Re: [stella] Sprite kernel (was: Distella --> DAsm problem)

Subject: Re: [stella] Sprite kernel (was: Distella --> DAsm problem)
From: Ruffin Bailey <rufbo@xxxxxxxxxxxxx>
Date: Sat, 22 Aug 98 14:38:37 -0000
Thanks for the help!  And here's my reply:

f/ Eckhard Stolberg:
>Your email program seems to wrap the text at column 75, so that some
>of the comments spill into the next line.

I believe you've found the problem.  I noticed that on Erik's quoted 
reply the error-causing "the" was sitting right there at the beginning of 
a line!  That was actually my only question (why Matt had trouble 
compiling a distella'd bin with dasm), and I'm afraid the answer was a 
bit too obvious.  Thanks again.

>Labels and equates are case sensitive in DASM. Therefore '.word Start'
>does not refer to the label START.

Hmmmm.  I actually got that from Nick's HtDaP.  I'm not even real sure 
what it's doing other than filling in the last bytes.  Sorry... :^P

>Why do you insist on using a MAC, when you obviously have the mindset
>of a PC user? ;-)

I'm taking that as a compliment.  ;)

f/ Erik Mooney:
>Nit-picky correction here.  The left controller port is usually referred to
>in the real documentation as Player 0, and the right one is Player 1.  To
>get around that confusion, I usually use "first player" and "second player"
>rather than "player 1" which could refer to either player.

Sorry, I assumed that there are more people familiar with just emulators 
than assembly itself on the list.  I actually debated what to call it for 
a while, and finally figured that anyone who knew the code wouldn't have 
any problem deciphering which one I meant (and I see you didn't! ;) .  
I'll start calling it P0 now though.  No reason to go easy on the 

>This whole section is a little messy, but there isn't an easy way to clean
>it up.. I'd guess that in a proper source listing, it'd be a little more
>spread out and labeled better.

Well, remember I'm commenting the code as I make it on my Mac, then 
assembling it with "RAsm" and then dissembling it with Distella and 
"re-commenting" it before send it on to the list.  Since I comment like 
crazy, I think it's actually easier to read this less-commented code.

How do you mean "spread out"?  Just the spacing as a text file?

>I believe there should be a STA WSYNC in that LF0B2 loop somewhere, if it's
>supposed to count off the remaining screen time after drawing the missile.

DOH!  Thanks.

>I'd suggest changing the kernel so that the same
>WSYNC counts off every line of screen, as follows:...
>This is a decent amount more streamlined and flexible.  Much easier to add
>more objects, and it's less prone to error - 

Yes, it is.  I'm afraid I wasn't really offering streamlined code.  As I 
see it, I'm going to have to have code that deals with PF, P0, and M0 
updates all in one scan line followed by PF, P1, and M1 updates the next, 
so I've been in a "substitute extra code to save cycles" mindset.  That's 
my excuse, anyway!  ;)

Thanks again for the help, and remember:
Einem geschenkten Gaul schaut man nicht ins Maul!  ;)

Ruffin Bailey           |  Write Atari 2600 games on your Mac!  
rufbo at  |

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