adlmidi_opl3: Fixed the dead loop when tone comes lower than zero

2 files changed, 4 insertions, 0 deletions

diff --git a/README.md b/README.md
index d390d0d..f6a3541 100644
--- a/README.md
+++ b/README.md
@@ -198,6 +198,7 @@ To build that example you will need to have installed SDL2 library.
  * Added an ability to manually specify the chip type (OPL2 or OPL3) at the DOS version of MIDI player.
  * Added an automatical detection of OPL2 or OPL3 chip depending on the BLASTER environment variable's value at the DOS version of MIDI player.
  * Added Nuked OPL2 and OPL3 Low-Level emulators (Kept disabled by default because they are too heavy for ordinary processors).
+ * Fixed a dead loop that might happen when final tone gets lower than zero.
 
 ## 1.5.1   2022-10-31
  * Added an ability to disable the automatical arpeggio
diff --git a/src/adlmidi_opl3.cpp b/src/adlmidi_opl3.cpp
index be84203..5690721 100644
--- a/src/adlmidi_opl3.cpp
+++ b/src/adlmidi_opl3.cpp
@@ -1058,6 +1058,9 @@ void OPL3::noteOn(size_t c1, size_t c2, double tone)
     // Hertz range: 0..131071
     double hertz;
 
+    if(tone < 0.0)
+        tone = 0.0; // Lower than 0 is impossible!
+
     // Use different frequency formulas in depend on a volume model
     switch(m_volumeScale)
     {