Could Jpcsp= Psp Emulation For Pandora?


sold

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I was wondering if there were any recent attempt in psp emulation for the pc and found this. It's an attempt to write a fully functioning psp emulator in Java http://jpcsp.org . Apparently, its been run in Ubuntu and works without porting. http://jpcsp.org/forum/viewtopic.php?f=4&t=11 but it's in early development

At the moment it only runs one demo, but it seems like its the only active project at the moment. There is another emulator called sam, but the website is down and it looks like its only for windows.

I read something about java for pandora somewhere so once the emulator progresses to the stage where it can run psp homebrew or even commercial games, could it be ported to pandora at least as a proof of concept? Or would this most likely require higher system requirements than the pandora could handle?
 

juanvvc

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sold said:
It's an attempt to write a fully functioning psp emulator in Java (...) Or would this most require higher system requirements than the pandora could handle?
A PSP emulator in Java? It will require higher system requirements than a nuclear power plant could handle.
 
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sold

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LOL. I believe you meant nucular :lol: j/k

On the forum there was a brief discussion about java being slow, but it was said that java 6 is only slightly slower than C. http://jpcsp.org/forum/viewtopic.php?f=4&t=6

EDIT: Also, the decision to use Java was so the emulator would be platform independent.
 

sindbad

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In theory it can be as fast or faster than C. Especially since they can do the dynrec in java assembly and have the JIT optimize it.
 

Adventus

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QUOTE
On the forum there was a brief discussion about java being slow, but it was said that java 6 is only slightly slower than C. http://jpcsp.org/forum/viewtopic.php?f=4&t=6
That's mostly marketing mumbo-jumbo. If you have to write large portions of a Java program without using the inbuilt libraries (ie emulation) it's in most cases significantly slower.

Edit:
QUOTE
In theory it can be as fast or faster than C. Especially since they can do the dynrec in java assembly and have the JIT optimize it.
True. However, have you ever seen a dynarec outperform precompiled code on a largescale?
 

Exophase

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A Java dynarec can be OK as far as dynarecs go. How OK I don't exactly know, but what I do know is that there are many bleeding edge things that it could not do, things that a PSP emulator for Pandora would just about require.

I'm familiar enough with the JVM instruction set to know that it's quite different from what most CPUs use. You don't have to worry about register allocation, but most instructions will end up taking multiple JVM instructions because of its stack machine nature. You are at the mercy of the JIT to convert multiple JVM instructions back into single target instructions, but I would not expect a perfect fit. Especially for ARM, that has various advanced capabilities, and I'm not sure if there's a good standard JIT JVM for it to begin with.

I'd love to see an example of a JITed recompiled code going back into the machine code it started as - for example, what jpc does. Their documentation doesn't give any hard examples of this, but it does indicate that in the end many x86 ops correspond to one source x86 op, many more than I'd consider great for a recompiler. It's a number that suggests their "percent native" figures are way off.

Even if you could get back anything close to the code you started with, you would still not be able to use MMU support to assist in emulating the target address space, nor would you be able to effectively map SIMD to SIMD and other low level nuances that help in emulation. And you probably wouldn't be able to register cache nearly as aggressively due to broader conventions that a JIT is likely to follow.

EDIT: http://www.megacz.com/research/papers/nestedvm.ivme04.pdf < C code compiled to MIPS, converted to JVM, typically about 10% performance (this is with a PowerPC JIT). It's worth noting that this is converting object code, which despite appearances is higher level than pure binary code (games you'd emulate) for the purposes of efficient emulation. So if it were translating a real linked binary it'd perform worse.
 

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Yea, Its certaintly an interesting approach, maybe the future for emulating older systems. Write an interpretter and get a crossplatform dynarec for free. XD.
 

Exophase

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Adventus said:
Yea, Its certaintly an interesting approach, maybe the future for emulating older systems. Write an interpretter and get a crossplatform dynarec for free. XD.
No, that's not the approach...

You write a recompiler to Java or JVM, not an interpreter (writing to Java is worse performance-wise). This is easier than writing one to a real machine language though.
 
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jaycee900 said:
sold said:
LOL. I believe you meant nucular :lol: j/k
No 'Nuclear' is right, I take it from your spelling your a yank? U 'spell it like it Sounds like' A


"nuclear" is of course the correct spelling, but i'm certain he was poking fun at how the word is pronounced by a certain US political figure. :rolleyes:
 
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conso

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mechanizeddeath said:
jaycee900 said:
sold said:
LOL. I believe you meant nucular :lol: j/k
No 'Nuclear' is right, I take it from your spelling your a yank? U 'spell it like it Sounds like' A


"nuclear" is of course the correct spelling, but i'm certain he was poking fun at how the word is pronounced by a certain US political figure. :rolleyes:

homer simpson?
 
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canguy247

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juanvvc said:
sold said:
It's an attempt to write a fully functioning psp emulator in Java (...) Or would this most require higher system requirements than the pandora could handle?
A PSP emulator in Java? It will require higher system requirements than a nuclear power plant could handle.


I work in a nuke plant and you would be amazed at how old the computers that run it are. My pda is more powerful - by a lot!
 
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waffles

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conso said:
mechanizeddeath said:
jaycee900 said:
sold said:
LOL. I believe you meant nucular :lol: j/k
No 'Nuclear' is right, I take it from your spelling your a yank? U 'spell it like it Sounds like' A


"nuclear" is of course the correct spelling, but i'm certain he was poking fun at how the word is pronounced by a certain US political figure. :rolleyes:

homer simpson?

....
 
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sam fisher

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Canguy said:
I work in a nuke plant and you would be amazed at how old the computers that run it are. My pda is more powerful - by a lot!
My geiger counter will warn me if you ever start getting close to me :p
 
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