Re: [stella] Combat questions aka Close to a new Mac Dev System!

Subject: Re: [stella] Combat questions aka Close to a new Mac Dev System!
From: Greg Miller <gmiller@xxxxxxxx>
Date: Wed, 31 Dec 1997 18:39:38 -0600
> Well, you CAN, but if you make any changes to the code, those locations
> will still point to the same location.  If the code is any larger or
> smaller, the graphics might get garbled.  You can compensate for this by
> using another origin pointer right before the sprite data to keep it

Another approach would be to start the game off with a JMP around the
data, and move the data right after the JMP.

> anchored to $F64F, or you can use whatever means your assembler has for
> evaluating the high and low bytes for labels.  Example:
> 
> SPRLO   byte  TankShape % 256, PlaneShape % 256, JetShape % 256
> SPRHI   byte  TankShape / 256, PlaneShape / 256, JetShape / 256
> 
> This assumed that % means modulo..... if your assembler can't evaluate
> modulus or remainders with an operator like that, you'll probably have
> to use some really stupid awkward equation, and if you have to do that,
> well then I suggest you find a new assembler.
> 
> Your assembler has GOT to have some means of evaluating the high and low
> bytes of variables, though.  It's essential for many implementations of
> indirect addressing.  Try eliminating the # sign.

I have seen a number of decent 6502 assemblers, tho, that neglected to
support the high and low-byte syntax for .byte and .word directives,
since that's a fairly uncommon usage.

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