World: r3wp

8

it is A

_a in my source

What do 16-bit arithmetic instructions use for an accumulator?

HL

but most of instructions act on A

Is 8-bit or 16-bit code more common?

8 bit

because it's more compact and faster

and many operations occur only on 8 bit registers

like rotation operations

and bit manipulations

but the first reason is that 8bit register operations are faster

Well, there is no reason to change that balance - the code expects 
it. 16-bit operations can be sped up using a few tricks if necessary, 
like temporary registers that are used internally. You can even name 
those registers _bc, _de and _hl if you like :)

Do the rotation instructions affect the carry flag?

some of them, it's an option

the carry flag can be injected to the left or to the right

or not

there are 12 different rotations

Z80 is good with rotation

How does your code handle exchanges?

badly

label EXX
	set.i tmp _b set.i _b _b' set.i _b' tmp 
	set.i tmp _c set.i _c _c' set.i _c' tmp
	set.i tmp _d set.i _d _d' set.i _d' tmp
	set.i tmp _e set.i _e _e' set.i _e' tmp
	set.i tmp _h set.i _h _h' set.i _h' tmp
	set.i tmp _l set.i _l _l' set.i _l' tmp
	(cont)

exchange of  b, c, d ,e , h , l, with b' , c', d', e', h', l'

It could be worse.

i don't see how :-)

You could be accessing all of those values indirectly to make the 
swap easier, but slowing down everything else :)

yeah or i could build another instance of the interpreter and swap 
them

Mwahahaha

I thought of that, except in my head it was a second set of BRAB 
blocks :)

so, to conclude this session, Rebcode needs union handling and swap 
instruction.

I was thinking vectors and opcodes to handle the struct! type, but 
a swap instruction would be nice too.

I would love a REBOL native swap instruction that worked like block 
set, but we all have dreams :)

good night Brian

Limited use though.

Good night.

Steeve <BTW, why rebcode thread is not on rebol.net ?>

Technically, it is because the group's description does not have 
"[web-pubiic]" in it.....Add that text to the description, and the 
last 300 messages will be on REBOL.net in around 10 minutes.
***

I suspect no one did that either for the reason BrianH suggests, 
or because no one has thought to do it.

I don't see any reason why it should not be a [web-public] group, 
but I'll leave the changing of the group description to the active 
participants. (hint: right-click the group name in the left-hand 
side list of groups)

Why not to write down your logical conclusions and throw them at 
RAMBO?

done

2 bugs found: poke doesn't work with tuples and when we poke an image 
with a  RGB tuple value , RGB channels are mixed in a strange manner.

new version of  galaga.r http://perso.orange.fr/rebol/galaga.r

use rebcode but not for the video emulation, so we can get it faster, 
soon...

only 86kb for the source + game rom

(game rom include)

this demo is the first stone of the future MSX emulator, but we could 
emulate lot of computer based on Z80 ship.

the next step is to  include the PSG emulation, yeah ! we will have 
music too.

hey, what about a 6502 emulator ??

Impressive, Steeve.

wow, that's great, Steeve!

I am getting some error - which is the latest rebcode release?