RE: 65816 long addressing in assembler

ruud.baltissen_at_apg.nl
Date: 2008-10-17 15:37:03

Hallo Spiro,


> *Without* the hash? 

OOPS! I now see what you mean; yes, there should be an hash as well! I'm
really getting old :(



Hallo Anders,


> On the other hand those operators almost make the # implied.

That thought ran across my mind as well. The only reason I can think of
is that omiting # will confuse a lot of people because they are used to
it. 


> Can the 65816 load 16-bit values to the accumulator as
> well as 8-bit values? 

Yep.


> > = high 8-bits of any address

I disagree. A lot of people are used to use it for selecting the upper 8
bits of a word in 6502 mode (this notation is used by other assemblers
as well!). Compiling a 6502 source in 65816 mode will result in the fact
that all > operands will become $00 because the upper 8 bits of an $xxxx
address will always be $00.


> << = low 16-bits of a 24-bit address

I my self already use '@'. '>>' isn't a bad idea but using only one
character means I can use the same routine for <, > and @. An extra
character means extra parsing etc. etc. Yes, I know, I'm a lousy
programmer :)


> >> = high 16-bits of a 24-bit address

I have given this a long thought. My only objection so far: there is no
65816 register that can make use of this; you fill it either with the
lower 16 bits, middle 8 bits or upper 8 bits. Not the upper 16 bits. 


> Add to that the operator to speficy if a given address should
> be stored as 8, 16 or 24 bits when it can't be determined.

I think I do not understand what you mean, please explain.


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