(WIP) Supermodel WIP Update - 模擬器

2011.07.13

Frequently, the best way to solve a frustrating problem is to step away
from it for a long while. Then, you'll be able to look at it with a
fresh pair of eyes. For a couple weeks, I was getting very frustrated
with my inability to get the Model 3's sound board to produce audio,
even when feeding it MIDI commands directly. Then, the other day, while
searching for the code that instructs the sound processor to play a
loaded sample, I stumbled across a bug in my old 68K emulator that I
had never caught before. It turns out that logical shifts behave
differently on the 68K and X86 architectures when the shift count
exceeds the register width. On the 68K, the result will be 0, but
on X86, it is undefined and can leave the register unmodified! This
was causing an important code path in Scud Race's sound driver to fail.

Fast forward a few days, Nik and I have not only got the Model 3 sound
board generating audio for many games, we've figured out how the PowerPC
and 68K communicate. We've even got a build with sound output up and
running, although it's still a bit jittery now and then due to the
overhead introduced by the sound board emulation. We're also now using
Karl Stenerud's excellent Musashi 68K emulator, which although slower
than Turbo68K, works in both 64- and 32-bit builds. There are still
some bugs and performance issues to work out, and the MPEG board is
not yet emulated, but stay tuned! Slowly but surely, we're on it.
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來源：http://www.trzy.org/Supermodel/WhatsNew.html

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