Re: A89: Beginner
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Re: A89: Beginner
BSS is just an area defined within your program for run-time data
storage. for example: ds.w 30 gives you 30 words (60 bytes) of
space to use. you can also use the video memory, since the 89 only
uses about 2/3 of it. $57b8 through $5aff should be fine, just use
equates like
spriteXcoord equ $5a00
and make sure you use abs addressing. Since BSS is within your
program the compiler is able to compute an offset, allowing you to use
(pc), but if you use video memory, using (pc) will crash.
BSS for things like sprite coordinates that you address a lot is
probably a good idea, since the use of (pc) will often save 2 bytes
everytime it's used and will outweigh the bytes the BSS occupies.
However, if you are storing a longword you might only access once or
creating a small table, you might want to use video memory. Another
advantage of video memory is that you use instructions like <move.w
d0,(spriteXcoord)>, which using BSS you would have to change to <lea
spriteXcoord(pc),a0 / move.w d0,(a0)>.
>
> I know that this does not help any, but I am interested to find out
what it
> is also. My guess would be that it is just a way to declare the
start of a
> data segment. Why would one use BSS? Is there any advantages?
>
> Thanks,
>
> Matt.
>
> >What does BSS mean. Ive seen it in several places, but nobody I
talk to
> >knows what it is.
>
>
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