[OMPT-svn-commit] SF.net SVN: modplug:[2139] trunk/OpenMPT/soundlib

[<sag...@us...>]

Revision: 2139
          http://sourceforge.net/p/modplug/code/2139
Author:   saga-games
Date:     2013-05-19 20:23:13 +0000 (Sun, 19 May 2013)
Log Message:
-----------
[Fix] FT2 compatibility: Emulate FT2's very weird frequency wraparound behaviour with 2xx effects (http://bugs.openmpt.org/view.php?id=386, test case: FreqWarparound.xm)

Modified Paths:
--------------
    trunk/OpenMPT/soundlib/Snd_fx.cpp
    trunk/OpenMPT/soundlib/Sndmix.cpp

Modified: trunk/OpenMPT/soundlib/Snd_fx.cpp
===================================================================
--- trunk/OpenMPT/soundlib/Snd_fx.cpp	2013-05-19 20:20:42 UTC (rev 2138)
+++ trunk/OpenMPT/soundlib/Snd_fx.cpp	2013-05-19 20:23:13 UTC (rev 2139)
@@ -4691,9 +4691,23 @@
 	} else if (GetType() == MOD_TYPE_XM)
 	{
 		if(m_SongFlags[SONG_LINEARSLIDES])
-			return XMLinearTable[period % 768] >> (period / 768);
-		else
+		{
+			uint32 octave = period / 768;
+			if(IsCompatibleMode(TRK_FASTTRACKER2))
+			{
+				// Under normal circumstances, this calculation returns the same values as the non-compatible one.
+				// However, once the 12 octaves are exceeded (through portamento slides), FT2 wraps the frequency around...
+				// Test case: FreqWraparound.xm
+				// 12 octaves * (12 * 64) LUT entries = 9216, add 767 for rounding
+				// Period is a 16 bit value in FT2, hence the "& 0xFFFF".
+				uint32 div = ((9216u + 767u - (period & 0xFFFF)) / 768);
+				octave = ((12 - div) & 0x1F) % 29u;
+			}
+			return XMLinearTable[period % 768] >> octave;
+		} else
+		{
 			return 8363 * 1712L / period;
+		}
 	} else
 	{
 		if(m_SongFlags[SONG_LINEARSLIDES])

Modified: trunk/OpenMPT/soundlib/Sndmix.cpp
===================================================================
--- trunk/OpenMPT/soundlib/Sndmix.cpp	2013-05-19 20:20:42 UTC (rev 2138)
+++ trunk/OpenMPT/soundlib/Sndmix.cpp	2013-05-19 20:23:13 UTC (rev 2139)
@@ -230,7 +230,7 @@
 					m_PatternCuePoints.push_back(cue);
 				}
 #endif
-			} else 
+			} else
 			{
 #ifdef MODPLUG_TRACKER
 				if ((m_nMaxOrderPosition) && (m_nCurrentOrder >= m_nMaxOrderPosition))
@@ -1909,7 +1909,7 @@
 			int32 ninc = Util::muldiv(freq, 0x10000, m_MixerSettings.gdwMixingFreq);
 			if ((ninc >= 0xFFB0) && (ninc <= 0x10090)) ninc = 0x10000;
 			if (m_nFreqFactor != 128) ninc = (ninc * m_nFreqFactor) >> 7;
-			if (ninc > 0xFF0000) ninc = 0xFF0000;
+			Limit(ninc, 3, 0xFF0000);
 			pChn->nInc = (ninc + 1) & ~3;
 		} else
 		{

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