Back-porting DOSBox-X features/fixes to DOSBox SVN

joncampbell123 / dosbox-x

DOSBox-X fork of the DOSBox project

GNU General Public License v2.0

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Back-porting DOSBox-X features/fixes to DOSBox SVN #975

Open joncampbell123 opened 5 years ago

joncampbell123 commented 5 years ago

Describe the solution you'd like Small incremental patches to DOSBox SVN to incorporate DOSBox-X bugfixes and enhancements (but only those related to DOS gaming).

joncampbell123 commented 5 years ago

Ideas:

Support for PC speaker frequency rapid changes/modulation (Apogee/Duke Nukem) [needs changes to mixer to support FillUp()]
Goldplay mode [needs changes to mixer to support FillUp()]
Option to render scanline by scanline (instead of requiring machine=vgaonly)
Addition of machine=mda as cut-down emulation of machine=hercules (pure MDA emulation) [DONE patch posted on Vogons forums]
MIXER_FillUp() calls in response to changes in state to OPL2/OPL3 and Tandy 3-voice emulation. There are a few games that play "digitized speech" on Adlib cards by rapid changes to an FM channel (Pinball Dreams, Star Control II), and there are a few games that play a digitized PCM channel on Tandy 3-voice (Skate or Die). [needs changes to mixer to support FillUp()]
Port DOSBox-X audio mixer to SVN [patch submitted, awaiting approval and integration]

andres-asm commented 5 years ago

first order of business would be asking them to use git :P DOSBox could benefit hugely from moving to git, there is so much fragmentation.

I have a github mirror I keep up-to-date here, git svn is a pain but it works at least. https://github.com/fr500/dosbox-svn

joncampbell123 commented 5 years ago

Okay...

Most of these items, excluding the machine=mda and scanline by scanline options, are impossible with the mixer as-is in SVN at the moment.

The mixer in SVN will need to be updated to support rendering up to the current emulator "time" at any moment, so the PC speaker, goldplay mode, OPL3 and Tandy code can call channel->FillUp() prior to changing state to support changes to state that occur faster than the 1ms interval the mixer is called to render audio.

joncampbell123 commented 5 years ago

When I submit a patch to do so, I'm going to go for minimal changes to the mixer, without all the lowpass filter and slew rate logic I put into DOSBox-X since those parts are probably not interesting to the DOSBox devs. Those features listed won't be possible until calls to FillUp() can trigger an accurate rendering of audio up to exactly that emulation time within the current tick interval.

joncampbell123 commented 5 years ago

first order of business would be asking them to use git :P DOSBox could benefit hugely from moving to git, there is so much fragmentation.

I have a github mirror I keep up-to-date here, git svn is a pain but it works at least. https://github.com/fr500/dosbox-svn

That would be nice, however there is the risk of losing the last 18 years worth of SVN commit comments.

joncampbell123 commented 5 years ago

Requested by others on the Vogons forums:

Integration of SDL1, and include support for external SDL2.
CGA bug fixes in vga_draw.cpp and vga_dac.cpp [hail-to-the-ryzen]
signed integer overflow in dbopl.cc [hail-to-the-ryzen]
ems/xms fixes to vanilla memory arrangement (ems.cpp, xms.cpp, dos_memory.cpp) [hail-to-the-ryzen]
INT 10h AH=1Ch save and restore code [hail-to-the-ryzen]
mpu401.cpp fixes [hail-to-the-ryzen]
SSE renderer fix in RENDER_StartLineHandler [hail-to-the-ryzen]