From e8882d58c9c4db8992b0620565e671979cd6a696 Mon Sep 17 00:00:00 2001
From: Vitaly Novichkov <admin@wohlnet.ru>
Date: Wed, 22 Aug 2018 00:51:52 +0300
Subject: Rotate octave on high out of range tone frequencies

---
 README.md            |  1 +
 src/adlmidi_opl3.cpp | 22 +++++++++++++---------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index b10577b..37773aa 100644
--- a/README.md
+++ b/README.md
@@ -177,6 +177,7 @@ To build that example you will need to have installed SDL2 library.
  * XMIDI now supports loops
  * Added working implementation of TMB's velocity offset
  * Added support for full-panning stereo option (Thanks to [Christopher Snowhill](https://github.com/kode54) for a work!)
+ * Fixed inability to play high notes due physical tone frequency out of range on the OPL3 chip
 
 ## 1.3.3   2018-06-19
  * Fixed an inability to load another custom bank without of library re-initialization
diff --git a/src/adlmidi_opl3.cpp b/src/adlmidi_opl3.cpp
index 94602ba..5ea2053 100644
--- a/src/adlmidi_opl3.cpp
+++ b/src/adlmidi_opl3.cpp
@@ -266,33 +266,37 @@ void OPL3::noteOff(size_t c)
 void OPL3::noteOn(size_t c, double hertz) // Hertz range: 0..131071
 {
     size_t chip = c / 23, cc = c % 23;
-    uint32_t x = 0x2000;
+    uint32_t octave = 0;
 
-    if(hertz < 0 || hertz > 131071) // Avoid infinite loop
+    if(hertz < 0)
         return;
 
     while(hertz >= 1023.5)
     {
-        hertz /= 2.0;    // Calculate octave
-        x += 0x400;
+        hertz /= 2.0; // Calculate octave
+        if(octave < 0x1C00)
+            octave += 0x400;
     }
 
-    x += static_cast<uint32_t>(hertz + 0.5);
+    octave += static_cast<uint32_t>(hertz + 0.5);
     uint32_t chn = g_channelsMap[cc];
 
     if(cc >= 18)
     {
         m_regBD[chip ] |= (0x10 >> (cc - 18));
         writeRegI(chip , 0x0BD, m_regBD[chip ]);
-        x &= ~0x2000u;
         //x |= 0x800; // for test
     }
+    else
+    {
+        octave += 0x2000u; /* Key-ON [KON] */
+    }
 
     if(chn != 0xFFF)
     {
-        writeRegI(chip , 0xA0 + chn, (x & 0xFF));
-        writeRegI(chip , 0xB0 + chn, (x >> 8));
-        m_keyBlockFNumCache[c] = (x >> 8);
+        writeRegI(chip , 0xA0 + chn, (octave & 0xFF));
+        writeRegI(chip , 0xB0 + chn, (octave >> 8));
+        m_keyBlockFNumCache[c] = (octave >> 8);
     }
 }
 
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