Initial BSMT2000 implementation for libvgm.

[RAintN22]

Contributors: Mao, cam900

This chip stands for "Brian Schmidt's Mouse Trap", is used for various pinball and video games such as Battletoads, Tattoo Assassins, etc.. and ticket games. The chip is basically a special masked-ROM version of a Texas Instruments TMS320C15 digital signal processor.

[toxieainc]

Hi! Small comment: The interpolation for PCM voices is AFAIR not there in the original hardware. From my testing back some years ago with PinMAME, one can also hear this in some samples (e.g. during the bonus count on the TFTC pinball), as apparently the sound designers relied on this behavior in some (rare) cases.

[ValleyBell]

Please fix the merge conflicts.

[cam900]

Yet Another comment: It has part of PinMAME source code, and its license is here. Its license is possibly conflict with GPLv2.0+?

[toxieainc]

Yes, unfortunately this is one of the files that is still under the 'old MAME' license, as we did not reach out to Aaron Giles yet on that one.
The changes we (as the PinMAME team) did after his initial implementation should be considered BSD3 though.

[toxieainc]

In general i wonder what the exact improvements are in this implementation variant here, over the one we have in PinMAME (just out of interest, no criticism). As mentioned above, one problem in this one here is IMHO the interpolation, as we had something similar implemented initially, but at least one pinball machine (Tales from the Crypt) relies on the samples being played back via nearest neighbor though, as otherwise some sound effects are sounding completely off. There might be more machines, on that one it is super obvious to hear though.

[cam900]

In general i wonder what the exact improvements are in this implementation variant here, over the one we have in PinMAME (just out of interest, no criticism). As mentioned above, one problem in this one here is IMHO the interpolation, as we had something similar implemented initially, but at least one pinball machine (Tales from the Crypt) relies on the samples being played back via nearest neighbor though, as otherwise some sound effects are sounding completely off. There might be more machines, on that one it is super obvious to hear though.

Contributor decided to interpolation always enabled, and extends interpolate fraction to 16 bit in BSMT2000 HLE core at this PR.