Re: A85: Dumb question
[Prev][Next][Index][Thread]
Re: A85: Dumb question
In a message dated 3/7/99 9:01:03 PM MST, evil_sam@hotmail.com writes:
> This is probably a stupid question, but which is faster "jp &addr" or
> "jr addr"? I thought jp was faster than jr, but with the & sign, I'm not
> sure.
>
> Also, has anyone written (on any z80 calc) a clipping sprite routine
> faster than those used in SQRXZ?
> Sam
Yeah, the ' jp &addr' is the faster instruction.
About the clipping routine, you should check out my own SDR routines (and
variations thereof) at <a href="http://www.dimension-
ti.org/macross/pages/projects.html">Macross Software: Routines</a>. I,
myself, have actually calculated the regular SDR routine to be 3X faster than
Jimmy's PutSprite routine, at almost exactly the same size, because, rather
than put each individual pixel (like in PutSprite), SDR will rotate each byte
in the sprite to line up with the offset, then copy many bits in at once.
I've also made a clipping variation (as well as a grayscale, clipping,
masking, and bg saving variation :) that uses extremely efficient self-
modifying code.
JL