From 8264e376ea6f2fdaa3813ff1a8463e368d95083c Mon Sep 17 00:00:00 2001
From: Martin Storsjo <martin@martin.st>
Date: Fri, 10 Nov 2023 11:39:50 +0200
Subject: Saturate additions in getEnvSfbEnergy in SBR encoding

This avoids wraparounds, which can trigger failed asserts with
some inputs. This fixes
https://github.com/mstorsjo/fdk-aac/issues/158.

The implementation of saturated addition loses the contents of the
lowest bit though, thus this change affects the output - but the
change is said to be acceptable.
---
 libSBRenc/src/env_est.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'libSBRenc/src/env_est.cpp')

diff --git a/libSBRenc/src/env_est.cpp b/libSBRenc/src/env_est.cpp
index cc8780a..e7eea37 100644
--- a/libSBRenc/src/env_est.cpp
+++ b/libSBRenc/src/env_est.cpp
@@ -637,8 +637,8 @@ static FIXP_DBL getEnvSfbEnergy(
     for (; l < stop_pos; l++) {
       nrg2 += YBuffer[l >> YBufferSzShift][k] >> sc1;
     }
-    accu1 += (nrg1 >> dynScale1);
-    accu2 += (nrg2 >> dynScale2);
+    accu1 = fAddSaturate(accu1, (nrg1 >> dynScale1));
+    accu2 = fAddSaturate(accu2, (nrg2 >> dynScale2));
   }
   /* This shift factor is always positive. See comment above. */
   nrgSum +=
-- 
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