Optimize dosbox for PSP

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Optimize dosbox for PSP

Postby mills26 » 2015-4-12 @ 16:11

Hi.

I love dos games and i wanted to compile dosbox for psp by myself, to optimize it for a couple of games (erase all unnecesary emulation, sound cards, etc)

I'm not a very skilled programmer, and i'd like a small guide to compile the eboot from source. Then, i'll just play with the code and try to learn from it.

I also sent a PM to crazyc (i suppose is the one who ported dosbox to PSP?)

Dosbox on PSP has a very jerky sound output, and emulation speed changes a lot depending on the game.
For example:
-"supaplex" works full speed using 2500 cycles, and it will just go slower with more tham that.
-Games with 3D gfx will run better until you reach 10000 cycles (wolfestein 3D or LBA2).

The main goal of this, is to create two eboots:

--1 to run "Little big adventure 2: twinsen's odyssey" (and surely some other 3D games):
if i force 10000 cycles it will became VERY playable on PSP, about 40% of the real speed.
Things it needs(these tested on PC DOSBOX ): cpu (12000 cycles), SB (it only needs wave playback), 8 MB RAM, 640x480 SVGA, (a TV mode could be added for PSP slim "720x480").
Things it won't need: mousse, internet, vga,ega,cga... adlib, gus, pc speaker.

--2 Emulate 386
Many 386 games will work full speed with 2500-3000 cycles, but the sound playback is a mess on PSP.
Things it needs: cpu 386 2500 cycles, OPL2 + 1 channel pcm, PC Speaker, mousse, 4 MB RAM
Things it won't need: the other cpu's, SB, GUS, SVGA, internet.
-------------------------------------------------------------------------------------------

A lot of improvement could be done for both versions, for example, make the sound card to be emulated by media engine or optimize adlib emulator.

If anybody is interested i'd love your help, PSP is a very good handheld for gaming.
We can always use an android phone, but these games are just not made for a touch screen...

Thanks a lot
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Re: Optimize dosbox for PSP

Postby F2bnp » 2015-4-12 @ 16:37

I don't think you'll have a lot of luck because:

a) This is not an official port of DOSBox, it is based on a way older version of DOSBox anyway (maybe 0.70?)
b) The PSP platform is quite very old. Any decent cellphone nowadays will be much faster. ( I agree on the touch screen issue)
c) You're not a very skilled programmer and are expecting most of the work to be done by other people.

I'm not saying you won't succeed, perhaps you could compile some of the latest versions and get a speed boost as well as better sound emulation, but I don't see this happening because of lack of interest. Aiming for specific games as well, seems like a bad idea. The PSP was a fantastic homebrew/emulation platform (I used to own one), however it's been obsolete for a few years now.

Also, the fact that you have no idea how to compile x86 code to whatever the PSP can run, makes me very skeptical. However, I wish you best of luck in your endeavors. Just keep in mind that unless you want to do this really really bad, nobody else will ever bother. If you do manage to succeed, you will have gained valuable coding and project management knowledge :).
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Re: Optimize dosbox for PSP

Postby mills26 » 2015-4-12 @ 17:32

F2bnp wrote:c) You're not a very skilled programmer and are expecting most of the work to be done by other people.


i'm not expecting most of the work to be done by other people.

I just want to compile it, create an eboot and do all the work = to test how changes in the code improve or not the speed.


I hoped it would not be difficult to compile, having all source (0.73) and psp related files for the cpu, render, and the vector processing chip (risc_x86.h, psprender.h,fpu_instructions_vfpu.h...)


Anyway, if this is ot possible, i'll aks at hardware forum for mini x86 handheld or something.
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Re: Optimize dosbox for PSP

Postby bloodbat » 2015-4-16 @ 04:42

mills26 wrote:i'm not expecting most of the work to be done by other people.
I just want to compile it, create an eboot and do all the work = to test how changes in the code improve or not the speed.


So...in effect you are expecting most of the hard work to be done by other people.
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Re: Optimize dosbox for PSP

Postby DADi590 » 2019-8-19 @ 17:16

mills26 wrote:Hi.

I love dos games and i wanted to compile dosbox for psp by myself, to optimize it for a couple of games (erase all unnecesary emulation, sound cards, etc)

I'm not a very skilled programmer, and i'd like a small guide to compile the eboot from source. Then, i'll just play with the code and try to learn from it.

I also sent a PM to crazyc (i suppose is the one who ported dosbox to PSP?)

Dosbox on PSP has a very jerky sound output, and emulation speed changes a lot depending on the game.
For example:
-"supaplex" works full speed using 2500 cycles, and it will just go slower with more tham that.
-Games with 3D gfx will run better until you reach 10000 cycles (wolfestein 3D or LBA2).

The main goal of this, is to create two eboots:

--1 to run "Little big adventure 2: twinsen's odyssey" (and surely some other 3D games):
if i force 10000 cycles it will became VERY playable on PSP, about 40% of the real speed.
Things it needs(these tested on PC DOSBOX ): cpu (12000 cycles), SB (it only needs wave playback), 8 MB RAM, 640x480 SVGA, (a TV mode could be added for PSP slim "720x480").
Things it won't need: mousse, internet, vga,ega,cga... adlib, gus, pc speaker.

--2 Emulate 386
Many 386 games will work full speed with 2500-3000 cycles, but the sound playback is a mess on PSP.
Things it needs: cpu 386 2500 cycles, OPL2 + 1 channel pcm, PC Speaker, mousse, 4 MB RAM
Things it won't need: the other cpu's, SB, GUS, SVGA, internet.
-------------------------------------------------------------------------------------------

A lot of improvement could be done for both versions, for example, make the sound card to be emulated by media engine or optimize adlib emulator.

If anybody is interested i'd love your help, PSP is a very good handheld for gaming.
We can always use an android phone, but these games are just not made for a touch screen...

Thanks a lot

Hello. Did you really get to do this? Would be interesting to have a more updated version on the PSP.
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