readme.txt

psp上的GBA模拟器

Q) Some games run fullspeed but the sound is messed up. Why?

A) At least 9 out of 10 times it means the game isn't really running
   full speed, but just that you can't notice the difference. Increasing
   frameskip will almost always improve sound quality in these
   situations, to a certain point (after around frameskip 3 you
   probably won't be seeing many more returns if it isn't already
   fullspeed). The rest of the time it means there's a bug somewhere else
   in the emulator, probably in the CPU core. Chances are that all you
   can do is wait for it to be fixed in a later release.


Q) The emulator crashed!

A) Most games that don't run will probably take the emulator down with
   it, or it could be an emulator bug completely unrelated to the game
   (but unlikely). Press home and wait for the next version.

   There is some information that comes up when the game crashes. This
   information may be slightly useful to me, but chances are it
   usually won't be all that interesting.

   These days games are more likely to exit with a "bad crash" error.
   This number is possibly useful to me, but to debug a game I'll have
   to reproduce the crash anyway. When this happens it's probably due to
   a bug in the CPU core that hasn't been fixed yet.


Q) Why won't my game save?

A) The game might need 128KB flash turned on and might not be listed in
   game_config.txt. See game_config.txt for more information regarding
   this. Be sure to include game_config.txt with the EBOOT.PBP file.

   Other games might simply have bugs in the save support. For now, use
   savestates as an alternative if you can't save.


Q) How do I change sound quality?

A) Right now, you can't. For those wondering, sound is locked at 44.1KHz
   (sounds a bit high? It is, but it's currently necessary to play
   everything correctly). I don't have any plans to allow changing this
   right now, because I don't think there's really much reason to be
   able to (it'd be a tiny speed boost at best and I don't think SDL even
   allows for anything besides this sampling rate on PSP)


Q) What is this emulator's name?

A) Um.. what? It's gameplaySP, isn't it? You call it gpSP for short.
   Somehow the name can't have the acronyms gbSP, gbapSP, or really
   just about anything else you feel like giving it. Oh, and if you
   really want to make me happy get the capitalization right too.
   That's gpSP, not gPSP, GPsp.. you get the idea.


Q) Does gpSP run Gameboy/Gameboy Color games? Will it later?

A) No. Even though GBA can run these games it uses separate hardware
   that proper GBA games have no access to (save for the audio chip),
   and thus there's no point including it in a GBA emulator (it
   doesn't help run GBA games). I recommend using a GB/GBC emulator
   like Rin for playing these games. It'll probably give you a lot
   more options anyway. gpSP will never actually emulate GB/GBC
   games. You'd may as well be waiting for it to emulate PS2 games...
   (that was an analogy. gpSP won't ever emulate PS2 games. >_>)


Q) Other emulators use the PSP's graphical hardware to accelerate the
   video emulation. Is this possible for gpSP?

A) I'm honestly not too sure at this point. It's definitely a rather
   complicated procedure, and I don't think it'll be possible to
   accurately accelerate alpha blending. On the other hand, affine
   transformations could perhaps receive a speed boost this way. Any
   solution would have to be hybrid hardware/software, which might be
   possible due to the nature of the PSP's VRAM. Maybe someone will
   be willing to help me think of possibilities here?

   But don't bother of you're just going to tell me to render a list
   of quads...


Q) Other emulators use the PSP's second CPU to offload the sound
   emulation. Is this possible for gpSP?

A) Yes, but it wouldn't improve it nearly as much as say, SNES9x TYL.
   This is because most of the processing that goes into sound on a GBA
   game is done in the CPU, not in dedicated audio hardware. It could
   help a little, but probably not a lot. Maybe enough to be worthwhile.
   It might also be possible to split the video rendering to the main
   CPU and the main emulation to the secondary one, but there are a lot
   of coherency issues involved.


Q) I heard gpSP can only load games 16MB or smaller in size. Is this
   true? What about zipped games?

A) As of version 0.8 gpSP can play 32MB ROMs. However, they must be
   unzipped. The reason for this is that parts of the ROM are constantly
   loaded to memory as needed, and for this to be as fast as possible the
   ROM has to be present on the memory stick in raw format.

   You might be wondering, why not just have gpSP unzip the ROM to a file
   then delete the file when it is done? The reason why is because this
   would impose a "hidden" requirement of 32MB on the user that very
   likely may not be there. Furthermore, there are only a few 32MB games
   that anyone actually wants to play. If you only have one 32MB game on
   your memstick then it'd actually require signifnicantly more free space
   to hold both the ROM and the 32MB raw file. With 2 32MB ROMs you only
   gain a around 10-25MB of free space, depending on how effective the
   compression is.


Q) Savestates? From other emulators??

A) See the savestates option in main menu. gpSP will probably never
   support savestates from other emulators, there's just too much in the
   way of emulator specific data in them.

   Savestates are currently 506,943 bytes. They would be a little smaller
   without the snapshot, but I find that very useful and it wouldn't help
   size immensely. Compression would help, but I wanted the size to be
   constant so you knew exactly how much you could hold and to improve
   save/load speed.


Q) What's with the zip support?

A) I hear stories that some games work unzipped and not zipped, so you
   might want to try unzipping them if it gives you problems. You also
   might want to try making fresh zips with WinRAR - users have
   reported some higher success rates doing this.


Q) What's with the config file? Should I make it read only?

A) There was a bug in version 0.6 that caused the config file to not
   get updated or get corrupted sometimes. Hopefully this is fixed now,
   but if it DOES get corrupted making it read only can prevent this
   from happening in the future.


Q) So when WILL the next version be released?

A) Sorry, but I almost never announce release dates. Furthermore, I'll
   probably be pretty hush hush on internal development, just to keep
   people from nagging me about it and building too much suspense.


Q) I don't like this emulator. Are there other alternatives?

A) Yes. Try PSPVBA by Zx-81 (http://zx81.dcemu.co.uk/). Overall I doubt
   the compatability is significantly higher than gpSP's anymore, but
   I'm sure there are some games it runs that gpSP doesn't.


Q) I heard there was a version of gpSP for PCs. Is that true?

A) I developed this emulator internally on PC. It might have a speed
   advantage over other PC GBA emulators, although the PSP version has
   more sophisticated optimizations. Most people have fast enough
   computers to run better GBA emulators for PC and gpSP lacks some
   important features (screen resizing) that the PSP version kinda
   hides. Even though gpSP spent a majority of its development
   gestation as a PC app it was always developed with the PSP in mind,
   so the PC version will probably not see the light of the day unless
   I get overwhelming demand for it. It is, however, possible to
   build it from the source. But I request that you don't distribute
   such builds. If you happen to find one, bear in mind that I don't
   offer any support for it, and as far as I'm concerned it won't
   exist.


Q) I hear there's a version of gpSP for other platforms too, like
   Dreamcast. And I hear they're slow! What gives?

   These are ports, done by other people (or maybe myself?). This is
   possible because gpSP is open source and its base version is fairly
   portable, but to run fast enough on anything but platforms quite a
   bit faster than PSP it at least needs a CPU specific dynarec backend.

   I don't (necessarily) maintain all builds of gpSP, so you'll have to
   contact the authors of these ports for more information. That
   notwithstanding, I try to get as involved in other ports of gpSP as
   I can.


Q) I want to modify gpSP. How can I do this, and am I at liberty to do
   so?

A) Yes, you are, under the terms of the GPL (see the included
   COPYING.DOC). You can download the sourcecode from whereever you
   downloaded this; if you can't find it please e-mail me and I'll give
   you a link to it. I would vastly appreciate it if you contacted me first
   before forking my project, especially if you're just looking to gain
   recognition without adding much to it. It's better to keep all changes
   tidy in one branch of development.

   I would like to stress this a little more seriously (hopefully those
   interested are reading this). Although you are legally entitled to
   release your own forks of gpSP it would be much more benficial to me,
   to you, and to the users of this program if you instead tried working
   with me to get your changes incorporated into the next version. I
   really don't feel like competing with other builds of my source
   anymore, so please do me a big favor and send me an e-mail if you want
   to work with gpSP.


Q) How do I build gpSP?

A) make will build it. You need to have SDL for PSP installed, as well
   as the standard PSP toolchain/PSPSDK and zlib. gpSP isn't much of a
   "build it yourself" program so please don't bother me much about how to
   build it unless you have a good reason for wanting to do so.


Q) What is with the version numbers?

A) Anything less than 1.0 means beta. Beta means that I still have major
   plans for working on it, and that I don't fully back it as being
   stable or reliable software. Of course, if it does hit 1.0, that doesn't
   mean it'll be perfect. It just means I'll have spent a lot of cumulative
   time working things out. The closer it gets to 0.9, the happier I am with
   it overall.


Q) Donations?

A) Very appreciated. [e-mail] on PayPal. <3


Q) How can I contact you?

A) [e-mail], Exophase on AIM, [e-mail] on MSN. I
   welcome IMs, but if you nag me a lot you'll make me sad inside. And
   don't ask me for ROMs or the GBA BIOS. I figured this was common sense
   but apparently not.


-- Credits --

Exophase: main developer
siberianSTAR: zip support
psp298: analog nub code

Beta testers for 0.7:
theohsoawesome1
thisnamesucks837
blackdragonwave9
dagreatpeewee
xsgenji

Beta testers for 0.8:
Runaway_prisoner
theohsoawesome1
tanyareimyoko
spynghotoh2020

Beta testers for 0.9:
RunawayPrisoner (my right hand man)
Veskgar (my left hand man)
qasim

-- Special thanks --

Quasar84: He's helped me in so many ways with this. We both kinda learned
GBA together, he did little demos for me and I got them emulated. It was
great trying out your more advanced code for your own projects once you
got to them, it was equally rewarding to see your work and to be able to
run it at the same time. Least of all I wouldn't have been able to do any
of this without your constant support and presence. I really owe this
release to you.

gladius: You are an amazing GBA coder. I wouldn't have been able to get
through some tough parts without your help. Its been good talking about
ideas with you.. I'm sure you're glad to see that there's finally a GBA
emulator with dynarec ;)


Many, many others of course, probably too many to name, and I don't want
to make anyone feel bad by putting others above them (well, except those
two, heh) so if you think you should be on here, you probably should be!
Just pretend you are for now, and maybe I'll put you here next time.