diff options
Diffstat (limited to 'audio/softsynth/mt32/LA32Ramp.cpp')
| -rw-r--r-- | audio/softsynth/mt32/LA32Ramp.cpp | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/audio/softsynth/mt32/LA32Ramp.cpp b/audio/softsynth/mt32/LA32Ramp.cpp index 4e4d6b4f30..b4ac6f1d46 100644 --- a/audio/softsynth/mt32/LA32Ramp.cpp +++ b/audio/softsynth/mt32/LA32Ramp.cpp @@ -1,5 +1,5 @@ /* Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009 Dean Beeler, Jerome Fisher - * Copyright (C) 2011 Dean Beeler, Jerome Fisher, Sergey V. Mikayev + * Copyright (C) 2011, 2012, 2013 Dean Beeler, Jerome Fisher, Sergey V. Mikayev * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by @@ -82,9 +82,13 @@ void LA32Ramp::startRamp(Bit8u target, Bit8u increment) { if (increment == 0) { largeIncrement = 0; } else { - // Using integer argument here, no precision loss: + // Three bits in the fractional part, no need to interpolate // (unsigned int)(EXP2F(((increment & 0x7F) + 24) / 8.0f) + 0.125f) - largeIncrement = (unsigned int)(EXP2I(((increment & 0x7F) + 24) << 9) + 0.125f); + Bit32u expArg = increment & 0x7F; + largeIncrement = 8191 - Tables::getInstance().exp9[~(expArg << 6) & 511]; + largeIncrement <<= expArg >> 3; + largeIncrement += 64; + largeIncrement >>= 9; } descending = (increment & 0x80) != 0; if (descending) { |