From 84b635cb488d8c2e02a7d8c28d895fa3261d96ea Mon Sep 17 00:00:00 2001
From: Sandesh Venkatesh <sandesh.venkatesh@ittiam.com>
Date: Mon, 19 Aug 2024 14:18:00 +0530
Subject: [PATCH] Fix for LTV crashes observed with changes made for issue 824
 (MR 541)

---
 lib_dec/fd_cng_dec_fx.c | 48 ++++++++++++-----------------------------
 1 file changed, 14 insertions(+), 34 deletions(-)

diff --git a/lib_dec/fd_cng_dec_fx.c b/lib_dec/fd_cng_dec_fx.c
index 48c91b684..dc234e502 100644
--- a/lib_dec/fd_cng_dec_fx.c
+++ b/lib_dec/fd_cng_dec_fx.c
@@ -2468,15 +2468,15 @@ void perform_noise_estimation_dec_ivas_fx(
         SWITCH( hFdCngDec->hFdCngCom->fftlen )
         {
             case 640:
-                rescale_fac = 83886; // 4/(640 * 640) in Q33
+                rescale_fac = 671089; // 4/(640 * 640) in Q36
                 move32();
                 BREAK;
             case 512:
-                rescale_fac = 131072; // 4/(512 * 512) in Q33
+                rescale_fac = 1048576; // 4/(512 * 512) in Q36
                 move32();
                 BREAK;
             case 320:
-                rescale_fac = 335544; // 4/(320 * 320) in Q33
+                rescale_fac = 2684354; // 4/(320 * 320) in Q36
                 move32();
                 BREAK;
             default:
@@ -2507,23 +2507,12 @@ void perform_noise_estimation_dec_ivas_fx(
 
             tmp_s = W_norm( W_tmp );
             tmp_q = sub( add( i_mult( sub( 31, fftBuffer_exp ), 2 ), tmp_s ), 32 );
-            IF( tmp_q < 0 )
-            {
-                W_tmp = W_shr( W_tmp, negate( tmp_q ) );
-            }
+            *ptr_per = W_extract_h( W_shl( W_tmp, tmp_s ) );
             IF( LT_16( tmp_q, min_q ) )
             {
                 reIter = ptr_per;
                 Word16 diff;
-                IF( tmp_q <= 0 )
-                {
-                    diff = min_q;
-                    move16();
-                }
-                ELSE
-                {
-                    diff = sub( min_q, tmp_q );
-                }
+                diff = sub( min_q, tmp_q );
 
                 WHILE( reIter > periodog )
                 {
@@ -2531,34 +2520,25 @@ void perform_noise_estimation_dec_ivas_fx(
                     *reIter = L_shr( *reIter, diff );
                     move32();
                 }
-                IF( tmp_q >= 0 )
-                {
-                    min_q = tmp_q;
-                }
-                ELSE IF( tmp_q < 0 )
-                {
-                    min_q = 0;
-                }
+                min_q = tmp_q;
                 move16();
             }
-            ( *ptr_per ) = W_extract_l( W_shr( W_tmp, sub( shl( sub( 31, fftBuffer_exp ), 1 ), min_q ) ) ); // Qmin_q
-            move32();
+            ELSE
+            {
+                Word16 diff;
+                diff = sub( tmp_q, min_q );
+                ( *ptr_per ) = L_shr( ( *ptr_per ), diff );
+            }
 
             /* Rescale to get energy/sample: it should be 2*(1/N)*(2/N), parseval relation with 1/N,*2 for nrg computed till Nyquist only, 2/N as windowed samples correspond to half a frame*/
-            ( *ptr_per ) = Mpy_32_32_r( ( *ptr_per ), rescale_fac ); // Q = min_q+2
+            ( *ptr_per ) = Mpy_32_32_r( ( *ptr_per ), rescale_fac ); // Q = min_q+36-31=min_q+5
             move32();
 
-            IF( tmp_q < 0 )
-            {
-                ( *ptr_per ) = L_shl( ( *ptr_per ), negate( tmp_q ) );
-                move32();
-            }
-
             ptr_r += 2;
             ptr_i += 2;
         }
 
-        hFdCngDec->hFdCngCom->periodog_exp = sub( 31 - 2, min_q );
+        hFdCngDec->hFdCngCom->periodog_exp = sub( 31 - 5, min_q );
         hFdCngDec->hFdCngCom->fftBuffer_exp = fftBuffer_exp;
         move16();
         move16();
-- 
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