From 8c4ebc434dbe595ccee6244a72384309dcebbb43 Mon Sep 17 00:00:00 2001
From: Walter van Niftrik
Date: Thu, 25 Nov 2010 11:19:46 +0000
Subject: SCI: Fix bug in MT-32 checksum computation. Thanks Sven for finding
 this.

svn-id: r54471
---
 engines/sci/sound/drivers/midi.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'engines/sci/sound')

diff --git a/engines/sci/sound/drivers/midi.cpp b/engines/sci/sound/drivers/midi.cpp
index ba4e719c92..7cc4e1922c 100644
--- a/engines/sci/sound/drivers/midi.cpp
+++ b/engines/sci/sound/drivers/midi.cpp
@@ -441,9 +441,9 @@ void MidiPlayer_Midi::sendMt32SysEx(const uint32 addr, Common::SeekableReadStrea
 		_sysExBuf[7 + i] = str->readByte();
 
 	for (int i = 4; i < 7 + len; i++)
-		chk += _sysExBuf[i];
+		chk -= _sysExBuf[i];
 
-	_sysExBuf[7 + len] = 128 - chk % 128;
+	_sysExBuf[7 + len] = chk & 0x7f;
 
 	if (noDelay)
 		_driver->sysEx(_sysExBuf, len + 8);
-- 
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