commit 0cada1cf6fd7b5cdcf41b5638b35d779b430efb8
Author:     khokh2001 <alexeytf2@gmail.com>
AuthorDate: Wed Oct 29 16:52:36 2014 +0900
Commit:     khokh2001 <alexeytf2@gmail.com>
CommitDate: Wed Oct 29 16:52:36 2014 +0900

    Update i_oplmusic.c
---
 src/i_oplmusic.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/i_oplmusic.c b/src/i_oplmusic.c
index bb9edcb4..45469dfb 100644
--- a/src/i_oplmusic.c
+++ b/src/i_oplmusic.c
@@ -715,10 +715,10 @@ static opl_voice_t *ReplaceExistingVoice(opl_channel_data_t *channel)
 static unsigned int FrequencyForVoice(opl_voice_t *voice)
 {
     genmidi_voice_t *gm_voice;
-    unsigned int freq_index;
+    signed int freq_index;
     unsigned int octave;
     unsigned int sub_index;
-    unsigned int note;
+    signed int note;

     note = voice->note;

@@ -754,6 +754,11 @@ static unsigned int FrequencyForVoice(opl_voice_t *voice)
         freq_index += (voice->current_instr->fine_tuning / 2) - 64;
     }

+    if (freq_index < 0)
+    {
+    	freq_index = 0;
+    }
+
     // The first 7 notes use the start of the table, while
     // consecutive notes loop around the latter part.