold = Anew;
-        Anew = Atmp[ k & 1 ];
-        for( n = 0; n < k; n++ ) {
-            Anew[ n ] = (silk_float)( ( Aold[ n ] - Aold[ k - n - 1 ] * rc ) * rc_mult2 );
+        for( n = 0; n < (k + 1) >> 1; n++ ) {
+            tmp1 = Atmp[ n ];
+            tmp2 = Atmp[ k - n - 1 ];
+            Atmp[ n ]         = (silk_float)( ( tmp1 - tmp2 * rc ) * rc_mult2 );
+            Atmp[ k - n - 1 ] = (silk_float)( ( tmp2 - tmp1 * rc ) * rc_mult2 );
         }
     }
-    rc = -Anew[ 0 ];
-    if( rc > RC_THRESHOLD || rc < -RC_THRESHOLD ) {
-        return 0.0f;
-    }
+    rc = -Atmp[ 0 ];
     rc_mult1 = 1.0f - rc * rc;
     invGain *= rc_mult1;
+    if( invGain * MAX_PREDICTION_POWER_GAIN < 1.0f ) {
+        return 0.0f;
+    }
     return (silk_float)invGain;
 }