Update to bsnes dsp release.

Okay, it's just blargg's. I hope he doesn't mind ...

I rewrote his S-DSP emulator in pure C++. Only took me seven hours,
not bad. anomie's took a few days.

Now, given, it's extremely similar of course. First, the algorithms
are going to be mostly the same regardless of who writes the code.
Second, I really didn't see a reason to waste too much time on this
reverse engineering a bunch of stuff myself, so I pretty much just
took the code and "rewrote" (read: copied) it in my unique style, and
changed a few things here and there. Code flow, variable names,
tables, exact algorithms, etc were blatant, direct copies.

Things I did change:
- counter rate 0 is now hardcoded to not ever hit zero
- counter read is now boolean instead of unsigned short
- a lot of multiplication was converted to shifts
- broke up the program into ~9 source files
- no more global functions anywhere, all in one class
- removed the hooks for things like external channel muting -- will
re-add if I ever add an option like that to bsnes
- modified VREG to not need the voice regs handle passed to it
- all voice functions take a reference instead of pointer to the voice
structs now
- packed 32-line timing table expanded to multi-line
- left everything in their own small chunk functions ... kind of torn
on whether I want to merge that with the main timing function. I like
the encapsulation, but it would remove the need to keep so many
struct-based state variables
- added a few more comments on parts that confused me at first
- removed assignment inside conditional stuff; even though I do that
myself on occasion in other code I write, heh
- yadda yadda, more minor stuff like that

Going to keep working at it -- wanted to get it working now, so that
finding regressions will be easier. I want to remove the double writes
for the ring buffer, make a decision on whether I want to rely on sign
extension, or use sclip<> for that, implement a compile-time option to
bypass libco (will save 2.048 million co_switch calls a second) since
the S-DSP's entire operation fits into a single switch table quite
easily, convert a lot of the mul / div stuff to shifts, convert those
clever split up branches in the envelope and BRR decoding routines to
switch / case tables, remove the shift tables from the BRR decoding,
and try and figure out what's going on with some of the code so that I
can try and document it :)

I'll see if I can contribute something back, too. Perhaps I can look
into what happens when you enable mute or something.

New WIP up which has the new core enabled by default. For those
without WIP access, I've posted the new source for reference. Comments
welcome.

    byuu.org/files/bsnes_dsp.zip


... man, feels weird posting a new topic.

[No archive available]
This commit is contained in:
byuu
2008-03-22 15:37:00 +00:00
parent 805398e5a8
commit e499670ad9
Update to bsnes dsp release.

Diff Content Not Available
