ROMcalls

King Harold · Post by **King Harold** » Wed 22 Nov, 2006 7:41 pm

I think everyone knows them, but do you all know what it actually takes to execute just a comon bcall?
Well let me tell you that it takes a whole lot of code before it actually starts executing the romcall, it even checks which kind of calc you have through port 2 and port 21 , and maps some memory through port 6, its crazy*..
*:not the memory mapping, but the HW checking
Well it could have been worse, but you would think it shouldn't have to check the HW version at every BCALL.

Thank you Dwedit for writing a Z80Disassembler

kalan_vod · Post by **kalan_vod** » Wed 22 Nov, 2006 11:49 pm

And that is why bcalls are slower, also the code isn't the best either.

Where is the disassemble?

King Harold · Post by **King Harold** » Thu 23 Nov, 2006 5:19 pm

kalan_vod wrote:Where is the disassemble?

what do you mean?
Does that mean you want to have the disassembled code?

I just dumped 16k, starting at 0, in an appvar, changed the extention to 8xp and disassembled it with Dwedit's Z80disassembler, I then asked the Frontend program to look at the code starting at $00EF (bcall is rst 28h so it jumps to $00EF), and then it took around 2 hours to firgure out what all that code was meant to do (but I dont fully understand it yet)

kalan_vod · Post by **kalan_vod** » Thu 23 Nov, 2006 7:26 pm

I found the program now, as it was what I was looking for

.

King Harold · Post by **King Harold** » Thu 23 Nov, 2006 7:36 pm

Oh ok, good
going to do the same as me then?

Post by **Dwedit** » Thu 23 Nov, 2006 8:48 pm

I've stepped through bcall as well, and it's not very pretty.

And it tests the hardware version to see where pages map to in apps. Bcall also handles calls between app pages. It even tests if the app is stored in a ram page or not, and refuses to switch ram pages for apps stored in RAM.

Post by **tr1p1ea** » Tue 05 Dec, 2006 12:38 pm

Ahh yes, BCALL's ... Seriously though, i very rarely use bcalls as i dont always have much need for them. The only ones i find really useful are _FindSym and maybe storing stuff to OP mem.