porting to mirage

[poopslayer78]

I was wondering if there was a simple way to get games written as asm programs to work from within Mirage OS.

[thepenguin77]

You would have to get the source and then recompile it with a mirage header. Besides that there isn't really an easy way.

[poopslayer78]

all the asm files are my own, so source is no problem. So does this mean that i wont have to change any of the actual CODE within the program? just the headers? Will TASM still compile files with mirage headers? and what exactly are the headers for mirage?

[FloppusMaximus]

You mean that the program is currently an 'Asm('-type program?

There are a few things you might need to do differently to adapt it for MirageOS (or any other shell.)

- Do not use GetKey.

- Do not use statVars, textShadow, or cmdShadow for temporary storage. There are lots of other areas you can use instead, such as appData, tempSwapArea, saveSScreen, and appBackUpScreen.

- If you modify your own code or data, changes get written back automatically (which may make your life easier or harder, depending on the circumstances.) Don't try to look up the original program's VAT entry.

- If you use any system routines that have the potential to throw errors (particularly floating-point math or variable manipulation routines) you absolutely must use an error handler.

- And of course, keep in mind the 8k limit: MirageOS will allow you to run programs larger than 8k, but if you have any code placed above C000h, it will crash.

[poopslayer78]

First of all, yes, they are Asm( programs

I will need to use some sort of function to get the current keycode. Is the one described in Learn z80 in 28 days ok? Im pretty sure it only uses IN and OUT to get a key input and send it to a register.

[DrDnar]

I didn't know you can't use GetKey, but GetCSC still works. The offical MirageOS information is here. If you're trying to get other games written by other people to work in Mirage, be careful, as they may have had reasons for not running them game in a shell. For example, the game might use RAM areas that Mirage needs for itself. For the most part, making a new game work in Mirage is mostly a matter adding a bunch of .dbs that form the header.

[DarkerLine]

Once you've decided to use MirageOS, one thing you can do is start taking advantage of the library routines it provides. For instance, you don't have to do the port-reading for direct input yourself, you can call the library routine "directin" instead (or, of course, just use _GetCSC for your key-reading needs). The sprite routines are especially useful.

You don't have to do any of this -- just edit the header and make sure you avoid the trouble spots, and you're good -- but it makes your program shorter and potentially faster.

[poopslayer78]

ok, ill give that a try