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Prevent int32 overflow when applying HARM FIR filter in NSQ.c by using a saturating sum. This matches behavior in NSQ_del_dec.c.

Signed-off-by: Jean-Marc Valin <[email protected]>

--- a/silk/NSQ.c

+++ b/silk/NSQ.c

@@ -262,7 +262,7 @@

         tmp1 = silk_SUB32( tmp1, n_LF_Q12 );                                    /* Q12 */

         if( lag > 0 ) {

             /* Symmetric, packed FIR coefficients */

-            n_LTP_Q13 = silk_SMULWB( silk_ADD32( shp_lag_ptr[ 0 ], shp_lag_ptr[ -2 ] ), HarmShapeFIRPacked_Q14 );

+            n_LTP_Q13 = silk_SMULWB( silk_ADD_SAT32( shp_lag_ptr[ 0 ], shp_lag_ptr[ -2 ] ), HarmShapeFIRPacked_Q14 );

             n_LTP_Q13 = silk_SMLAWT( n_LTP_Q13, shp_lag_ptr[ -1 ],                      HarmShapeFIRPacked_Q14 );

             n_LTP_Q13 = silk_LSHIFT( n_LTP_Q13, 1 );

             shp_lag_ptr++;